94 LT1 Rough running
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Joined: Jun 2006
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94 LT1 Rough running
This old chestnut!!! just replaced all 3 oxygen sensors due to rough running/misfiring/stalling/ not restarting ...just been for a run (about 25mins) and its so much smoother so its nearly sorted but misfire on acceleration recurred on the way home.... car mileage is 50000, have fitted new hd battery, adjustable fuel regulator, fuel filter changed leads but not plugs yet....I dont think it is opti...people have mentioned egr valve/dirty mass air meter or ignition control module. ...any thoughts..
Last edited by ukpete; Jun 29, 2008 at 02:44 PM.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Check the fuel pressure to make sure you are not running excessive fuel pressure. To much will make it run to rich.
Does the digital readout for the temperature sensor perform normal with expected temperatures?
A stuck open EGR would cause you some problems. Check it cold, see how it moves with your fingers.
I would also check the codes just to see if something shows up.
Does the digital readout for the temperature sensor perform normal with expected temperatures?
A stuck open EGR would cause you some problems. Check it cold, see how it moves with your fingers.
I would also check the codes just to see if something shows up.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
This is off the cuff so take it with a grain of salt. Idling should be about 38 – 42 psi. And when you rev it, it should go to about 40 – 45 psi. I think anything much above 45 would be out of line and excessive. 
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
A little more info just FYI.
Actually it could very well be the opti. Don’t discount it by any means, its definitely in the running.
However, hears a recent post with symptoms very similar to yours where it really sounded like classic opti symptoms but with a slight twist. Turned out to be the ICM which kind of surprised me but just another similar set of symptoms like an opti.
http://forums.corvetteforum.com/show....php?t=2070919
Sometimes you just have to make a decision and try a part to see what might work after you diagnose it to death. I changed the ICM chasing a problem once but did not fix it. But now I have an extra part so next time I can eliminate or replace that item quickly. It can be changed in no time at all.
Actually it could very well be the opti. Don’t discount it by any means, its definitely in the running.
However, hears a recent post with symptoms very similar to yours where it really sounded like classic opti symptoms but with a slight twist. Turned out to be the ICM which kind of surprised me but just another similar set of symptoms like an opti.
http://forums.corvetteforum.com/show....php?t=2070919
Sometimes you just have to make a decision and try a part to see what might work after you diagnose it to death. I changed the ICM chasing a problem once but did not fix it. But now I have an extra part so next time I can eliminate or replace that item quickly. It can be changed in no time at all.
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Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Is it only happening after reaching a certain temperature? Are you getting a check engine light?
A couple of people are having the same issue as you and have diagnosed it as the pcm, food for thought.
Here's a link to their thread:
http://forums.corvetteforum.com/show....php?t=2055839
A couple of people are having the same issue as you and have diagnosed it as the pcm, food for thought.
Here's a link to their thread:
http://forums.corvetteforum.com/show....php?t=2055839
