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Tuner
2 BAR SD Tune LQ9, stuck in open loop
ive got an 05 SS truck with a 2 bar SD tune, wont go into closed loop... if I force it into closed loop via command, it will go into closed loop. ALL the parameters are being met for closed loop, no codes that would prevent it either. ive double and triple checked the tune for any little thing that might be stopping it from happening- its all good. everything is set at 131 or 155 deg for closed loop at LTFT, etc. STFT in open loop enabled as well, yet NO fuel trims or corrections are occurring, at all. there are NO FUEL TRIMS, period, unless commanded into closed loop. anyone come across this? ive been tuning for years and never seen this. it has had other issues, like throwing strange parameters that aren't possible to two different scanners of mine- like reading -64* advance, 41 msec on B2 injectors, etc. this is while the truck is running, and not missing- running normal. I was thinking maybe a bad PCM, but don't want to throw parts at it... any ideas?
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Senior Tuner
Post the tune. And a log.
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Tuner
KPtune1.0(2BAR.SD)basefile.hptI don't have a log file right now, partly as it never seems to log anything within even the parameters (and changes everytime I restart the log file...) but heres the tune. its just the basefile, (his old MAF tune the truck came in with + some VE table changes for a rough base; proper codes turned off/to no CEL)
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Tuner
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Tuner
KPtune1.0(2BAR.SD)basefileLOG1A.hplKPtune1.0(2BAR.SD)basefileLOG2.hplokay here is two logs, one is short. only time you see the fuel trims kick in is when commanded via the VCM scanner. also it went from showing crazy parameters like -60 deg advance while engine running normally... to now just showing several basic parameters as "unsupported". I downloaded and installed the latest version of HPT and scanner still doing the same thing. checked with Tech 2, everything does show normal on there (such as ignition advance... etc)
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Senior Tuner
Documents-hptuners-vcmscanner-vehicles Delete the contents of the folder, this should fix your scanner. Then find and fix your leak.
Last edited by mecanicman; 12-11-2014 at 12:07 AM.
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Tuner
fix what leak...? any idea about the closed loop issue??
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Senior Tuner
You have an air leak. Intake gaskets, broken
Manifold bolts. Something to that effect. Fix that and see what happens.
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Tuner
what makes you so sure of that? i didnt give you any specs on the motor, and its running like shit in the log... also even if it had a leak it should still be going into closed loop and trying to correct itself
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Senior Tuner
Bank 2 is out by about 31% while bank 1 is around 8%. As the idle looks reasonably steady I don't think its a miss. Looks like an air leak.
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Tuner
while you are correct, that a vacuum leak WILL cause that... its far from the only thing that can/will cause that. also, it is dead missing. traced the issue to fuel injectors, then to the PCM. used GM SI diagnostic to follow the issue, it also calls for a PCM. stripped the tape/loom off the inj wires all the way to the pcm. no issues, no short or open. seems the PCM drivers for the injector control circuit are not working properly. this would also explain the closed loop issues. installing the PCM tomorrow, we will see!
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Tuner
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