I've bought my truck about 6 months ago and changed the heads because they were cracked. So new heads, valves, new thermostat, new gaskets (including plenum), new sparkplug wires, cap and rotor. I've been having random misfires sins the beginning. About a week ago, one cylinder (i suspect number 8), doesn't fire on petrol and i have a great loss in power. I do run a Liquified Petrol Gas system witch bypasses the oxygen sensors and cuts off the injectors. When i switch to LPG (goes trough the throttle body as a gas) the engine runs smoother and has power but you can still hear a misfire on the same cylinder.
I did a compression test and i've got 150 PSI all around so that's not the problem.
I checked my cat yesterday just to find out that it's empty so no restiction there.
When i do a readout of my ODB2 system, it gives me a "random misfire" and "oxygen sensor reacting too slow" code (the check engine light only comes on only when i run on petrol).
Does anybody have an idea of what to check to get this engine running smooth?

Thanx!!

 

Whew, a petroleum setup? Why and what for? Not judging, just curious:-P I had, and continue to have, problems with my spark plug wires. Make sure your wires are quality, and there's a way to route them to help guard against this. My wires made mine miss so badly, especially when it was wet, my check engine would start flashing. I bought a can of spray silicone and doused the wires, been ok since. Also, Maybe a problem with that injector? If you can aquire Sea-Foam engine cleaner, dump that in your fuel tank. Also, check you O2 sensor. Hope this helps!!

 

Did you route the plug wires properly? There's a TSB that covers this. That's my first suspicion.

 

PICKUP COIL AND CRANK POSITION SENSOR are areas to look at. Also check the injector as well.

 

Did that too, it helped a little but didn't solve the problem.

 

Then check the pickup (CKP sensor) in the distributor. Make certain the electrical contacts are clean and free of dirt/grease.

 

make sure your distributor doesn't wobble at the shaft

 

why a petroleum setup?? Gaaaaaaa!!! It's been driving me crazy all day!!!

 

The petroleum setup is a way to drive cheaper over here. We pay about $3.50 per gallon of fuel here and a gallon of LPG costs about 95 cent.

I'll check the crank position sensor this weekend. The coil is ordered, still waiting for it...

I fixed a major problem on my cruise control, it was bothering me for months! The only thing i haven't checked was the actuator and it had holes in it, probably caused by a leaking battery from the previous owner. I repaired the actuator and now the truck runs a lot better and the CC works but i still have a miss on one cylinder. I'm guessing that i have a leaking intake gasket, i think that the "gasket paste" i used isn't good for sealing fuel passages. I do have all the gaskets to replace it so i think i will do that this weekend or the first available day I'm free.

Thanks for the help!!

Bigster

 

Ok, that makes sense. Thanks! Keep us posted!