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fluctuating idle??? HELP!!!!

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Old May 3, 2006 | 09:22 PM
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Default fluctuating idle??? HELP!!!!

While I'm in park my idle will stay normal for a few seconds then it will rev up slowly about 200-400rpm and stay there for a few seconds and then it will go right back to normal.. then after a few seconds it will rev up slowly 200-400rpm and stay there for a few seconds and then it will drop back down to normal for a few seconds and then repeat this over and over and over again. What could be causing this? I'm thinking the TPS is going bad. or could it be the IAC sensor? How do I check? If I do buy the TPS will I have to reset it since I have the TB blade screw adjusted for the cam and also a custom tune..... or can I just pull the old TPS out and put the new one in? I need opinions and help. any help will be appreciated. thanks
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Old May 4, 2006 | 11:05 AM
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anyone??
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Old May 4, 2006 | 11:26 AM
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Can't say I've seen that before. Did this just happen out of the blue one day? Do you have any means to log data (IACs and TPS positin)?
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Old May 4, 2006 | 05:34 PM
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This is why I'm not a huge fan of dyno tunes.

When stuff goes wrong, you don't know how to change it.

If you can log, you'll be able to see what's causing the problem.

Do you know what your Spark table in Park looks like?
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Old May 4, 2006 | 05:37 PM
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Sounds like timing and airflow to me.
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Old May 4, 2006 | 05:42 PM
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my car is having a similar problem, its annoying as hell. I was wondering if it was the TPS as well.
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Old May 4, 2006 | 10:14 PM
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Saturday I replaced my front fried o2 sensors with Bosch o2 sensors. It actually started happening after I cleaned my throttle body out with carb cleaner on Tuesday. It was caked up with all of the EGR/oil/dirt mix and looked really nasty, so I figured I'd clean it. I'm thinking I may have gotten some of the dirt or resedu on one of the sensors, and may just need to clean it out. Although I did take my car back to my tuner on Wednesday and he hooked the car up to his HP tuners program with the laptop and everything and said my o2 sensors were fried. I told him that I jsut replaced them on Saturday and he asked what kind I put in. I replied" Bosch" he said that was my problem because Bosch usually fail and go bad for some reason on LS1 cars really quick. So that day I went down the read and bought some o2 sensors from GM and put them in. I took it back to him and everything worked great. So I left and once I got to work within the next hour or so, the idle was fluctuating again when I put it in park. So I'm thinking either the TPS or the IAC sensors are going bad. Or could my new GM o2 sensors be fried for some reason? If the o2 sensors are fried again, what the hell could be causing me to burn up a pair of o2 sensors within a matter of an hour or so????? or could it just be that the TPS or IAC sensors are going bad???? Any more help will be appreciated. thanks
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Old May 4, 2006 | 11:10 PM
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Sounds like a vaccum leak. If not thenI say when you tried to clean your IAC out you just jammed more crud into it. You have to be very carful on how you clean them because some times you just make it worse. Try cleaning your IAC out again, if not i would replace it.
-Alex
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Old May 5, 2006 | 12:49 AM
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Yeah I'm going to take the IAC and TPS sensors out tomorrow and give them a good cleaning and see if that fixes the problem.

Originally Posted by Slo_240sx
Sounds like a vaccum leak. If not thenI say when you tried to clean your IAC out you just jammed more crud into it. You have to be very carful on how you clean them because some times you just make it worse. Try cleaning your IAC out again, if not i would replace it.
-Alex
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Old May 6, 2006 | 03:06 PM
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Never tried it, but can Carb cleaner hurt sensors?

I wouldn't think it'd be too friendly.
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Old May 6, 2006 | 04:32 PM
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Yeah your not supposed to use carb cleaner as it can cause damage.
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Old May 6, 2006 | 05:51 PM
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....I guess I'll use the Electrical cleaner then.

Originally Posted by LS1Cryo
Yeah your not supposed to use carb cleaner as it can cause damage.
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Old May 6, 2006 | 05:52 PM
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The only thing I've ever used to clean sensors was "residue free electronic cleaner."

I get it from radio shack.

Carb cleaner is some corrosive crap!
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Old May 7, 2006 | 09:58 PM
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I cleaned the TPS sensor out today with electrical cleaner and its still doing it. FYI: my idle ony fluctuates while I'm in park. I took the TPS sensor out and I didn't know what to clean since ther was just a metal rod coming out of the TB so I just put that back in. Any suggestions?
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Old May 7, 2006 | 10:03 PM
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So this happened right after working on the TB?
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Old May 8, 2006 | 06:54 AM
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Someone I know was having a problem with his TP sensor which seemed to give irratic readings. The washer between the sensor and the throttle spindle was missing.

May be worth a look.
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Old May 8, 2006 | 10:06 AM
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yes...

Originally Posted by Camaro ChriSS
So this happened right after working on the TB?
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Old May 8, 2006 | 10:07 AM
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I'll look at it again but I don't think anything was missing. I never took the TPS sensor out before I cleaned it yesterday trying to find out if it was causing my idle problem.

Originally Posted by PaulFLS6
Someone I know was having a problem with his TP sensor which seemed to give irratic readings. The washer between the sensor and the throttle spindle was missing.

May be worth a look.
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