Irritating missfire / idling problem

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TerryG

New Member
Posts
13
Location
Staffordshire
Hi boys and girls,
This has been driving me nuts since the weekend so now is time to ask for some help!
I have a 1994 Range Rover LSE with a 4.6 engine fitted. It was rebuilt about 7000 miles ago. The problem is that it sounds like this:
VIDEO0445.mp4 video by terryg1982 - Photobucket
If i advance the timing to where i think it should be then it idles a bit more quickly and smoothly but under load there is a squeaking noise that is engine speed / throttle position related so i assume is pinking but i could be wrong.
The car misses under load and when i put it in drive from neutral / park the revs drop right off and it sometimes stalls but flicking it in to neutral it recovers.
It doesn't really like reving over 2500rpm when it's in gear but runs through the range in neutral.
the "chuffing" noise sounds like it is coming from inside the plenum.
so far i have replaced the plugs, leads, rotor arm and dizzy cap. I have tried a spare stepper motor and MAF sensor, disconnected the water temperature sensor, reset the base idle, checked for air leaks, replaced the plug on the ignition amp as one of the wires broke off when i was adjusting the timing.
Nothing seems to fix the miss or stop it sounding like a train on idle. I have run out of ideas.
Any suggestions what i can try next would be greatly appreciated!
Cheers.

Forgot to mention that it has an LPG kit fitted and it does the same thing on both LPG and Petrol.
 
Hi boys and girls,
This has been driving me nuts since the weekend so now is time to ask for some help!
I have a 1994 Range Rover LSE with a 4.6 engine fitted. It was rebuilt about 7000 miles ago. The problem is that it sounds like this:
VIDEO0445.mp4 video by terryg1982 - Photobucket
If i advance the timing to where i think it should be then it idles a bit more quickly and smoothly but under load there is a squeaking noise that is engine speed / throttle position related so i assume is pinking but i could be wrong.
The car misses under load and when i put it in drive from neutral / park the revs drop right off and it sometimes stalls but flicking it in to neutral it recovers.
It doesn't really like reving over 2500rpm when it's in gear but runs through the range in neutral.
the "chuffing" noise sounds like it is coming from inside the plenum.
so far i have replaced the plugs, leads, rotor arm and dizzy cap. I have tried a spare stepper motor and MAF sensor, disconnected the water temperature sensor, reset the base idle, checked for air leaks, replaced the plug on the ignition amp as one of the wires broke off when i was adjusting the timing.
Nothing seems to fix the miss or stop it sounding like a train on idle. I have run out of ideas.
Any suggestions what i can try next would be greatly appreciated!
Cheers.

Forgot to mention that it has an LPG kit fitted and it does the same thing on both LPG and Petrol.

Sounds like a knackered inlet valve.
 
Sounds Like you have a inlet valve stuck open and the tapping noise is the tappet rattleing, have you done a compression test or had the rocker covers off to check the valve operation...?
 
It had new rockers from RPI fitted when the engine was rebuilt so I was clutching at straws that it was something quick / easy to sort before i started taking the top of the engine apart.
 
If there are any mobile mechanics on here in East London that fancy waving their magic spanner over this tomorrow afternoon / friday let me know. Most of my tools are 160 miles away and i don't fancy any of the local garages.
 
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