VS on gas destroying plugs/backfiring

[Old Colts in Oz]

A nice Christmas present for me - my wagon limped home after a long towing effort . It's happened twice now - brand new plugs and runs ok, then after about a 3 hour drive under load ( car trailer ), the car backfires and seems to drop a cylinder or two. I pulled the plugs out and the ceramic on 4 out of 6 plugs was cracked - they were brand new this time! So not sure whether the gas backfire caused the plugs to crack or the other way around. Any ideas? I'm using NGK BPR6EF-13 plugs and they seem to be gapped at about 1.3. This morning I scraped together some old plugs that weren't cracked and regapped them to 1.5 to see if it would run on petrol - still misfiring. I've had constant problems with LPG and poor fuel economy so I think I will just try and get the car running back on Petrol now. Which plugs should I buy for standard petrol?

Thanks in advance and merry christmas

[Old Colts in Oz]

Picture of the plugs. I can't remember which are which but the oldest ones were just under 5000kms old, the newer ones about 500km old.....

[Paul13pp]

To me, it looks like they were broken when you removed them with the socket.
Any side movement while undoing them will crack them like this.
Always support the socket as close as you can to the plug and don't allow any side movement while putting pressure on to undo the plug.
The spark plug socket you are using may also have lost the rubber insert that helps protect the ceramic upper part of the plug as well as holding the plug firm in the socket so it is easy to put them back in so they don't fall out of the socket while installing them.

[Old Colts in Oz]

Ah cool mate, I did wonder that as I'm using an old socket. Mmm, I guess it doesn't help me with why the car starting running bad then.....

[Old Colts in Oz]

Ok so I've done some more testing and checked for error codes. There's a definite miss under acceleration on both Gas and Petrol. Initially I got error codes:
19 - Throttle Sender Stuck
44 - RH Oxygen sensor Lean
45 - RH Oxygen Sensor Rich
57 - Injector Power Supply Voltage Variation
64 - LH Oxygen Sensor Lean
76 - Air Fuel Ration variation
32 - Manifold Air Flow sensor

I disconnected the battery and reset the comp and now I'm only getting error 32. The engine light is staying on all the time now. Would this error cause a misfire.....?

[HamaTime™]

NGK iridium plugs should do fine. I have them on my VS on gas, never had a problem, only backfired a couple of time when I had a vaccum hose problem.

Probably plugs are blowing as a result of the backfires or a fault in the mixtures and tune. In terms of backfiring, I'd be checking your tune to make sure you not running lean. Common for LPG to backfire when running lean or timing is a little off.

Start there, see how you go.

[Old Colts in Oz]

Thanks mate, good advice. It really does feel like it's plugs/points/coil packs related now. I drove it on petrol tonight and with only slight acceleration it's smooth as, but then under more load it breaks down and misfires. Codes are down to 32 and 57 now. Hopefully Sprints are open tomorrow and I'll get new plugs and leads. I reckon I'll set it up to run on petrol for now and if I get confident I may switch back to gas .

[pjdm1980]

Thanks mate, good advice. It really does feel like it's plugs/points/coil packs related now. I drove it on petrol tonight and with only slight acceleration it's smooth as, but then under more load it breaks down and misfires. Codes are down to 32 and 57 now. Hopefully Sprints are open tomorrow and I'll get new plugs and leads. I reckon I'll set it up to run on petrol for now and if I get confident I may switch back to gas .

Have fun trying to find the points on a VS, LOL!
I had dramas with my VS on gas and turned out to be a DFI/Coil pack.

[sticksicks]

Damage to the ceramic outers of these plugs is certainly caused by installation/removal and would likely lead to some of the current leaking straight to your engine block!!!!! This arcing may have 'confused' some sensors and thus given you codes that are wrong; there's always hope
Suggest use of Eagle leads to replace your (possibly) old spark leads, stay away from Bosch Australia plugs and leads! They're over priced for their quality.
Check other connections like your altenator and especially your battery connections as any, I mean ANY looseness can create even breif voltage changes that might leave you with a plenum full of raw gas that with a stray spark goes BOOM. SNAFU for ecotech engines. Check tightness of injectors in the manifold -engine off, batt disconnected! I've seen loose old injectors contribute to these issues.
BUY a workshop manual, best $50 you'll ever spend if you like working on your wheels )

[Old Colts in Oz]

Thanks guys! Ha ha, I'm used to old car with my "points" slip. Ok just finished replacing the plugs and leads. I got side-tracked and did the Tailshaft Centre bearing - that is one crap job!! Ok, the misfire is still there . At idle and slight acceleration it's fine but under load it breaks down. I'm still getting error codes 32 and 57. I had a spare plate that the coil packs bolt too ( is that the DFI Module? ) so I swapped that over with no luck. I also read on the forum somewhere that to test Coil Packs you take the leads off and if the spark jumps straight across the pack is ok. If that's true then the coil packs seem fine.

I wonder if your comments sticksicks are causing the error 57? I've just had to pack it in as have other stuff to do but I'll be back out there tonight. I'll check all the injectors etc to see if I can spot anything. A workshop manual is definitely on the cards!

[strgas]

NGK BP7EF gapped to 0.9 mm good set of low resistance leads with a spiral core , gas master , IC&E , top gun , bosch sports core , check your spark plug socket and see if has the rubber insert inside to avoid cracking the plugs and do not over tighten the plugs , check for vacum leaks around gasket and seal surfaces after repeated back fires gasket and seals become loose or split from the backfire pressures, I have seen IAC o rings leak injector o rings blown out of shape so check carefully for any leaks in and around the manifold , also looking carefully at the mixer set up if its a simple mixer ring it may no longer be sealed to the throttle body correctly if its a impco style system it may have splits in the rubber hose from the throttle body to the mixer

[strgas]

code 57 is normal for a non injected system as the power to the injectors is switched of by the gas system and results in code 57 , can be resolved by replacing the power to the injector pins at the ecm but not needed

[Old Colts in Oz]

Update - got the old girl driving again. I ended up replacing all 3 coil packs and the missfire is gone. Interestingly it's running better on LPG than petrol. On the freeway today the car seemed kinda jerky on petrol and when i flicked it to gas it actually gained power and was smooter. Bit strange as I'm assuming the plugs are set up for petrol. So in the past week I've replaced the tailshaft centre bearing, new leads, plugs, and all 3 coil packs. Expensive week!