Intermittent Lean Fueling
04-10-2013, 08:28 PM
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Intermittent Lean Fueling One side of motor is running dead lean.
8.1L motor/ 4L80e / Rock crawler
I have been slowly learning and tuning the motor over the last couple months. No major problems. I have gotten to the point of suspecting running out of fuel pump capacity. To log FP I have purchased an Aeroforce fuel pressure sensor and 5v power supply.
I installed the fittings and sender on the fuel rail. I went ahead and cranked up the motor to check for leaks. No problems. Motor fired up, idled like normal for about a minute. I shut it down and proceeded to wire up the gage to my HPTuner interface.
Tapped a 12v switched circuit, wired up the 5v supply, verfied the output leg at 5v with meter. Finished wiring. Setup sensor in HPT.
I had trouble with the interface connecting to the PCM. I tried a dozen connect sequences before I found the loose connection on the serial connector side of interface. During this trial and error I probably started the motor 4 or 5 times. On one startup the motor was real rough sounding. I assume now it was running lean.
Attached is the log file from the first startup where I had the interface connected and scanning. Motor starts up fine, runs for 40 seconds and then looses fueling to one side of the motor. I have dual wide bands but I don't know which side is currently pluged to which input. Motor runs lean for 12s, then clears up, then runs lean again for 12s. Then i shut it down.
On the next start up and every start since, the motor stays lean.
I used the VCM controls to force the fuel trim on, and bank 1 attempts to recover but maxes out.
I suspect I have pulled a ground loose but I can not find it. I have run a jumper ground from the battery to the local ground post, no change. I have checked all the fuses with meter. FP gage shows very low pressure in HPT, but I have verified 50 psi with mechanical gage.
What should I check next?
8.1L motor/ 4L80e / Rock crawler
I have been slowly learning and tuning the motor over the last couple months. No major problems. I have gotten to the point of suspecting running out of fuel pump capacity. To log FP I have purchased an Aeroforce fuel pressure sensor and 5v power supply.
I installed the fittings and sender on the fuel rail. I went ahead and cranked up the motor to check for leaks. No problems. Motor fired up, idled like normal for about a minute. I shut it down and proceeded to wire up the gage to my HPTuner interface.
Tapped a 12v switched circuit, wired up the 5v supply, verfied the output leg at 5v with meter. Finished wiring. Setup sensor in HPT.
I had trouble with the interface connecting to the PCM. I tried a dozen connect sequences before I found the loose connection on the serial connector side of interface. During this trial and error I probably started the motor 4 or 5 times. On one startup the motor was real rough sounding. I assume now it was running lean.
Attached is the log file from the first startup where I had the interface connected and scanning. Motor starts up fine, runs for 40 seconds and then looses fueling to one side of the motor. I have dual wide bands but I don't know which side is currently pluged to which input. Motor runs lean for 12s, then clears up, then runs lean again for 12s. Then i shut it down.
On the next start up and every start since, the motor stays lean.
I used the VCM controls to force the fuel trim on, and bank 1 attempts to recover but maxes out.
I suspect I have pulled a ground loose but I can not find it. I have run a jumper ground from the battery to the local ground post, no change. I have checked all the fuses with meter. FP gage shows very low pressure in HPT, but I have verified 50 psi with mechanical gage.
What should I check next?
