p38 4.6 lpg nightmare

Bought a p38 a few months ago , drove to a petrol station to refuel with gas and petrol, found it extremely hard to restart again, Had to hold throttle to floor for it to fire and it only picked up and actually ran on about the fith attempt at this , although when running it went well. mileage clocks were not working, had them fixed at cost of £200, replaced the crank sensor, no different ,eventually traced warm starting problem to dodgy temperature sensor . before i found this out i noticed no air filter so i fitted one , jeep ran ok for about a week although warm start still a problem, and then it started to miss fire and cut out when driving and would hardly drive at all. removed air filter again replaced the temp sensor and jeep started well then no problems but developed a misfire at 1800-2000 revs so had to keep kicking it down and revving it to make it go.. this worked ok for short journeys of a few miles .. on journeys of over 6 miles it would misfire badly and fail to drive , i had to really coax it to get home , fitted a second hand MAF metre and it sounded worse, disconnected the battery before removal and re fiting,, Jeep is presently sitting in my drive after a real struggle to get home today after a round trip of 35 miles, only other thing that showed up ion computer was an air temp sensor in airbox, currently waiting on new one ,, at a real loss here prev owner said it never missed a beat when he had it.. but it obviously did have the warm starting problem , he made sure it was cold when i picked it up any input would be greatly appreciated , thanks in advance

Well, FIRST off, it is a Range Rover! A Jeep is a copy, a very poor copy at that.. I digress.

The P38 is a V8 and as such, can suffer from camshaft wear.

However, since it is LPG converted, my 1st port of call would be O2 sensors, plug leads and plugs. The V8 is particularly prone to a dislike for poor plugs and leads. And since you have replaced the MAF, it seems next in line.

Don't worry Doo has a thing about cam shafts

biketeacherdave said:

Don't worry Doo has a thing about cam shafts

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Only because it's a known

What's your take on it Dave?

On mine you can get the engine just to run on petrol if required and leave the lpg on standby as it were.
See if it changes anything if you have that option.
Camshafts/valvetrain tend to be noisy if worn to the extent that it causes problems like this.
Diagnostics is the way to go tbh.
I used to have a Cherokee once - I don't now

I use the term jeep loosely as i tend to apply it to any 4x4 as most people do in Northern Ireland , Sorry for the confusion,
the car has only developed this misfire from no where . tonight i disconnected the battery and reset the ecu as defined on forums on the net, seems to be a little better and it could now be learning to operate all over again, i was thinking since i put the air filter in , it confused the ecu and then this misfire began,, unknowingly i replaced the MAF only to confuse the ecu even more. so when i disconnected the battery and reset ecy this time i did so with air filter in place ,,, the vehicle started easily but would hardly reverse and cut out ,, i managed to get it to run and it was terrible it hunted for revs for about 6 mins and i didnt touch the throttle at all, hen after that i revved it and it revved clean.. but still would not drive,, after eventually getting it to drive , coaxing it slowly at first, i found it still to have the misfire around 1800=200 revs,, i took it for a run for a few miles and found it to gradually get better and better,, although still not fixed i will drive it some more tomorrow and see how it pans out and post my findings on here, thnks for the help guys . iv a feeling its things that have been done rather than things that have failed has caused this e.g the removal of the MAF replacing the temp sender etc i believe the ecu needs to recalibrate in some way. but as im not a RR techie im only guessing

Neil Brownlee said:

I use the term jeep loosely as i tend to apply it to any 4x4 as most people do in Northern Ireland , Sorry for the confusion

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Wiv found a jeep user, can we burn him.................

Bobsticle said:

Wiv found a jeep user, can we burn him.................

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Sounds like he may be going to BURN his RR if he can't get to the bottom of its problem, plenty of the Jeep brand have been destroyed by disgruntled owners, usually making a youtube video whilst in the destruction process!
And I have to say if I was having similar problems with my Landy truck, (I call them truck, not Jeep), I would be most temped to make my own video production for general viewing on youtube as the truck met its demise.

Another current post for you to read that begins with a filling station visit, not sure if it's sorted yet or even if it's connected to your problem, but you both developed a similar issue after putting fuel in the tank.
https://www.landyzone.co.uk/land-rover/misfiring-at-2-3000rpm.309292/

Do these models have a vapour recovery system with charcoal canister?

what year rr?

What does it run like if you can get it to switch to lpg is it the same smoother or rougher? as that would rule out fuel problem. Have you changed the plugs and ht leads when was the lpg last serviced or filter changed?

Have you checked that the ht leads are connected to the coil pack in the correct order very easy to get wrong worse if its the thor engine
.

My take on it is.....plugs, leads and coil packs as its misfiring on both ????? No air filter would not cause this problem so don't worry about that, maf maybe does it run the same with the maf connected and dissconnectted ???? You really do need a geniuin maf for these to work properly

Genuine maf didn't cure @ukadamwest 's. Both he and this op encountered problems after refuelling.
The noise from the parts canon is quite deafening...