2000 Cadillac STS engine reving

Tiny
DANIELF
  • MEMBER
  • 2000 CADILLAC STS
  • 4.6L
  • V8
  • FWD
  • AUTOMATIC
  • 174,000 MILES
I just replaced the air intake manifold coupling and gaskets. After putting everything back together and cleaning well. Now when I stay the car, the computer think I have the gas pedal to the floor. I don't know how to trouble shoot this one. I've checked everything I replaced, no leaks everything is in its proper spot. Help?
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Sunday, May 17th, 2015 AT 3:19 PM

11 Replies

Tiny
HMAC300
  • EXPERT
Try driving it the iac may have to reset itself as you pulled the manifold off. Or there is a massive vacuum leak. Do it if there is little traffic around. If it continues have a pro look at it.
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Sunday, May 17th, 2015 AT 3:47 PM
Tiny
DANIELF
  • MEMBER
I'm not able to even put it into gear. As soon as I fire it up it jumps to 4,000 rpm and is bouncing. There is a loud hissing sound but I can't pinpoint it's exact location. Trying to figure it out. But everything I removed looks clean and I see no oil coming from the manifold gaskets. I'm assuming it's something on the inside side of the throttle body. Throttle body does not move but something says it's getting air. Or could it be an injector issue? I know sometimes cleaning things can cause other problems. I was really careful and only had to clean the o rings. I know the code for the throttle body position sensor is p0106, when I run diagnostics I have no pcm codes. Now I try to stay out and it's just stalling. Had to relieve fuel pressure during procedure. Never done that before, maybe didn't do it right when I cranked it back up? I have no idea lol
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Sunday, May 17th, 2015 AT 6:39 PM
Tiny
HMAC300
  • EXPERT
If there is a loud hissing you have a vacuum leak causing it to rev high you'll have to find it, check larger hoses like going to brake etc. Check around where you replaced the gaskets an dpull engine cover off so you can check around manifold if you can' t find anything have a pro check it for you. Make sure all your air ducts are installed correctly leading to engine and no holes in them.
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Monday, May 18th, 2015 AT 7:05 AM
Tiny
DANIELF
  • MEMBER
So if installed the gaskets incorrectly it would only take air in? No oil coming out? If so that may be the problem, I've been checking for oil around it. Any chance that would be the throttle position sensor? And is it ok to remove and reinstall manifold with same gaskets? I guess I just need to take it back apart and check my work. I'd hate to have to get it towed to my mechanic.
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Monday, May 18th, 2015 AT 7:28 AM
Tiny
DANIELF
  • MEMBER
It's just stalling now
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Monday, May 18th, 2015 AT 7:30 AM
Tiny
HMAC300
  • EXPERT
No it isn't ok to reuse intake gaskets. Recheck all your work I fit didn't' do it prior to working on it then you screwed something up. And it wouldn't be the tps. If anything the iac would need to readjust which you do by driving.
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Monday, May 18th, 2015 AT 7:35 AM
Tiny
DANIELF
  • MEMBER
Ok, thank you so much. I will walk back through everything when I get home tonight.
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Monday, May 18th, 2015 AT 7:42 AM
Tiny
DANIELF
  • MEMBER
Ok, took everything back apart and seen that the rubber flange on the plenum was folded because of the tight squeeze. So fixed that and replaced everything. Only getting revs to 2000 rpm now. But won't stay running long enough for me to get out and listen for anymore hissing. I'm gonna let it cool and check all my bolts and look over everything again.
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Monday, May 18th, 2015 AT 4:10 PM
Tiny
DANIELF
  • MEMBER
And when I press the gas pedal it wants to choke out then revs up and shuts off. Tried putting it in gear to take it around the block. Brakes were stiff and was jumping and stalled in the driveway. I noticed the rps get higher when I turn the fan on?
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Monday, May 18th, 2015 AT 4:15 PM
Tiny
HMAC300
  • EXPERT
Did you put new manifold gaskets in like I said? Have a pro look at it, it 's still something you have done and I can't give any more suggestions.
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Monday, May 18th, 2015 AT 4:27 PM
Tiny
DANIELF
  • MEMBER
Yes I did, ok thanks for all your help
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Monday, May 18th, 2015 AT 4:46 PM

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