Need Some help w/ weird Knock
03-21-2006, 05:02 AM
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Need Some help w/ weird Knock I have a 00 Vette w/ A&A ATI kit.. pushing 5-6# of boost....
Right now I am getting this weird knock problem and I have been fighting it for a while.
In 4th gear I can mash it WOT all the way to 6k and get maybe 1* of knock around 57-58k, but when I am in 2nd or 3rd gear and do the same thing I will get 5-8* of knock same thing I will get knock from about 0.72 (g/cyl) @ 3800rpms all the way up to 6k WOT....
I changed my plugs and ran a can of sea-foam through the motor to clean all the carbon and crap out...
Also i already have the maxium amount timing set at 6* WOT....
Right now I am getting this weird knock problem and I have been fighting it for a while.
In 4th gear I can mash it WOT all the way to 6k and get maybe 1* of knock around 57-58k, but when I am in 2nd or 3rd gear and do the same thing I will get 5-8* of knock same thing I will get knock from about 0.72 (g/cyl) @ 3800rpms all the way up to 6k WOT....
I changed my plugs and ran a can of sea-foam through the motor to clean all the carbon and crap out...
Also i already have the maxium amount timing set at 6* WOT....
03-21-2006, 03:27 PM
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My guess is that you are running lean. I'm thinking the engine spools faster in 2nd and 3rd, therefore runs out of fuel quicker than in 4th. I would also be interested to see what the commanded AFR is.
03-22-2006, 05:10 AM
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the commanded AFR is 1.1992 across the whole rpm range... the last dyno i had the wideband hooked up and it was 10.2 the whole way across the rpm...
03-22-2006, 10:51 AM
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Could be... MAF is dirty or not correctly dialed in, or VE table is not dialed in.
Log PCM calculated airflow and see if the knock occurs when the airflow increases sharply.
Log PCM calculated airflow and see if the knock occurs when the airflow increases sharply.
03-22-2006, 11:03 AM
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Looking at the attached graph, looks like there's an issue with fuel. Couple of observations:
Also, as an aside. If the PE multiplier is 1.1992, that works out to a commanded AFR of 12.24 (14.68/1.1992). If you were seeing 10.x AFR, then something else is adding fuel.
I'll send you a PM with my email. If you want, send me your bin file and I'll take a look at it.
- Injector duty cycle is 85%
- Injector durations are 20 msec. This seems like an awful long duration to me
- Timing advance is only 2.5*
Also, as an aside. If the PE multiplier is 1.1992, that works out to a commanded AFR of 12.24 (14.68/1.1992). If you were seeing 10.x AFR, then something else is adding fuel.
I'll send you a PM with my email. If you want, send me your bin file and I'll take a look at it.
Last edited by muncie21; 03-22-2006 at 11:20 AM.
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03-22-2006, 12:15 PM
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From my understanding (and I could be wrong here), KR is a result of:
1) Lean condition
2) Too much timing
3) False knock
From your graph, I would eliminate #2 from the equation.
1) Lean condition
2) Too much timing
3) False knock
From your graph, I would eliminate #2 from the equation.
03-22-2006, 01:07 PM
#9
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Originally Posted by muncie21
From my understanding (and I could be wrong here), KR is a result of:
1) Lean condition
2) Too much timing
3) False knock
From your graph, I would eliminate #2 from the equation.
1) Lean condition
2) Too much timing
3) False knock
From your graph, I would eliminate #2 from the equation.
5) Intake air too hot
6) Spark plugs too hot
7) Bad gas
8) Too much oil (thru PCV)
9) CR too high
What about #7 and #8...?
And lean condition can be caused by airflow calculation not being correct (MAF, VE table, MAF table).