Hi. I am new to this forum previously running defender TDis.

I am having an issue with a misfire, felt as a stuttering when my 2012 LR4 HSE LUX 5.0 is under load. It happens when driving slowly up steep hills. Interestingly only when the engine is running at temperature, when cold there is no issue. I have replaced both high pressure fuel pumps but the issue remains. Spark plugs are now and no visible issue with coils. I regularly use a good fuel cleaner and the gearbox is fairly new with just 16k miles and shows no faults.
has anyone come across the same issue and can share what they found to be the cause.
thanks

 

Misfires should throw a code do you have any codes at all ?

 

Thanks Richard
ill check my GAP tool again, but last time i looked there was no codes.
on the Land Rover diagnostic it showed a misfire but on the V8 it doesnt show where.
ill post again after checking.
mark

 

Richard
i checked codes yesterday and there are none for a misfire, no engine codes at all, but the issue is still present.
maybe my GAP tool doesn’t register. I can see fuel injector pulse widths which are all the same across the 8 cylinders at idle and at 1500 rpm, but haven’t looked at results under load.
whats interesting this issue is exaggerated under load and non existent when the engine is cold and for the driver feels like a light judder or stutter. After I’m cruising at 45mph and above I feel no issue.
appreciate any other insights for the experts in this forum
mark

 

@Parky2012 yea I hate those, could it be transmission hunting. Try S mode and manually select gears, it is a bit annoying but it would l rule out a transmission issue.

 

It’s a newer transmission, just 16k miles. It does happen in S mode as well.
no transmission faults are being thrown. What would caise transmission hunting and would it throw a fault..

based on live values from the gap tool i am attaching some screen shots , that to my limited knowledge of how to read it, shows a missfire somewhere.

 

@Parky2012 Sure looks like misfires, but if you check you have no codes at all correct ?

 

Thanks Richard,
Ill check…

 

Richard
here are the faults. Not sure if they are relevant to the issue

 

@Parky2012 nope those are some of the random codes these trucks get. The whole thing is weird I would expect a misfire code, my thought is what grade gas are you running. These things want 89 or 91 good quality gas.