Engine over revs after a repair.
Thread Starter
Safety Car
Joined: May 2003
Posts: 3,814
Likes: 105
From: Dearborn Heights Michigan
Engine over revs after a repair.
Replaced a broken valve spring on my cammed and modified LS1 and upon starting the motor revs to the maximum and will not slow. Shut it off immediately fearing damage to something. Tried several times with the same result. Double checked to make sure spring, keepers, pushrod, etc., are correctly installed.
Any thoughts please?
Thanks.
Any thoughts please?
Thanks.
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
No throttle cable on these cars. Throttle blade stuck open, floor mat causing pedal to stick. Horrible vacuum leak from the brake booster line being disconnected. Check the easy stuff first. Start with floor mat then brake booster vacuum line then remove hose from front of throttle body and check the blade.
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Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
Make sure the MAP sensor plug is in the MAP sensor. Check all the wiring to make sure it is plugged in, and plugged in correctly. Check the pins on the male plugs to make sure none have been bent. Check all the grounds at the frame and chassis terminations to make sure none have been broken or were not reinstalled correctly. It could also be the throttle control module. It's mounted right in front of the PCM.
The thing that is throwing me is if anything is wrong with the throttle circuit, there are numerous checks, both electrical and positional, and there are several 'sanity' checks that should put the motor into 'Reduced Power Mode' if any failure of this type occurs.
Was the PCM reprogrammed prior to restarting it after you fixed your springs?
Man, that must have been like,
, when that happened.
One last thing to check would be to see if any wires got caught between anything and shorted or crimped.
The thing that is throwing me is if anything is wrong with the throttle circuit, there are numerous checks, both electrical and positional, and there are several 'sanity' checks that should put the motor into 'Reduced Power Mode' if any failure of this type occurs.
Was the PCM reprogrammed prior to restarting it after you fixed your springs?
Man, that must have been like,
, when that happened.One last thing to check would be to see if any wires got caught between anything and shorted or crimped.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The engine will go into REDUCED POWER if there is a disparity between the ordered and actual throttle position. Like it was previously mentioned, it sounds like a massive vacuum leak. Brake booster hose,,Map sensor fitting, etc.....
BC
BC
Race Director
Joined: Mar 2008
Posts: 12,413
Likes: 502
From: Rio Rancho NM
No throttle cable on these cars. Throttle blade stuck open, floor mat causing pedal to stick. Horrible vacuum leak from the brake booster line being disconnected. Check the easy stuff first. Start with floor mat then brake booster vacuum line then remove hose from front of throttle body and check the blade.
Safety Car
Joined: Aug 2000
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From: San Rafael CA
Drifting
Joined: May 2005
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From: Littleton Colorado
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
Like BC said, the throttle blade being stuck will shut the car down in reduced power mode, so I nixxed that idea. TPS voltage must equate to pedal position. When the two disagree, shutdown.
Thread Starter
Safety Car
Joined: May 2003
Posts: 3,814
Likes: 105
From: Dearborn Heights Michigan
Haven't been able to get back to the problem yet. Probably not until next week. Thanks for all the suggestions. Will check them all out and report back.
For sure it's not the floor mat!
For sure it's not the floor mat!