My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles cold fine, and runs fine warmed up. When warm and I put it in neutral (AT) the idle oscillates between 1800 and 2200 with about 1/2 second cycle time.

MAS was the first guess -- so I put a rebuilt mass airflow sensor assy in and same problem. Checked all the connections and vacuum - all OK.

Also took the throttle assy apart and cleaned all - helped the running but still oscillating. Cleaned Idle air motor, checked voltages and resistance for all sensors and also voltages coming from the computer, and all OK.

About out of ideas -- anyone have some thoughts on how to start troubleshooting this?

Thanks in advance.

Bob

"Guv Bob" wrote in message
m...
My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles cold
fine, and runs fine warmed up. When warm and I put it in neutral (AT) the
idle oscillates between 1800 and 2200 with about 1/2 second cycle time.

MAS was the first guess -- so I put a rebuilt mass airflow sensor assy in
and same problem. Checked all the connections and vacuum - all OK.

Also took the throttle assy apart and cleaned all - helped the running but
still oscillating. Cleaned Idle air motor, checked voltages and
resistance for all sensors and also voltages coming from the computer, and
all OK.

About out of ideas -- anyone have some thoughts on how to start
troubleshooting this?

Thanks in advance.

Bob




Have you looked for an air leak (using carb cleaner or blowtorch gas)?

I suggest you try a car repair group though, this isn't one.


Gareth.

"Gareth Magennis" wrote in message ...


"Guv Bob" wrote in message
m...
My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles cold
fine, and runs fine warmed up. When warm and I put it in neutral (AT) the
idle oscillates between 1800 and 2200 with about 1/2 second cycle time.

MAS was the first guess -- so I put a rebuilt mass airflow sensor assy in
and same problem. Checked all the connections and vacuum - all OK.

Also took the throttle assy apart and cleaned all - helped the running but
still oscillating. Cleaned Idle air motor, checked voltages and
resistance for all sensors and also voltages coming from the computer, and
all OK.

About out of ideas -- anyone have some thoughts on how to start
troubleshooting this?

Thanks in advance.

Bob


Have you looked for an air leak (using carb cleaner or blowtorch gas)?

I suggest you try a car repair group though, this isn't one.


Gareth.


Thanks Gareth. Yes, checked already. Vacuum, electrical connections, mechanical etc., all seem to be OK. It's definitely in the electronics. Car groups are good but gotten better help with auto electronics from these elec groups.

"Guv Bob" wrote in message
...
"Gareth Magennis" wrote in message
...


"Guv Bob" wrote in message
m...
My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles
cold
fine, and runs fine warmed up. When warm and I put it in neutral (AT)
the
idle oscillates between 1800 and 2200 with about 1/2 second cycle time.

MAS was the first guess -- so I put a rebuilt mass airflow sensor assy
in
and same problem. Checked all the connections and vacuum - all OK.

Also took the throttle assy apart and cleaned all - helped the running
but
still oscillating. Cleaned Idle air motor, checked voltages and
resistance for all sensors and also voltages coming from the computer,
and
all OK.

About out of ideas -- anyone have some thoughts on how to start
troubleshooting this?

Thanks in advance.

Bob


Have you looked for an air leak (using carb cleaner or blowtorch gas)?

I suggest you try a car repair group though, this isn't one.


Gareth.


Thanks Gareth. Yes, checked already. Vacuum, electrical connections,
mechanical etc., all seem to be OK. It's definitely in the electronics.
Car groups are good but gotten better help with auto electronics from
these elec groups.





Cars aren't really my forte. Is the engine management light on?

Try the youtube route if you haven't already, particularly how to find
vacuum leaks, even though you're sure you don't have one.
http://www.youtube.com/watch?v=d1I_rgw58rI


These ODB readers are really cheap now if you don't already have one:
http://www.youtube.com/watch?v=bbJMHZv7OEA



Sorry if you've done all this already, but you haven't given a lot of data!


Good luck.


Gareth.

Oops,

meant to include this one too:


http://www.youtube.com/watch?v=PKJnW08-Z8c



Gareth.

Guv Bob wrote:

Thanks Gareth. Yes, checked already. Vacuum, electrical connections,
mechanical etc., all seem to be OK. It's definitely in the electronics.
Car groups are good but gotten better help with auto electronics from
these elec groups.


It's a 22 year old rice burner, doesn't the junk yards still give $50 for
them?

I don't know if this applies, but the description of the symptoms is nearly
identical to a problem a freind of mine had with a same vintage (1990)
pontiac.

After trying everything you listed you've done, including swapping out the
computer/brain box, something lead him to the magnet sensor thing on the fly
wheel.

It wasn't the sensor itself (that was replaced) but the magnet glued to the
flywheel. Turned out it cracked, causing the pulse it sent to the computer
was distorted or too narrow to get an accurate reading.

While cold, the reading is ignored, along with some other sensor readings
until the engine came to operating temp, once it got into the picture, the
idle speed went up and varied.

Keep in mind the pulse was still being sent, but apparently deformed and
however it was translated into a reading, was off enough for the computer to
think it was idling too slow.

-bruce

Thanks, Gareth!

"Gareth Magennis" wrote in message ...


"Guv Bob" wrote in message
...
"Gareth Magennis" wrote in message
...


"Guv Bob" wrote in message
m...
My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles
cold
fine, and runs fine warmed up. When warm and I put it in neutral (AT)
the
idle oscillates between 1800 and 2200 with about 1/2 second cycle time.

MAS was the first guess -- so I put a rebuilt mass airflow sensor assy
in
and same problem. Checked all the connections and vacuum - all OK.

Also took the throttle assy apart and cleaned all - helped the running
but
still oscillating. Cleaned Idle air motor, checked voltages and
resistance for all sensors and also voltages coming from the computer,
and
all OK.

About out of ideas -- anyone have some thoughts on how to start
troubleshooting this?

Thanks in advance.

Bob


Have you looked for an air leak (using carb cleaner or blowtorch gas)?

I suggest you try a car repair group though, this isn't one.


Gareth.


Thanks Gareth. Yes, checked already. Vacuum, electrical connections,
mechanical etc., all seem to be OK. It's definitely in the electronics.
Car groups are good but gotten better help with auto electronics from
these elec groups.





Cars aren't really my forte. Is the engine management light on?

Try the youtube route if you haven't already, particularly how to find
vacuum leaks, even though you're sure you don't have one.
http://www.youtube.com/watch?v=d1I_rgw58rI


These ODB readers are really cheap now if you don't already have one:
http://www.youtube.com/watch?v=bbJMHZv7OEA



Sorry if you've done all this already, but you haven't given a lot of data!


Good luck.


Gareth.

Thanks, Bruce, will check it out.

"Bruce Esquibel" wrote in message ...
Guv Bob wrote:

Thanks Gareth. Yes, checked already. Vacuum, electrical connections,
mechanical etc., all seem to be OK. It's definitely in the electronics.
Car groups are good but gotten better help with auto electronics from
these elec groups.


It's a 22 year old rice burner, doesn't the junk yards still give $50 for
them?

I don't know if this applies, but the description of the symptoms is nearly
identical to a problem a freind of mine had with a same vintage (1990)
pontiac.

After trying everything you listed you've done, including swapping out the
computer/brain box, something lead him to the magnet sensor thing on the fly
wheel.

It wasn't the sensor itself (that was replaced) but the magnet glued to the
flywheel. Turned out it cracked, causing the pulse it sent to the computer
was distorted or too narrow to get an accurate reading.

While cold, the reading is ignored, along with some other sensor readings
until the engine came to operating temp, once it got into the picture, the
idle speed went up and varied.

Keep in mind the pulse was still being sent, but apparently deformed and
however it was translated into a reading, was off enough for the computer to
think it was idling too slow.

-bruce

Any idea what this part is? Has 4 leads, and looks like a solenoid but can't find it in Haynes or other manuals I have.

Not sure if the first photo took, so uploaded it again...

http://imageshack.us/photo/my-images/833/dsm1g20.jpg/
http://img593.imageshack.us/img593/8655/dsm1g20.jpg

Thanks,

Bob

"Bruce Esquibel" wrote in message ...

Guv Bob wrote:

Thanks Gareth. Yes, checked already. Vacuum, electrical connections,
mechanical etc., all seem to be OK. It's definitely in the electronics.
Car groups are good but gotten better help with auto electronics from
these elec groups.


It's a 22 year old rice burner, doesn't the junk yards still give $50 for
them?

I don't know if this applies, but the description of the symptoms is nearly
identical to a problem a freind of mine had with a same vintage (1990)
pontiac.

After trying everything you listed you've done, including swapping out the
computer/brain box, something lead him to the magnet sensor thing on the fly
wheel.

It wasn't the sensor itself (that was replaced) but the magnet glued to the
flywheel. Turned out it cracked, causing the pulse it sent to the computer
was distorted or too narrow to get an accurate reading.

While cold, the reading is ignored, along with some other sensor readings
until the engine came to operating temp, once it got into the picture, the
idle speed went up and varied.

Keep in mind the pulse was still being sent, but apparently deformed and
however it was translated into a reading, was off enough for the computer to
think it was idling too slow.

-bruce

Guv Bob wrote:
Any idea what this part is? Has 4 leads, and looks like a solenoid but can't find it in Haynes or other manuals I have.

Not sure if the first photo took, so uploaded it again...

http://imageshack.us/photo/my-images/833/dsm1g20.jpg/
http://img593.imageshack.us/img593/8655/dsm1g20.jpg

Thanks,

Bob

"Bruce Esquibel" wrote in message ...


Guv Bob wrote:


Thanks Gareth. Yes, checked already. Vacuum, electrical connections,
mechanical etc., all seem to be OK. It's definitely in the electronics.
Car groups are good but gotten better help with auto electronics from
these elec groups.


It's a 22 year old rice burner, doesn't the junk yards still give $50 for
them?

I don't know if this applies, but the description of the symptoms is nearly
identical to a problem a freind of mine had with a same vintage (1990)
pontiac.

After trying everything you listed you've done, including swapping out the
computer/brain box, something lead him to the magnet sensor thing on the fly
wheel.

It wasn't the sensor itself (that was replaced) but the magnet glued to the
flywheel. Turned out it cracked, causing the pulse it sent to the computer
was distorted or too narrow to get an accurate reading.

While cold, the reading is ignored, along with some other sensor readings
until the engine came to operating temp, once it got into the picture, the
idle speed went up and varied.

Keep in mind the pulse was still being sent, but apparently deformed and
however it was translated into a reading, was off enough for the computer to
think it was idling too slow.

-bruce



Fuel pump relay?

it is a relay, that's is for sure. 2 wires are the coil and the other
two are the contacts. and it looks like you have burnt leg.


Jamie

On Jun 2, 11:28*pm, "Guv Bob"
wrote:
"Gareth Magennis" wrote in ...

"Guv Bob" wrote in message
om...
My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles cold
fine, and runs fine warmed up. *When warm and I put it in neutral (AT) the
idle oscillates between 1800 and 2200 with about 1/2 second cycle time.

MAS was the first guess -- so I put a rebuilt mass airflow sensor assy in
and same problem. *Checked all the connections and vacuum - all OK.

Also took the throttle assy apart and cleaned all - helped the running but
still oscillating. * Cleaned Idle air motor, checked voltages and
resistance for all sensors and also voltages coming from the computer, and
all OK.

About out of ideas -- anyone have some thoughts on how to start
troubleshooting this?

Thanks in advance.

Bob

Have you looked for an air leak (using carb cleaner or blowtorch gas)?

I suggest you try a car repair group though, this isn't one.

Gareth.

Thanks Gareth. *Yes, checked already. *Vacuum, electrical connections, mechanical etc., all seem to be OK. * It's definitely in the electronics. *Car groups are good *but gotten better help with auto electronics from these elec groups.

Try to find a Mitsubishi online forum. If I have trouble with my Golf,
I go to vwvortex.com . Ninety percent of the time, someone else has
had my problem and solved it, with a step-by-step DIY posted, along
with pics.

"spamtrap1888" wrote in message ...
On Jun 2, 11:28 pm, "Guv Bob"
wrote:
"Gareth Magennis" wrote in ...

"Guv Bob" wrote in message
om...
My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles cold
fine, and runs fine warmed up. When warm and I put it in neutral (AT) the
idle oscillates between 1800 and 2200 with about 1/2 second cycle time.

MAS was the first guess -- so I put a rebuilt mass airflow sensor assy in
and same problem. Checked all the connections and vacuum - all OK.

Also took the throttle assy apart and cleaned all - helped the running but
still oscillating. Cleaned Idle air motor, checked voltages and
resistance for all sensors and also voltages coming from the computer, and
all OK.

About out of ideas -- anyone have some thoughts on how to start
troubleshooting this?

Thanks in advance.

Bob

Have you looked for an air leak (using carb cleaner or blowtorch gas)?

I suggest you try a car repair group though, this isn't one.

Gareth.

Thanks Gareth. Yes, checked already. Vacuum, electrical connections, mechanical etc., all seem to be OK. It's definitely in the electronics. Car groups are good but gotten better help with auto electronics from these elec groups.

Try to find a Mitsubishi online forum. If I have trouble with my Golf,
I go to vwvortex.com . Ninety percent of the time, someone else has
had my problem and solved it, with a step-by-step DIY posted, along
with pics.

===

Yes, I've been searching a lot but had so many things out of adjustment it's taken many weekends. This is a great newsgroup because most auto repair sites are mostly for mechanical fixes. Electronics folks can pretty much solve any type of electronics problem regardless of what the application is. This newsgroup and rec.craft.metalworking are always good for helpful folks. Any group that has "computer" in the name is worthless as far as anything inside the cover goes.

Bob

Finally!! It's idling and running stable and like new again. Here's an excellent procedure on how to isolate the idle speed stepper motor from the ECU, reset it and then set the idle. Much easier to follow and better illustrations than most shop manuals.... http://www.vfaq.com/mods/BISS-1G.html

It's amazing how "easy" it was now that it's all done. LOL!!! Edison was right about it being 90% perspiration.

Bob

"Guv Bob" wrote in message m...
My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles cold fine, and runs fine warmed up. When warm and I put it in neutral (AT) the idle oscillates between 1800 and 2200 with about 1/2 second cycle time.

MAS was the first guess -- so I put a rebuilt mass airflow sensor assy in and same problem. Checked all the connections and vacuum - all OK.

Also took the throttle assy apart and cleaned all - helped the running but still oscillating. Cleaned Idle air motor, checked voltages and resistance for all sensors and also voltages coming from the computer, and all OK.

About out of ideas -- anyone have some thoughts on how to start troubleshooting this?

Thanks in advance.

Bob

Hold on, **** all this. If you can't find it in the codes, it can only be a few things.

Dig up, the first check is to keep it running until it does it. If it won't do it out of gear get some really good wheel chocks. When the idle hits a high point, unplug the IAC (or it's equivalent). If the hunting stops there are one of two things possible, but one solution might do it.

More than likely the IA path is partly clogged, especially where the pintle goes down. This skews the actual IACS from the true reading, indicating to the computer the amount of IA is higher than it is.

The IAC responds based on presets in the computer so therefore it will cut the IAC postiton to where it does not give enough IA. Then the computer goes into "stumble" mode, thinking (rightly) that it is about to stall because the idle speed has dropped too much. It will then open up the IAC to allow more air. The computer will always look for the lowest idle attainable. This sustains the oscillation. (hunting)

Now, if you rebuild the throttle body, it will be cleaned and hopefully be alright but then there is a possibility that the seat for the pintle valve has been eroded too much. You usually cannot machine this out because you cannot usually readjust the IACS to compensate.

But if you see a bunch of black **** in there of course clean it somehow. Throttle bodies really never need much of a rebuild other than that, if it's worn you might have to machione down a bore so the IAC drops lower into the hole. (same **** happened to carbs that were run a long time without an air filter, but the solutions were different)

However, if it is actually worn like that there is a workaround. There is a tang on the throttle linkage right there on GMs, it may be hard to find. On an American car it is a tang and you just bend it, on other cars you might have to shim it, or even find the actual adjustment. This will keep the throttle from closing too much. You MAY have to do something about the TPS if it is not adjustable.

The drawback to not replacing the throttle body for this problem is that the IAC pintle might get thrown down into the seat so hard the it will get stuck there, and then you will have a stalling ocndition and a constant check engine light.

So if you **** with the idle position of the throttle, do it only as much as you need. (both of these solutions are against "code" but legal if it pases emissions, and it should)

If you don't do something though, it will eventually start stalling at red lights. Alot of people told me "well it was doing that idle thing for years and now it stalls". What, did you think it was going to fix itself ?

But it is not sensors. It is probably not the IAC itself, it is that things have changed for the IAC. The parameters of the intake cuircuit.

J

MOTHER****ING Google groups ****ed me all up and now I look like an asshole. I didn't get the end of this thread before I replied.

Well, maybe what I said might help someone, or maybe help someone to understand exactly what happened here.

j

wrote in message ...
MOTHER****ING Google groups ****ed me all up and now I look like an asshole. I didn't get the end of this thread before I replied.

Well, maybe what I said might help someone, or maybe help someone to understand exactly what happened here.

j

LOLLLL!!! Nope, you look like a genius to me! You are THEE guru for this as far as I'm concerned! I had never opened the hood of this car until this problem came up. Before this, the last car I worked on before this was a 1971 Impala, so you know the learning curve I was under. Took me several weekends and a lot of past due fines on some of the god-awfulest library shop manuals to finally get to the stuff you said right off the bat in 2 minutes.

The best thing I learned is how few real mechanics there are out there working in shops. The Mitsubishi place wanted $150 to read the codes (It takes 2 minutes).

Bob