Engine Ping Problem, Help!
Thread Starter
Pro
Joined: Mar 2008
Posts: 552
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From: Dubuque Iowa
Engine Ping Problem, Help!
1987 Corvette Z52 with a 4+3 and 76,000 Miles.
So I get this engine ping only under heavy throttle, and only when the engine temp is above 190 degrees. A few weeks ago I had the chevy dealership diagnose the problem and they said it was a bad EGR. Well I finally got around to replacing the EGR today.
It still pings...
The engine runs absolutly perfect otherwise. It has good idle, and great throttle response. The ping sounds like a big rattle coming from the engine compartment and will happen somewhere in the middle of the powerband, and when it stops higher in the powerband i feel noticibly more power. The ping must be causing the engine to retard.
Has anyone had this problem? Could anyone help me diagnose this problem? The vette is just no fun to drive if you can't ever get on it...
So I get this engine ping only under heavy throttle, and only when the engine temp is above 190 degrees. A few weeks ago I had the chevy dealership diagnose the problem and they said it was a bad EGR. Well I finally got around to replacing the EGR today.
It still pings...
The engine runs absolutly perfect otherwise. It has good idle, and great throttle response. The ping sounds like a big rattle coming from the engine compartment and will happen somewhere in the middle of the powerband, and when it stops higher in the powerband i feel noticibly more power. The ping must be causing the engine to retard.
Has anyone had this problem? Could anyone help me diagnose this problem? The vette is just no fun to drive if you can't ever get on it...
Thread Starter
Pro
Joined: Mar 2008
Posts: 552
Likes: 2
From: Dubuque Iowa
I should mention that I run 93 Octane.
I have been searching some posts and it seems to be somewhat common for L98's. I am going to try some top engine cleaner tomorrow. I just wish this problem would go away haha.
I have been searching some posts and it seems to be somewhat common for L98's. I am going to try some top engine cleaner tomorrow. I just wish this problem would go away haha.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
As soon as the ECM sees a signal from the knock sensor it pulls timing out at a rate /time period as set in the calibration on the memcal.
Check timing is at factory 6 degrees before checking anything else.
If KC is faulty or disconnected car will run like #@%& across the range and throw a code.
Check timing is at factory 6 degrees before checking anything else.
If KC is faulty or disconnected car will run like #@%& across the range and throw a code.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Just my opinion, but if it were the knock sensor you wouldn't, I don't think feel that power in the higher RPMs, simply because if the KS detects knocks it will retard timing, and if it does that you won't feel increased performance. Another thing is the octane you're running........doesn't do a damn thing for your 87, 87s were (or I should say required at the time) to run 87 octane! Per my 87 owners manual! Base timing is a good thing to check, original base for an 87 was 6*, mine runs better at 8*. I do use SeaFoam once a yr. and that helps clear carbon (which can cause pinging or knocking,removes condensation in the tank) and also helps keep the fuel system clean.
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Melting Slicks
Joined: Mar 2008
Posts: 2,444
Likes: 342
From: SC
Just my opinion, but if it were the knock sensor you wouldn't, I don't think feel that power in the higher RPMs, simply because if the KS detects knocks it will retard timing, and if it does that you won't feel increased performance. Another thing is the octane you're running........doesn't do a damn thing for your 87, 87s were (or I should say required at the time) to run 87 octane! Per my 87 owners manual! Base timing is a good thing to check, original base for an 87 was 6*, mine runs better at 8*. I do use SeaFoam once a yr. and that helps clear carbon (which can cause pinging or knocking,removes condensation in the tank) and also helps keep the fuel system clean.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
One other thing. You said the problem was diagnosed as an EGR, and you replaced that, well, 95% of the time when a EGR code is thrown it usually is the EGR switch, cheap part, not the EGR itself. So watch for an EGR code to re-surface, and mine was an intermittent.
Thread Starter
Pro
Joined: Mar 2008
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From: Dubuque Iowa
From what I can tell, most of the additional EGR components are discontinued... Solenoid, switch, temp sensor... I had a hard enough time getting the corect EGR. I ordered it 3 times through the local parts store and the correct part number came but evertime the EGR wasn't correct, had a different base. Finally the right one in the same box and part number as the others came in.
Thread Starter
Pro
Joined: Mar 2008
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From: Dubuque Iowa
*Update*
I checked out my timing and it was advanced off the tab... So I set it at about 7 degrees, and it doesn't ping anymore!!
However, the car doesn't seem to be as fast... It runs great and all but it seemed quicker before I changed the timing.
What would be an optimal timing setting where my engine would be just as quick and not ping?
I checked out my timing and it was advanced off the tab... So I set it at about 7 degrees, and it doesn't ping anymore!!
However, the car doesn't seem to be as fast... It runs great and all but it seemed quicker before I changed the timing.
What would be an optimal timing setting where my engine would be just as quick and not ping?
Last edited by ride250s; Nov 24, 2008 at 12:02 PM.
Thread Starter
Pro
Joined: Mar 2008
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From: Dubuque Iowa
I just ran some gm top engine cleaner through it, and I got a lot of smoke, but not out of the tail pipe! I think it was coming from an emissions tube on the passenger side exhaust manifold. Is this bad?
Advanced
Joined: Aug 2008
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I am going through this same thing right now! This is driving me nuts! My 1990 does the same thing at mid range throttle...bogging down then at 3/4 to full throttle... BAM the power comes back. I have a KS code and an EGR code. Can I just disconnect the KS or put in a resistor? I hope we can get to the bottem of this. ZR1clone
Thread Starter
Pro
Joined: Mar 2008
Posts: 552
Likes: 2
From: Dubuque Iowa
I am going through this same thing right now! This is driving me nuts! My 1990 does the same thing at mid range throttle...bogging down then at 3/4 to full throttle... BAM the power comes back. I have a KS code and an EGR code. Can I just disconnect the KS or put in a resistor? I hope we can get to the bottem of this. ZR1clone
So check your timing!
