V8 Range Rover misfire

[Brummmie]

I had a 400se, I went through everything turned out to be camshaft, lobes were worn out.

[Steve_D]

OP
While you are waiting for your chap to get the plug out go buy an infra red heat gun from ebay.
They are not the most accurate of things but when pointed at each of the exhaust ports will quite quickly show which cylinders are not pulling their weight.

Steve

[Steve_D]

Brummmie said:

I had a 400se, I went through everything turned out to be camshaft, lobes were worn out.

Whilst I accept this may have been the issue with your car in most cases the RV8 is very good at hiding cam issues and you normally have to work quite hard to identify them.
I doubt the cam is an issue in this case but they do have a reputation for being made out of chocolate.

Steve

[Brummmie]

Steve_D said:

Brummmie said:

I had a 400se, I went through everything turned out to be camshaft, lobes were worn out.

Whilst I accept this may have been the issue with your car in most cases the RV8 is very good at hiding cam issues and you normally have to work quite hard to identify them.
I doubt the cam is an issue in this case but they do have a reputation for being made out of chocolate.

Steve

Ive seen it on a 500 Griff, and a Range Rover also..

[Harleyboy]

Afternoon, so a further update for you:

All plugs now changed. Running nicely in neutral but no power under load. Will get to 50-60 on the flat but get to an incline and its down to 20-30 very quickly, albeit still running on all 8.

I took it to a guy who got it running much more smoothly and suggested to try an Mass Air Flow meter, then an ECU.

I know a guy who might have some known good units I can borrow for elimination purposes. Mechanical failure (cam, HG etc) seems to have been ruled out.

Thanks again for your thoughts/advice
Adam

[GreenV8S]

Too lazy to re-read the whole thread and I don't remember all the details. If it is running smoothly but well down on power I'd be looking for either an obstruction on the air intake (severely worn cam, caked filter, delaminated intake trunking etc), very lean mixture or very retarded ignition.

You could measure plenum depression with a vac gauge to detect air intake obstructions upstream of the plenum.

You could use an ordinary timing strobe to check the mechanical advance is working correctly. Remember to establish a TDC reference first rather than relying on timing marks on the front pulley.

You could use a wideband sensor to detect a lean mixture. If the engine picks up noticeably when you pump the throttle, that might also point to a lean mixture making it unusually sensitive to transient enrichment.