Question about idling problem

[Hellion]

My buddy has a 97 GST with a JDM 4g63 turbo motor in it. When you first start the car, either cold or hot, it idles very choppy and erratic, almost like a cammed big block. It does this for a few minutes then, after it warms up, it runs fine. Any clue what this could be?

 

[numlock666]

You can do a few searches and tests before asking a question. Check for spark when it first starts, how are A/F R's at start up. Temp sensor, could cause that. Plugs, wires. Wrong size injectors on stock ecu if his engine is truly "Jaydem".

 

[Hellion]

You can do a few searches and tests before asking a question. Check for spark when it first starts, how are A/F R's at start up. Temp sensor, could cause that. Plugs, wires. Wrong size injectors on stock ecu if his engine is truly "Jaydem".

I did search and I couldn't really find anything like this. Plugs and wires are new. Air/fuel ratio is good. We were thinking/told the coolant sensor could be the cause, but I was not aware it could cause it to act as it does. If it were the wrong size injectors, wouldn't it cause it to run bad throughout the curve rather than when it is first started? Or is this time the period that it takes the ecu to adjust to the injectors?

 

[Turbo Talon DL]

Is your MAF hacked? Are you using the fast idle air valve under the T-body? Make sure coolant lines are hooked up to that. Check your ignition timing and set your BISS accordingly. This may sound weird, but you want the car to idle as close to 800 RPM as possible, even if its cammed out. Does your 'friend' have a datalogger or a check engine light on? I recommend the logger and if he has a CEL on, that needs to be resolved ASAP in order for us to help you troubleshoot.

 

[Hellion]

Is your MAF hacked? Are you using the fast idle air valve under the T-body? Make sure coolant lines are hooked up to that. Check your ignition timing and set your BISS accordingly. This may sound weird, but you want the car to idle as close to 800 RPM as possible, even if its cammed out. Does your 'friend' have a datalogger or a check engine light on? I recommend the logger and if he has a CEL on, that needs to be resolved ASAP in order for us to help you troubleshoot.

the car idles to the point that it almost stalls out. no. the MAF isn't hacked.

 

[Turbo Talon DL]

So what are you guys doing to keep the car idling then since it almost wants to die? FPR, vacuum leaks out the a** or what? Never did answer my other questions.

 

[Hellion]

So what are you guys doing to keep the car idling then since it almost wants to die? FPR, vacuum leaks out the a** or what? Never did answer my other questions.

It will stay running on its own. it just idles extremely low. it will drop down below 100rpm's then jump up around 200 or 300.. it will do this for about 5 minutes then it idles fine. this happens at every start up. I don't think its the FPR.. Maybe vacuum leaks but I couldn't find any.

 

[94cyclone]

Try the search again. If you can't find any info on this problem, you may be spelling something wrong.

Idle problems are one of the most common discussions on this forum. You'll find all the info you need if you use the search.

 

[Turbo Talon DL]

I dont mind if people dont use the search, it takes a good deal of patience and a little experience to use it effectively. The thing is you havent told us if you have any trouble codes or not. Do you have a logger? If so, what DTC's have you pulled? Do you have a Haynes/Chilton/Factory Service manual(s)? My car ran like that for a while because it was running too rich with a bad FPR that stayed shut at idle. Fouled out my plugs and some other stuff. I didnt have the idle set right either. Ground out the timing connector, get a timing light, and set your timing PROPERLY. Thats what a search would probably yeild for you to do. Im sure this thread is near being closed by now.

 

[Hellion]

First of all, I want to say again that this really isn't my car: therefore I don't know every specific little detail about it. I know it isn't fouling plugs and I know that it isn't throwing any codes. He doesn't have a datalogger either. And I'm not stupid and I know how to use the search function, but all I could find were idling problems that were different from this one. He has tried mostly everything, even had a shop look at it. That's why I'm asking everyone on here, because somebody may know from experience. And before anyone else wants to tell me to "use the search," I suggest you read rule number 1 under the "before you reply" section which specifically states: "No "Use the Search" replies - answer the question, link to the answer, or don't reply." Thanks!

 

[Turbo Talon DL]

Tell your 'friend' to get a DSMtuners account so he can post on his own behalf then. Collectively we have solutions to EVERY problem you can imagine but we just have to know exactly whats happening. No malice from me to you my friend. I have a couple ideas though:

-Idle speed control motor
-closed-throttle switch (make sure throttle plate fully closes when switch is CLOSED)
-throttle cable adjustment (make sure its tight, but loose enough to allow throttle plate to close)
-idle speed adjustment (ground test connector and set ign to 3-5 BTDC 800 RPM)
-basic tune-up (plugs, wires, both fuel filters, FPR)
-close the BISS almost all the way (the car can idle at 800-ish rpm even cammed out)

This is the best I can do. Encourage your friend to buy a datalogger. For the $100 you'll spend at Welcome to OBDloggers you will save him lots of headaches and question marks. A datalogger may answer most of your questions too BTW.