Help with knock retard
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From: Macedonia ,OH
Car: Formula
Engine: 6.0 LSX
Transmission: 4L60E
Axle/Gears: 9 Bolt 3:27
Help with knock retard
All of a sudden I seem to be getting massive knock retard at 2000 while crusing at 70MPH with no load on the engine. I'm getting anywhere from 15-39 degrees retard making the car shake and stumble. only until i press on the throttle more then 1/2 way does it go back to 00 and the car takes off. Also Fromt a stand still I get about 25 degrees retard all the way to 3000 RPM. And more more thing while going 30 and downshifting it'll spike to 40 degrees max retard. Timing is at 8* new knock sensor, Disabled EGR in the chip with no change, unplugged maf and ran that with no change. I'm at a total loss. WOT Spark advance is at 24* and crusing spark is at 34* degrees. My only guess is that the ECM is bad. I cant possibly think anything else is wrong. TPS is working fine and gradually rising. No matter when chip I use, Stock , Ed Write, my own modified it all does the same. Never used to until like 3 days ago. Car is an 89 TPI 350
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Joined: Apr 2001
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From: USA
Car: yy wife, crazy.
Engine: 350, Vortecs, 650DP
Transmission: TH-350
Axle/Gears: 8.5", 3.42
Have you checked your EGR to make sure it's working?
I noticed you disabled it, but that can cause more knock at cruise than anything else.
I understood HOW the EGR works, but I never understood WHY the EGR works. Everyone I ever asked said "It cools the combustion temps"... which I didn't understand because exhaust is HOT!! How can putting it in the intake tract help???
But here's what I found. 
That last question is what I thought. 
Shows how smart I'm not. 
Here's more....
So...... check the EGR. 
I noticed you disabled it, but that can cause more knock at cruise than anything else.
I understood HOW the EGR works, but I never understood WHY the EGR works. Everyone I ever asked said "It cools the combustion temps"... which I didn't understand because exhaust is HOT!! How can putting it in the intake tract help???
But here's what I found.
The purpose of the exhaust gas recirculation process was to simply put a small, carefully metered amount of exhaust gas back into the combustion chamber. Exhaust gas has already spent its fuel, so to speak, and is considered an inert gas and will not support combustion. This precise amount of recirculated inert gas slows the burning process in the combustion chamber where NOx is produced. Slowing the burning process lowers the temperature during combustion, thereby reducing or eliminating nitrogen oxide production. This action is most needed during cruise conditions and not at idle or heavy throttle conditions. Some may still incorrectly believe that the EGR is supposed to recycle the exhaust gas - burning it twice must be enough to reduce emissions, right? Wrong.
Shows how smart I'm not. Here's more....
We just said the exhaust gas won't support combustion - it's already been burned. So, the main purpose? Reduce NOx. The side benefits? Better fuel economy for one, and maybe performance as well. Consider some of the advanced strategies for EGR flow control on some of the later engine applications. The inert exhaust gas actually displaces a small amount of space in the combustion chamber, which in turn reduces a small amount of volume that the air/fuel charge occupies. This can have an effect on fuel economy, albeit slightly, if the EGR valve is malfunctioning.
Thread Starter
Supreme Member
iTrader: (8)
Joined: Jan 2000
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From: Macedonia ,OH
Car: Formula
Engine: 6.0 LSX
Transmission: 4L60E
Axle/Gears: 9 Bolt 3:27
OK i'll look into that I sure hope that its not that. i do not want to pull my superram off
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Joined: Jul 1999
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From: Sacramento, CA
Car: 89 Iroc
Engine: 383
Transmission: 700R4
Axle/Gears: 3.45
Originally posted by Mkos1980
OK i'll look into that I sure hope that its not that. i do not want to pull my superram off
OK i'll look into that I sure hope that its not that. i do not want to pull my superram off
It hasn't thrown any codes yet and my pinging *seems* to have disappeared even though I am running more timing (8º now and was at 0º before).
I'm not taking that thing off unless I absolutely have to.
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