82 Corvette running problems
Melting Slicks
Joined: Mar 2006
Posts: 2,248
Likes: 67
From: Warrington PA
Finalist 2020 C4 of the Year - Unmodified
Real rich is a vacuum leak or O2 sensor. The 02 sensor would through a check engine light so think vacuum leak. Did you check the plenum? Also it really is a must on CFI to pull the plenum, clean and install the Felpro gasket. Its not much and its not hard if you take your time.
You said you checked the EGR valve with wD40??? The diafram is not what you need to check. Its the plunger under the EGR that lets exhaust into the intake. If its stuck open your car will never idle. But you said, manually you can hold the car at 5-700 rpm a bad EGR would make it run very rough at that rpm and so would a plenum leak.
Also the IAS motor should be kicking in on cold starts. Your idle should shoot up to 1700rpm when cold. If its not, that motor in the TB is not working and needs to be cleaned or replaced.
You said you checked the EGR valve with wD40??? The diafram is not what you need to check. Its the plunger under the EGR that lets exhaust into the intake. If its stuck open your car will never idle. But you said, manually you can hold the car at 5-700 rpm a bad EGR would make it run very rough at that rpm and so would a plenum leak.
Also the IAS motor should be kicking in on cold starts. Your idle should shoot up to 1700rpm when cold. If its not, that motor in the TB is not working and needs to be cleaned or replaced.
thanks for any info...................................T om
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
New question:
Just noticed my after market breather was cocked sideways, probably I did it messing around. Its and aftermarket as I do not have the stock air cleaner setup anymore. Two free standing air cleaners. Anyway, back to the topic, is the breather knocked sideways the same as a vacuum leak? Will it affect performance. Having a bit of a problem with surging lately.
Just noticed my after market breather was cocked sideways, probably I did it messing around. Its and aftermarket as I do not have the stock air cleaner setup anymore. Two free standing air cleaners. Anyway, back to the topic, is the breather knocked sideways the same as a vacuum leak? Will it affect performance. Having a bit of a problem with surging lately.
Thread Starter
Intermediate
Joined: Jul 2013
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I sprayed the WD-40 forty on the shaft for the plunger it then closed. I'm going to replace the EGR valve, 02 sensor, coolant sensor. Will also get the Plenum gasket. When I started it this morning it did start and idled about 500 rpm was a little rough. Listening to it run it doesn't sound quite right to me. I suspect vacuum leak though I have checked and could not find one. Another thought that a sensor is giving the ECM the wrong signal. Next weekend project. Thanks for the help
Thread Starter
Intermediate
Joined: Jul 2013
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Update: Replaced 02 sensor, and coolant sensor in front. Started car steel idles at about 300 and idles rough. Took it out for another drive about 1 mile acts like its running worse then will clear up and run rough again. I'm going to check the EGR to see if it stuck open. I also got a gasket for the plenum so I'm going to change that next and check the intake bolts. It does put out black smoke I noticed when I took it for a drive. Does not seem to be running as rich.
Thread Starter
Intermediate
Joined: Jul 2013
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OK this is what I have done so far: replaced throttle sensor, map sensor, coolant sensor, rebuilt both throttle bodies, replace plenum gasket checked intake bolts, replaced plugs, wires, rotor, cap, coil, vacuum hoses, 02 sensor, I ordered a new EGR valve but it was the wrong one but does seem to be working. Still running rich have put two sets of plugs in the car. at the rear exhaust both sides have a miss. Any suggestions
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Le Mans Master
Joined: Jul 2000
Posts: 6,664
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From: columbia city in
when the car does run ,how does the spray from the injectors look ?something is telling the computer to put out more gas .if all sensors have been replaced ,it may be the computer.just a quess.
Burning Brakes
Joined: Feb 2013
Posts: 1,173
Likes: 152
From: norway
Burning Brakes
Joined: Feb 2013
Posts: 1,173
Likes: 152
From: norway
OK this is what I have done so far: replaced throttle sensor, map sensor, coolant sensor, rebuilt both throttle bodies, replace plenum gasket checked intake bolts, replaced plugs, wires, rotor, cap, coil, vacuum hoses, 02 sensor, I ordered a new EGR valve but it was the wrong one but does seem to be working. Still running rich have put two sets of plugs in the car. at the rear exhaust both sides have a miss. Any suggestions
Melting Slicks
Joined: Mar 2006
Posts: 2,248
Likes: 67
From: Warrington PA
Finalist 2020 C4 of the Year - Unmodified
check the following:
1-ignition module
2-PROM chip
3-ECM
Last edited by 74 LS4-454; Aug 31, 2013 at 09:23 PM.
Thread Starter
Intermediate
Joined: Jul 2013
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would this cause it to run rich if there is a drip? It seems to have a miss from both sides of the exhaust pipes. When I removed the plenum there was black exhaust powder under it does this help with anything. Also could pvc cause it to run rich?
Melting Slicks
Joined: Mar 2006
Posts: 2,248
Likes: 67
From: Warrington PA
Finalist 2020 C4 of the Year - Unmodified
that is enclosed inside of the ECM.....
it (PROM chip) could along with a combination of other items that are not functiong properly....pcv could have a minor effect, pull the pcv out of its location and shake it. if you hear a rattle, most likely it is still good, if no rattle, replace it.
ECM is located in front of the battery box in back of the drivers seat. first thing to do is disconnect the battery before you try or do anything electrical. check all connections, you have access to the PROM which is under a cover on the ECM. if you find any unusual substance in the area, then there is something that is not right. you should have the Shop Manual for further troubleshooting. I will try to look up some additional info for you in the AM.
and you really need to check out the ignition module, which can be tested at most any local auto parts store.
did you recheck the timing and what did you come up with?
and you really need to check out the ignition module, which can be tested at most any local auto parts store.
did you recheck the timing and what did you come up with?
Last edited by 74 LS4-454; Aug 31, 2013 at 10:36 PM.
Thread Starter
Intermediate
Joined: Jul 2013
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on the EGR solenoid relay sensor has a broken peace on the vacuum to the EGR valve. I plugged it directly in the TB. I cant seem to find one of these sensors could this cause it to run rich not being hooked up? Any suggestions on what to use as a replacement sensor?