Jump in RPM
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08-26-2016, 11:49 PM
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#2
08-27-2016, 07:07 AM
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08-27-2016, 07:53 AM
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08-27-2016, 02:53 PM
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The RPM increase about 500 RPM. transmission is a manual 6 speed 102k miles. Banks engine brake and edge tow chip 40 hp
The RPM increase only happens while towing my 5th wheel toy hauler very heavy my guest load about 13k pounds its like it won't let engine over speed. I'm thinking PCM because there is no ground to the GPR the EOT has a false reading.. I disconnected it to smooth out the idle.
This is what I've done so far: replaced ICP,CPS,EOT,fuel filter, Batteries, GPR, clean EBP tube, repaired VCH ( $.50 fix) and checked continuity from PCM connector to all sensors and IDM to injectors, clean oil and proper level in HPOP, checked all injectors all have correct resistance no shorted or open circuits to injectors.
I did all these things 2 year ago checked all connectors twice and it started to run correct, but started again this year. Both times these problems started I was at high elevation between 5k and 8.5k 85*to 50*F.
I'm thinking the PCM is not responding to the altitude. I'm stumped!
The RPM increase only happens while towing my 5th wheel toy hauler very heavy my guest load about 13k pounds its like it won't let engine over speed. I'm thinking PCM because there is no ground to the GPR the EOT has a false reading.. I disconnected it to smooth out the idle.
This is what I've done so far: replaced ICP,CPS,EOT,fuel filter, Batteries, GPR, clean EBP tube, repaired VCH ( $.50 fix) and checked continuity from PCM connector to all sensors and IDM to injectors, clean oil and proper level in HPOP, checked all injectors all have correct resistance no shorted or open circuits to injectors.
I did all these things 2 year ago checked all connectors twice and it started to run correct, but started again this year. Both times these problems started I was at high elevation between 5k and 8.5k 85*to 50*F.
I'm thinking the PCM is not responding to the altitude. I'm stumped!
#5
08-27-2016, 07:10 PM
Thanks for telling us it's a manual trans. That would have been nice to know at the beginning. Most manual transmissions do not downshift on their own.
The PCM has NOTHING to do with the engine RPM!!!! ALL of the RPM control is YOU, via the shift lever. YOU put it in a gear and that determines the engine RPM.
Unless the clutch is slipping. That's the ONLY way the RPM can jump when YOU haven't moved the shift lever.
If the tach is showing the same RPM, but it sounds like the engine has sped up by 500 RPM, that's the engine cooling fan engaging. It's normal.
The PCM has NOTHING to do with the engine RPM!!!! ALL of the RPM control is YOU, via the shift lever. YOU put it in a gear and that determines the engine RPM.
Unless the clutch is slipping. That's the ONLY way the RPM can jump when YOU haven't moved the shift lever.
If the tach is showing the same RPM, but it sounds like the engine has sped up by 500 RPM, that's the engine cooling fan engaging. It's normal.
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08-27-2016, 08:05 PM
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