RPM changing up then drops, up then drops
08-28-2010, 11:00 PM
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RPM changing up then drops, up then drops
when the car first starts the Idle is very erratic, drops like its gonna die then jumps up to 700-800 then falls back down like its gonna stall out and shots up again. Does this until I get on the road. Once I have driven a few miles- it is smooth at stop lights. Any ideas? I am in desperate need of help- Racking my brain. Once it is smooth is is fine. I shut the car off- start it back up and here we go again. Kinda reminds me of the old speedos before they break when they would bounce.
08-28-2010, 11:09 PM
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Re: RPM changing up then drops, up then drops
when the car first starts the Idle is very erratic, drops like its gonna die then jumps up to 700-800 then falls back down like its gonna stall out and shots up again. Does this until I get on the road. Once I have driven a few miles- it is smooth at stop lights. Any ideas? I am in desperate need of help- Racking my brain. Once it is smooth is is fine. I shut the car off- start it back up and here we go again. Kinda reminds me of the old speedos before they break when they would bounce.
New engine has about 200 miles on it.
08-29-2010, 02:48 PM
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Car: 1987 Trans AM
Engine: Twin Turbo 6.0 LS2
Transmission: T56
Re: RPM changing up then drops, up then drops
Was the ecm tuned for the changes? If not it will not run properly until it enters closed loop and uses the O2 sensor(s) for on the fly AFR adjustments.
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