Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time -
15 years or more.

My 'new' car has it - again with Bosch petrol injection - and it seems to
have a fault. At low speeds, when pressing the throttle pedal, it can do
nothing - but the engine doesn't stall. Just like you'd taken your foot
off the pedal. It's at its worst after leaving the car for an hour or so
when it was hot before stopping. And seems to be mainly around the closed
throttle position. Go for a fast takeoff, and it's OK. But not something
you can do in heavy traffic.

It would seem to me like a worn track on a pot.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.

--
*Never put off until tomorrow what you can avoid altogether *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time -
15 years or more.

My 'new' car has it - again with Bosch petrol injection - and it seems to
have a fault. At low speeds, when pressing the throttle pedal, it can do
nothing - but the engine doesn't stall. Just like you'd taken your foot
off the pedal. It's at its worst after leaving the car for an hour or so
when it was hot before stopping. And seems to be mainly around the closed
throttle position. Go for a fast takeoff, and it's OK. But not something
you can do in heavy traffic.

It would seem to me like a worn track on a pot.

I dismantled mine on my old Fiesta last year, as it was running a bit
erratically, and I suspected the pedal assembly (as it turns out, it was
something else). But yes, there's a carbon track pot in there. At
least that's what it is on mine.

Ask your question in uk.rec.cars.maintenance - you'll get a good answer
in there. And maybe try getting an OBD2 fault code reader. Cars can be
pretty good at diagnosing themselves these days.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.

Dave Plowman (News) wrote:
Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time -
15 years or more.

My 'new' car has it - again with Bosch petrol injection - and it seems to
have a fault. At low speeds, when pressing the throttle pedal, it can do
nothing - but the engine doesn't stall. Just like you'd taken your foot
off the pedal. It's at its worst after leaving the car for an hour or so
when it was hot before stopping. And seems to be mainly around the closed
throttle position. Go for a fast takeoff, and it's OK. But not something
you can do in heavy traffic.

It would seem to me like a worn track on a pot.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.


Oh, I see you already know about u.r.c.m .

On 15/08/2016 12:56, Dave Plowman (News) wrote:


It would seem to me like a worn track on a pot.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.


Depends on the car, the old ones were, the newer ones use a sort of
rotary encoder. There are a few Youtube videos about it.

This one (diagnosis and teardown) is somewhat entertaining.

On the other end, same thing, could be either
Interestingly, some diesels don't use a throttle body at all and just
rely on the MAF

On 15/08/2016 13:20, Lee wrote:
On 15/08/2016 12:56, Dave Plowman (News) wrote:


It would seem to me like a worn track on a pot.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine
end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.


Depends on the car, the old ones were, the newer ones use a sort of
rotary encoder. There are a few Youtube videos about it.

This one (diagnosis and teardown) is somewhat entertaining.

On the other end, same thing, could be either
Interestingly, some diesels don't use a throttle body at all and just
rely on the MAF

Forgot the link
https://www.youtube.com/watch?v=JvTX...ature=youtu.be
There are plenty of others.

Dave Plowman (News) wrote:

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?

Dunno about Porsche but the BMW system seems to use two pots (I get two
values out of INPA on my M47) but, yes, pots are common. It's a
generally reliable and long lived system so I presume other sorts of
encoder are unnecessarily expensive.

The actuator end is usually just a servomotor arrangement. On my Jag
S-Type, with the ignition on (engine not running) and the intake pipe
off you could watch the throttle flap open and close with the pedal
position.

--
Scott

Where are we going and why am I in this handbasket?

On 15/08/2016 12:56, Dave Plowman (News) wrote:
Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time -
15 years or more.

My 'new' car has it - again with Bosch petrol injection - and it seems to
have a fault. At low speeds, when pressing the throttle pedal, it can do
nothing - but the engine doesn't stall. Just like you'd taken your foot
off the pedal. It's at its worst after leaving the car for an hour or so
when it was hot before stopping. And seems to be mainly around the closed
throttle position. Go for a fast takeoff, and it's OK. But not something
you can do in heavy traffic.

It would seem to me like a worn track on a pot.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

I believe many VWs use two pots in parallel, running in opposite
directions so they can rule out/detect noise on one track, and I'd not
be surprised if this was common. The throttle body end is usually a
stepper motor IME, and with some you have to let it re-learn it's end
stops after working on it:

http://wiki.ross-tech.com/wiki/index...Alignment_(TBA)

Oddly, SWMBO's Lupo has a physical throttle cable, a sensor on the body,
and a stepper motor on the body to adjust opening, which can be a bit
odd when it adjusts it under your foot.

"Dave Plowman (News)" wrote in message
...
Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time -
15 years or more.

My 'new' car has it - again with Bosch petrol injection - and it seems to
have a fault. At low speeds, when pressing the throttle pedal, it can do
nothing - but the engine doesn't stall. Just like you'd taken your foot
off the pedal. It's at its worst after leaving the car for an hour or so
when it was hot before stopping. And seems to be mainly around the closed
throttle position. Go for a fast takeoff, and it's OK. But not something
you can do in heavy traffic.

It would seem to me like a worn track on a pot.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.

I had horrendous problems with a worn track on the throttle pot on my 1993
Golf (petrol) many years ago. It was probably the first car with electronic
throttle because my previous cars had all had carburettors, whereas this had
fuel injection so could have electric rather than mechanic control. Very
occasionally the car would hesitate and stall, or else fail to accelerate,
when pulling out of a junction. It was in the VW garage several times and
they couldn't find the problem. Eventually they detected the fault: I
remember the mechanic phoning me in a state of delight to say "we know what
it is and we've fixed it; bad news is there's a big labour bill for
diagnosing" :-( Luckily I had kept the old garage bills which showed that
I'd first reported the symptom while the car was still in warranty, even
though it was now several thousand miles out of warranty. So the VW warranty
paid up.

I've never had any problem with the throttle pot on any other car since -
I've had several diesel Peugeots. Interestingly, the Golf (and maybe one of
the Peugeots) still had a throttle cable which connected to a pot under the
bonnet, rather than having the pot in the footwell by the accelerator pedal.
I'm not sure why they do this when there's no mechanical connection to
carburettor or fuel injection system so no need for a Bowden cable.

On 15/08/2016 12:56, Dave Plowman (News) wrote:

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.


Honda jazz throttle position sensor is £400+. Actual part is made
by Bosch, so probably common to many cars. Wiring loom connector
has 5 or 6 pins, so god knows what it does. The only mechanical
connection is the cable attached to the throttle pedal. One day
I will try and take it apart to satisfy my curiosity.

On Mon, 15 Aug 2016 14:20:27 +0100
Andrew wrote:

Honda jazz throttle position sensor is £400+. Actual part is made
by Bosch, so probably common to many cars. Wiring loom connector
has 5 or 6 pins, so god knows what it does.

CAN bus, maybe? Remember, your car knows more than you do!

--
Davey.

That sounds like daylight robbery to me, its probably an optical encoder of
some sort to get away from the wear issues.
Brian

--
From the Sofa of Brian Gaff Reply address is active
Remember, if you don't like where I post
or what I say, you don't have to
read my posts! :-)
"Davey" wrote in message
...
On Mon, 15 Aug 2016 14:20:27 +0100
Andrew wrote:

Honda jazz throttle position sensor is £400+. Actual part is made
by Bosch, so probably common to many cars. Wiring loom connector
has 5 or 6 pins, so god knows what it does.

CAN bus, maybe? Remember, your car knows more than you do!

--
Davey.

"pamela" wrote in message
...
On 14:20 15 Aug 2016, Andrew wrote:

On 15/08/2016 12:56, Dave Plowman (News) wrote:

Hence the question. It is a pot they use as a pedal position
sensor? Or some form of solid state rotary position device? How
about the engine end? Is it a stepper motor, or a PCM
controlled solenoid? Or something else? Not even sure if this
car has a throttle body. Or several.

The other things that is confusing me is why it would be worse
after the engine 'heat soaks'. As it is a mid engined car - so
the actual pedal some way from the engine.

When I first experienced it thought it was a fuel vapour lock.
But the perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But
being a curious soul, like to have an idea what the fault might
be.


Honda jazz throttle position sensor is £400+. Actual part is
made by Bosch, so probably common to many cars. Wiring loom
connector has 5 or 6 pins, so god knows what it does. The only
mechanical connection is the cable attached to the throttle
pedal. One day I will try and take it apart to satisfy my
curiosity.

£400 !!!

Interesting. As far as I remember (and it was about 20 years ago) the part
for my VW Golf was dirt cheap but it was the labour for fault-finding and
diagnosing the fault which would have been the really expensive bit - if the
warranty hadn't paid up when I produced the magic bit of paper proving that
I first took the car to the garage while it was still within the warranty
mileage.

Dave Plowman (News) wrote:

It would seem to me like a worn track on a pot.

I don't think they use a pot, more likely a Gray encoder, or some other
rotary encoder ...

Dave Plowman (News) explained on 15/08/2016 :
Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time -
15 years or more.

The idle is entirely separate / independant of the fly by wire sytem,
though both are controlled by the engine ECU. The throttle
potentiometer just signals the ECU to indicate how much speed/ power is
required. When at rest, the idle routine in the ECU takes over to hold
the engine speed precisely at the correct idle speed.

Which means your throttle sensor might not be the cause of the problem,
there are numerous other possibilities.

"Dave Plowman (News)" wrote in message
...
Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time -
15 years or more.

My 'new' car has it - again with Bosch petrol injection - and it seems to
have a fault. At low speeds, when pressing the throttle pedal, it can do
nothing - but the engine doesn't stall. Just like you'd taken your foot
off the pedal. It's at its worst after leaving the car for an hour or so
when it was hot before stopping. And seems to be mainly around the closed
throttle position. Go for a fast takeoff, and it's OK. But not something
you can do in heavy traffic.

It would seem to me like a worn track on a pot.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.

It would help if you said exactly what model it is.

On 15/08/2016 18:37, Andy Burns wrote:
Dave Plowman (News) wrote:

It would seem to me like a worn track on a pot.

I don't think they use a pot, more likely a Gray encoder, or some other
rotary encoder ...

Yes, but you're a Real Engineer. These guys understand price, and might
not know a Gray encoder if it bit them.

Andy

Andy Burns formulated on Monday :
Dave Plowman (News) wrote:

It would seem to me like a worn track on a pot.

I don't think they use a pot, more likely a Gray encoder, or some other
rotary encoder ...

Most/ all use a pot..

In article ,
NY wrote:
I had horrendous problems with a worn track on the throttle pot on my
1993 Golf (petrol) many years ago. It was probably the first car with
electronic throttle because my previous cars had all had carburettors,
whereas this had fuel injection so could have electric rather than
mechanic control. Very occasionally the car would hesitate and stall, or
else fail to accelerate, when pulling out of a junction. It was in the
VW garage several times and they couldn't find the problem. Eventually
they detected the fault: I remember the mechanic phoning me in a state
of delight to say "we know what it is and we've fixed it; bad news is
there's a big labour bill for diagnosing" :-( Luckily I had kept the
old garage bills which showed that I'd first reported the symptom while
the car was still in warranty, even though it was now several thousand
miles out of warranty. So the VW warranty paid up.

I've a feeling that is a different thing. Don't think 'drive by wire' was
around in 1993. More like about 10 years later.

But virtually all electronic injection systems have a throttle position
sensor (TPS) Basically a pot, the output voltage of which tells the ECU
how wide the throttle is open.

'Drive by wire' replaces a mechanical connection between pedal and
throttle with an electronic servo system.

--
*Husband and cat lost -- reward for cat

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andrew wrote:
On 15/08/2016 12:56, Dave Plowman (News) wrote:

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.


Honda jazz throttle position sensor is £400+. Actual part is made
by Bosch, so probably common to many cars. Wiring loom connector
has 5 or 6 pins, so god knows what it does. The only mechanical
connection is the cable attached to the throttle pedal. One day
I will try and take it apart to satisfy my curiosity.

That's not 'drive by wire'

--
*I finally got my head together, now my body is falling apart.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
NY wrote:
Honda jazz throttle position sensor is £400+. Actual part is
made by Bosch, so probably common to many cars. Wiring loom
connector has 5 or 6 pins, so god knows what it does. The only
mechanical connection is the cable attached to the throttle
pedal. One day I will try and take it apart to satisfy my
curiosity.

£400 !!!

Interesting. As far as I remember (and it was about 20 years ago) the
part for my VW Golf was dirt cheap but it was the labour for
fault-finding and diagnosing the fault which would have been the really
expensive bit - if the warranty hadn't paid up when I produced the
magic bit of paper proving that I first took the car to the garage
while it was still within the warranty mileage.

My old Rover SD1 has just about the earliest EFI on a UK car. Basically
Bosch, but the ECU made by Lucas, who also did the mapping. The TPS on
that is a vast carbon pot which does wear out - at about 100,000 miles.
Luckily, Vishay make a conductive plastic generic type which can be
persuaded to fit, and being just an electronic product, under half the
price.

There are no diagnostics on early Lucas injection, so it requires some
skill to fault find. But electronics fault finding is usually well above
the pay grade of the average garage fitter.

Lucas produced a number of test sets to make it easy for them - basically
good or bad LEDs in a box. At vast cost. Which tell you nothing a DVM
can't.

--
*HOW DO THEY GET DEER TO CROSS THE ROAD ONLY AT THOSE YELLOW ROAD SIGNS?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andy Burns wrote:
Dave Plowman (News) wrote:

It would seem to me like a worn track on a pot.

I don't think they use a pot, more likely a Gray encoder, or some other
rotary encoder ...

Could be. The fact that it happens just above idle - where a pot would get
the most wear - made me wonder if it was.

I've looked up spares on Ebay. Of course it doesn't say how it works. But
does appear to have more than the three wires you'd expect with a simple
pot. And looks nothing like one - more like an electric motor.

--
*I went to school to become a wit, only got halfway through.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Harry Bloomfield wrote:
Dave Plowman (News) explained on 15/08/2016 :
Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time -
15 years or more.

The idle is entirely separate / independant of the fly by wire sytem,
though both are controlled by the engine ECU. The throttle
potentiometer just signals the ECU to indicate how much speed/ power is
required. When at rest, the idle routine in the ECU takes over to hold
the engine speed precisely at the correct idle speed.

The fault I have is nothing to do with idle control. Although I suppose
the same servo that opens the throttle could be used for that too.
Mechanical throttle systems usually had a separate idle valve.

Which means your throttle sensor might not be the cause of the problem,
there are numerous other possibilities.

--
* I like you. You remind me of when I was young and stupid

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Vir Campestris wrote:
On 15/08/2016 18:37, Andy Burns wrote:
Dave Plowman (News) wrote:

It would seem to me like a worn track on a pot.

I don't think they use a pot, more likely a Gray encoder, or some other
rotary encoder ...

Yes, but you're a Real Engineer. These guys understand price, and might
not know a Gray encoder if it bit them.

With some of the super long warranties now available, the days of cost
cutting to that extent may be gone.

But I don't know what a Gray encoder is either. ;-)

--
*Why can't women put on mascara with their mouth closed?

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News" wrote
Andrew wrote
Dave Plowman (News) wrote

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine
end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after
the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal
some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.


Honda jazz throttle position sensor is £400+. Actual part is made
by Bosch, so probably common to many cars. Wiring loom connector
has 5 or 6 pins, so god knows what it does. The only mechanical
connection is the cable attached to the throttle pedal. One day
I will try and take it apart to satisfy my curiosity.

That's not 'drive by wire'

Just as much drive by wire as the stuff in your first para.

There is no mechanical linkage between the throttle pedal
and whatever determines the speed at which the engine runs.

"Dave Plowman (News)" wrote in message
...
In article ,
Vir Campestris wrote:
On 15/08/2016 18:37, Andy Burns wrote:
Dave Plowman (News) wrote:

It would seem to me like a worn track on a pot.

I don't think they use a pot, more likely a Gray encoder, or some other
rotary encoder ...

Yes, but you're a Real Engineer. These guys understand price, and might
not know a Gray encoder if it bit them.

With some of the super long warranties now available, the days of cost
cutting to that extent may be gone.

But I don't know what a Gray encoder is either. ;-)

https://en.wikipedia.org/wiki/Gray_c...ition_encoders

On 16/08/2016 00:52, Rod Speed wrote:
Dave Plowman (News" wrote
Andrew wrote
Dave Plowman (News) wrote

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.


Honda jazz throttle position sensor is £400+. Actual part is made
by Bosch, so probably common to many cars. Wiring loom connector
has 5 or 6 pins, so god knows what it does. The only mechanical
connection is the cable attached to the throttle pedal. One day
I will try and take it apart to satisfy my curiosity.

That's not 'drive by wire'

Just as much drive by wire as the stuff in your first para.

There is no mechanical linkage between the throttle pedal
and whatever determines the speed at which the engine runs.

I suggest you re-read Andrews post. Many cars had a throttle cable
directly coupled to a butterfly valve and a position sensor. The sensor
was typically used to enrich at high throttles. That doesn't make it
"drive by wire!.

In article ,
Fredxxx wrote:
On 16/08/2016 00:52, Rod Speed wrote:
Dave Plowman (News" wrote
Andrew wrote
Dave Plowman (News) wrote

Hence the question. It is a pot they use as a pedal position
sensor? Or some form of solid state rotary position device? How
about the engine end? Is it a stepper motor, or a PCM controlled
solenoid? Or something else? Not even sure if this car has a
throttle body. Or several.

The other things that is confusing me is why it would be worse
after the engine 'heat soaks'. As it is a mid engined car - so
the actual pedal some way from the engine.

When I first experienced it thought it was a fuel vapour lock. But
the perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being
a curious soul, like to have an idea what the fault might be.


Honda jazz throttle position sensor is £400+. Actual part is made by
Bosch, so probably common to many cars. Wiring loom connector has 5
or 6 pins, so god knows what it does. The only mechanical connection
is the cable attached to the throttle pedal. One day I will try and
take it apart to satisfy my curiosity.

That's not 'drive by wire'

Just as much drive by wire as the stuff in your first para.

There is no mechanical linkage between the throttle pedal
and whatever determines the speed at which the engine runs.

I suggest you re-read Andrews post. Many cars had a throttle cable
directly coupled to a butterfly valve and a position sensor. The sensor
was typically used to enrich at high throttles. That doesn't make it
"drive by wire!.

It is Wodney, after all. Can't expect him to understand something that
subtle. Or anything made after the Model T Ford.

All the petrol injection systems I've ever seen have some type of TPS.
Drive by wire - with no mechanical connection between pedal and throttle
is an entirely different thing.

--
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Dave Plowman London SW
To e-mail, change noise into sound.

Fredxxx wrote
Rod Speed wrote
Dave Plowman (News" wrote
Andrew wrote
Dave Plowman (News) wrote

Hence the question. It is a pot they use as a pedal position sensor?
Or
some form of solid state rotary position device? How about the engine
end? Is it a stepper motor, or a PCM controlled solenoid? Or something
else? Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after
the engine 'heat soaks'. As it is a mid engined car - so the actual
pedal some way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.

Honda jazz throttle position sensor is £400+. Actual part is made
by Bosch, so probably common to many cars. Wiring loom connector
has 5 or 6 pins, so god knows what it does. The only mechanical
connection is the cable attached to the throttle pedal. One day
I will try and take it apart to satisfy my curiosity.

That's not 'drive by wire'

Just as much drive by wire as the stuff in your first para.

There is no mechanical linkage between the throttle pedal
and whatever determines the speed at which the engine runs.

I suggest you re-read Andrews post.

No point, that has no relevance to Dave's terminal stupidity there.

Many cars had a throttle cable directly coupled to a butterfly valve and a
position sensor.

The Honda Jazz doesn’t.

The sensor was typically used to enrich at high throttles.

The Honda Jazz doesn’t.

That doesn't make it "drive by wire!.

But the Honda Jazz is.

"Dave Plowman (News)" wrote in message
...
In article ,
Fredxxx wrote:
On 16/08/2016 00:52, Rod Speed wrote:
Dave Plowman (News" wrote
Andrew wrote
Dave Plowman (News) wrote

Hence the question. It is a pot they use as a pedal position
sensor? Or some form of solid state rotary position device? How
about the engine end? Is it a stepper motor, or a PCM controlled
solenoid? Or something else? Not even sure if this car has a
throttle body. Or several.

The other things that is confusing me is why it would be worse
after the engine 'heat soaks'. As it is a mid engined car - so
the actual pedal some way from the engine.

When I first experienced it thought it was a fuel vapour lock. But
the perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being
a curious soul, like to have an idea what the fault might be.


Honda jazz throttle position sensor is £400+. Actual part is made by
Bosch, so probably common to many cars. Wiring loom connector has 5
or 6 pins, so god knows what it does. The only mechanical connection
is the cable attached to the throttle pedal. One day I will try and
take it apart to satisfy my curiosity.

That's not 'drive by wire'

Just as much drive by wire as the stuff in your first para.

There is no mechanical linkage between the throttle pedal
and whatever determines the speed at which the engine runs.

I suggest you re-read Andrews post. Many cars had a throttle cable
directly coupled to a butterfly valve and a position sensor. The sensor
was typically used to enrich at high throttles. That doesn't make it
"drive by wire!.

It is Wodney, after all. Can't expect him to understand something
that subtle. Or anything made after the Model T Ford.

We'll see...

All the petrol injection systems I've ever seen have some type of TPS.

Drive by wire - with no mechanical connection between
pedal and throttle is an entirely different thing.

And that's what it has with the wiring loom connector, ****wit.

Dave Plowman (News) wrote:
Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time -
15 years or more.

My 'new' car has it - again with Bosch petrol injection - and it seems to
have a fault. At low speeds, when pressing the throttle pedal, it can do
nothing - but the engine doesn't stall. Just like you'd taken your foot
off the pedal. It's at its worst after leaving the car for an hour or so
when it was hot before stopping. And seems to be mainly around the closed
throttle position. Go for a fast takeoff, and it's OK. But not something
you can do in heavy traffic.

It would seem to me like a worn track on a pot.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal some
way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.


Thel last one I had trouble with used a stepper motor at the engine
end. The problem showed up as an idle error, but was actually a faulty
oxygen sensor which via the on board computer was causing the wrong
setting of the stepper motor, but only when hot. It came and went which
was very frustrating, the diagnostics did not show the faulty sensor, it
was only by replacing all the bits one by one, that I cleared the fault.

Just to try and clarify what it is to those who still don't understand.

It merely in essence replaces the throttle cable. Could be used on a
carburettor car if you wanted to. Doesn't need to interface with the ECU
of an injection system - although may well in practice.

--
*Just give me chocolate and nobody gets hurt

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 15 Aug 2016 12:56:28 +0100, Dave Plowman (News) wrote:

Can one of our teccies explain how this is achieved in practice?
My last car had a throttle cable - although newer versions of the same
model went over to drive by wire. So it has been around for a long time
- 15 years or more.

My 'new' car has it - again with Bosch petrol injection - and it seems
to have a fault. At low speeds, when pressing the throttle pedal, it can
do nothing - but the engine doesn't stall. Just like you'd taken your
foot off the pedal. It's at its worst after leaving the car for an hour
or so when it was hot before stopping. And seems to be mainly around the
closed throttle position. Go for a fast takeoff, and it's OK. But not
something you can do in heavy traffic.

It would seem to me like a worn track on a pot.

Hence the question. It is a pot they use as a pedal position sensor? Or
some form of solid state rotary position device? How about the engine
end?
Is it a stepper motor, or a PCM controlled solenoid? Or something else?
Not even sure if this car has a throttle body. Or several.

The other things that is confusing me is why it would be worse after the
engine 'heat soaks'. As it is a mid engined car - so the actual pedal
some way from the engine.

When I first experienced it thought it was a fuel vapour lock. But the
perfect idle says otherwise.

The car is going back to the dealer for a warranty fix. But being a
curious soul, like to have an idea what the fault might be.

I had an intermittent drive by wire fault on the Fiat Ducato camper (2001
engine/chassis).

This was also intermittent and more likely to happen when warm.

The effect was that it wouldn't accept anything less than half throttle,
which made for interesting driving.

The engine warning light did come on during the fault condition, though.

After the main dealer finally getting the diagnostic kit to work it turned
out to be intermittent throttle sensor (or near offer). They then checked
through all the wiring for the throttle and found a couple of poor
connections. Once these were cleaned up then it all worked fine.

Cheers


Dave R



--
Windows 8.1 on PCSpecialist box

In article ,
David wrote:
I had an intermittent drive by wire fault on the Fiat Ducato camper
(2001 engine/chassis).

This was also intermittent and more likely to happen when warm.

The effect was that it wouldn't accept anything less than half throttle,
which made for interesting driving.

The engine warning light did come on during the fault condition, though.

After the main dealer finally getting the diagnostic kit to work it
turned out to be intermittent throttle sensor (or near offer). They then
checked through all the wiring for the throttle and found a couple of
poor connections. Once these were cleaned up then it all worked fine.

I'd certainly considered a poor connection, as the car is low miles and
I'd expect such a device to last for at least 100,000 miles.

Just hoping the dealer finds the fault. There was no warning light. I'd
expect anything which stored a code to give a warning something is amiss?
Of course this sensor doesn't *have* to be connected to the ECU.

--
*The early bird gets the worm, but the second mouse gets the cheese *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote

Just to try and clarify what it is to those who still don't understand.

You're the one that has never understood. The Honda Jazz doesn’t
have a throttle cable between the pedal and what determines the
speed at which the engine runs, that is done entirely by electrical
signals, otherwise known as drive by wire.

It merely in essence replaces the throttle cable. Could be used on
a carburettor car if you wanted to. Doesn't need to interface with
the ECU of an injection system - although may well in practice.

Duh.

On 15/08/2016 15:47, Brian-Gaff wrote:
That sounds like daylight robbery to me, its probably an optical encoder of
some sort to get away from the wear issues.
Brian


£400 is the part price. You also need to fit it and use a diagnostic
kit to tell the ECU about it.

http://honda-tech.com/forums/tech-mi...ensor-2169249/

Post number 10.

On 16/08/2016 00:42, Dave Plowman (News) wrote:
In article ,
Vir Campestris wrote:
On 15/08/2016 18:37, Andy Burns wrote:
Dave Plowman (News) wrote:

It would seem to me like a worn track on a pot.

I don't think they use a pot, more likely a Gray encoder, or some other
rotary encoder ...

Yes, but you're a Real Engineer. These guys understand price, and might
not know a Gray encoder if it bit them.

With some of the super long warranties now available, the days of cost
cutting to that extent may be gone.

But I don't know what a Gray encoder is either. ;-)


Break open a stepper motor and you should find one.
Instead of a variable resistance that gives an analogue
output (which can vary with wear) a grey encoder is a
series in interlaced fingers with a slider that passes
across them and the output is normally a series of pulses
that the ECU can count. Presumably avoids the need for
an analogue to digital encoder and analogue
calibration. A grey encoder only needs a method to tell
the ECU when it is at a zero position.

In article ,
Andrew wrote:
But I don't know what a Gray encoder is either. ;-)


Break open a stepper motor and you should find one.
Instead of a variable resistance that gives an analogue
output (which can vary with wear) a grey encoder is a
series in interlaced fingers with a slider that passes
across them and the output is normally a series of pulses
that the ECU can count. Presumably avoids the need for
an analogue to digital encoder and analogue
calibration. A grey encoder only needs a method to tell
the ECU when it is at a zero position.

So there is still a sliding contact of sorts? Bit like an old stud fader?

I'd have thought contactless Hall effect etc would be the way to go these
days.

I've bought a pirate copy of the Porsche factory manual off Ebay for 10
quid. Everything in PDF format. Shows the pedal value sensor (Porsche
speak) as being a twin pot device.

--
*IS THERE ANOTHER WORD FOR SYNONYM?

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote
Andrew wrote

But I don't know what a Gray encoder is either. ;-)

Break open a stepper motor and you should find one.
Instead of a variable resistance that gives an analogue
output (which can vary with wear) a grey encoder is a
series in interlaced fingers with a slider that passes
across them and the output is normally a series of pulses
that the ECU can count. Presumably avoids the need for
an analogue to digital encoder and analogue
calibration. A grey encoder only needs a method to tell
the ECU when it is at a zero position.

So there is still a sliding contact of sorts?

Not likely anymore.

Bit like an old stud fader?

Unlikely.

I'd have thought contactless Hall effect
etc would be the way to go these days.

Much more likely to be optical these days.

I've bought a pirate copy of the Porsche factory manual off
Ebay for 10 quid. Everything in PDF format. Shows the pedal
value sensor (Porsche speak) as being a twin pot device.

Certainly some do it that way.