Hi All,

The remains of my poor old Corsa 1.0 (3 cylinder Ecotec) is/are
poorly. The engine is running really rough at low revs, though it
drives fine at high revs, as soon as you ease back on the gas, the
power drops dramatically. A friendly garage checked the computer and
it had an error code showing, I forget the number, but it translated
to

"throttle position sensor low voltage".

The garage owner Googled that, and suggested I get a second hand
throttle body and he'd fit it and that would PROBABLY fix the
problem.

I had a quick Google myself, and haven't seen anything that says
anyone has fixed the fault that way, but did see a suggestion that
it's often bad earth or dirty contacts.

I had a look at the throttle body and it has a potentiometer type
widget on the back (furthest away from the radiator grille) which is
actuated by the rod that runs through the throttle butterfly, and
another electronic thingie which just seems to be actuated at very low
revs and has a spring on it (some kind of damper?)

I took the first item off and examined it, couldn't see any phsical
damage, put it back on and sprayed some silicon spray into the
connector contacts. Also did the same with the contacts for the other
item.

Net result......... The car doesn't run any worse :=((

Does anyone know:

1. if the electronic items are likely to be avail separately, either
from Vauxhall, or someone who sells Bosch stuff?

2. Which of the items is the most likely culprit?

3. If I am barking up completely the wrong tree and can se me
straight?

Come back carbies all is forgiven!

Chris

wrote:
Hi All,

The remains of my poor old Corsa 1.0 (3 cylinder Ecotec) is/are
poorly. The engine is running really rough at low revs, though it
drives fine at high revs, as soon as you ease back on the gas, the
power drops dramatically. A friendly garage checked the computer and
it had an error code showing, I forget the number, but it translated
to

"throttle position sensor low voltage".

The garage owner Googled that, and suggested I get a second hand
throttle body and he'd fit it and that would PROBABLY fix the
problem.

I had a quick Google myself, and haven't seen anything that says
anyone has fixed the fault that way, but did see a suggestion that
it's often bad earth or dirty contacts.

I had a look at the throttle body and it has a potentiometer type
widget on the back (furthest away from the radiator grille) which is
actuated by the rod that runs through the throttle butterfly, and
another electronic thingie which just seems to be actuated at very low
revs and has a spring on it (some kind of damper?)

I took the first item off and examined it, couldn't see any phsical
damage, put it back on and sprayed some silicon spray into the
connector contacts. Also did the same with the contacts for the other
item.

Net result......... The car doesn't run any worse :=((

Does anyone know:

1. if the electronic items are likely to be avail separately, either
from Vauxhall, or someone who sells Bosch stuff?

2. Which of the items is the most likely culprit?

3. If I am barking up completely the wrong tree and can se me
straight?

Come back carbies all is forgiven!

Chris

The spring loaded thing maybe the idle control valve (think slow running
control on a real carb)
The throttle potentiometer is telling the engine management computer how
far the throttle is open. If the engine is pulling well and not drinking
fuel, the throttle position pot. it probably working.

Poor slow running can be air leaks round the butterfly control rod -
just like a worn carb will do. Take the throttle body off and clean it
with carb cleaner and check if the butterfly seals properly and there is
no play in the shaft seals.

If so do as the man says and fit a new (different) body

As for which parts are available - talk to your vauxhall agent - you
don't have to buy the parts there.

Bob

On Sep 17, 3:13 pm, wrote:
Hi All,

The remains of my poor old Corsa 1.0 (3 cylinder Ecotec) is/are
poorly. The engine is running really rough at low revs, though it
drives fine at high revs, as soon as you ease back on the gas, the
power drops dramatically. A friendly garage checked the computer and
it had an error code showing, I forget the number, but it translated
to

"throttle position sensor low voltage".

The garage owner Googled that, and suggested I get a second hand
throttle body and he'd fit it and that would PROBABLY fix the
problem.

I had a quick Google myself, and haven't seen anything that says
anyone has fixed the fault that way, but did see a suggestion that
it's often bad earth or dirty contacts.

I had a look at the throttle body and it has a potentiometer type
widget on the back (furthest away from the radiator grille) which is
actuated by the rod that runs through the throttle butterfly, and
another electronic thingie which just seems to be actuated at very low
revs and has a spring on it (some kind of damper?)

I took the first item off and examined it, couldn't see any phsical
damage, put it back on and sprayed some silicon spray into the
connector contacts. Also did the same with the contacts for the other
item.

Net result......... The car doesn't run any worse :=((

Does anyone know:

1. if the electronic items are likely to be avail separately, either
from Vauxhall, or someone who sells Bosch stuff?

2. Which of the items is the most likely culprit?

3. If I am barking up completely the wrong tree and can se me
straight?

Come back carbies all is forgiven!

Chris

plenty of likely lookers on ebay

Jim K

Thanks for the answers, just to clarify, it's not just at tickover that the problem occurs, it's from there all the way to approx halfway through the rev range (hard to be specific as this horrid little car doesn't have a tacho.

explained :
Thanks for the answers, just to clarify, it's not just at tickover that the
problem occurs, it's from there all the way to approx halfway through the rev
range (hard to be specific as this horrid little car doesn't have a tacho.

The resistance track sounds as if it may be worn out - most wear will
be around the low end of the throttle range.

It is, as you already know, just a simple potentiometer used to
feedback the throttle position to the engine ECU. They usually have a
voltage on one pin (5V ?), ground on the other, then a third (middle on
the pot) pin which provides the signal back to the ECU.

You should be able to check the voltage at various positions and at
throttle closed. It needs to provide a steady changes in value and
repeatable values at closed. The ECU checks the feedback is within
range on switch on and during use. Variation from normal will be
flagged up as a fault.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk