2004 L322, hunting, idle, non responsive throttle

Hello all I'm one month into ownership of a v8 4.4 L322, I love it (when it's working)

Can anyone shed some light on to this problem............... Drove the ranger to work this morning, all fine. Put into park and gave the engine a bit of a rev, circa 4000rpm, nothing too serious. As the revs decreased and came back to idle the engine started hunting badly and now will barely run at all.

I have an engine safe prog warning, the engine wont rev at all, it's hunting like mad and running on 5ish cylinders. It's also popping occasionally through the airbox. If I put the car into reverse ie under some load the hunting calms down a little but still won't rev, it eventually stalls.

Other problems that have instantly happened - Brakes hardly strong enough to hold the car still when in reverse, suspension failure, trans safe mode. I suspect the fault is a result of revving the engine, but what can it be?
The RAC man plugged in his fault reader which flagged up :-

Throttle position
MAF sensor
Throttle body position

I can't believe all these systems have failed due to revving the engine.

Please, if anyone has experienced I'd like very much to hear your thoughts.

I'd say it's the MAF, but live data on diagnostics would confirm it. If it is the MAF, don't buy a cheapy on Ebay as they often do not work.

911r said:

Hello all I'm one month into ownership of a v8 4.4 L322, I love it (when it's working)

Can anyone shed some light on to this problem............... Drove the ranger to work this morning, all fine. Put into park and gave the engine a bit of a rev, circa 4000rpm, nothing too serious. As the revs decreased and came back to idle the engine started hunting badly and now will barely run at all.

I have an engine safe prog warning, the engine wont rev at all, it's hunting like mad and running on 5ish cylinders. It's also popping occasionally through the airbox. If I put the car into reverse ie under some load the hunting calms down a little but still won't rev, it eventually stalls.

Other problems that have instantly happened - Brakes hardly strong enough to hold the car still when in reverse, suspension failure, trans safe mode. I suspect the fault is a result of revving the engine, but what can it be?
The RAC man plugged in his fault reader which flagged up :-

Throttle position
MAF sensor
Throttle body position

I can't believe all these systems have failed due to revving the engine.

Please, if anyone has experienced I'd like very much to hear your thoughts.

Click to expand...

Why rev it to nearly two thirds of its limit??? pointless exercise that can lead to damage.

The BMW M62TUB44 as used in the Range Rover differs from the version used in the Bimmers in the fact that the ECM is tuned for torque not speed, while a Bimmer tuned M62 (and esp. the S62) like a good deal of revs and don't mind a thrashing every now and then, the Land Rover tuned M62 is more used to and designed for sedate plodding and low end torque!

Anywho.....the M62 (as opposed to its predecessor the M60) uses a fly by wire throttle system so on the throttle pedal is a potentiometer and on the throttle body is a stepper motor.....I would check the pedal pot with a good meter and check for a smooth rise and fall of resistance with no spikes...maybe your quick boot has moved the pot to a seldom used portion that had direct contacts/wiper and now it is getting a dirty signal...

The Diagnostics seem to point to the probable cause...the pot on the pedal and or the throttle butterfly stepper motor...the system wont know which is causing issue...but the 3 together would indicate an issue with the induction of air, be it throttle position, throttle butterfly position of the amount of air entering the system.

Blocked and breaking down of exhausts cats are a known issue on the Bimmers and so far not heard much on if it can occur to the L322, but if the cats are blocked, your revving will only cause a back pressure and misfires!

I'd also be inclined to check for timing chain jumping as the guides wear and the chain becomes slack...sudden acceleration can cause them to jump...giving all sorts of misfires, backfiring and lumpy running!

Check VANOS timing too as the 4 cams are run on chains...if the chain tensioners are worn inbetwwen the inlet and outlet cams on each head, the VANOS drive chain can jump and knock VANOS tuning out! very rare...but yer never know!

Thank you both for your replies, I've found the problem.

It would seem the air inlet hose and oring was not correctly fitted at some point.

Revving the engine sucked in the oring which was then trapped in the throttle body and not allowing it to close fully. Guess this explains the problem with throttle position and MAF.

Funny how something like that can happen and cause such a headache! Everything now correct assembled, faults cleared, back in motoring heaven again.