2001 Yukon xl SLT 1500 4wd 5.3L Major Electrical Gremlin (New ECM Still won't run HELP!!)

Handy Man

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Help!! Multiple DTC's!! 2001 5.3l Gmc Yukon XL SLT 1500 4wd w 190,000 mi
Originally Unable to get SMOG Cert due to SES MIL light illum. (or Inc. Cat Monitor)
Currently has P0101, P0155, P0300, & p0756 (after replacing ECM, Coils, Wires, & Plugs)
Previously had P0171 that wouldn't go away ( the following has transpired over approx last 18 mo's)
Initially the service engine soon light (MIL) came on found P0171 code.
Erased code, Cat Monitor won't complete before another stored P0171 DTC illum's MIL
B1 short fuel trim varied from -20 to +25 but typical was -5 to +5,
B1 long fuel trim rarely went below +25 and up to +40 at times
B2 short fuel trim avg. -2.5 to +2.5, long fuel trim avg -14.8 to +15,
Note; after each repair I would erase codes and do GM drive cycle. all monitors would Complete
except the Cat monitor then mil illum w p0171
since then have replaced the following:
O2 Sensors B1S1 & B1S2 (p0171 still)
New fuel pump & filter, Press 48 psi, pulse 39-40psi (p0171 still)
Vacuum leak test (no leaks detected)
New air fltr, Mass Air Flow Snsr, Battery, Pos & Neg Batt cables, Alternator, Cleaned all obvious Ground's (p0171 still)
Smoke press. test intake, found very small intermittent wisps around intake #3 cyl
Replaced Intake manifold gaskets, (p0171 still) (Also new water pump, Radiator, Oil & Fltr,(unrelated to drivbility issues)
No codes but still Cat monitor won't complete and after numerous drive cycles
and intermittent MIL (it would go off by itself) found intermittent p0171 usually pending
but stored when MIL stayed illum) also engine would intermittently sputter and hickup at higher revs on freeway with blinking then steady then no MIL (p0171 at times stored usually pending & sometimes P0300 pending, MIL intrmtntly on & off by itself other than that engine performance was pretty good with no MIL's for days / weeks at a time. (still no Smog cert. Cat monitor doesn't fail it just won't complete. Then.....
Suddenly started running really rough, coughing, sputtering, no power, no throttle response, (no rpm's except in P or N) or eventually (3-10 sec's w thrtl deprssd) when manually placed in L1, upon manual shift to higher gear at higher rpm 3k-5k rpm drop and cough, and frequently stall when shifted even at higher revs.
MIL constantly Flashing or On steady. Found Numerous DTC's Stored and Pending,
Lean Bank 1, Multiple/Random Cylinder Misfire, MAF out of Range, EGR oor, Shift Solenoid Malfunction, Throttle Position Sensor Error, O2 Sensor oor B1S2 & B2S2, Evap Rec. Systm Mlfnctn, VSS Error,
Removed ECM and after visual inspection (connectors and visible wiring, smell, etc...) Reinstalled.
Running like Shit after a minute or two, Idles fine but a little rough. Multiple DTC's again
Decided at this point that the ECM must be faulty.
Replaced ECM w/ Remanufactured and Pre Programmed ECM (matched to orig VIN prgrming)
Engine crank but won't run for more than .5 sec.
After sorting out V.A.S. issues (key relearn) engine starts & barely runs w blinking MIL. P0300 DTC
Replace Coils, Plugs, and Wires. Reset MIL, Starts and runs OK? within first mile (minute) starts sputtering. gets worse, within 2 miles (or approx 2-3mins) no throttle response (xcept in N or P), fuel light illum & gauge sporadicly goes to E then back to 1/4, but confirmed at least 1/4 tank, no power, seems to occur or get worse as engine warms up. cold start engine runs and drives OK? for about less than 5 min's or under 2 miles
then it sputters and dies. cranks but wont run with DTC's P0101, P0155, P0300, P0756.
Starts and drives (when cold?) but not for very long or far.
Kinda at a loss here as far as what to check next? I'm thinking wiring, Grounding problem?
My scan tool is limited to OBDII emissions only so not really much help.
Any suggestions, advice, or Tech info will be greatly appreciated Thx
 

rockola1971

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Search Big 3 ground wires. Id clean, repair, retighten all the big grounds. Firewall to engine block rear, ground at chassis directly under driver door near the firewall (on chassis) and check its other end, ground off battery and its other end. Wire brush the terminals and where they are bolted to. Clear all codes and see what comes back. Just FYI, The downstream O2 sensors have nothing to do with how your engine runs. They are only there to warn you of a failed catayltic converter. You may have B1 converter bad or the o2 you put in there is bad, wrong, wiring harness problem. I always replace upstream o2 sensors as a set. While you have the hood up and when you get to the point of restarting the engine, how about letting us know what your alternator output is (battery charge voltage).
 
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Handy Man

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alternator output under full load is 14.2v @ 1200 rpm in prk (frt heater fan hi, rr htr fan hi, a/c compressor on, hi beams, fog lights, rr wndw defrost, drvr & pssngr seat htrs lo, I also have a 12vdc 25A solar panel up top to provide supplemental charging for the 2 grp 26 gel cells that run an AC Inverter (1500w) to power my laptop and 19" monitor and Bose Sound Pod . oh, and thanx 4 th suggestions. I was planning on doing thorough rework of all ground connections I can find. I believe there are around 56 total. inside and out.
 

rockola1971

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alternator output under full load is 14.2v @ 1200 rpm in prk (frt heater fan hi, rr htr fan hi, a/c compressor on, hi beams, fog lights, rr wndw defrost, drvr & pssngr seat htrs lo, I also have a 12vdc 25A solar panel up top to provide supplemental charging for the 2 grp 26 gel cells that run an AC Inverter (1500w) to power my laptop and 19" monitor and Bose Sound Pod . oh, and thanx 4 th suggestions. I was planning on doing thorough rework of all ground connections I can find. I believe there are around 56 total. inside and out.
Looks good on the alternator output. Id just pay attention for now on the big 3 ground connections. They are the ones that could definitely cause your problems. Our chassis is notorious for funky stuff to happen with the PCM and BCM when one or more of those grounds is corroded or broken. Do this all in order. You dont want to be throwing parts at it to find out it was simple bad ground. PCM and Stealership programming can get expensive.
 
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Handy Man

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Completely redid 5 major ground points to bare metal w dielectric compound. still running ******. P0300 w mil blinking at startup where it runs ok. then steady on after warm up when operational efficiency decreases as. temp increases. at operating temp (205f+-) no power or response to throttle input at all (except in N or P) w DTC's P0101, P0300, P0404. (note; new ecm, maf snsr, plugs, wires, coils, O2 snsrs B1 S1&2, fuel pump & filter, intake manifold gaskets, battery, pos & neg batt cables, alternator, not chronologically accurate list)
 

Doubeleive

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I would check and elliminate a couple possible issue's
1. do a backpressure test
2. check the MAF
just to rule them in/out
 

rockola1971

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Next I would check FPR and see if vac line to it is wet (gas). Pull a plug after running engine for a minute and see if it is substantially wet also.
 

Fless

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SWAG has a cam-crank correlation been done with an advanced scan tool?
 

Axel62

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Help!! Multiple DTC's!! 2001 5.3l Gmc Yukon XL SLT 1500 4wd w 190,000 mi
Originally Unable to get SMOG Cert due to SES MIL light illum. (or Inc. Cat Monitor)
Currently has P0101, P0155, P0300, & p0756 (after replacing ECM, Coils, Wires, & Plugs)
Previously had P0171 that wouldn't go away ( the following has transpired over approx last 18 mo's)
Initially the service engine soon light (MIL) came on found P0171 code.
Erased code, Cat Monitor won't complete before another stored P0171 DTC illum's MIL
B1 short fuel trim varied from -20 to +25 but typical was -5 to +5,
B1 long fuel trim rarely went below +25 and up to +40 at times
B2 short fuel trim avg. -2.5 to +2.5, long fuel trim avg -14.8 to +15,
Note; after each repair I would erase codes and do GM drive cycle. all monitors would Complete
except the Cat monitor then mil illum w p0171
since then have replaced the following:
O2 Sensors B1S1 & B1S2 (p0171 still)
New fuel pump & filter, Press 48 psi, pulse 39-40psi (p0171 still)
Vacuum leak test (no leaks detected)
New air fltr, Mass Air Flow Snsr, Battery, Pos & Neg Batt cables, Alternator, Cleaned all obvious Ground's (p0171 still)
Smoke press. test intake, found very small intermittent wisps around intake #3 cyl
Replaced Intake manifold gaskets, (p0171 still) (Also new water pump, Radiator, Oil & Fltr,(unrelated to drivbility issues)
No codes but still Cat monitor won't complete and after numerous drive cycles
and intermittent MIL (it would go off by itself) found intermittent p0171 usually pending
but stored when MIL stayed illum) also engine would intermittently sputter and hickup at higher revs on freeway with blinking then steady then no MIL (p0171 at times stored usually pending & sometimes P0300 pending, MIL intrmtntly on & off by itself other than that engine performance was pretty good with no MIL's for days / weeks at a time. (still no Smog cert. Cat monitor doesn't fail it just won't complete. Then.....
Suddenly started running really rough, coughing, sputtering, no power, no throttle response, (no rpm's except in P or N) or eventually (3-10 sec's w thrtl deprssd) when manually placed in L1, upon manual shift to higher gear at higher rpm 3k-5k rpm drop and cough, and frequently stall when shifted even at higher revs.
MIL constantly Flashing or On steady. Found Numerous DTC's Stored and Pending,
Lean Bank 1, Multiple/Random Cylinder Misfire, MAF out of Range, EGR oor, Shift Solenoid Malfunction, Throttle Position Sensor Error, O2 Sensor oor B1S2 & B2S2, Evap Rec. Systm Mlfnctn, VSS Error,
Removed ECM and after visual inspection (connectors and visible wiring, smell, etc...) Reinstalled.
Running like Shit after a minute or two, Idles fine but a little rough. Multiple DTC's again
Decided at this point that the ECM must be faulty.
Replaced ECM w/ Remanufactured and Pre Programmed ECM (matched to orig VIN prgrming)
Engine crank but won't run for more than .5 sec.
After sorting out V.A.S. issues (key relearn) engine starts & barely runs w blinking MIL. P0300 DTC
Replace Coils, Plugs, and Wires. Reset MIL, Starts and runs OK? within first mile (minute) starts sputtering. gets worse, within 2 miles (or approx 2-3mins) no throttle response (xcept in N or P), fuel light illum & gauge sporadicly goes to E then back to 1/4, but confirmed at least 1/4 tank, no power, seems to occur or get worse as engine warms up. cold start engine runs and drives OK? for about less than 5 min's or under 2 miles
then it sputters and dies. cranks but wont run with DTC's P0101, P0155, P0300, P0756.
Starts and drives (when cold?) but not for very long or far.
Kinda at a loss here as far as what to check next? I'm thinking wiring, Grounding problem?
My scan tool is limited to OBDII emissions only so not really much help.
Any suggestions, advice, or Tech info will be greatly appreciated Thx
I won’t repeat my 2003 version of your 2001 suffering… Yikes! On any given Sunday, one might just light it on fire and drive away…
 

Fless

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He may have done that, still working on it, or fixed it and drove on. Been 2 months since the OP's been on. Would be nice to know if anything got fixed.
 

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