KR from running too lean or something else?
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From: St.Louis, MO
KR from running too lean or something else? Logged a couple runs at the drag strip last night. I’m getting significant KR throughout the entire run. 1st gear was from 3.9* tapering to 3.1*. 2nd and 3rd gear continued to taper off until the end of the run where I was getting about 2.1* KR. There was never a time during the run where I was getting zero KR.
Other readings that may or may not have had an affect…IAT was as high as 118* at launch (thanks a lot Free Ram Air) and tapered to 81* at the end of 3rd gear going through the traps. Timing Advance was never higher than 28.5*. There’s a lot of other data like injector duty cycles and such that I don’t know how to interpret. I don’t know if that info is needed or not.
The only horsepower mods I have done over the winter are a SLP smooth air bellow and a Bauer ported TB. My car “sounds” lean but without a wideband O2, I guess there isn’t a way to know for sure.
What can cause true spark knock?
Other readings that may or may not have had an affect…IAT was as high as 118* at launch (thanks a lot Free Ram Air) and tapered to 81* at the end of 3rd gear going through the traps. Timing Advance was never higher than 28.5*. There’s a lot of other data like injector duty cycles and such that I don’t know how to interpret. I don’t know if that info is needed or not.
The only horsepower mods I have done over the winter are a SLP smooth air bellow and a Bauer ported TB. My car “sounds” lean but without a wideband O2, I guess there isn’t a way to know for sure.
What can cause true spark knock?
TECH Regular
Joined: Nov 2003
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From: Dallas
Originally Posted by PewterZ28
Logged a couple runs at the drag strip last night. I’m getting significant KR throughout the entire run. 1st gear was from 3.9* tapering to 3.1*. 2nd and 3rd gear continued to taper off until the end of the run where I was getting about 2.1* KR. There was never a time during the run where I was getting zero KR.
Other readings that may or may not have had an affect…IAT was as high as 118* at launch (thanks a lot Free Ram Air) and tapered to 81* at the end of 3rd gear going through the traps. Timing Advance was never higher than 28.5*. There’s a lot of other data like injector duty cycles and such that I don’t know how to interpret. I don’t know if that info is needed or not.
The only horsepower mods I have done over the winter are a SLP smooth air bellow and a Bauer ported TB. My car “sounds” lean but without a wideband O2, I guess there isn’t a way to know for sure.
What can cause true spark knock?
What can cause true spark knock?
What causes real knock?
- too much spark advance
- carbon build-up leading to hot-spots and detonation
- mixture too lean -> hotter combustion chamber -> detonation
- bad fuel
Hope this helps...
Thread Starter
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From: St.Louis, MO
O2 readings were bewteen .920 and .950 range at WOT. However, I noticed at idle they weren't oscillating between .999 and .100 like they usually do. The data was sort of "floating" around .200 volts with little to no fluctuation. Could this possibly be a sign of bad O2's?
One other thing that happend recently. Last week I had my car out for the first time since last November. While shifting from 2nd to 3rd I heard a shattering noise that sounded like brittle metal or glass breaking. I've heard two different theories. One being that it was one of my bullet mufflers, another being that it was a converter bolt. While I haven't had a chance to look at the converter bolts, I did look at the housing and there weren't any holes. Performance wise the car feels normal. I've heard that a loose flywheel or converter could also cause KR. What about a blown muffler?
Finally, can anyone explain what, if any, relationship there is between IAT, timing advance, and detonation?
One other thing that happend recently. Last week I had my car out for the first time since last November. While shifting from 2nd to 3rd I heard a shattering noise that sounded like brittle metal or glass breaking. I've heard two different theories. One being that it was one of my bullet mufflers, another being that it was a converter bolt. While I haven't had a chance to look at the converter bolts, I did look at the housing and there weren't any holes. Performance wise the car feels normal. I've heard that a loose flywheel or converter could also cause KR. What about a blown muffler?
Finally, can anyone explain what, if any, relationship there is between IAT, timing advance, and detonation?
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Joined: Sep 2003
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From: Atlanta, GA
the higher the Intake Air Temp, the less Timing is fed, because hotter air is less dense and more prone to detonation. Also the IAT can be used to calculate the MASS of air as well for fuel adjustments. Usually Speed density move p=vt(sp?), does this, there are times when the MAF is not available but usually on a 1/4 run its doing its work unless you turn it into a popsicle.
log your o2's again while cruising, both should be sweeping with the same peak and trough values (not at the same rate/time/sync) .
Also log when warming up. A bad heating element will show up cause the o2 sensor that has a bad heating element will take minutes (first start cool morning) versus 30-60 seconds to register a reading. I've been trying to track down a P0135 heater bank 1 s1 issue for a while, i think its my extensions i bought suck ***.
cause i can't catch one of the two o2's behaving any differently, cold or hot.
damn extensions.
log your o2's again while cruising, both should be sweeping with the same peak and trough values (not at the same rate/time/sync) .
Also log when warming up. A bad heating element will show up cause the o2 sensor that has a bad heating element will take minutes (first start cool morning) versus 30-60 seconds to register a reading. I've been trying to track down a P0135 heater bank 1 s1 issue for a while, i think its my extensions i bought suck ***.
cause i can't catch one of the two o2's behaving any differently, cold or hot.
damn extensions.
