Low RPM related stumble
05-05-2006, 08:57 AM
#1
Race Car
Thread Starter
Low RPM related stumble
After removing the intake manifold and putting everything back together, I'm now experiencing a low RPM stumble (~2500ish) that goes away as RPMs go up. I am pulling the same vacuum at warm idle as I did before (18-19 inHg), so I don't think I have a vacuum leak. I tried "re-clocking" the MAF to the 10 o'clock position and it cleaned up ever so slightly, but the stumble is still there. The rest of the rev range is fine. If I am coasting to a stop and I put in the clutch, the RPMs drop past the idle point and the car will sometimes cathch itself, and sometimes die. Where do I need to start looking to fix this issue?
LR stage II MAF, Vitesse software, 55# injectors, 3bar fuel pressure in case that helps.
LR stage II MAF, Vitesse software, 55# injectors, 3bar fuel pressure in case that helps.
05-05-2006, 09:30 AM
#3
Race Car
Thread Starter
Have not tried the O2 sensor. If that is bad, uplugging it will clear up the stumble? Idle was not set with by jumping the IAS. I pulled the screw out, cleaned it up, and reinstalled it so I had the same ~900 RPM idle I had before. I will try that as well. What are the symptoms of a TPS that needs adjustment?
05-05-2006, 11:29 AM
#4
Race Car
Join Date: Jun 2004
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Sounds like the classic TPS.
Adjust or Failure.
Search TPS or the full name Throttle Position Switch
The Turbo TPS can fail anywhere along its travel unlike the na TPS.
http://www.arnnworx.com/tps-repair.htm
Adjust or Failure.
Search TPS or the full name Throttle Position Switch
The Turbo TPS can fail anywhere along its travel unlike the na TPS.
http://www.arnnworx.com/tps-repair.htm
05-05-2006, 08:49 PM
#6
Race Car
Thread Starter
WOW...I didn't think the idle was that bad on my car. I guess I was wrong. The screw was about 3 1/2 turns off the seat. Adjusted the idle properly and the car runs much smoother now. I *think* this cleared up my issue.
Thanks!
Thanks!
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05-13-2006, 10:18 AM
#8
Race Car
Thread Starter
after a track event, the damn stumble is back. and my idle is high again. the adjustment screw keeps working it's way out, adding a dab of silicone on it didn't help either (per clark's garage). do i have something else wrong with the tb or the screw itself?
05-13-2006, 10:48 AM
#9
Addict
Rennlist Member
Rennlist Member
You might try some blue loctite, which doesn't harden all the way, and you did get a new o-ring? The threads may be damaged, might be time to scout ebay for a spare but I would try the blue loctite and set the idle again.
