Dead gas pedal trying to drive when cold started and not warmed up
04-03-2018, 10:55 AM
#1
11 Second Club
Thread Starter
iTrader: (43)
Dead gas pedal trying to drive when cold started and not warmed up 6.0 engine, rear mount 76mm turbo, 80# injectors, 3 bar OLSD tune
Once warmed up a few minutes, it still seems slightly LEAN, (at tip-in) but at cold start, and limited coolant temp, if trying to driveaway after just a minute or less, it acts as if the car is not getting fuel...it's that lean. Like it won't take any fuel...or there isn't anywhere to get it from.
Never really noticed it before, but I also (almost) always let it warm up a few minutes before attempting to drive off.
What parameters should I LOG to help diagnose this?
I attached a copy of tune, but wondering if I do a cold start log, then what specific parameters should I include, along with the basic stuff?
Once warmed up a few minutes, it still seems slightly LEAN, (at tip-in) but at cold start, and limited coolant temp, if trying to driveaway after just a minute or less, it acts as if the car is not getting fuel...it's that lean. Like it won't take any fuel...or there isn't anywhere to get it from.
Never really noticed it before, but I also (almost) always let it warm up a few minutes before attempting to drive off.
What parameters should I LOG to help diagnose this?
I attached a copy of tune, but wondering if I do a cold start log, then what specific parameters should I include, along with the basic stuff?
Last edited by rel3rd; 02-06-2020 at 08:42 AM.
04-03-2018, 10:58 PM
#4
Once cold started it should be in open loop. Afr will be richer to help with warm up. Look in the open loop tables for these settings. Once around 160* ecm will convert to closed loop but u dont run o2s so your full open loop.
Im betting at idle its sitting around 60kpa map/VE.
Once moving your map changes and so does VE. Basicly meaning u need more tuning for drivability. If its stumbling its probably going lean with not enough fuel on a cold engine. Best to let it fully warm up.
Im betting at idle its sitting around 60kpa map/VE.
Once moving your map changes and so does VE. Basicly meaning u need more tuning for drivability. If its stumbling its probably going lean with not enough fuel on a cold engine. Best to let it fully warm up.
04-04-2018, 06:14 AM
#6
11 Second Club
Thread Starter
iTrader: (43)
Thanks for the reply. I'm sloooowwwwly, but surely, getting it's streetability back into a useable tune.
Evidently, the car (built & dynotuned down in Texas, I am in MD.) was tuned just for WOT, and very dependent on the methanol. I have made the non-methanol numbers a bit richer, so if I have a meth injection failure, it is still "safe". It was in the neighborhood of 13:1 with meth getting it high 11:1 afr. Now it's mid to high 11:1, with the meth (at 8 psi or more) forcing it into the high 10:1 afr ratio. I know it's killing power, but rather not swap head gaskets every few few weeks, lol.
The car had no wideband until I installed one.
The car also didn't have (still doesn't) it's upstream narrowband O2 sensors, or even a functional IAT sensor. It was zip-tied to something under the hood, so measured under hood temp, not intake air temp.
I used a later model style screw in IAT, into the charge pipe between the methanol injection nozzle and the throttle body, which seems to have helped.
The old (previously installed) Duramax MAP sensor's numbers were all over the place, so I've recently swapped in a new EFISource 3 bar sensor, which meant all new calibration numbers, and some tune changes, yet again.
I also have an 8 foot wideband extension harness coming, which will allow me to swap the wideband to AFTER the turbo (already welded in the bung), since I have a REAR MOUNT TURBO and a 4 inch "downpipe". Right now, the wideband sensor is installed in the original left side narrowband location...
Probably a dumb question, but re-adding the narrowband sensors, should/would I simply need to adjust the open/closed loop enable temp? It looks like that's the only thing changed, set to 285* right now.
.
Evidently, the car (built & dynotuned down in Texas, I am in MD.) was tuned just for WOT, and very dependent on the methanol. I have made the non-methanol numbers a bit richer, so if I have a meth injection failure, it is still "safe". It was in the neighborhood of 13:1 with meth getting it high 11:1 afr. Now it's mid to high 11:1, with the meth (at 8 psi or more) forcing it into the high 10:1 afr ratio. I know it's killing power, but rather not swap head gaskets every few few weeks, lol.
The car had no wideband until I installed one.
The car also didn't have (still doesn't) it's upstream narrowband O2 sensors, or even a functional IAT sensor. It was zip-tied to something under the hood, so measured under hood temp, not intake air temp.
I used a later model style screw in IAT, into the charge pipe between the methanol injection nozzle and the throttle body, which seems to have helped.
The old (previously installed) Duramax MAP sensor's numbers were all over the place, so I've recently swapped in a new EFISource 3 bar sensor, which meant all new calibration numbers, and some tune changes, yet again.
I also have an 8 foot wideband extension harness coming, which will allow me to swap the wideband to AFTER the turbo (already welded in the bung), since I have a REAR MOUNT TURBO and a 4 inch "downpipe". Right now, the wideband sensor is installed in the original left side narrowband location...
Probably a dumb question, but re-adding the narrowband sensors, should/would I simply need to adjust the open/closed loop enable temp? It looks like that's the only thing changed, set to 285* right now.
.