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Old 10-06-2004   #1
GTA_340
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Join Date: Aug 2004
Posts: 45


rpm idle bad Alternator??

hi, my gta has had idle problems and i have spent a small fortune trying to get it fixed repaced computer maf and various relays? Trying to bounce ideas will a bad alternator cause idle issues if the computer is underpowered? because at low rpms the volt meter goes down to about 9-10volts (low rpm is an idle right) so are the two related help!
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Old 10-06-2004   #2
MunsonGTA
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Join Date: Jun 2004
Location: Ravenna, OH
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GTA Year: 1987
GTA Engine: Custom
Re: rpm idle bad Alternator??

you should check into the IAC and TPS. What exactly is it doing? All you said is that it's having problems. Is it idling low or bouncing around? Does it start up and idle real high? http://www.thirdgen.org/newdesign/tech/tpimod2.shtml
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Old 10-07-2004   #3
speed88
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Join Date: Feb 2003
Location: St. John's, NL, Canada
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Re: rpm idle bad Alternator??

Quote:
Originally Posted by GTA_340
hi, my gta has had idle problems and i have spent a small fortune trying to get it fixed repaced computer maf and various relays? Trying to bounce ideas will a bad alternator cause idle issues if the computer is underpowered? because at low rpms the volt meter goes down to about 9-10volts (low rpm is an idle right) so are the two related help!
My volts drop have dropped like that before. Once I needed to have the alternator rebuilt and the other time was a lose fan belt. Have you checked those?
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Old 10-07-2004   #4
GTA_340
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Join Date: Aug 2004
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Re: rpm idle bad Alternator??

thanks for the replies the tach bounces around and the car may often stall, when the car is warm it does it much less but still idles rough. I have noticed that the voltmeter bounces around with the tach any corrilation? i have spent a small fu***#@* fortune on this problem and working fast food as a student really sucks as it is.
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Old 10-07-2004   #5
Fred91GTA
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Join Date: Oct 2001
Location: Brooklyn, NYC
Posts: 1,656


Re: rpm idle bad Alternator??

Not sure about the alternator, but check your vac lines. A vacuum leak can cause RPMs to be unstable like that. It's simple, it's easy and it's a very cheap solution. (Free to diagnose, just a few bucks for vac line if you find a leak)

Also, a bad alternator, I don't think should cause problems because once the alternator goes, the car starts running off the battery until the juice is zapped dry. But, when the engine is running, it's spinning the alternator to get power. if the engine isn't spinning fast enough, volts will drop obviously. I'd still go check the vac lines first and make sure that isn't the problem.

Just to be safe, get your alternator tested at Autozone after you test for Vac leaks. And also as statd above, do the proper checks at the TPS and IAC.
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Last edited by Fred91GTA; 10-07-2004 at 03:44 PM.
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