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96 Olds Eighty Eight Racing idle (3800)
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eberg86
New User
Aug 2, 2010, 6:24 PM
Post #1 of 5
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96 Olds Eighty Eight Racing idle (3800)
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Hey guys, im literally stumped on this and im not to bad when it comes to working on cars but, this problem is driving me nuts.
The details: Subject is a 96 Oldsmobile Eighty Eight with the 3800 and no supercharger 110k miles
The problem: Racing idle. When cold it idles around 1200 rpm but when the engine gets to operating temperature itll start to steady climb to around 2800 rpm and at times even pegs out the rev limiter.
What Ive done so far: Automatically I thought vacuum leak. So I proceeded to change all of the vacuum lines, clean the ports I could get to, and tried rerouting them every which way I could, all with no change in the behavior.
Had a guy run what he called a smoke screen test on it and he told me the intake was leaking. So I replaced the entire upper intake plenum and was very disappointed when I got it all back together that it did the exact same thing.
Ran a scanner check thinking it could be a bad sensor, even tho I don't have a check engine light.
Everything seems to be ok there. At first it read 0 for the map sensor as far as the vacuum but that straightened up on its own the next time I ran the scanner. Also the map sensor was reading 5.5 volts(its a 5v sensor) and wasn't fluctuating but I swapped that out with a new one and it still didn't change.
So its gotta be the lower intake then right? I mean the guy told me it was the intake and I figured since it was a plastic intake that had to be it but no. How does a smoke test work? Does it show where the leak is or just gives you a broad idea as to where it could be?? If its not the lower intake could it be one of the heads maybe? Because I really don't want to pull the heads if I don't have to.
This is a really nice car and I got it for cheap but now im pouring money into with no luck so im kinda afraid to replace the lower intake and get the same result.If its likely to be one of 4 or so things and I cant narrow it down i am gonna cut bait and sell it cause i am broke. So thanks in advance for any responses and for wasting your time if this is something duh simple.
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 2, 2010, 6:36 PM
Post #2 of 5
(3301 views)
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Re: 96 Olds Eighty Eight Racing idle (3800)
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Did that upper intake include a new throttle body? The smoke test pumps smoke into the intake system so you can watch for where it leaks back out. They should have been able to be more specific.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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eberg86
New User
Aug 2, 2010, 6:54 PM
Post #3 of 5
(3295 views)
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Re: 96 Olds Eighty Eight Racing idle (3800)
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Thanks for the quick response
No it was just the plenum, some fittings,and the gaskets.
And thats what I thought but I cant get a hold of the guy and I wasn't there to see it
But apparently he saw it and knows its just kinda mean he didnt tell me that. O well ill have someone run another one or can I do it myself?
(This post was edited by eberg86 on Aug 2, 2010, 6:55 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 2, 2010, 6:57 PM
Post #4 of 5
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Re: 96 Olds Eighty Eight Racing idle (3800)
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Sure you can if you own a $1000 smoke machine.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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eberg86
New User
Aug 2, 2010, 7:07 PM
Post #5 of 5
(3284 views)
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Re: 96 Olds Eighty Eight Racing idle (3800)
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Yea all I should have asked was the smoke screen question huh? Kinda obvious none pain the ass next step.
Yea sorry about that really and thanks for the help.
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