4 Degrees Knock Retard
06-14-2005, 10:59 AM
#1
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4 Degrees Knock Retard Why the f**k does my VCM pull 4 degrees of knock retard, starting at 3600 rpm, at WOT? Can't figure it out!
Burst is set to 0.
Burst is set to 0.
06-14-2005, 11:06 AM
#2
TECH Senior Member
not getting any SES lights for knock sensors... correct?
4* is the max the PCM will pull at WOT, are you sure it's not detonating?
How much timing are you running? (or trying to run) and what octane gas?
4* is the max the PCM will pull at WOT, are you sure it's not detonating?
How much timing are you running? (or trying to run) and what octane gas?
06-14-2005, 11:10 AM
#3
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No SES lights.
No detonation.
27 degrees, then it pulls 4 down to 23.
104 u/l.
No detonation.
27 degrees, then it pulls 4 down to 23.
104 u/l.
Originally Posted by horist
not getting any SES lights for knock sensors... correct?
4* is the max the PCM will pull at WOT, are you sure it's not detonating?
How much timing are you running? (or trying to run) and what octane gas?
4* is the max the PCM will pull at WOT, are you sure it's not detonating?
How much timing are you running? (or trying to run) and what octane gas?
06-14-2005, 11:21 AM
#6
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It's all new FMS stuff, bumper to bumper. QTP headers, Y pipe, no cats, Magnaflow exhaust. It makes lots of noise but I can't hear any "rattles." The VCM just insists on puilling 4 degrees at 3600 rpm and up, even when banks 1 and 2 are at over 900 mv.
06-14-2005, 11:27 AM
#7
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check under the car to make sure the y-pipe isnt banging the tranny cross member. My y-pipe made some noise until i took it to the shop and had them tighten down on the clamps and flange a whole lot. Its a beast to adjust the QTP stuff to get it not to bang. For a quick fix stick some rubber between the y-pipe and spots closest to the chassis. If all else fails check to make sure no wires are pinched under the intake
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06-14-2005, 12:20 PM
#8
Is it always exactly 4 degrees when you get it? Or does it start at 4 and taper down to 0? If that's what's happening either your knock sensor harness is not plugged in or is grounding out against the valley cover, or your knock sensors got water in them. That would cause an ses light, but it could have been turned off.
06-14-2005, 01:49 PM
#9
Originally Posted by P Mack
Is it always exactly 4 degrees when you get it? Or does it start at 4 and taper down to 0? If that's what's happening either your knock sensor harness is not plugged in or is grounding out against the valley cover, or your knock sensors got water in them. That would cause an ses light, but it could have been turned off.
06-14-2005, 03:26 PM
#11
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It always knocks/retards at 3500 rpm and always pulls out 4 degrees of timing. The timing line on the scan graph is perfectly flat. It has got to be something easy and obvious.
06-14-2005, 08:51 PM
#13
Originally Posted by bickelfirebird
It always knocks/retards at 3500 rpm and always pulls out 4 degrees of timing. The timing line on the scan graph is perfectly flat. It has got to be something easy and obvious.
