98 WOT timing issues
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Teching In
Joined: Oct 2003
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98 WOT timing issues I'm working on tuning my 98 TA A4. I have 2 timing issues. First is what appears to be burst knock indicated by the scanner (SnapOn mt2500)under WOT operation. It indicates 3-4 degrees of knock retard without ever indicating knock 'yes'. Second problem is that the indicated timing advance under WOT is anywhere from 4-8 degrees lower than programmed in the timing tables. It appears that at times it is averaging timing between the low and high octane tables. I am using tunercat to tune it and I can't seem to find any tables or constants relating to burst knock other than burst knock vs coolant temperature. I would swear I have read about a similar problem on here before but I could not find it by searching. Any help would be much appreciated.
It sounds like either a spark modifier table or the notorious 98 knock sensor problem.
https://ls1tech.com/forums/generation-iii-external-engine/736391-somthing-every-98-ls1-owner-should-do.html
https://ls1tech.com/forums/generation-iii-external-engine/736391-somthing-every-98-ls1-owner-should-do.html
Thread Starter
Teching In
Joined: Oct 2003
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All of the modifier tables that I have examined appear to have no effect at the temperature, throttle opening , map reading, etc. that I am operating in. This is the first time I have heard of the knock sensor issue. This car was built 6/98 but I suppose I will have to pull the intake to know for sure what is in there. It would appear that 98s are the 93s of the LS1 F bodies.
Staging Lane
Joined: Aug 2005
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I went to update the knock sensors on my '98, only to find it already had the newer ones. Door sticker says built 6/1998.
Not to say you definately have the new ones, and also it's been a known issue that the knock sensor connectors can get corroded from water getting down in the intake valley. there is a GM TSB on it.
I am no timing guru, but check to see if you motor is going lean at the RPM/iraflow areas where you are getting KR.
Also, from what I gather from these forums, the PCM constantly interpolates between the high an low oct. timing tables depending on knock activity, so there might be why your logged timing does not match the high octane table.
But are you tuning SD mode without the MAF? Because then the '98's only use the backup VE table, and I think only the high oct. timing table as well.
Not to say you definately have the new ones, and also it's been a known issue that the knock sensor connectors can get corroded from water getting down in the intake valley. there is a GM TSB on it.
I am no timing guru, but check to see if you motor is going lean at the RPM/iraflow areas where you are getting KR.
Also, from what I gather from these forums, the PCM constantly interpolates between the high an low oct. timing tables depending on knock activity, so there might be why your logged timing does not match the high octane table.
But are you tuning SD mode without the MAF? Because then the '98's only use the backup VE table, and I think only the high oct. timing table as well.
TECH Fanatic
Joined: Mar 2004
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From: Laguna Niguel, CA
Where on the door sticker does it say when it was made?
And is it true that the dealer can tell you if you had the older or the newer style knock sensors just by typing in your vin number?
And is it true that the dealer can tell you if you had the older or the newer style knock sensors just by typing in your vin number?
