TB42e rough idle/stalls/backfires/low power???

[GQ Bear]

I've got this damned Gremlin in my engine. Any thoughts or solutions?

It first happened in Queen's Birthday w/e in June up at Gembrook. Car was running fine then hit puddle/bump and it backfired, lost power and stalled. Blew airbox apart so tie-wired that back together and it was idling rough as guts. Tacho needle was all over the shop and the eng mgt light was displayed.

We played around with a few things and, suspecting water, pulled air ducting and airflow meter off. Putting these back on seemed to reset fault and away we went. Happened a couple more times that w/e and same remedy fixed it.

Went to Woods point on snow discovery trip and it ran beautifully all day untill we were ready to head home and it played up big time on a very difficult 4wd track. Not the place to break down. Impossible to tow a vehicle out of this place. Anyway the airflow meter trick seemed to work and as long as ran on gas it was ok for about 5ks or so and die. 5ks and die. All the way home (about 100ks). Tedius stuff.

Anyway i got a new airbox and had no problems untill the next time i went 4wheelin'. Friday night plugging through deep water and mud was not a problem in Narbethong. First decent hill at Big River the next day and the problem came back to haunt me again. This time it wouldn't reset. Parked car at camp and it purred like a kitten the next morning - untill we hit first 4wd track when it once again played up. Still suspecting water i siliconed anything and everything that wasn't already silicon or rubber. The air induction system is now so watertight it could be used as a low suction, mobile vacuum cleanerPulled distributer apart and cap and rotor were in terrible condition, Hmmmmmmmmmmmm.

Got a new cap and rotor and car drove like a new machine. OK, let's go wheelin' again!! Headed out to Gembrook a couple of weeks ago for a day trip as it's nice and close. First 4wd track, you wouldn't believe it! Bloomin' thing loses power and stalls just after hitting first decent bump in Low 2nd. Starts running rough again. Stuck on an incline i pushed it up this hill in low 1st with eng mgt light still on and running like a bag of shite.

We pulled dissy apart again and cleaned it up a bit more, etc, etc. Eng mgt light stayed on all day and car ran like a bag of shite all day. Pushed it out up and down hills, over rocks, through creeks, the works. Limped it home that night and she's still sick (even in 2wd this time).

I took vehicle to local Nissan dealership and they did a diagnostic test. Came back showing no faults. Their mechanic reckons it sounds like cylinder problem or split exhaust valve in no.5 cylinder. I've recently had the head surfaced, new h/d valves and springs put in and gaskets replaced. Originally being an intermittent fault doesn't ring true with cylinder problem. When it had a blown head gasket eng mgt light never illuminated. This problem must be electrical. But what??

My mate told me his mate's VL commodore suffered a very similar problem which turned out to be the Crank Angle Sensor located in the distributor. I've sourced one locally and will be fitting it on thursday. I'll also have a look at Power Transistor, if CAS doesn't solve it then PT will be the next target on the hit-list.

Anyone had anything similar? Any ideas?

Thanks

[awill4x4]

I would be suspicious of the air flow meter especially if you have had some backfires on LPG, it's a common fault on efi cars (especially Fords) that have suffered from backfiring.
Regards Andrew.

[GQ Bear]

Distributor was full of gunk and water. Crank Angle Sensor was sitting in a pool of water and was obviously splashing up over successive bumps 4wdriving, thus the original intermittent problem.

New CAS, replaced bearings in dissy, good clean up. Beautiful

[Jimbo]

What did that end up costing you?

[GQ Bear]

Jimbo, You should be able to get CAS for about $220 from a fuel injection joint and looking at about 1hr labour from mechanic.

Runs beautifully on gas but seems to have a bit of a flat spot on petrol. Do you think it may just need a dynotune, or may have been tuned to gas and therefore prefers this fuel? Mechanic noticed that the Throttle Position Sensor (TPS) had been adjusted at some stage. Could this be a likely cause? Would it be likely that this was adjusted last time it was dynoed?

[Jimbo]

When i got mine it didnt run on petrol. After a lot of stuffing around i ended up getting another fuel pump and it fixed the problem (bought a walbro pump on ebay for $90). It now runs great on both fuels but does have a little flat spot on petrol and also the idle is a bit crap on both fuels.

I took off the dizzy cap and it was clean and seemed in good condition. The leads were changed when i bought the car and the previous owner installed those platinum plugs which are meant to last 100,000km.

I have never touched TPS but it could be a problem. Any idea ho to tell how it should be set?

Jimmy