Stalling Issue Help

BLKsteeda

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Jul 12, 2004
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I have a 2001 GT with full bolt ons, ported heads and cams. Last year around December my car was tuned and we had a recurring stalling issue after the tune where the car would stall when I slowed down...eventually the tuner adjusted the throttle screw on my accufab throttle body after trying many things in the tune to fix it and that solved it for months. About a month ago I started having idle issues while driving where the car would idle high at 1300-1400rpm. That lasted for a couple weeks and eventually went away. Now I'm starting to have occasional stalls or the car attempts to stall under the following conditions:

Car has to be at full running temp and it will only stall or attempt to stall when I come to a complete stop and it doesn't do it every time. When I start to slow down the rpm's will hang around 1200 and when I come to a complete stop it will either drop to the normal 900rpm idle or drop to 400-500 and attempt to stall or completely die. Never does it with the air on which I assume it's due to the extra RPM's I gain from running it.

I attempted to adust the throttle screw myself and bumped it up a little bit but it was idling a little high but it kept if from stalling. I figured it might be general maintenence so I removed my CAI and cleaned out and lubricated the throttle body, put some seafoam through the vacuum lines as well as in the crank case which after that was done my car was idling about 200rpm higher than before so I bumped back down the throttle screw to compensate. That was good for a few days but it still attempts to die and actually stalled a couple of time in the last two days. I replaced the IAC in Jan so that is only a few months old. I don't know if this has anything to do with it but my stock MAF crapped out on me last week and I had to have a new stock one put in. I feel it might be a mechanical/electrical issue but I'm not sure where else to look...you have any ideas as to what it might be? Is it possible that the EGR is giving me issues? I appreciate any help or suggestions you can offer.

Thanks
 
If the EGR was screwy it should throw a code. Hows the fuel pressure? Maybe a regulator going bad?

Now that I read further...the issue started after the tune or after the install of parts? Did you drive it at all after the parts install and then tune? If it is after the tune I'd look there.
 
Do a search for "dashpot", speak to your tuner about what you learn from that search, and try to get the screw back to where it was you are not supposed to adjust it.
 
If the EGR was screwy it should throw a code. Hows the fuel pressure? Maybe a regulator going bad?

Now that I read further...the issue started after the tune or after the install of parts? Did you drive it at all after the parts install and then tune? If it is after the tune I'd look there.


Initially the stalling problem occured after the tune. For a couple weeks after the tune the stalling problem continued and it was during that time I replaced the IAC to eliminate that as a possible problem...it didn't correct it. Everything in the book was tried to fix the problem in the tune but no luck until the screw was adjusted by the tuner then the problem was gone for months and the car ran and idle'd perfectly.
 
Kilgore is right about the screw. You are not supposed to have to adjust it. I'm still thinking they missed something in the tune.

Since it is a subsequent problem after having no issues check and see if there are any stored codes. May be a clue there even if the CEL isn't on.
 
BLKsteeda:

You'll need your tuner to do this if you don't have a TwEECer or SCT's Pro Racer Advantage program....

What worked for me was to increase the values of air in the isc_idle_drive_air and isc_idle_air_neutral below the idle speeds. (I don't have those parameters exactly right but your tuner will recognize them). And, you might try increasing the dashpot preposition in the very low RPM range. Coming to a stop requires a transition from dashpot to idle control and it can be a real bear to get just right.

HTH,

Chris
 
BLKsteeda:

Yup, when power steering is used, the load on the engine increases and more air (and fuel) is required to keep things going. The problem is curable but it is going to take a little work and time. Datalog when driving around, at idle, and when you are slowing down and turning into a parking space. Then, send that info to your tuner and see what he can do for you. It might take a few tries but it is possible to fine tune by e-mail.

Chris
 
before I take it back to my tuner this week I did a couple more things yesterday...I removed my fairly new IAC as well as the EGR off the side of the plenum and cleaned it with the Seafoam lubrication and cleaner spray. Reinstalled and went for a drive...still noticed my RPM's were hanging so I went back to the throttle stop screw. I left the car at idle and started backing that screw off...I almost had it backed all the way out and I was not hearing any difference in idle at all so I screwed it back in a little bit and locked it down. Upon driving after my cleaning and adjusting of the screw, the RPM's drop pretty quickly upon slowing down, almost to idle speed. I need to drive it some more to see how it's going to behave but the only time it attempted to stall so far was under a very hard stop...if that means anything.

Thanks