Supercharged starts
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so i've been paying attention to how my car has been starting lately and i've noticed something rather weird....we all know that in the morning when the engine is usually cold it runs "rich" {around 1500rpms for me} until it reaches operating temp, then it goes down {to around 900}....however, doing the usual stop and go driving I do, in between time the engine doesn't cool all the way down...it could be at 180-200* and still start up and jump to 1500rpms, then it'll drop in about 10 secs to the normal 900....and now i'm noticing that sometimes i'll start it {around 180-200+*} and the rpms won't jump at all....it'll just be at 900....
and ideas/reasons for it doing that?
and ideas/reasons for it doing that?
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A warmed up motor should start at the normal operating RPM'* of about 800-900 like you are seeing. Only reasoning I could suggest for the higher RPM'* when already warmed up might be a bad sensor telling the pcm to warm up when not necessary or possibly the outside air temperature being cold enough to warrant a little choke ensuring the pcm is sure the motor is properly warmed up.
Again...this is assumed and speculative.
Again...this is assumed and speculative.
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:::update:::
seems as thought the condition as gotten worse.....
2nd night in a row that this has happened, so i'm starting to wonder....
both days i drove the car to work...didn't go anywhere on break...so the car sat for about 7-8hrs.....then when i go to start the car, it starts up.....starts to rev a lil' {like it did before} but then it will die down...almost to the point where it seems like its going to shut off....then there'* a major surge up to 2000rpms..it hold for a few seconds...then dies down to about where it should be..
is it possible that some sort of sensor is maybe going crazy??
seems as thought the condition as gotten worse.....
2nd night in a row that this has happened, so i'm starting to wonder....
both days i drove the car to work...didn't go anywhere on break...so the car sat for about 7-8hrs.....then when i go to start the car, it starts up.....starts to rev a lil' {like it did before} but then it will die down...almost to the point where it seems like its going to shut off....then there'* a major surge up to 2000rpms..it hold for a few seconds...then dies down to about where it should be..
is it possible that some sort of sensor is maybe going crazy??
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The veterans can offer more support.
Check your battery connections at both ends. I'm thinking that it'* possible your pcm thinks it'* not getting power for a while and is losing idle. These cars if disconnected form their batteries will forget how to idle. GM procedure to learn idle is to set the parking brake, start car and put it in gear. Letting it hunt around for the best possible idle and it learns in 20 to 30 min.
Does the idling problem go away after by the time you get home or does it act wonky at stoplights also?
Check your battery connections at both ends. I'm thinking that it'* possible your pcm thinks it'* not getting power for a while and is losing idle. These cars if disconnected form their batteries will forget how to idle. GM procedure to learn idle is to set the parking brake, start car and put it in gear. Letting it hunt around for the best possible idle and it learns in 20 to 30 min.
Does the idling problem go away after by the time you get home or does it act wonky at stoplights also?
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Could also be a Throttle Position Sensor issue...
Do you have an intake system on the car... Or is it all still factory? And if the MAF screen still in the throttle body?
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Do you have an intake system on the car... Or is it all still factory? And if the MAF screen still in the throttle body?
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the idling problem is only when i first start up the car...at stop lights and such its basically fine....and i haven't done any mod'* to the car so the intake is factory and i think that the MAF screen is still there {haven't checked, but don't see why it would be gone} i was thinking maybe a vacuum leak, but that would effect boost, right? and that is fine...
but the battery theory sounds like that may be it since when i first went to look @ the car the battery was disconnected...who knows for how long...it first started at 2000 rpms and held...but since it has gotten better.... it usually just jumps to 1500 then slowly goes down...until recently. But today all my starts have been fine...
as for the learning procedure...would setting the parking brake and placing it in "neutral" count as a gear? cuz i think i've read somewhere that just letting your car sit in drive or something isn't good for your transaxle.....could be wrong though
but the battery theory sounds like that may be it since when i first went to look @ the car the battery was disconnected...who knows for how long...it first started at 2000 rpms and held...but since it has gotten better.... it usually just jumps to 1500 then slowly goes down...until recently. But today all my starts have been fine...
as for the learning procedure...would setting the parking brake and placing it in "neutral" count as a gear? cuz i think i've read somewhere that just letting your car sit in drive or something isn't good for your transaxle.....could be wrong though
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If you have disconnected the battery the PCM should relearn the IAC or Idle...
Usually the car will need to be at normal operating temps.... Then you will need to drive above 40 Mph or so, at that point the PCM should relearn the IAC position...
But just for sake do go ahead and check all of the vacume lines... Any unmetered air can cause diffrent issues...![Wink](https://www.gmforum.com/gm/images/smilies/icon_wink.gif)
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Usually the car will need to be at normal operating temps.... Then you will need to drive above 40 Mph or so, at that point the PCM should relearn the IAC position...
But just for sake do go ahead and check all of the vacume lines... Any unmetered air can cause diffrent issues...
![Wink](https://www.gmforum.com/gm/images/smilies/icon_wink.gif)
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#10
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Take a look at the pic in this one. It has the brake booster vacuum hose and other small black hoses circled. Basics are look for small black hoses coming out of the intake manifold/TB. You may also see small black tubes, they have connection hoses at each end that can dry rot and cause issues.
http://www.bonnevilleclub.com/forum/...cruise+control
http://www.bonnevilleclub.com/forum/...cruise+control