VT SS 5.0L Intermittent injector Pulse to cyl 2

[SatansVS]

Hi Guys

As Stated in the title at work i we have a vt ss 5.0l v8 which has a running issue really bad when its cold better when warm, so far we have changed coolant temp sensor, tried another distributor, ignition module and ecu the trouble is what ever we try we can not get a consistant injector pulse to cylinder 2 while all the others get a good one the pulse is random and at best erratic without any sign of a pattern.
we have checked all wiring and from what we can see on the wiring diagrams all injectors are controlled from the ecu even at the ecu we have the random pulse on cyl 2 whilst the others are ok.

any ideas or help would be greatly appreciated mayb in our thoughts we might have missed something (i hope)

Cheers Cam

[db_notso]

nope sounds like ecu is sending incorrect pulse to ONLY cyl2
loose pin in ecu at output cyl2injpulse... new ecu

[Dev]

Check the injectors may be leaking. Im having the same problem inectors are leaking, id say sending the wrong message to the ecu. whilst the car is running get a water bottle and spray around injectors. If there is a leak you will notice te idle change when spraying the water or here a suckong noise. I recently bought the same car. Is the engine light comming on ?

[dirt drifter]

my vs had a similar issue with no 8 injector (i know its not sequential like a vt) at all temps, tried leads, plugs, dizzy cap, rotor button, new injector. nothing completely fixed it.

was stuffing around with it the other day and noticed the flat woven earth lead from the alternator bracket area was loose at the body. cleaned and tightened it and it seems fine now. dunno how the hell that works but anyway, maybe an earth issue?

[IBLOWN]

If you've changed all the parts like you've said then it can only be a wiring problem. Going to have to backprobe and check earthing to that injector lead.

[SatansVS]

thats what we thought we went back and rechecked everything again this morning we even cut the wire from the computer to the injector just to make sure that it wasnt overloading the driver in the ecu tho it did get a little better it didnt fix it, we also tightened all the terminals in the ecu. also this morning tho we did move the coil and put the sleeving back over the ignition leads some how this helped a bit as the injector pulse is consistant now but still has a miss mayb 1 in 10 injector pulsesis missing now which is good but not fixed argh

[SatansVS]

ok so here it is, at the end of last week we had a high end diagnostics tech visit and check over the car. neways long story short what he found that the variable pressure solenoid was creating a noise along the est(electconic spark timing) circuit which was upseting the ecu giving us the intermittent injector pulse. the way in which he fixed this was to make up a basic noise supressor which on his scope aressted 99% of the noise and instantly the car ran better.

goes to show sometimes you can change so many different things but without the right tools you will never find the problem. the scope this guty bought with him was worth over $40k and looked like something you would only ever see in a specialist brain surgery clinic by far amazing and a good learning curve