Intermittent misfire on VP

[dlp1969]

hope someone can help.

On my VP V6 I've had an intermittent problem for a couple of months now. What happens always goes like this. About 15-20 minutes after start up in the morning it will start misfiring/running rough and the engine management light will come on. At the beginning if I turned the ignition completely off for a minute and restarted it was fine for the rest of the day. Lately this doesnt work but usually after arriving at my first job for the day it would be fine when I left an hour or so later.

I also noted it would continually run rough if it got down to less than 1/8th of a tank and would be fine once filled. I noted a fuel smell when this occured. I replaced the fuel filter, injector cleaner, and cleaned intake manifold and throttle body but problem still there.

I had it checked by a friend who runs a Profix, checked all pressures and sensors and codes and couldnt find a problem.

I last week had another mechanic friend replace the radiator and asked him to check fuel pump and lines. He found a leaking line into the fuel rail and replaced and checked fuel pressure ok. Ran tank almost dry with no fuel problem.

Car is still doing it and I havent a clue what it is. Its only ever done it early morning about 15 minutes in and is fine at other times. The only other sympton was a complete loss of electrical power after five minutes for a second but its only done this once and may be unrelated (checked battery leads etc after)

I'm thinking maybe coil pack but not sure, any ideas would be appreciated

[hi_ryder]

sounds like the coil packs to me... also check the charge coming off the alternator with a multi meter just for shits and giggles, should be about 13.5 to 14 volts... does it lose power and run rough when you accelerate? could be inlet manifold gasket... also if its running rough after it warms up to operating temp might be your crank angle sensor... someone else with more experience will chime in soon with more answers...

[Pickle']

I used to have something kinda like this with my old VR but only when idleing, when i'd pull up to lights or just have it running it would get abit lumpy like a miss then come back to and be fine intermittently. Some days it would run all day without an issue somedays it wouldn't get better. I changed plugs, Leads, Coil packs and injectors and it still done the same thing, Finally thought i'd change my alternator and that fixed the problem. I never had any dash Light come on though!

[defecat0r]

this is only a small thing, but if you're playing around with coil packs, take a close look at the contacts on the DFI module (the bit the coil packs plug onto). I'm on LPG and had constant backfiring problems for like 2 years (backfiring on lpg is caused by intermittant misfires). Anyway, my issue turned out to only be dirty contacts on this DFI module all along, so take a close look and give em a scrub if they're dirty.
Only other thing i can think is MAP sensor. I've had issues with the MAP sensor plug connector, with the car running rough as and stalling when it's not plugged in properly. The plug connector is ~20cm to the right of the throttle body, dunno where the sensor is, maybe more experienced peoples might know if MAP sensor fits the symptoms tho.