85' Vette Pinging Problem...STILL!!!
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
Just a though, had Bosch plugs in my 87 and had some issues, replaced with Delco's and new wires and cleared up the problem. Not sure if this will work for you, but just a though
Drifting
Joined: Mar 2003
Posts: 1,828
Likes: 214
From: Charlestown IN
Cruise-In V Veteran
Yes, when you take out the knock sensor, you should lose some coolant. It screws into the water jacket. It won't squirt out, but you should see some. When your motor is running, go to the passenger side, hood up, and drop a 1/2" extension about 12" long on its end against the top of the exhaust manifold. Hold it about 3" above the manifold. When it hits, you should hear the motor stumble as it retards the timing. This will let you know if the sensor is doing its job. The second thing you need to do is go to the ESC module and run a ground from the frame to the ground wire on the module. I use to know which one it is. You'll be surprised what that ground wire will do. Give it a shot. It's cheaper than a crate motor. 
Intermediate
Joined: Mar 2003
Posts: 31
Likes: 0
From: Irvine ca
The EGR valve has a vacuum line that goes to it. I disconnected that and applied a vacuum source to it. The diaphram should go up and stay up. Mine hissed and didnt move. Another way to check if you don't have a mityvac is to reach under the valve and push the diaphram up and hold your finger over the vacuum nipple....it should stay up when you stop holding the diaphram up.
A bad valve will not set a code on OBD1 cars. The ECM only checks the electrical components - solenoid and temp switch.
If the valve tests good...check the cheesey plastic tubes under the plenum for breaks...you can replace with vacuum hose if you need to. Lastly....if you need to replace the valve make sure to get the correct part. OEMs use a zillion different ones and I wouldn't trust the one Autozone shoves across the counter unless it is an EXACT match.
Gud luck!
A bad valve will not set a code on OBD1 cars. The ECM only checks the electrical components - solenoid and temp switch.
If the valve tests good...check the cheesey plastic tubes under the plenum for breaks...you can replace with vacuum hose if you need to. Lastly....if you need to replace the valve make sure to get the correct part. OEMs use a zillion different ones and I wouldn't trust the one Autozone shoves across the counter unless it is an EXACT match.
Gud luck!
Drifting
Joined: Jan 2002
Posts: 1,261
Likes: 4
From: Middle River MD
Originally Posted by ductape
The second thing you need to do is go to the ESC module and run a ground from the frame to the ground wire on the module. I use to know which one it is. You'll be surprised what that ground wire will do. Give it a shot. It's cheaper than a crate motor.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 136
Likes: 0
Okay, I just got back into town so now it's back to workin on the Vette. I haven't tried grounding the ESC because I don't know what wire I need to ground. Anyway, I replaced both the module and the knock sensor with brand new parts and it made no difference. BTW, I did take the knock sensor out and fix the lack of coolant problem I was having. Poked an ice pick through and got a hot coolant shower :o The only thing I can think of; if it is an electrical problem, is that there is a wire in the harness that's been cut. (i.e. the knock sensor wire.) But I doubt it. However, I will beat on the manifold and see what happens 
As for the EGR valve. I have heard many people suggest that I reach under the EGR diaphram, and push up on it. Even the manual I have says to do that. But how in the world am I supposed to get my big man hands in there to push up on it??? I have tried every angle I can think of and I can't get more than close enough to barely touch it. If I have to take the plenum off to do this, then I will just buy a new valve and replace it while I'm under there...even if it's not bad.
As for the EGR valve. I have heard many people suggest that I reach under the EGR diaphram, and push up on it. Even the manual I have says to do that. But how in the world am I supposed to get my big man hands in there to push up on it??? I have tried every angle I can think of and I can't get more than close enough to barely touch it. If I have to take the plenum off to do this, then I will just buy a new valve and replace it while I'm under there...even if it's not bad.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 136
Likes: 0
I tried the knock sensor test. No change. What gives??? I couldn't find a 1/2 drive extention at the house, so I used the end of a "Club" It's metal. Anyway, I tried it at 3" above, then 4" then I started tapping lightly...then harder...then harder...until I stopped because I didn't want to break anything. But Yeah no reaction from the engine. BTW. When I started the car up it smoked what looked like white smoke. I'm not 100% sure that it's not condensation because it's kinda cold and it's raining, but it's possable that I've blown the head gasket in the process of trying to solve my pinging problem. 
I'll check again in the morning.
I'll check again in the morning.
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Burning Brakes
Joined: May 2004
Posts: 1,182
Likes: 14
From: POINT PLEASANT NEW JERSEY
I had a similar problem with my 87 Trans am years ago. I went absolutely nuts trying to figure it out. It turned out to be something stupid. It seemed that whenever I put EXXON gas in it it would ping like crazy. Even with Premium. Its a far shot but try going with SUNOCO Ultra 94 or BP/AMOCO Ultimate for a month and see if it makes any difference. I went so far as to put a few gallons of Cam 2 in it to increase the octane further and it solved the Pinging.....then the car was stolen and I never saw it again...so I couldnt really say how long it would have run .....or how long I would have been able to afford Cam 2 every week either for that matter. All BS aside .. give the gas change a try. Sometime its something as simple as that!!!! Good luck. Oh by the way have you made any Mods...like Computer Chip? Hi flow exhausts, hollowed Cat??? or the like??? All can contribute to a screwed engine/ Pinging problem. 
Le Mans Master
Joined: Dec 2002
Posts: 6,715
Likes: 2
From: Santa Teresa New Mexico
Originally Posted by Chewch87
I had a similar problem with my 87 Trans am years ago. I went absolutely nuts trying to figure it out. It turned out to be something stupid. It seemed that whenever I put EXXON gas in it it would ping like crazy. Even with Premium. Its a far shot but try going with SUNOCO Ultra 94 or BP/AMOCO Ultimate for a month and see if it makes any difference. I went so far as to put a few gallons of Cam 2 in it to increase the octane further and it solved the Pinging.....then the car was stolen and I never saw it again...so I couldnt really say how long it would have run .....or how long I would have been able to afford Cam 2 every week either for that matter. All BS aside .. give the gas change a try. Sometime its something as simple as that!!!! Good luck. Oh by the way have you made any Mods...like Computer Chip? Hi flow exhausts, hollowed Cat??? or the like??? All can contribute to a screwed engine/ Pinging problem.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 136
Likes: 0
OKAY, I have started another chapter in my pinging Vette saga. Check it out here http://forums.corvetteforum.com/showthread.php?t=997991 
