AU2 LPG won't fire.

[FalconXV]

Ok. I bought a cheap AU2 on gas with 140 xxx kms, thinking safe bet, good trouble free investment.
Little did I know, the last owner has neglected the sh** out of it. Front springs have been cut within an inch of their life, rear tyres are retrograte 205/R15!, original motorcraft leads, neglect.
I did about 8,000 kms before a backfiring problem develops, below 2000 rpm. This goes on for at least a month, with some cringe-inducing backfires, which I suspect blew a hole in the flexible rubber inlet pipe.
Against my better judgement, I pressed on until it cut out one day, and wouldn't start.

Got it towed home, fitted 6 new plugs ( NGK non-iridium), new leads. Does not fire on 3 cylinders. Reluctantly cranks over sometimes. Buy a new coil pack, same issue.
Thought it might be leads, as when I tested spark, it was intermittent on 3 of the cylinders. Replaced the leads, won't even kick now. (Top Gun leads).
What do I do now, I can't afford to get it towed to a mechanic, and I am goign to see if theres a repair manual I can borrow at the library, or pdf.
Could it be a sensor issue or am I way out of my depth?

[JC]

Backfires can stuff the MAP sensor, they can also create a gasket or vacuum leak which will make the car hard to start and run. Are you in the NRMA/RACV etc? If so, time to call them out - they should at least diagnose the issue.

[Bushbasher]

First mistake was buying those god awful Top Gun leads, sorry but they're utter garbage. If you've still got $60 in the kitty, lose the leads and get a set of Eagle Leads HERE. (I've got a set on our wagon that have done 200k now and still out perform the factory leads.)

Double check your coil connections to the wiring loom to make sure the plug isn't full of crap or something and causing a bad connection. Then double check that you've got the leads the right way round on the coil. I remember the first time I did a lead change I managed to put the leads on wrong. Then trace every vacuum line and make sure it's still connected. All those backfires will probably have blown one or two of them off. Make sure your PCV valve hasn't disintegrated. Also, have you gapped the plugs to 0.9mm? Good luck with it.

Bushbasher

[Evgeni]

Just wondering which cylinders have spark. The coil pairings are
1-6, 2-5 and 3-4.
How are you testing for spark? If you connect a testlight to battery negative, then pull a lead off and get someone to crank it. You can stick the tip of the test light closer to the plug wire in the case of weak spark. It should at least be able to jump half an inch.


The sequence of events will go, crank sensor, PCM, Coil pack, leads then spark plug....
With new plugs, leads and coil pack, what you can do is go to the wiring connector between intake runners 5 and 6. You will be able to access the control pins to the coil pack - I dont have the pin numbers off hand, but you can access them on this website via the tech resources.
They are ground switched - so with the testlight connected to battery negative, you should be able touch each pin and they will fire one of the three coils - again provided they have a ground source to jump to.
This will at least by pass the crank sensor and the computer which will help isolate the problem.

[Mr Hardware]

The three blokes above have some great ideas so nothing left for me to add.
Is it an egas? or can you run it on petrol?
Backfires are my 'change leads on the weekend' indicator.
I average 53k to a set of leads.

[Bushbasher]

Originally Posted by Mr Hardware

I average 53k to a set of leads.

Dude, you got to have a problem if you're burning up leads every 50k The Eagle leads on the wagon have gone 200k so far and still going strong?

Bushbasher

[FalconXV]

Originally Posted by Mr Hardware

The three blokes above have some great ideas so nothing left for me to add.
Is it an egas? or can you run it on petrol?
Backfires are my 'change leads on the weekend' indicator.
I average 53k to a set of leads.

Its a factory egas.