Thanks, I read something more and found out that even on LPG the PCM is still active, the LPG controller "only" controls the LPG injectors based on the infos from the PCM. So basically the PCM is doing all his fuel and ignition controls, only the LPG controler takes the fuel injector signals and prolongs them for the LPG injectors.
So as it is running fine on LPG, I think it can just be the wiring. Would make sense, too, as it is intermittent and sometimes goes away on its own.

Will replace the whole wiring to get rid of that problem.

Thanks for your help!

 

So when you are running on gasoline, does the injector signal still go thru the LPG controller?

 

As far as I understand: no.
It takes the signal from the PCM, switched on some resistors to emulate the petrol injectors to the PCM and sends a signal to the LPG injectors.
See page 69 (page 70 in the PDF file):

https://lpgshop.co.uk/content/lpg-so...I-2.0_V2.0.pdf

 

Looking at the wiring diagram, yes, the signal does indeed go thru the LPG controller, and the direct link to the Petrol PCM is cut...... An interesting experiment would be to re-splice the wire for injector 7 back together, run on gas, see if the misfire disappears.

 

Thanks for your reply.
Will have a closer look once I'm back from holidays.

But from what I understand, the LPG controller switches some relais inside these "injection modules".
I already bought some adapters to remove these modules and shorten the wires so it runs on petrol only and the wires are shortened.
But that also makes the signal run through the modified wiring.

So in the end I will have to check the whole wiring for the injectors. Luckily I bought some new connectors last time I ordered some stuff online.
Maybe I will try what you said and do a temporary direct connection from injector 7 to the petrol ECU.

 

So, today I wired the control wire completely new from the injector to the LPG emulator connector.
It was a bit difficult because the guy who installed it didn't use the connection points like in the manual. But I measured for continuity and found the wire. Soldered a new one in. Also replaced the ignition wires.

Now at least on the test drive the code did not come back.

But the initial problem came back with the stuttering when being shortly before stopping or when stopped. But not permanent. Revs were dropping down to 450rpm, then went back to 600s, car "dancing" a little forward. Foot on the brake and it stops. Foot off the brake and it doesn't "dance".
So freaking strange. And ONLY when running on petrol, NOT on LPG!

Would it make sense to also re-wire the other feed (the +12v common feed line where all injectors are soldered to) to the PCM? But then it would have given other errors and not only cylinder 7?!

 

I suspect there is something else going on there, causing the idle issues. Might try cleaning the throttle body, and making sure there is a genuine Mopar IAC valve in there.

 

I'm really not sure at all, as it all started (I think I mentioned it on the first page) after I was "cleaning" up the wiring a little bit by using some zip ties etc.
So I'm quite sure it has something to do with it. Why would it run perfectly smooth now on LPG?

With the new ignition wires it now runs smoother than ever on LPG.

When starting on gas it feels "rough" sometimes, sometimes it does the "shaking"/"dancing" thing, but not all the time.

Maybe I should think about a Chrysler DRB III emulator thing?!

 

Sure wouldn't hurt.

 

Had no time to check for a DRB III thing, but the P0307 is gone now, did not come back the last 1000 miles.

The P0300 was coming back though. I had to install a new battery and that reset the PCM it seems so it is gone now and did not come back for 300 miles. BUT: on gas it is still doing that vibrating/hesitating. Damn!!

I had a longer drive today and switched to gas a few times to try to reproduce it. So from what I "feel" and "hear" the vibration is somewhat "constant" or "rhythmic". From what I'd expect from a faulty wiring, the vibrations would be unrhythmic and random.
So maybe there is something different going on?
Camshaft sensor or crankshaft sensor or O2 sensor?!

I know that I tried to drive without the pre-cat O2 sensors in "open loop" mode and the problem was the same. So can rule that out?

Any more ideas maybe? It really is driving me nuts...