Need HELP diagnosing idle problem

[Ironair]

I'm looking for some help from people that have been doing this stuff way longer than I have. Car was running good, just a slight issue with the idle speed rising and falling about 200 rpm after the car warmed up. No problems at all with starting. One cooler morning recently I went out to start the car and it started but then almost immediately died. It recovered and almost died several times before it finally did stall. It will stay running if you give it some gas, but it revs up and almost stalls several times while warming up. Take your foot off the gas before it is warmed up and it will stall. When it is warmed up fully it will idle at about 580 rpm foot off the gas. It is pretty much undriveable because it will stall if you put it in neutral rolling up to a stop sign 50 percent of the time. I reinstalled an older tune in the car to see if it might have been a change in the tune that is causing the problem, but it is still having issues with the old tune, so ruling out the tune. I've checked fuel pressure, it is about 63 when running. Plugs are pretty dark, and it is running pretty rich from the smell of the exhaust. I'm open to any suggestions as to what to do next. I'm thinking maybe throttle body problem at this point, not sure how to test it without getting another one to try. Any help would be greatly appreciated.

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[Ironair]

Anyone?

This video was from a few weeks ago. Now it won't even do this, it just dies.

[ame]

 

[cdq85]

Hmmm. Very interesting. I have different set up (roush phase 2) but a somewhat similar issue arises when my car sits outside overnight and it drops in temperature. My idle will hunt for a little bit (not as bad or as long) and sometimes stall. Then I fire it back up and it seems fine. It is very sporadic but can be annoying as hell.

 

[Tommy V]

First thing I would do is check for vacuum leaks.And can u post your fuel trims at idle?

 

[dubster99]

First thing I would do is check for vacuum leaks.And can u post your fuel trims at idle?

Definitely this. Also, I assume you have a stock fuel pump/system and are running pump gas? 63 seems kinda high at idle to me, but if you're running a stock fuel pump it's got the regulator inside the pump assembly.

 

[CVCashmere]

I had a similar problem with my Thunderbird. In this case, it was the idle control valve that needed replacing.

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[Ironair]

No vacuum leaks that I can find. Pulled all hoses off the supercharger and plugged the ports. No change, actually it revs up some with a vacuum leak. Makes sense, because it is starving for air I think.

Not sure about fuel trims. Measured a/f is 1.00 when it warms up. One tune has stft at .91 and another one has it at 1.09. But they both act up when starting cold.

I think I did read once that the stock fuel hat should regulate the pressure to no more than 58, so it's a little high. Don't know if that's enough to cause a problem or not, I wouldn't think so, but maybe.

Pretty sure there is no idle control valve. I think it is all built into the throttle body opening controlled by the computer.

Thanks for the replies, I'm almost ready to just try a new throttle body and see what it does. They're only like $130 new, unless someone has one laying around I could try. I'd pay shipping, and you can have it back after my test.

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