P2761, burned boot, and misfire underload at RPM
05-08-2010, 03:10 PM
#1
P2761, burned boot, and misfire underload at RPM I've done some research here but haven't been able to diagnose my issue.
Setup:
There are NO performance mods done.
Items replaced include:
The front o2s were NOT replaced.
Under load, it has a misfire(I believe). In diagnosing the issue, I found the following:
According to my FSM for the engine, code P2761 is related to automatic transmission. Shouldn't have been in the PCM but OTOH, I don't think it should have been popping it up anyways.
Would the burned boot cause a misfire only under load? I would think if a burned boot was causing a misfire, it would always misfire.
Related to the burned boot, I'm not sure why it got burned... I did not see it leaning on anything that would burn it. Would I be better off using stock wires with the metal "guards"? I removed the stock wires for the MSD ones.
I have not looked at the spark plugs themselves yet. They are the stock ones that came with the truck from the factory.
I haven't done an official data log on it yet. I'm using a program called Diagnose by Roadman. I used Jet DST to program the PCM with a "emailed" program.
I've been talking with the tuner but so far, not much luck. I don't believe the misfire is related to the tune because it had the same misfire with a mildly modified stock tune.
Any help would be greatly appreciated.
Setup:
- LQ4 from 2004 Silverado 2500HD (came with 4l80e) It had 30k miles on it when I swapped it in. I've put about 15 miles on it during my farting around the block.
- NV4500
- PCM tuned for manual (I think)
- Stock wiring harness reworked (only VSS wires removed and replaced) all other wires were extended, shortened, or removed
- Swapped into an old Toyota Land Cruiser
There are NO performance mods done.
Items replaced include:
- Spark plug wires (msd wires)
- VSS
- Air diverter valve and wiring removed
- Rear o2 sensors and wiring removed
- Hooker headers
The front o2s were NOT replaced.
Under load, it has a misfire(I believe). In diagnosing the issue, I found the following:
- Error code: P2761
- Burned boot on one spark plug wire
According to my FSM for the engine, code P2761 is related to automatic transmission. Shouldn't have been in the PCM but OTOH, I don't think it should have been popping it up anyways.
Would the burned boot cause a misfire only under load? I would think if a burned boot was causing a misfire, it would always misfire.
Related to the burned boot, I'm not sure why it got burned... I did not see it leaning on anything that would burn it. Would I be better off using stock wires with the metal "guards"? I removed the stock wires for the MSD ones.
I have not looked at the spark plugs themselves yet. They are the stock ones that came with the truck from the factory.
I haven't done an official data log on it yet. I'm using a program called Diagnose by Roadman. I used Jet DST to program the PCM with a "emailed" program.
I've been talking with the tuner but so far, not much luck. I don't believe the misfire is related to the tune because it had the same misfire with a mildly modified stock tune.
Any help would be greatly appreciated.
05-08-2010, 09:17 PM
#2
I just checked the o2 sensors and they looked good. BUT, it appears that my exhaust guy screwed the pooch *mad*
I am running a single exhaust. The passenger side crosses under the oilpan and hooks into the driverside. But here lies the problem: The shop put the driverside o2 sensor BEHIND where the passenger side connects. In my mind, this causes the driver side to read 2x the o2 reading and thus leans out the driverside engine.
Does my logic seem sound?
So, in order to get the exhaust shop to fix it, I'm looking at a 45 minute drive. Is it possible to "tune out" the o2 sensors so I can make that drive?
I am running a single exhaust. The passenger side crosses under the oilpan and hooks into the driverside. But here lies the problem: The shop put the driverside o2 sensor BEHIND where the passenger side connects. In my mind, this causes the driver side to read 2x the o2 reading and thus leans out the driverside engine.
Does my logic seem sound?
So, in order to get the exhaust shop to fix it, I'm looking at a 45 minute drive. Is it possible to "tune out" the o2 sensors so I can make that drive?
