LPG Discussion Forum

i have a running fault with the gas switched on .
It happened while driving ,THE engine cut out and stopped >it will only run on petrol now , unless engine is above 2500 rpm when switching over to gas then it fades and stalls ,switct to petrol and it runs fine again
i have to day removed and tried to run the car witout the final filter with no change and refitted it .strippid out the vaporisor unit and refitted it topping up the anti freeze after with on change
changed the injector fuses for new items and the lock off valve fuse all with out change to running condition.
I then contacted the manufacturer prins and spoke to the technision on the phone who diagnosed the Emulator to be at fault with these symptoms, so my question is where would i find the emulator fitted on the vehicle ?

There'll be two emulators, each for four cylinders. Fag packet size black boxes. Follow the wire bundle from the gas ECU to find them, they might be inside or near the box behind the battery.

I really can't see how the phone help arrived at that conclusion though, unless you are getting OBD fault codes you haven't mentioned.
Sounds much more like a sticky regulator (did you actually clean the small moving parts, or use new rubbers?) or failed solenoid, front or rear, or wiring below. Absolutely sure there is gas in the tank?

martin3134 wrote:unless engine is above 2500 rpm when switching over to gas then it fades and stalls ,switct to petrol and it runs fine again

As Ross says, it's a bit of a guess without having seen the car although the symptom MAY confirm it. If an emulator had failed you could be running on petrol and gas at the same time, which would cause the engine to fade and die (as it drowned in the ridiculously over-rich mixture). But, if you immediately switched to petrol it would still run like a dog because of all the excess fuel laying around in there. If it runs perfectly immediately you switch back to petrol, that isn't the fault.

Thank you for the replies to the post guys .with regard to the questions asked i didnt completely strip thr vaporisor unit as i havn't any spare gaskets or daphrams for the unit.so the inspection of the unit was only to check the water flow,
As to the running after the gas is switched on at 2500 rpm it revs unevenly as if its on four cylinders, then faides and stalls with the exhaust smelling very rich restarting with petrol only.
It fires up fairly instantly and setteles to its orignal tickover and revs freely.
This is the content of the conversation i had with the technision at Prins who concloded the symptom given was caused by the emulator
he was adiment that if the emulator has a twisted pair of red black wires to feed the injectors it was a sure bet that would be the fault
knocking out one bank of cylinders ,resulting in this running condition.
I am open to sugestions as to other faults to cause this problem as my knowledge of gas is restricted to LPG forklifts for the past 20 years
they only employ a lock off valve and a vaporisor unit using single point injection to run and are far simpler than the systems used on road vehicles. finaly all testing is there for blind and without the aid of a laptop the see what is going on with the system

The only failures I have seen of the older style emulators are single-channel ones, that is to say affecting one cylinder only. You wouldn't notice that on a V8 apart from it bringing on a petrol management fault light and code. But it's certainly not impossible for a whole unit, or perhaps more likely, a command wire failure to crease 4 cyls or even all 8.
You presumably haven't found out if you actually do have older style?

I'd still put my bet on a gummy regulator. (You're right, don't go in there without a rubbers kit)

A session on a laptop with Prins software would reveal all.

HI THANKS AGAIN FOR THE INPUT I HAVE BITTEN THE BULLIT AND BOOKED IN FOR A DIAGNOSTIS WITH A CHAP IN CODICOTE AS PRINS WOULD NOT SELL ME ANY PARTS DIRECT !
SO UNTILL NEXT THURSDAY ITS ON UNLEADED FUEL @@@@@ OUCH

HI i have been to the prins dealer who pluged the car up to the laptop ,
the fault .It wont run on gas .
Was doagnosed to the ECU BEING CORRUPTED and over pressurising the system. caused by the battery running flat ,the car has a Becu fault and it will not go to sleep .my remidy is to remove the earth to the battery !
This has affected the gas ecu .I was given two potion
1 upgrade the software in the orignal ecu
2 purchase a new or replacment ecu
As the car is 1998 and 131000 miles !! anybody out there know of a reasonable solution to bring thr car back to LPG ?.
It did leave the garage running on gas but went back to failsafe stalled on my way home, and only runs on petrol now
regards martin

martin3134 wrote:anybody out there know of a reasonable solution to bring thr car back to LPG ?

Sort out the BeCM problem that is causing you to have to disconnect the battery. The most common cause is a local radio transmission in the 433MHz band that keeps the BeCM awake waiting for a valid unlock code from the keyfob. Disconnect the wire from the etched aerial on the offside rear side window to the feyfob receiver under the plastic trim panel. This will make the receiver a bit deaf (you'll need to be much closer to the car to lock and unlock) but will allow the BeCM to go to sleep.

433MHz is used for 'momentary operated low power devices' such as car keyfobs, wireless doorbells, wireless garage door openers, video sender remote repeaters, oil storage tank level sensors, remote weather stations and numerous other things. Unfortunately, when they go faulty, unlike most things that simply stop working, they often work all the time. You can complain to Ofcom and an engineer will come out and sort out the source (and we like them because they are dead easy to find with the right equipment and often cause a good laugh in the office too!). However, if we find that the complainant is also the owner of the faulty item, you get sent a bill........

martin3134 wrote:HI THANKS AGAIN FOR THE INPUT I HAVE BITTEN THE BULLIT AND BOOKED IN FOR A DIAGNOSTIS WITH A CHAP IN CODICOTE AS PRINS WOULD NOT SELL ME ANY PARTS DIRECT !
SO UNTILL NEXT THURSDAY ITS ON UNLEADED FUEL @@@@@ OUCH

This maybe a bit of a grey area here but Prins may not be allowed to do this, there is an eu law appertaining to the right to repair, which includes service information, spare parts and the diagnostic equipment necessary to maintain your own vehicle which you have a right to do, when I worked for Volvo Penta we had to make available with a part number to consumers the VODIA tool which became the adopted diagnostic tool for all ecu controlled VP units, this could be restricted to prevent a consumer from altering certain parameters which would affect the emissions output of the unit from going over its upper limits, but was able to scan the ecu and remove fault codes etc, any special tools without a part number where designated dealer only but over a period of time everything tool wise came with a part number so was available for sale through a VP dealer, Prins being an aftermarket add on may be exempt from the right to repair law but it would be interesting to find out if indeed the should comply with it.

martin3134 wrote:HI i have been to the prins dealer who pluged the car up to the laptop ,
the fault .It wont run on gas .
Was doagnosed to the ECU BEING CORRUPTED and over pressurising the system. caused by the battery running flat ,the car has a Becu fault and it will not go to sleep .my remidy is to remove the earth to the battery !
This has affected the gas ecu .I was given two potion
1 upgrade the software in the orignal ecu
2 purchase a new or replacment ecu
As the car is 1998 and 131000 miles !! anybody out there know of a reasonable solution to bring thr car back to LPG ?.
It did leave the garage running on gas but went back to failsafe stalled on my way home, and only runs on petrol now
regards martin

Hi Martin, when the car stalled/cut out did you get a rather loud farty noise for a second or so??.if you did the vaporiser is at fault and causing the overpressuer scenario.
I have fitted every version of software since day one and have never seen or heard of the software causing overpressure.
A good few years ago there were some spuriouse and very odd happenings where one or more of the parameters would mystreriously change of their own accord and cause a problem ,usually stopped the lpg from opperating.
The prins ecu is the eprom type so disconecting the power to the ecu will not wipe the memory much like all the other ecu,s,all it will do is wipe any fault codes logged.
Upgrading software is a 5 minute job normally incorporated in a service .

Try the car again,if it works ok for a period tomorrow then i reckon its a vaporiser,when they do go overpressure the fault code is generated and the ecu will stop any further attempt to run on gas for a period of time [30 mins or so],you can wipe the code by pulling the main 10a fuse which will then allow it to try and change to gas,if then it does exactly the same you will need a new vaporiser.

hth woody

Wot woody said.
It is possible to upset a VSI with (really) old firmware by battery shenagigans. It is simple for a dealer to update the firmware to overcome that issue.
No amount of upset ECU can give overpressure; that can only be mechanical problem in the reducer.

On the stay-awake BECM, a modified radio module has been available for a decade that overcomes most of the problems, but there'll still be cars that don't have it yet depending on what environment they have been living in. Lots on t'net about it, example
http://www.rangerovers.net/forum/7-rang ... drain.html

Ahh, but the modified receiver is a) bloody expensive and b) will only work sometimes. It has much better selectivity than the original design and means that the receiver will reject signals on adjacent frequencies. However, LR keyfobs (and most other cars) operate on either 433.920 or 433.980 MHz so it has to cover that range. Other low power devices operate within the band on 433.050 to 434.790 but this band was enlarged about 5 years ago, prior to that everything was crammed into 433.85 to 434.05. So, although it's much better than the original one and won't be affected by things like high power Hi band TETRA on 425MHz and amateur repeaters on 434.6MHz, it will still be affected by the faulty wireless doorbell on 433.95MHz.

Now we are into the two main things in my life..... Range Rovers and wireless, the hobby and the job!

mm, but offset the cost of an RF unit to the cost of inconvenience and/or a ruined battery. It's an option.

But if the interfering source is within the passband of the new receiver then the problem will remain, whereas disconnecting the aerial will make the system deaf so the interfering signal doesn't cause the problem.

Thank you for your input Guys i will now carry out some tests on the vaporisor unit to see if it is as you sugest a vaperisor fault by tapping into the PRV port with a guage, this will then enable me to better see the real time running pressure in the vaporisor i hope!!
thanks again for you input to my problem regards martin

Akk, don't do that ... disabling the PRV on a suspect vap ??
The system has a pressure sensor built in, but of course you would need external software on a laptop to read it.

yes i understand that reply thanks.
However i have found a rebuild kit for the vaporisor pt nu 03017
it has the daphrams and o rings for £40
i will rebuild the vaporisor and see if it cures the fault
thanks again for your input in this ongoing fault

you will still need to see what the delivery pressure is after the rebuild,you could tee into the pipe feeding the filter if you cant get to a Prins guy.
As Rossko said dont mess with the PRV.


woody

onward and forwards i have orded the regulator vaporisor repair kit from a firm in holland !
i have also orded a prins gas software and lead kit from good old ebay,
This i hope will enable me to acuratly test the system functionality,
A couple of question would a Lexus vs1-8 ecu be compatiable with the range rover unit fitted ?
Will the prins software be able enable that ecu to resyncronise with the range rover parts already fitted? As it only allows for the versions up to v4 without A prins dealer present although later versions are on the disc.
Finaly where would i be likly to locate the prins ecu fitted to the range rover?
Regards martin

Think I would have organised the software first; regulator problems is only speculation.

There are two variants of Prins VSI regulator which require different refurbish kits, by the by

Why would a Lexus ECU fit any Range Rover? How could the presence of a gas system help it fit? Not sure I understand this.

Follow the wires from the gas injectors or regulator to find the Prins ECU