Hesitation on LPG 3.9 Disco

Nov 27, 2006 4 Replies

Hi anybody any ideas?



I have a 3.9V8 Disco Safari 1998 Model. It has developed a problem whilst running on lpg on sharp acceleration it will hesitate or backfire but will only do it if I am accelerating from below 1000RPM once the engine is reving it wil behave fine up to about 3000RPM sometimes further then it again hesitates as if not getting enough fuel or spark to rev higher. If I pull away gentle it will hesitate a bit but once the revs reach above 1000 then it will pull away fine and only struggles when it reaches higher revs as said above.



On petrol it starts and pulls away fine at any throttle opening and revs to 5000 fine although it occasionally sounds like it is missing a little but mostly fine.



I am guessing an electrical problem which is worse when running on LPG as it is more difficult to ignite etc.



So far I have changed HT leads, Rotor arm, new plugs(ngk BPR6es) next on my list is new Dizzy cap(tho mine looks very new) then a new coil.



any ideas guys?



snipped-for-privacy@hotmail.com uttered summat worrerz funny about:

Depends on what system you have got. Firstly stop spending money and take it to a specialist.

My LPG system stopped working when in the South of France thanks to a break down and French Technicians, bless them.

Got home and took it to a local fitter expecting to be fleeced as you do... they fixed the fault, tuned him up removing a "hunting" at low rpm and sent me away with a smile for £20. I may have been very lucky but what is evident is that I'd never have been able to get rid of the "hunting" as it was a tweak of the mapping for the fuel that sorted it.... no amount of my 'ammers would have sorted that.

It had the "hunting" since we bought it and I just had it as a feature of the LPG system.

Software for most systems are doing the rounds... though I was quoted £95 for a lead to plug my laptop in to the car... given the likelyhood I'll neeed it and the greater likelyhood I'd c*ck up the system fiddling with it I elected to return to my local chappy if it has "issues" in the futre.

HTH

Lee D

Probbably sensible advice Lee!

BUT I am a man who enjoys fiddling with my Disco.

Leads were old and looked knackered anyway, Rotor arm again looked worn.

Garage I bought it from a few months ago gave it a service but had put the wrong plugs in! the plugs I pulled out of it were for the 1999on

4=2E0 Ltr Disco 2 Probbably an easy mistake as its a `1999 registered (T) Series 1 but the chassis number says its a 1998 built.

It's a Landi Renzo System at least a few years old with 2x35ltr tanks in place of the old petrol tank with 2x40lts under sill tanks plus an

8Gal pertol tank behind the rear O/S wheel arch. i get about 120 ltrs into it which including getting up to temp on petrol gets me about 350 miles.

I am new to lpg but like to try to understand as much as possible and do as much myself.

any suggestions are welcom

did you gap the plugs properly? (slightly reduced for LPG works better). no air leaks anywhere in the intake side?

When my car runs badly at lower/higher revs on LPG it is down to the points (so shouldnt be a problem for you), but would suspect ignition system.

I would also second Lee's advice of taking it somewhere. I have the same local place as him and they are great. Going there a few times and talking to them has taught me a lot and now i can sort it out myself - but what they have told me helped that an awful lot.(loyal customer now!)

Thanks Tom I will get round to checking the intake side for leaks.

Reluctant to change Spark gap at the moment as I know it was running fine before on standard gap plugs. It has a K&N cone filter but again it has been running fine with this fitted before.

Dont know anywhere around here that has a good reputation for Working on LPG Vehicles.

When I first got my Disco it the guage was reading full and I could only get 25ltrs into the tanks. the guage was reading empty after 50 milies and I was concerned about not running it empty so I took it to an LPG converter who changed a tank solenoid and charged me =A395 for checking the system! It turns out nothing wrong with the tanks just the guage if i ignore the guage it will do 350miles and fill up with almost 120ltrs. He should have known that!

If anyone knows a good garage in Essex please let me know!

Thanks

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