P38 4.6 warm running problem

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Ray38

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Location
Watford
Hi all. My P38 had been parked up for about a month. On wednesday i went to take it out in the snow. It started fine and drove perfectly whilst it was warming up. However once warmed up it wouldnt run properly. It wouldnt rev out and it was back firing through the intake, wouldnt hold idle. I had to park it up for a couple of days untill i could go back and get it (today). So today i picked it up, and once again it started fine and ran perfectly whilst cold. On warming up the same problem came back, i was on the motorway and only really had power under full throttle where it would rev fine. I pulled over and let it cool for 15 mins. After pulling out (i had to floor it up to about 60) it was a bit hesitant at first, but then after that it ran fine all the way home and was sat on my drive for ages idling fine and reving lovely.

Now it seems it has fixed itself but i'd rather not take the chance. After searching the forums it seems it might be two things, the MAF or the cam sensor. Any opinions on that? Where would i find the cam sensor?

Thanks for any suggestions,

Ray
 
if its been backfiring through the intake my money would be on the MAF

killed my maf when my old one did it
 
run it for a few days before changing parts willi nilli, if the fault doesnt re appear just put it down to the weather/circumstances.

take it for a test drive on a cold morning see if it re appears!
 
Yer i will see if it comes back again before i do anything else, its just going to be at the back of my mind all the time if i dont do anything with it. Its a second car so doesnt get used that much at all at the moment so its not too important.

Thanks for the suggestions though guys
 
maybe if it doesnt get used very often its the cause of the issue?

i'd have a look for water ingress to anything electrial. i think even a bit of condensation can cause havoc!
 
Ok the problems still there. Can it be hooked up to any diagnostics machine to check faults or does it have to be a land rover specific one?
 
probably not if its tech2 that he has, you need a unit that will read iso 9141-2

i think vauxhall use kwp, you can try it.

you might be better with just a generic obd scanner rather than a manufacturer type!
 
Well i think ive diagnosed the problem. Out in it today it start playing up so i unplugged the maf and it drives perfectly again now. Will it cause any problems running it like this while i find a replacement? And what are these £40 jobbies off ebay like, am i better off getting a guniune second hand replacement.

Thanks
 
Right ive got a new MAF now and fitted it. It was all going well (well on and off throttle is a bit jerky) until i tried to start the car when it was warm. It just wouldnt start until i unplugged the MAF. Then with the car running i plugged it back in and everything was fine. What is going on please?
 
kooky_guy said:
Just a guess, but your ecu might have adapted to the bad MAF and might now need the adaptive values cleared out....

Guy
Click to expand...

I was wondering this. How would i reset it?

It was a MAF off Ebay but it wasnt one of the particularly cheap ones.

Thanks
 
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