High idling rpm (racing engine)

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  #1  
Old 05-11-07, 09:19 PM
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High idling rpm (racing engine)

1997 Chevy Lumina, 133K miles, V6
This is an occasional problem, but becoming more frequent (a few times a week).
In the morning, start the car, pull out of drive way (do not notice racing engine at this point), drive out of neighborhood (1/5 mile), stop at 4-way stop, notice high idling rpm (and difficult to stop), shift gear to Park (about 2000 rpm), turn off ignition, restart engine, normal idling (about 800 rpm). Sometimes, I don't notice until the first traffic light (1 mile from house).

I wonder if some control/sensor gets stuck in the high idling position. Engine restart solves problem. Problem only at cold start, I mean cold engine, not cold outside temperature.

Thank you.
 
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  #2  
Old 05-11-07, 09:51 PM
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if the check engine light ever comes on would probably start there and have codes read it could have a sticking idle air control motor or a tps that may be going bad but would expect a check engine light on a vehicle idling at 2000 rpm
 
  #3  
Old 06-13-07, 08:10 PM
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Sorry for not having replied earlier.
There is an error code, P0440. It has something to do with fuel vapor purge valve. It's always been on for 2 or 3 years (I mean check engine soon light has always been on). No other error code related to high idling rpm.

By the way, it's getting more frequent now. I cleaned idle air control motor once before (off the vehicle), but I will either clean it up one more time or replace it. Last time I had a trouble with tps (not on this car), there was an error code. Do you still suspect tps? Thanks.
 
  #4  
Old 06-14-07, 02:49 AM
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if you havent had codes read recently would start there as there may be additional codes now that may of not been there previously and seeing how the check engine light has been on for so long do to a problem you really have no idea when a new code may be set.
obd2 vehicles are fairly good at detecting sensors reading out of range but often it has to see the fault on 2 consecutive key cycles to throw a code wich it may not be seeing if you only have to restart it once and it runs fine for the rest of the trip.
if you had access to a scanner im sure the problem could be determined fairly quickly if you had it hooked up while it was acting up and monitoring throttle percentage and idle air control counts, suspect that it is either tps or iac related.
 
  #5  
Old 06-14-07, 08:23 PM
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The error code was read yesterday.

2 consecutive key cycle for error code registration: Thanks for the explanation. At this rate, sooner or later it will happen.

Scanner: I don't have access to this. As of now, high idling is still sporadic. But it's starting to get on my nerve.

idle control motor and tps: Each costs $40. I will flip a coin and choose which to replace first.

Thanks.
 
  #6  
Old 06-15-07, 10:14 PM
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Smile

yeah, I'd have to flip a coin to figure out who don't get paid for the month. Wait a minute, I don't have a coin,LOL
 
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