Well,Obviously nothing is guaranteed...but I was thinking more on a level of how "correct" is this kind of fix knowing that you are kind of subverting something that is there to protect your investment...
My problem seems to be quite a bit different than Craig's...only getting one set code (43 EST), and it's intermittent. Got a scan tool hooked up and let someone drive it while I watched the info. Sure would have liked Diacom, but I could see the info. Sometimes the code will set right away from a cold startup. Most of the time it won't come on until after going into closed loop. I'll be driving along with no SES light and when I start from a standstill, there it is like a punch in the face. SLOW acceleration out of nowhere.
Knock counts on the scan tool after a 20min hot engine drive counted no more than 6. When the driver would accelerate, the knock retard was up to 20deg right away...never more that 20, never less. Different starts (more / less pedal) produced the same timing retard. The other values in the scan appeared ok...A/F ratio moving in an expected manner, crosscounts by the O2 sensor climbing rapidly, coolant temp, MAP, MAT, TPS volts and percent fine...never any other codes set...just this one.
I even took the "advice" of my GM service manual and went through the flowchart for the ESC system to test the knock sensor with an AC voltmeter, but I never saw *any* AC voltage from the sensor. Checked my ground to make sure it was ok, and the ground was fine. I don't exactly know if any of this points to the possibility of a bad sensor, but it's the only part of the knock sensing system that hasn't been replaced. Got the most recent EPROM release from GM (has knock "module" on the memcal).
Bruce talked about reading the plugs...this sounds like a good idea, but I don't have the experience to know what to look for under this type of situation. How can you "see" which cylinder is under detonation if it is at all? I changed the plugs / wires / cap & rotor all about a week ago, and every plug that came out looked the same. Slightly browned, but clean and the insulator and tip were all intact. No oil residue, no white powdery coating...is this telling me anything I should be picking up on? I could just go out and replace the sensor for another $50, but I don't know if that is the problem, and I won't learn anything about what is going on here. Anything else to look for in reading?
DK
At 06:05 AM 6/22/00 -0400, you wrote:
> How "safe" is it actually to do this? Nothing is totally safe. There are no guarantees, even with things all oem. I have a knock sensor > problem with my 91 LB9...no audible knock and quality gasoline. Can't > solve the problem. Are the pllugs showing detonation? Replaced the prom, but still get intermittent codes... What codes? I > wouldn''t mind a fix real soon since every time I hit the gas I get 20 deg > retard right away. Really slows the thing down quite a bit. Well what are you running?. Gotta a diacom file?. What actual diagnostics have you done Grumpy > > DK > > At 01:42 PM 6/22/00 -0700, you wrote: > >Hi Craig, > >I had a problem with the sensitivity on my 92LT1. Ended up using a straight > >+ 45 degree M/F 1/4 pipe fittings to move away from the block. Now it works > >great. The teflon tape and less torque deal did 0 for me. Just remember > >before you do any of this make sure you have no audible detonation and the > >plugs show no signs of detonation. > > Jim > >Subject: Knock Sensor Question > >Seems I read somewhere you can 'adjust' the sensitivity of the knock sensor > >by using teflon tape on the threads, or screwing it in tighter or looser.... > >can someone verify this and explain how this works? This is for an '85 > >L98..... > >Thanks! > >Craig M. ---------------------------------------------------------------------------- To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes) in the body of a message (not the subject) to majordomo@lists.diy-efi.org
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