Eratic idle! Help! 2002SS
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From: Sioux Center, Iowa
Eratic idle! Help! 2002SS Been dealing with this issue since last fall put the car away for the winter and forgot about it but this spring the car remembered. Everytime I drive the car i have no idea how it's gonna idle. Idle is set to 900 and sometimes i push in the clutch it's perfect and falls right to there and holds like a rock like it should all day long. Shut the car off go into store come back out and fire it up and the car barely runs, idle hunts all over the place 300rpm-2000-300-2000 yada yada yada does this until I shut it off. Restart and it's perfect.....that is until a full throttle run, whenever I floor the car it idles solid at 2200rpm afterwards and won't change until I shut the car off. Restart and it's back to the other 2 scenarios, either perfect or super idle hunting. I am fed up to say the least. I am leaning towards the IAC valve but anything else it could be?! I hate driving the car now because of this.....
*Notes:
- whether cold or warm it also revs to about 3000 on startup, everytime
- car is e85 speed density openloop tuned
- intake is TPIS 90mm with 90mm throttle body
- entire PCV system is removed and blocked off, I run a breather only setup on the valve covers
- TPS sensor is working good, ALWAYS 0% at idle so throttle body is not hanging.
*Notes:
- whether cold or warm it also revs to about 3000 on startup, everytime
- car is e85 speed density openloop tuned
- intake is TPIS 90mm with 90mm throttle body
- entire PCV system is removed and blocked off, I run a breather only setup on the valve covers
- TPS sensor is working good, ALWAYS 0% at idle so throttle body is not hanging.
Last edited by NW Iowa WS6; Apr 14, 2014 at 11:44 AM.
What throttle body are you using?
Have you tried to visually inspect for blade hanging, I do not know how accurate the information is but I read the TPS sensor can self zero itself out.
Have you tried to visually inspect for blade hanging, I do not know how accurate the information is but I read the TPS sensor can self zero itself out.
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Yup, one of the times it was hanging at 2200rpm after a full throttle run, I popped the hood and the throttle cable was resting on the set screw thing like normal, car just sat there idling at 2200 all by itself for about 2min I could blip the throttle and rev it and settled at 2200 everytime until I shut it off, restarted and after it did its normal embarrassing ricer 3000rpm start up rev it settled at 900 and ran perfect fthe rest of driving it until I shut the key off again.
I fought a lot of similar behavior until I switched throttle bodies and now it's nearly all perfect. Still does the rev thing on startup though, but mine doesn't go that high, only 1800-2000rpm for a few seconds then falls down to 1100 or so then revs a tad before falling down to settle on desired idle..
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My buddy I bought this TPIS 90mm from never had this issue the 2 years he had this intake/tb combo and I didn't either the first year I had it until last fall right before I put it in storage for the winter and again this spring.....I'm leaning towards IAC valve but its about $150 at my local GM dealer
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That's the problem, lost touch with my friend that I had hptuners access through, but when i did data log last year nothing stood out, TPS followed my foot perfectly and no matter what was going on at idle it said 0% and full throttle was always 99%. No DTC's or anything, and it all started out of nowhere, it was great for about 6months after my tune from a reputable local shop.
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Thread Starter
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From: Sioux Center, Iowa
Had a tear in my AIC valve o ring and replaced, problem is maybe a little better but still there, doing a little research it looks like my problem may be the TPS sensor. Everywhere I read about them going bad I have the symptoms, intermittent hunting idle/idle hanging/bucking and surging(even though I have a decent cam 232/236 112 it bucks a lot worse than people with larger cams than me I'm around) $30 bucks for a new one I'm gonna give that a try
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