Sooty Lambdas on Petrol, wont LPG

Sorry to be a pain but I am running out of ideas (not that I had that many).

History:
Thor equipped 1999 P38 Rangie with LPG conversion (how I bought it in 2005).
Stopped running on LPG (just cut-out on a long run and would never run on LPG again).

Local LPG specialist looked and said "Both Lambda's are burnt out so that's why it won't run on LPG. For petrol it defaults to fall-back settings and will run".

He recommended only use LR Lambdas as Aftermarket will burn out in 3-months. I thought ..."but a Lambda is a Lambda, so what?" Guess what...put aftermarket ones on and sure enough LPG and petrol worked fine for 3 months and then LPG dead again after about 3 months usage.

Just put 2 more new aftermarket Lambda's on and the emissions readings (before & after the new Lambda's) when running on petrol are exactly the same and it still won't run on LPG.

Lambda's that were just removed are totally "sooty" so on petrol it's running way too rich anyway.

Big question is what to do next?

Does the ECU drop into a default "super-rich" setting when the Lambda's fail?
If so, how do you reset it to start looking at the Lambda's?

Currently she's drinking petrol like it is going out of fashion. <9MPG.
No idea what to do next, need help, advice & guidance if anyone has been in this position before.

Many thanks in advance.

Dan.

It does revert to pre-set values if the lambdas fail&#8230;



If it thinks the lambdas are not working your MIL light should also it on. If it isn't there may be another fault, or it might just be over fuelling it because the broken lambdas are telling it to!

You can also reset the "adaptive" values, but you'll need diagnostics like a Nanocom to do that.

You need new decent Lamdas and diag to set the engine up.

naff lambdas will not stop the lpg from working.

Thanks for all the responses folks.
I am surprised that failed Lambda sensors will not affect the LPG subsystem as the LPG software suggests that the Lendirenzo Omegas system requires Lambda output to enable the triggering of the LPG injectors.

I will keep plugging away.

Does the EMS need to be reset to stop the EMS using "open-loop" settings, if so how do you reset it? I can (of course) disconnect the battery and re-enable starting via the EKA procedure.

I am a complete NOOB at this stuff.

DanClarke said:

Thanks for all the responses folks.
I am surprised that failed Lambda sensors will not affect the LPG subsystem as the LPG software suggests that the Lendirenzo Omegas system requires Lambda output to enable the triggering of the LPG injectors.

I will keep plugging away.

Does the EMS need to be reset to stop the EMS using "open-loop" settings, if so how do you reset it? I can (of course) disconnect the battery and re-enable starting via the EKA procedure.

I am a complete NOOB at this stuff.

Click to expand...

When it picks up a plausible signal from the lambda it should revert to Closed Loop and start to adjust itself the fuelling again, but the fault will still be logged in the ECU.

If the fuel trims are so far out of whack and the internal adjustments can't keep up with the amount of trimming needed, it will need to be on diagnostics to reset the trims back to the nominal values, to which the system will then start to re-adjust as necessary following the fitment of the new sensors.

output from the lambdas is shown on the the software to allow the lpg to be tuned,quite often installers do not wire them in.the lambdas are only used by the petrol ecu.

Look at the MAF to start with, look for 22kgs /h on idle with all loads off. If you've got anything different report back

+1 on Checking the MAF.

Thanks folks.
I bought a cheap(ish) OBD2 scanner from a nice man in Hong Kong.
While it says it supports LR and models 1996 onwards it has a lot of trouble connecting to the OBD2 port.

When it does connect it doesn't tell me much but the "live data" shows one Lambda (says O2S/1 and O2S/2, which I take to mean O2 Sensor(s) 1 & 2, to be @ 0.45V and the other at 0.95v. So obviously something is out of kilter here.
The scanner has an uncanny ability to lose comms to the ODB port but it can be re-established by starting again. I cannot get it to do a freeze-frame to store the data but I can read the live data variables. One of which is the MAF which at 745 RPM with no loads on reads 9.26G/s??? not sure if that really means 9.26Kg/S or truly 9.26Grammes/Second. If it is 9.26Grammes/Sec then that would be 5.556Kg/Hr. i.e. lower than the 22Kg/H mentioned above.

You need decent diagnostics. Generic ODB stuff really is quite crap on the RR.

Any old ODB2 scanner won't work on a P38. They're not ODB2 compliant, so whilst it may do some stuff (the engine ECU I think is actually readable) it won't be able to tell you whole story.

Also, when you fitted your replacement O2 sensors, are you sure you got ones that work in the same range? Some go from 0v to 5v some from 0v to 1v. I thought the P38 was on 0v to 5v ones so your readings could indicate the wrong type of sensor fitted.

If the output voltage only reaches ever 0.95v the car will always think it's running very lean and try to over fuel to compensate.

EDIT - IT CHANGED WITH THE THOR ENGINE, 0v to 1v LOOKS CORRECT FOR THE THOR ENGINE. WAS YOU WERE!

domino said:

You need decent diagnostics. Generic ODB stuff really is quite crap on the RR.

Click to expand...

Yes I agree. This OBD2 scanner was only £15.95 on flea-bay.
But while it is a bit "flakey" it did read 27 real-time items.

Better than now't (just about).

Thanks for the help though, I do appreciate it.

MrGorsky said:

Any old ODB2 scanner won't work on a P38. They're not ODB2 compliant, so whilst it may do some stuff (the engine ECU I think is actually readable) it won't be able to tell you whole story.

Also, when you fitted your replacement O2 sensors, are you sure you got ones that work in the same range? Some go from 0v to 5v some from 0v to 1v. I thought the P38 was on 0v to 5v ones so your readings could indicate the wrong type of sensor fitted.

If the output voltage only reaches ever 0.95v the car will always think it's running very lean and try to over fuel to compensate.

EDIT - IT CHANGED WITH THE THOR ENGINE, 0v to 1v LOOKS CORRECT FOR THE THOR ENGINE. WAS YOU WERE!

Click to expand...

Yeah, these sensors were stated as being the correct one's for the 1999 "Thor" system and were identical to the ones already on their as were fitted previously by me Aftermarket LR specialist garage (DS Automotive in Southend On Sea). So, I was pretty sure they were the correct ones.

I hope the new MAF sensor sorts it out when it arrives.

Thanks for the help, it is much appreciated.

Just a quick update and a really big THANK YOU to all who offered advice & guidance on my no LPG running and "running rich" on petrol issues.

The new MAF arrived an hour ago. It was an "Instant Fix".

I have been out for a reasonable little test ride and performance on LPG is restored to pre-issue levels. Switching between Petrol & LPG is nice & seamless and I am hopeful the EMS will be able to trim back to some nice economic mixture levels.

Many, Many thanks guys.

I am going to try and work the same magic on the brakes with a new ABS accumulator tomorrow (another "cure" to a current problem that I have).

Really enjoying the LandyZone Experience.

Oh damn & blast, I spoke too soon!
After yesterday's MAF sensor change and the immediate ability to run perfectly fine on LPG once more I was convinced that the MAF had been the culprit.
Today, I took the car out and not only did it die on LPG switchover, it then died on Petrol tickover. There is definitely something a bit "odd" going on here. I have never had a problem on petrol before (apart from it running over-rich) since it stopped running on LPG.
So, maybe it wasn't the MAF after all and the seemingly instant and miraculous recovery was pure chance/luck?

DanClarke said:

Oh damn & blast, I spoke too soon!
After yesterday's MAF sensor change and the immediate ability to run perfectly fine on LPG once more I was convinced that the MAF had been the culprit.
Today, I took the car out and not only did it die on LPG switchover, it then died on Petrol tickover. There is definitely something a bit "odd" going on here. I have never had a problem on petrol before (apart from it running over-rich) since it stopped running on LPG.
So, maybe it wasn't the MAF after all and the seemingly instant and miraculous recovery was pure chance/luck?

Click to expand...

I think you need to reset the fuelling trims.

Datatek said:

I think you need to reset the fuelling trims.

Click to expand...

Hi Datatek,

I would love to but I don't know "how" and don't have any magic eqpt, to do it.
I guess it's time to pay a very nice man at a non-dealership Landy Shop that has the tools for this.

It would be great if there was a "reset to basic config & I will learn it all from there" button like on a simple PC, but I doubt that this is the case.

Is there way of forcing a "default settings" without recourse to expensive tools?

DanClarke said:

Hi Datatek,

I would love to but I don't know "how" and don't have any magic eqpt, to do it.
I guess it's time to pay a very nice man at a non-dealership Landy Shop that has the tools for this.

It would be great if there was a "reset to basic config & I will learn it all from there" button like on a simple PC, but I doubt that this is the case.

Is there way of forcing a "default settings" without recourse to expensive tools?

Click to expand...

Nanocom, maybe there is someone near you who can do it.

OK, I'm getting freaked out now.
Removed & re-attached the wiring-harness to the MAF and it runs again (for a few start-up and LPG switchover attempts anyway). Then switch off, let it alone for an hour or 2 and try again....will start on petrol OK but dies on changeover to LPG again. Remove MAF connector and re-attach and all OK again (for a few cycles).

Rinse-repeat.

Duff MAF? Broken/cracked wire in harness/connector? Dodgy connector?

Driving me bonkers. LOL.

No idea what voltage is meant to be on the wires or what resistance etc.
Anyone had "fun" with this before?