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Old 12-05-2012, 01:32 AM
Graham132white Graham132white is offline
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Location: Manchester UK
Join Date: Dec 2012
Posts: 41
Mein Auto: E53 4.4i X5
Help! Very technical problem!

Hi guys..

Ok, so I've got a 4.4 V8 E53 2001...LPG converted 80k

Im very mechanically minded but this problem is very hard to get my head round,, basically the car will not run right on petrol, it won't go over 3k revs and splutters and misfired badly although it will idle perfectly. If I unplug the MAF it runs like a race car v8 so I'm discounting bad coils etc, plugs are brand new.
I've got no fault codes either!!

It runs perfect on LPG while driving and has perfect response on the throttle but idle on LPG is fine until you touch the throttle a little which makes it bounce up and down to about 2k revs down to 0 and sometimes cuts out.
The BRC LPG installer says he has fuelled the LPG correctly to run right, which it does.
On petrol the short term trims go up high only when you rev it and the longs are hovering about +12.

All this would tell me there is a vac leak or bad maf but that wouldn't explain it's smooth running on LPG, or would it? I've sprayed all over the manifold looking for leaks and gaskets were done not long ago.

I just ain't got a clue rom here.... Any help would be greatly appreciated!
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