Engine RPM drops when idle, then bounces
02-20-2008, 11:56 PM
#1
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Engine RPM drops when idle, then bounces
I have a very weird problem. When I go to stop, and I clutch in and put the car in neutral, the RPM's drop down to 800-600 RPM. then they bounce up to 1100-1200 RPM, and back down to the normal idle of 900 RPM.
What can cause this?
I have a system partially hooked up. Basically only the capacitor is wired up right now, the amp is set to stay off all the time.
Please help me
What can cause this?
I have a system partially hooked up. Basically only the capacitor is wired up right now, the amp is set to stay off all the time.
Please help me
02-21-2008, 12:06 AM
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yea mine does it too.... except when it happens it makes a screeching noise coming from the engine bay... i don't wanna take it to the dealer basically cuz they mess **** up and also cuz it doesn't do it all the time so its a waste of time for them to drive my car just to tell me they could not duplicate the problem... let alone take my **** apart and not put it back together correct (missing bolts/nuts etc.)
when i tap the gas a little it usually stops... it hasn't gotten worse so fck it
when i tap the gas a little it usually stops... it hasn't gotten worse so fck it
02-21-2008, 12:09 AM
#8
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oo dont worry, i think i have it the worst, my car does it so hard, sometimes jumps from 200-2,000 rpms, then itll stall every so often, seems to only do it in the really really really cold weather for me, maybe 40 and lower it does it bad. I cant even drive the car below 20 degrees, it gets so bad the stiffened tranny mounts just make the whole car raddle when its down in the 200 rpm range trying to get back up, if not it will cough and die
02-21-2008, 12:20 AM
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02-21-2008, 12:24 AM
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I have an 05 LS, and I have noticed that it is worse during cold weather when I first start out. I'm bringing my car to the dealer for some free parts, maybe I'll mention it to them.
02-21-2008, 12:45 AM
#12
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trust me go get the reflash
It only did it once since the reflash and that right after I left the dealer
I was pissed but after that last time it never happened again
Just mention to them that a friend had the same problem and that the car was reflashed and it fixed it. they will check to see what flash you have and they will update it if needed. my dealer said they could tell that it wasnt current
It only did it once since the reflash and that right after I left the dealer I was pissed but after that last time it never happened againJust mention to them that a friend had the same problem and that the car was reflashed and it fixed it. they will check to see what flash you have and they will update it if needed. my dealer said they could tell that it wasnt current
Last edited by JRelly; 02-21-2008 at 12:45 AM. Reason: Automerged Doublepost
02-21-2008, 08:17 AM
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02-21-2008, 01:39 PM
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trust me go get the reflash It only did it once since the reflash and that right after I left the dealer I was pissed but after that last time it never happened again
Just mention to them that a friend had the same problem and that the car was reflashed and it fixed it. they will check to see what flash you have and they will update it if needed. my dealer said they could tell that it wasnt current
It only did it once since the reflash and that right after I left the dealer I was pissed but after that last time it never happened againJust mention to them that a friend had the same problem and that the car was reflashed and it fixed it. they will check to see what flash you have and they will update it if needed. my dealer said they could tell that it wasnt current
02-21-2008, 03:49 PM
#20
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As for cold weather being the cause of the problem.......
Dont let them tell you that becuase its not the cold weather mine did it in the middle of the summer. Most service departments will just give you the simplest answer becuase they dont know what the **** they are talking about.
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02-21-2008, 04:34 PM
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Not necessarily, I had the reflash done in mid 2007 so the 2007s may not have the updated flash either. His car is a 2005 anyway.
As for cold weather being the cause of the problem.......
Dont let them tell you that becuase its not the cold weather mine did it in the middle of the summer. Most service departments will just give you the simplest answer becuase they dont know what the **** they are talking about.
As for cold weather being the cause of the problem.......
Dont let them tell you that becuase its not the cold weather mine did it in the middle of the summer. Most service departments will just give you the simplest answer becuase they dont know what the **** they are talking about.
02-22-2008, 01:28 AM
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i do not own a cobalt but i know the answer. your car has an electronic idle control, which is usually on your airbox, if any dust particle travel through and hit the sensor, usually during idle, the cars rpms will drop, when the dust particle passes on, the computer will trip, causing the rpms to "jump". usually you just disconnect the sensor every month or so and wipe it off and it will fix it. I have a mustang, and i have had to replace the sensor in mine, and i guess you are supposed to hcange it every 30,000 miles.
