VS Ecotech Ute missing under load

[Azzman460]

Hey guys, my mate has a VS V6 Ecotech ute.

It has recently been randomly stopping when he slows down at traffic lights or whatever, the engine would just cut out. After it happened he couldn't get it started again so he called the RACV. They told him the reason it was stopping was the fuel pump, and they got back to him with a $2000 quote to fix everything wrong with the car, so he told them to do the fuel pump and give him the car back.

I have recently completed a major service on the car, fixing everything on the RACV's list including the plugs and leads.

The stalling problem persisted.

The car ran fine however (except for the stalling), after doing the service, for about a month until i flushed out the cooling system the other day.

Just after i did the cooling system and fired the car up, it had a miss when you put your foot down on the road, and just in park or neutral. It idles fine, and takes off slowly fine, but just under a bit of load she misses on 1 or 2 cylinders.

I thought it may have got a bit of water in an injector or coil or something silly and the problem would go away which it did, after about 5 mins driving, and after 2 days, its back

So what do you reckon this problem could be?

I think the RACV are bullsh!t artists as they charged $200 to replace the fuel pump and it still stalls randomly so i dont know if the random stalling and the missing are related.

If its an injector problem i thought it would be missing all the time not just under load.

Could it be a coil problem?

Any help to diagnose this problem is much appreciated! Cheers

[buzuki]

maybe try crank angle sensor, other then that i know my ignitions leads are like 3months old and stated missing last friday, turns out one was loose fit on plug and was slowly coming off, causing a miss under load only.

[Azzman460]

ah cool i will check that.

Also it has trouble starting sometimes, just won't fire for ages, turns over ok just won't fire, which more often than not flattens the battery, however if you jump start it, it starts fine. Could this be related?

I just checked the coils then, the coil for cylinder 3 and 6 showed no resistance on the secondary side (thats checking the resisteance between the 2 poles where the leads plug onto the coil)

I think this is supposed to show between 5-7k ohms which it did on the other 2 coils, just not on that one. I thought if there was an open circuit on the secondary side it would miss all the time not just under load.

Could this be the problem?

[greenacc]

Those coils do die, and can be a pain in the ass to diagnose. You might be able to see sparks jumping off the dead coil if you run the motor in the dark and give it a revv.
Cheap coils are only about $50 from Repco if you need one, or get a whole set from wreckers. Since you have measured it to be faulty it probably is .

[cander24]

If the coil has no secondary resistance you can be pretty sure you've just found the problem. Just incase the problem lies with the DFI module (alloy plate under the coils) try and borrow a coil from a neighbour/mate if possible to try it first and if that sorts it then go and but youself one.

[Azzman460]

yeah i thought that but i dont quiet understand how there can be no secondary resistance but it still runs ok at idle and under normal taking off speed.

after we took the coils off to measure the resistance the car still missed at idle, but my mate said on his way home it cleared up again and seems to be ok, so i told him to take it for a squirt tonight and see if it goes away or comes back.

[Azzman460]

So if this problem is the crank angle sensor, which part usually fails? The sensor itself or the "tonewheel" if you like, behind the harmonic balancer?

[-=ApheX=-]

unless the "tonewheel" has been damaged, which is an unlikely occurance, the CAS is almost always the part that will fail.. there have recently been a number of these threads and concerns about this CAS issues comming up read through those!