HELP!!!! fuel trims goin nuts!!!
05-19-2005, 12:20 PM
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HELP!!!! fuel trims goin nuts!!! ok ive got a problem..... first off a heads up, 00' s-10 blazer LQ4 swap t-73 turbo custom manifolds and downpipe svo 38lb/hr injectors (brown top) tuning with hp tuners.
ok the problem im having is at idle the fuel trims are -10ish for B1 &B2 but at PT the fuel trims start to freak out and read B1 -27ish and B2 +9ish now if i blip the throttle it clears up and starts to run fine again but then goes back to acting weird. At times the 2 will switch and vise-versa (B1 +9ish B2 -27ish)
now those #s are just examples, but thats were it seems to act up...
I asked before about my o2 sensors and there location but never got a straight answer.. I have them located inline (about 4 inches apart)in the downpipe about 2' from the outlet of the turbo, COULD this location be affecting anything? Should i relocate them before the turbo? (I have always heard its hard on them)
I have the inovative wideband on the truck and its running 14.3-7 when driving normal and 10.0-3 when WOT so i know its still a real rich when WOT but when driving normal it reads good until the trims start to act up then it starts to read 13.5-16.5 ish bouncing back and forth. The truck starts to miss and sounds like its loading up until you blip the throttle then it clears up for a few seconds and then starts to repeat the whole process.
Any help is GREATLY appreciated
Blake
ok the problem im having is at idle the fuel trims are -10ish for B1 &B2 but at PT the fuel trims start to freak out and read B1 -27ish and B2 +9ish now if i blip the throttle it clears up and starts to run fine again but then goes back to acting weird. At times the 2 will switch and vise-versa (B1 +9ish B2 -27ish)
now those #s are just examples, but thats were it seems to act up...
I asked before about my o2 sensors and there location but never got a straight answer.. I have them located inline (about 4 inches apart)in the downpipe about 2' from the outlet of the turbo, COULD this location be affecting anything? Should i relocate them before the turbo? (I have always heard its hard on them)
I have the inovative wideband on the truck and its running 14.3-7 when driving normal and 10.0-3 when WOT so i know its still a real rich when WOT but when driving normal it reads good until the trims start to act up then it starts to read 13.5-16.5 ish bouncing back and forth. The truck starts to miss and sounds like its loading up until you blip the throttle then it clears up for a few seconds and then starts to repeat the whole process.
Any help is GREATLY appreciated
Blake
05-20-2005, 11:09 AM
#3
If you're still running the stock VE table, that's where I believe you need to start...a good VE tuning session or two or three.
Your LTFT behavior sounds fine for a mis-tuned VE and/or MAF table. Watch your LTFT Cell field while blipping the throttle, you should observe this data changing also...expect your LTFTs for both banks to change as the PCM hops from Cell to Cell.
Your LTFT behavior sounds fine for a mis-tuned VE and/or MAF table. Watch your LTFT Cell field while blipping the throttle, you should observe this data changing also...expect your LTFTs for both banks to change as the PCM hops from Cell to Cell.
05-20-2005, 01:08 PM
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That (thermal history) behavior sounds like cold or
crusty O2s to me. Post-turbine the gas is going to
be expansion-cooled, maybe at idle it's just too
much (low EGT to begin with, cooled more on the
outlet side).
I think there might be something weird could happen,
if the two "front" O2 sensors are in the same pipe;
Bank2 can push on Bank1 readings & vice versa,
they might start stepping on each others' toes and
go to chest-bumping.
crusty O2s to me. Post-turbine the gas is going to
be expansion-cooled, maybe at idle it's just too
much (low EGT to begin with, cooled more on the
outlet side).
I think there might be something weird could happen,
if the two "front" O2 sensors are in the same pipe;
Bank2 can push on Bank1 readings & vice versa,
they might start stepping on each others' toes and
go to chest-bumping.
