Have you done an ECU self test and pulled the codes? There might be something in there to suggest the problem.

Also have you done a compression test. It might be possible you have a rooted cylinder and when the MAP sees the pressure drop from that cyliinder it fires an excessive amount of fuel for that fuel cycle.

I suppose lastly, since it was on LPG, which means someone would have been d**k with the wiring loom to turn off the injectors, that someone has accidentally shorted the injector trigger for those cylinders to ground, basically causing them to continuously fire. If its not a factory LPG then the quickest way most installers would go would be to cut the ground trigger at the ECU and splice in a relay.

I'm pretty sure the injector trigger wires go directly from ECU to injector, so if you were to take the ECU out and pull a good injector plug and check the continuity from the trigger wire to a ground, you should get nothing. Then check one of the bad injectors and see if you get continuity or not. If you get continuity on a good injector, then my test is invalid... I don't have my wiring books in front of me to see.

If it runs fine on lpg then I'd be checking the ecu wiring for sure. On my car I couldn't get 2,4,6 to fire and when I inspected the wiring where the lpg fitter joined into the injector wiring at the ecu I found a bad connection on the 2,4,6 wire. Depending on the quality of the lpg install (mine was poor!) it could quite easily be that.

Pin 58 1 3 5
Pin 59 2 4 6

Hi all,

The plot thickens. We took it for a drive around tonight to check it was OK on LPG. It started quite rough, but settled down after 15-20 seconds. It's pretty gutless, but not alarmingly so. Definitely driveable.

Now I have a second problem: the auto transmission is shifting oddly. Starting off, it won't upshift from first. I had to rev it to 4500RPM then quickly close the throttle to force it to shift to second. Then it went to third, but wouldn't shift back down at any speed. I had to manually pull it back to 2nd. Then coming home it wouldn't go any higher than 2nd, even at 80kmh with the transmission in Drive.

This car is determined to make me crazy. What can make a transmissin do this?

Thanks.

The gear selector switch might be buggered.....it's on the passenger side of the tranny.

Aftermarket LPG installs will usually have two relays controlling the injector cct's, one for each line for bank fired systems (EA/EB/ED/EL), so as mentioned, 1,3,5 has a problem. It will be setup normally for the relays to get power to their coils when on petrol. Normally, terminals 30 & 87 simply cut into each line from ECU to injector harness. Most likely, the relays might be in the cavity behind the ECU - if they are, there might be another as well - this will be for O2 sensor switchover.

Check the wiring on those relays, as mentioned about the overfuelling, sounds likely - if it was open cct, the plugs wouldn't be black, as there'd be no fuel admitted.

Can't remember exactly, but overfuelled cylinders won't be shut down - EF's are different, as an affected cylinder will be shut down. EF's are bank fire like the others, but they do have individual lines for each injector back to the ECU. unlike two lines for 135 and 246.

An ECU diagnostic is always a good idea, but possibly in this scenario, if the ECU is pulseing the 2 injectors lines okay, it may not see a problem if it's downstream in the line. Still do it though, as other codes might come up.

Yep, what he said.
ECU output (injectors are switched to ground).
LPG relays and wiring (they intercept either the injector +12 rail or each bank).
Injector loom.