Persistent misfire under load only

[powershift]

The GAP is oversold and illegal since they reverse engineered SDD and resold the software on a device. Its a lot like buying priated TV, but aside from that I'd focus on the missfire. It could be a coil pack, you gotta get your hands dirty and figure it out or hire a mechanic.

 

[greiswig]

The GAP is oversold and illegal since they reverse engineered SDD and resold the software on a device. Its a lot like buying priated TV, but aside from that I'd focus on the missfire. It could be a coil pack, you gotta get your hands dirty and figure it out or hire a mechanic.

I'd be interested in seeing your evidence for this. It was my understanding that the GAP tool was developed with some input from LR, and it's in pretty common use by people here.

 

[powershift]

I'd be interested in seeing your evidence for this. It was my understanding that the GAP tool was developed with some input from LR, and it's in pretty common use by people here.

Lets see evidence it is not? The SDD TOS is all you need. The GAP did not develop their tool in partnership with Land Rover. That is a total lie.

 

[greiswig]

One more piece of data from this, which I hope might point someone to what might be at the heart of this: this morning, when I was able to get it to misfire again (again, flooring it from 50mph), the misfire "stuck," with the engine running rough and obviously misfiring consistently right down to idle, until I cleared the code. Then everything smoothed right out. Does this help someone ID the problem?

 

[Rover Range]

When you have a misfire, the PCM cuts off the injector to that cylinder. So no raw fuel is going into the cat convertor.
When you erase the DTC, the PCM is starting fresh. Until the misfire is detected again.

 

[jlglr4]

Are you still getting misfire code/live data only in one cylinder? I was thinking the misfire was causing the fuel trim code, but that time recording of fuel trims you posted in the other thread is showing identical behavior in both banks. Fairly lean most of the time with massive lean spikes. I think a misfire can probably cause those lean spikes, but not in both banks at the same time if it's only one cylinder misfiring. Maybe clear the misfire code and re-run that fuel trim time recording at idle, and then holding the throttle steady around 1500 rpms, and again around 3000 rpms, just to see how the fuel trims hold up without the misfire. Maybe also look at fuel rail pressure demand and actual. I'm wondering if you have a general issue like a fuel pump getting weak, and it's just causing a misfire in one or two of the most susceptible cylinders under load.

 

[greiswig]

Thank you, @Rover Range for explaining that part. I assume, then, that the computer doesn’t care what is causing the misfire?

@jlglr4 Thank you as well. I’ll give that test a try. And yes, indications are only one cylinder misfiring. I recorded a log where only cylinder 4 was misfiring, although the code is for cylinder 5. I still don’t know which is correct.