Thread: Disco backfired this morning on gas :( What to do?

Originally Posted by Young Angus

Well I reset the timing to something much closer to 10 deg BTDC (it was still set on 2) and heard a noticeable drop in the idle so I'll have to find the idle screw and bump it up again. I also got out all the plugs and checked them all and none were worn but they were pretty sooty so I gave them all a bit of a clean (fine sandpaper and toothbrush) and put them back. Old leads are still on which I'll replace when I get back from overseas but re-routed them too so they're a bit tidier. Made sure the dizzy was nice and tight (it was so tight to begin with I had to struggle to get it loose) and then away we went.

Took it for a drive and straight away even on premium unleaded (which it was already set on) it felt much better. Then switched it over to lpg and no problems so for now all is well.

Cheers for the advice too, all helped a lot and for now it all seems good so I'm touching lots of wood

There is no idle screw, Idle is controlled by the ECU and the Stepper or IAC valve.
Only Base idle can be set, but unless some one has fiddled with it, then best to leave it alone.
But saying that, the GAS mixer has an idle screw.

Originally Posted by It'sNotWorthComplaining!

There is no idle screw, Idle is controlled by the ECU and the Stepper or IAC valve.
Only Base idle can be set, but unless some one has fiddled with it, then best to leave it alone.
But saying that, the GAS mixer has an idle screw.

Yep, with the extra advance the engine starts with more revs from the same opening setting of the stepper, then the ECU returns it to a lower idle speed.

The gas mixer will have a mixture screw which affects the idle speed but it is best left well alone as reducing mixture can cause more backfiring.

Ah well I'll leave it be. Took it to the airport this morning and ran gas the whole way and it was great so aside from maybe updating the leads and perhaps rodding the radiator someday I'll leave it alone. She drives very well, now it's off to japan

Good to hear your driving it and enjoying the experience. It's going to be Very quiet on here while your away. Enjoy your trip.

Haha hey guys I got back about a week ago and I've been totally flat out since...two gigs on the weekend along with jet lag and going to see two gigs at the grand prix and a few late nights thrown into the mix!

Good news is the Disco has been running pretty well for the most part. No backfires to speak of since.

It's still not quite right though...but I think I'm getting closer From cold the Disco runs great on gas or petrol. As soon as it heats up and has been driven for a while I notice that it feels like it starts to lose little spurts of power when accelerating in first, second, and third gear unless I'm really pounding the gas pedal...even then it doesn't feel quite right. It kind of feels like a "miss" of some sort. Today on the freeway on the way home I did a test and when I was speeding up and slowing down in traffic (through 1st, 2nd, 3rd, 4th, back to 2nd...etc.) and on gas it was missing or just lurching slightly, almost as if I was bunny hopping the clutch, that kind of feeling, but not as bad. Then I switched it over to petrol and hey presto it accelerated just fine even when I wasn't putting my foot on the pedal as much through the gears and purposely not giving it as much throttle as it should have when accelerating. So the problem is definitely gas related.

Perhaps when it gets hot it affects the spark and hence the gas more than it does for petrol...

Originally Posted by Young Angus

Haha hey guys I got back about a week ago and I've been totally flat out since...two gigs on the weekend along with jet lag and going to see two gigs at the grand prix and a few late nights thrown into the mix!

Good news is the Disco has been running pretty well for the most part. No backfires to speak of since.

It's still not quite right though...but I think I'm getting closer From cold the Disco runs great on gas or petrol. As soon as it heats up and has been driven for a while I notice that it feels like it starts to lose little spurts of power when accelerating in first, second, and third gear unless I'm really pounding the gas pedal...even then it doesn't feel quite right. It kind of feels like a "miss" of some sort. Today on the freeway on the way home I did a test and when I was speeding up and slowing down in traffic (through 1st, 2nd, 3rd, 4th, back to 2nd...etc.) and on gas it was missing or just lurching slightly, almost as if I was bunny hopping the clutch, that kind of feeling, but not as bad. Then I switched it over to petrol and hey presto it accelerated just fine even when I wasn't putting my foot on the pedal as much through the gears and purposely not giving it as much throttle as it should have when accelerating. So the problem is definitely gas related.

Perhaps when it gets hot it affects the spark and hence the gas more than it does for petrol...

Yep, that's why anyone who drives a lot on gas puts in the colder plugs we told you about earlier. They work better!

I had a hunch that might be it Cheers, I'm going to get some of them in this weekend!

IMHO

Part of your problem is this.



LPG mechanics who care about doing the thing correctly will move your PCV port from the plenum to before the LPG mixer ring. This is so that any crankcase spark sometimes found in worn engines doesn't find itself in a nice fuel rich environment after your LPG mixer, where it gets to explode your air intake system.

You should also clean or replace the flame trap on top of the RHS rocker cover.

Diana