software and lead to sort switch back to petrol problem

[bonny]

Hi folks,

I recently bought a Mercedes ML500 Sport which generally seems to run well on the LPG conversion it has, until more recently I notice it switching back to petrol early in a journey.

So, 2 questions:

1) What do I need in terms of lead and software to have a look at the setup and do some diagnosis?

The ECU is branded EMER, but I can see the details on the back stamped as AEB 2568D (I will try to work out how to add photos later) and it has a superseal (?) 4 pin connector on a fly lead from the ECU which I assume is for the diagnostic/setup connection.

2) once I've got a workable diagnostic setup, what am I looking for?

The car starts on petrol and I get a mile or so down the road, switches to LPG, no problems, all appears fine. I checked this morning just running in the workshop and the vapouriser is getting good and warm.
About a mile further on the switch shows the lpg light flashing and I'm back running petrol. No alarm for low pressure and no indication of a problem.

If I stop and restart the car, it will switch to lpg a bit down the road, then indicate I'm back to petrol again a bit further on. My local run is into town for shopping. When I start the car after shopping, it switches to lpg and stays on Lpg all the way home.

So, it's not a huge deal, but its a bit annoying and I'd like to sort it.

I did recently have to change the thermostat which meant draining some coolant and have had to top up coolant a couple of times recently. I wondered if there was air in the system/vapouriser preventing it heating up, but that did not seem to be the case when I tested this morning and I think that would impact the initial switch over to lpg rather than causing a switch back, but I may be wrong.


Your input would be very welcome.

Thanks
Paul

[bonny]

ECU
https://photos.app.goo.gl/Yz2RtjkWyjV4QWnp6

Connector
https://photos.app.goo.gl/Bsyvp5rebG44Futw9

[Brian_H]

Normal aeb lead should do it, tinleytech have one listed and the software available for download. Will post link later if you can't find it.

It may be set to switch back, I'd have a look at the software and see if there anything obvious there. There are several settings that can have that effect. An airlock in the vaporiser also might cause it if the temp seems lower than expected

[bonny]

Brilliant, thanks Brian, I'll get onto Tinley and get one ordered.

[Gilbertd]

If it runs on LPG for a while then switches back, my money would be on insufficient coolant flow so the vaporiser is cooling down so it is switching back, particularly if you've been working on the cooling system.

[bonny]

Thanks for that - I've ordered a lead and downloaded the software, so hopefully I'll be able to get some data and see what is happening later this week.