VR V8 Stato Backfiring/Stalling LPG/ULP

[psharpli]

Guys, 94 v8 Stats, on gas, big problems with poss electrical issue, car starts but when slight accelleration is applied, engine misses & if more pedal applied backfires badly blowing airbox to bits, on ULP car misses a litle but only stalls if left to idle a while. When driving its worse, gas - farts bangs hesitation, switch to ulp & away she goes...? only to stall later at the lights. Igntion module issue? as this code has come up, but according to some sources if this unit fails it just stops period. Power steering is also very stiff since this has come about. Gremlins galore here !! Plugs & leads have been replaced some 10k ago & dissy cap etc. Oxy sensor replaced 1k ago. Bring on the ideas guys.... Regards. :-)

[Burnout124]

sensors do often just die but on the odd occassion they do play up i would replace the ignition module as that is the code. also some times it could be the wires that conecet to the ignition moduel can have a break and cause a problem.

[psharpli]

Ok thanks will do...i failed to mention that as the engine heats up to normal temp after 20 mins approx of running time these issues disappear ? & it runs fine ? But after stopping for a bit & restarting, hence having cooled slightly, the painful symptoms return only to go away eventually when hot. But when cold...its near impossible to drive... unless on ULP, then all seems ok.

[psharpli]

May have to have Auto Elect. do some checks to identify area of concern. Thanks for your input Burnout124 :-)

[scvs6]

My VS V6 is on gas and when it backfires, I change the spark plugs and then its alright for 30,000-40,000kms. And then it starts backfiring again. I put bosch platinum spark plugs in and hasn't played up for ages.

[psharpli]

Thanks superch'd. will do them also & let you know. will plugs fail when cold, i have heard that plugs need to be in top nick to survive gas...?

[scvs6]

Thanks superch'd. will do them also & let you know. will plugs fail when cold, i have heard that plugs need to be in top nick to survive gas...?

Yeah i know for a fact that Spark Plugs don't last as long will LPG. You wont believe what just happened on my way home from work tonight, I was 15kms from home, let go of the accelerator to turn a corner, accelerated, next thing *BANG*, so loud it nearly gave me a heart attack haha, and the engine lost all power for a moment. Then it was fine the rest of the way home. I just had a look under my bonnet and the airbox was blown off, plastic cover on gas mixer went loose and was nearly off, and where the intake pipe goes onto the throttle body was completely off. When it happened, I said to my dad (who was in the car with me) "looks like its due for spark plugs". I think that direct injection gas is the way too go because you wont have these problems, only thing is the cost of getting it put on.

Let me know how yours goes anyway i'm about to go back outside and put the intake back together.

[psharpli]

Bud sorry to hear that i must have jinxed you... damn airboxes, at least you can re-assemble, mine was blown to 3 large pieces which i intend to fibreglass back to health. well i have replaced plugs with the platinum ones & wow what a difference...when cold its a pure joy to drive now...not a single miss. I will do the change over with the ignition module as this did come up on the diagnostic ck. I am amazed that i only got 10,000 ks out of the last set of plugs NGK's. Thinking it can't be them already, but obviously not so... Thanks for the tips mate appreciate your help & to all others on this subject... regards.. Pete.

[scvs6]

Bud sorry to hear that i must have jinxed you... damn airboxes, at least you can re-assemble, mine was blown to 3 large pieces which i intend to fibreglass back to health. well i have replaced plugs with the platinum ones & wow what a difference...when cold its a pure joy to drive now...not a single miss. I will do the change over with the ignition module as this did come up on the diagnostic ck. I am amazed that i only got 10,000 ks out of the last set of plugs NGK's. Thinking it can't be them already, but obviously not so... Thanks for the tips mate appreciate your help & to all others on this subject... regards.. Pete.

Thats awesome mate. Glad to hear the spark plugs worked. NGK are the ones I was using as well until I switched to platinum. I know what you mean with the airbox, I have gone through a few of them. My dad has a VR Statesman 5.0L same as yours and he converted his to LPG. Its had the same spark plugs in it for years and hasn't played up once (except when the coil went on it) so I think he must have platinum plugs in it as well.

[_senator_]

that's the problem with gas any small wear on leads plugs will cause this i had same thing happen to me there is a trick if you lift up bonnet at night start her up and use a mist bottle of water the spark will jump around and you will find the problem if not change plugs.

only problem i had when i replaced the all this and airbox on my car it would ran crap on fuel still as the backfire through the airbox stuffed the maf sensor something to think about also if your starting to stall on fuel

and finally the last piece of advice try to run on fuel for the first few 100 meters i was always told you should allow engine to start on fuel and warm up before kicking over to gas apparently dont qoute me but you may get more out of your plgs ignition system

[scvs6]

try to run on fuel for the first few 100 meters i was always told you should allow engine to start on fuel and warm up before kicking over to gas apparently

This is true. I alway run my car on petrol until it warms up, then switch to gas. If you don't then the fuel injectors can block up and even cease. Thats one thing that I forgot to mention.

[brodster]

Air flow meter not working ,does the engine lite come on as a fuel pump or old battery do same thing

[scvs6]

Air flow meter not working ,does the engine lite come on as a fuel pump or old battery do same thing

I don't think that the VR V8's had a air flow meter.