Hi Folks,
My error codes show I am running both lean and rich. There is a slight lumpiness when the engine is idling. My local garage did a misfire count and it showed some misfiring on all 8 cylinders. I have an LPG conversion but the lumpiness is there on LPG or petrol. The MAF sensor and PCV are brand new. It has been suggested that I put injector cleaner in a few tanks of petrol and run that through before any other investigations. Is that sage advice. If so, which cleaner should I use?

Cheers

Kirton Alan

How long have you owned it?
Has a valve saver system been fitted?

I have owned it for about 6 years. I had the LPG system installed, it is BRC.
As to a valve saver, I have no idea what that is.

Kirton Alan

Valve saver system tries to combat valve seat recession when lpg converted, the jag engine needs it, get a leak down test to confirm whether you have an issue or not.
But it doesn't sound promising by being apparent on both fuels.
How long have you tried it on petrol only to see if the issue remains when only on petrol?

Hi

I had exactly the same issue, with exactly the same engine, feels like someone is bouncing up and down in the back seat when on idle , get your garage to check the inlet vacuum values, it is a spot on indicator of valve seat wear , if it is not too bad you will get away with re shimming the valves (£1400) if you have burnt the valve seats then its heads off i am afraid, if the inlet vacuum value is within tolerance then you have another issue and you can breath again !

Has anyone ever experienced this on a car without lpg? Chaps who have/had the problem what were your fuel trims like? Mine are low on the long term (3 to -3 ) but short term they are up to 20

Gavinn are you on lpg too? Trying to work out if I have the same or different issues Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

I put Forte injector cleaner into a half tank of petrol. The engine management light went out after less than 100 miles. Question is, do I still get the injectors cleaned or follow other diagnostics as suggested here?


Kirton

Is it still bouncing about when on lpg as in your original post you said it was the same on both fuels a tank of treated petrol wouldn't have sorted out the lpg end would it

If its misfiring on either fuel I would think it isn't a fueling problem, as lpg will use different injectors to the petrol ones. So your problem should be mechanical (after the fuel system, e.g. valves) or electrical.