Cold Idle help with 2.0 Options

[ned911]

Car starts fine and when warmed up runs like a champ. However, when first started she doesn't want to hold idle and driving is very difficult even after a 5 minute warm up. Is there a FI adjustment or is this a timing or points issue?

Thanks,

Ned

[Bartlett 914]

Car starts fine and when warmed up runs like a champ. However, when first started she doesn't want to hold idle and driving is very difficult even after a 5 minute warm up. Is there a FI adjustment or is this a timing or points issue?

Thanks,

Ned

There is a thing called an AAR valve. Auxiliary air regulator. I lets in extra air until the valve is warmed up. It has a built in heater. This valve may be stuck

[Cupomeat]

I'd look into your temp sensors for mixture control.

The default failure position on the AAR is wide open, IF it isn't gunked or rusted.

[ned911]

Thanks guys. Will check the AAR when I get home today.

Ned

[Dave_Darling]

Also check the ignition system. It is a lot more prone to problems than the AAR is, I believe.

--DD

[Cupomeat]

Yes, (IMG:style_emoticons/default/agree.gif)

The AAR justs ups the idle, so I'd look more into mixture and ignition.

The AAR might help you get the car warm and mitigate the others, but unless it is REALLY cold, I think it isn't your answer.

[TheCabinetmaker]

Aar? Really? The aar won't make the car run bad. The head temp sensor enrichens the mixture when cold. If its not hooked up or is faulty, the ecu does not supply extra fuel for cold start and warm up. The car will run fine with a stuck aar, it just won't idle. You can fool the ecu by unplugging the head temp sensor and grounding the wire from the harness.

Btw, the aar has no default position. It opens and closes according to temperature. When it sticks, it sticks where it is.

[falconfp2001]

You should first state weather this is a new issue, the car has been sitting for a while, this is a new to you car, etc. etc.

AAR is easy to check. Just start the car cold and remove the hose that goes from the AAR to the intake elbow at the Intake elbow end before the throttle body and check for suction. No suction then it is stuck closed. If there is suction then let the car warm up for 20 min I think and then check again for suction. If no suction then it is closed and operating correctly and you should look at other possibilities.

Not saying that your problem is definitely the AAR but I've had this happen before on an engine I purchased complete with EFI, wiring and intake. PO had let it sit in the garage for about a year. I checked everything with the exception of the AAR because it is true they, usually fail open but that symptom is a surge during idle after completely warmed up. I checked the symptoms on Ander's sight which point out the possible problems and things to check. One is a stuck closed AAR.

I replaced with a known good one and problem was solved. You can attempt to rebuild it but I think it is a hit and miss type of rebuild.

[ned911]

Car is new to me. Really hard to drive in a parking lot or in traffic until she's been running for a good 30 minutes. Then everything is fine.

[ned911]

Pulled the AAR - can blow air through it.

While the car was running I pulled the hose off the top of the pressure regulator and the idle picked up and the car ran perfectly. Is this a sign of an issue?

[JamesM]

Pulled the AAR - can blow air through it.

While the car was running I pulled the hose off the top of the pressure regulator and the idle picked up and the car ran perfectly. Is this a sign of an issue?

pressure regulator? Post a picture of what you are talking about because the only pressure regulator on a 2.0 is the fuel pressure regulator and the only hoses on that are fuel.

If you are talking about the manifold pressure sensor, pulling the vaccum line off of that at idle would richen the mixture quite a bit. If that made it run better then check your head temp sensor resistance while cold and make sure you have the proper sensor for your ECU.

[TheCabinetmaker]

Are you talking about the small can with three vacuum hoses to it? On the passenger side of the engine near or on the manifold pressure sensor? Thats the deceleration valve. Disconnecting a hose creates a vacuum leak and a high idle.

[falconfp2001]

Are you talking about the small can with three vacuum hoses to it? On the passenger side of the engine near or on the manifold pressure sensor? Thats the deceleration valve. Disconnecting a hose creates a vacuum leak and a high idle.

If the decel valve is plumbed wrong it could cause rough idle speed. You can check the diagrams here http://www.pelicanparts.com/914/technical_...4_20FI_diag.htm

If the vacuum hoses are correct then you may just need to adjust the idle speed valve.

It is the screw with the spring in this picture. Counter Clockwise will increase idle speed.


You should really consider consulting a known good 914 mechanic though.

[76-914]

"when you pulled the vac line it ran fine". was it warm or cold?
after warm it should idle in the 950-1000 range. cold idle is around 1500rpm. if pulling this line helps with cold idle i would suspect the AAR. if it helped when warm then you need to do a few things to find your problem.

[ned911]

It was cold. Car runs fantastic once she warms up, it's the cold idle and trying to drive in a parking lot and traffic that is troublesome. Once shes been going for 15-20 minutes all is good.

Going to check out the head temp sensor next.