Hi all was hoping someone could help me with a Questions, my el xr8 is on gas an since i bought it I've never ran it on petrol because the fuel pump was shagged. Put a new fuel pump in it a bottle of octance booster $35 premium an a new fuel filter an finally it ran on petrol but didn't want to rev above 1500rpm. Traced it back to the air flow metre so got another one of them now it revs above 1500 but is missing badly so gonna clean out the injectors tomoro to see if that helps. While the car was running I pulled one of the injector plugs off an it didn't change anything so guess that's the problem, but that's not the question I have. Since putting the other afm in the gas feels very gutless an is gas surging? You will be cruising at bout quarter throttle at about 1800rpm then it will surge up to bout 2200rpm or there abouts an it's very sluggish in changing gears now Ect altho the really bad pinging noise that I had is gone which is a plus. Anyone had this before? Cheers

It all depends how this gas system was installed. Many dodgy installs are done where they don't turn off the injectors when running gas and this kills the injectors.
If it's missing badly on both gas and fuel you have an ignition problem(and not necessarily an ignition fault).....possibly it's because the car may have been "tuned" with a dead MAF and now that it has a working MAF the EEC can now calculate load correctly and the spark advance does not match it's fueling ie; it may now have too much advance at some point in the rev range. I'd get your petrol side working correctly first and then work on the gas.

maybe the cars had the ignition timing advanced for gas only since the fuel pump was rooted and the maf was aswell, maybe if you adjust the timing back to factory specs it could fix some of the problems on both petrol and gas
gas is a higher octane than petrol so you can run more advance on the ignition but once you go back to petrol the car will ping if its too far advanced

Actually turning off the fuel pump while on LPG kills the injectors.
As does not running on Petrol ever so often. Seals dry up, but importantly, the injectors "Boil" - leaving the crud at the pintle. Hence most systems either running the pump, or in the case of some ford systems running the pump intermittently

Not revving sounds a lot like the fuel filter could be blocked perhaps.

Another issue is that a lot of fitters dont disconnect the o2 sensors, or put just one under emulation. The ECU sees a fault, and either stops doing learn, or actually trains the "injectors" (that arent running) to go either too lean or rich under load. You can check for that one though by disconnecting the battery for 30 mins.

XR9Ute might have some other ideas as well. Have you put a diagnostic reader on the car? - or used the test light/led? - then reset the codes. That will re-enable many things that the ECU has faulted due to simple LPG Installs

Nigel

Nothing more to add from me yet Nige, and there's enough info here for a start. I think we're all pretty much on the same page.

Thanks for all the replys, talking to a mate today dont think its iginition troubles will chuck a timing light on it tomoro an get it retuned. also put other injectors in it today semi fixed the problem but now it seems to be missing below 1500 on both petrol an gas an feels like it just bogs down an goes no where. it struggles getting to 110km :\

ok so timing was at 22degrees an is now back at the std 30degrees helped a little but its still missing on petrol an gas mate said to get a compression test and go from there, so gettin that done hopefully tomoro if not monday. was hoping it woould be somethihng small lol