Dying at idle? But nowhere else?

[SHOFire]

I have had a little issue with my Sho for the past couple of days. I was driving it around a bit to keep it warm from -17 degree weather, and as I was driving it, it started to want to die when I let it Idle, and I had to keep it around 1500rpm to keep it alive. At first I thought it was the fuel, as I let it get really low. With a can of fresh gas in there, it ran fine. Then when I ran it yesterday, it did it again, and I noticed the check engine light came on as it died. I am going to check for codes and see if it shows anything. It seems to run fine today, but you never know. It might be the CPS going but it doesen't show all characteristics of that. Help!

 

[Rob94]

At these cold temperatures, it is possible that you may have some icing in the fuel lines. It is normal to get a check engine light when a car stalls out, but I would definitely check the stored codes. A bottle of isopropal alcohol (dry gas) probably wouldn't hurt either.

 

[NotSoSlowSHO]

AIB valve. Thats what it does, is manage the air required for proper idle. If it is stuck closed, then it will not idle.

Does it start without the need to press the gas pedal?

 

[NiNeTy Fo SHO]

AIB => IAB (idle air bypass valve I believe)

Just so he can find out lots more info. if he/she searches for IAB.

I would agree that it is the IAB, if you have to press the gas pedal to keep it going (aka it wont idle on its own). If it were the gas, I would think you would have problems across the board.

If you do need to press the gas pedal to start it, this is another sign of the IAB not opening letting air into the engine.

 

[SHO#7]

Check to make sure that the air intake hose is tight. I just had to re-tighten mine the other day when it was like 4 here. I know that my car is weird about little dumb stuff like that.

 

[SHOFire]

I don't think it is the IAB valve because the car has to warm up and run for about 10 min, and it only happens occasionally. I checked for codes, and nothing showed up. I did a KAOB test (I think that's what it's called) for slow codes and it came up that the AIC valve isn't working, and my O2 sensors are bad. The O2 sensors could be the reason why I have a bit erratic performance out of it. But the car does start right up without touching anything, but on colder days I do need to touch the gas pedal. I'm not too worried because I will have to store the car for 2 years before I fix anything. Thanks for the help though.

 

[NiNeTy Fo SHO]

When mine first started to go, it only did it when it was warm and was random. Sometimes I would put the clutch in to coast and it would die..for the next 2 days, no symptoms.

The IAB can be tricky when it is on its way out...also, I think the natural higher idle when the engine is cold is why it may not do it until your car warms up.

Some food for thought...

 

[NotSoSlowSHO]

The IAB can stick in the cold weather.
Not-so much when warm.

And if you need to depress the gas pedal to start it, then YES, the IAB needs cleaning or replacement.

 

[revhardSHO]

Im with kenny on this one

 

[95SHO32]

o2 sensors are ignored in open loop. I'd clean the IAB and ck the throttle body for coking , coking is caused by oil vapors from the crankcase, as the engine cools it coats the throttle blade with varnish. and it seals up the min throttle clearance, which ruins the idle control setting.

 

[SHOFire]

Allrighty, I'll check those things out. Thanks for the help.

 

[sdpatt]

I don't think it is the IAB valve...

I checked for codes, and nothing showed up. I did a KAOB test (I think that's what it's called) for slow codes and it came up that the AIC valve isn't working, and my O2 sensors are bad.

The Key On Engine Off (KOEO) test is the one that can retrieve memory codes.

There is not a "slow" code. Hard faults and memory codes only.

If a code shows that the "AIC valve isn't working" then you might need to check to see if that is actually the IAC valve. That would be the idle air control valve, a.k.a. the idle air bypass valve. That is the engine computer controlled valve responsible for maintaning the correct air flow at engine idle with the throttle closed. That would be a very good reason your engine cannot maintain idle speed.

Didn't bypass the coolant path to the throttle body did you? That would allow intake air freeze-up in conditions not even as cold as you are experiencing.

Oh, and for those that have performed this "modification" for performance reasons, the coolant only heats the spacer between the throttle body and the idle air bypass valve for idle pypass air flow. It does not heat the air coming through the throttle body's main path.

 

[stevemainian]

I have the exact problem.

My MAF, o2 sensors, and the valve that opens and closes the egr was bad. I had the MAF, and the egr valve sensor replaced, and it still randomly did it.

My car has to be warm in order for it to go out too. Except I never have to press the gas to start it.

I havent replaced the o2's yet. But some think this may be the problem. I hope so. I already bought the o2's. 42 bucks a peice. Havent had a chance to throw them on yet.

 

[todras]

Sounds like my problem. Does the idle bounce up and down and then stall? I've replaced the IAC twice, TPS and the ECT. Only has these issues when the air is cold. Runs fine at initial start up but acts in 2 minutes when you start driving.

 

[stevemainian]

Sounds like my problem. Does the idle bounce up and down and then stall? I've replaced the IAC twice, TPS and the ECT. Only has these issues when the air is cold. Runs fine at initial start up but acts in 2 minutes when you start driving.

lol, seems like a lot of people are having this problem.... No cure for it yet though. I was thinking the IAB, but nevermind now.

Gonna have to look into the crank position sensor.

 

[bertha66]

When I had the 60k mantinance done the SHO machanic said that the fuel pump pressure was down a little and that it would do what you guys seem to be talking about. So when it started dieing out at a idle I put in a new fuel pump and the problem wemt away. Just my $.02 worth.

 

[stevemainian]

When I had the 60k mantinance done the SHO machanic said that the fuel pump pressure was down a little and that it would do what you guys seem to be talking about. So when it started dieing out at a idle I put in a new fuel pump and the problem wemt away. Just my $.02 worth.

Odd you say that, someone said my fuel pump was incredibly loud, and was probably about to go.