1996 VS Commodore V6 Misfire?

[Changa]

Hey guys,
On occasion my VS seems to lose like 300-400 rev then recovers again. Its almost as if its going to stall but then recovers. Happens whenever, like can happen when im driving or just sitting idling. Sometimes happens multiple times in a trip or only once. Nothing seems to trigger it like revving or anything, seems to happen at random. Have checked the leads and ignitions coils with a multimetre. Dont know how to check the DFI module, and unsure on the Crank Angle sensor, as I have been told these might cause this problem. Is there anyway to check the DFI module? Or you just replace it? They are expensive thats all and I dont want to replace it if its unnecessary. Havent pulled the plugs out, but they were replaced wiht the leads which would be barley 3000kms ago. My transmission has pretty much had it as the Torque clutch converter no longer locks up properly but I dont think this could be related as the misfire also occurs sitting in neutral idling.

Also another thing to add is when it does misfire and drop revs the engine light flicks on for like half a second and then its gone again. So yeah dont know if that clarifies anything or not.

Thanks in advance guys,
Alex Short

[-ToM-]

try getting some carby cleaner and going over your throttle body and IAC. I had a similar problem, which was caused by the gunk in the throttlebody

[Changa]

Nah mate the TB is clean as. Im fairly sure it has to be an ignition problem

[Chris E]

Edit: Sorry man only read half your post

Your best bet would be to run the error codes or take it to a mechanic and ask their opinion. I don't think its a problem with the gearbox I've gone through four transmissions it never affects the engine.

[Changa]

It did come up with an error code 46 but that was because I hadnt connected the battery terminal tight enough and it was losing the circuit lol, hence causing ignition problems, but this is different.

[JA2Z]

Question:

does this rev drop occur when your fan engages? if so, maybe your alternator is not too healthy and just as the fan starts your Computer might not getting enough juice and cutting out for a split second?

Cheers,

[Changa]

Im not sure coz the fan doesnt automatically turn on unless the engine gets to a certain temp. But Im fairly sure it cant be your suggestion, if the alternator was screwed then when the fan turned on and the computer cuts out, wouldnt like everything turn off, like the stereo and lights and such? Plus this problem occurs at anytime like just when you start it up when its cold, so the fan wouldnt be on then.

[delcowizzid]

dfi modules have been on ebay brandnew for $57 bucks

[Changa]

Holy crap really? I thought they were like $300 new from holden.

[delcowizzid]

~ NEW VN SERIES 2 TO VY V6 IGNITION MODULE ~ - eBay Ignition Systems, Ignition, Charging, Car Parts, Accessories, Cars, Bikes, Boats. (end time 11-Jun-09 03:05:47 AEST)

[Changa]

The guy who is selling that module has some really bad reputation comments I dont think I could buy of them.

[delcowizzid]

haha didnt even bother reading his feedback at your own risk i spose not factory GM part either

[greenacc]

have you tried cleaning all the engine earths ? especially the one under the coils and DFI. Could be worth pulling the coils and DFI off the bracket then remove the bracket and clean the whole lot.

[Changa]

Yeah ok I might try pulling off all of it. I have no idea where anyof the earths are though so I cant do much about that.

[Changa]

haha didnt even bother reading his feedback at your own risk i spose not factory GM part either

Yeah there was some pretty bad stuff said about that guy like wrong items, cheap imitations, stuff that didnt even look like the pic. I dont think I could go through that guy.

[greenacc]

you will find the earths as you go. there's one under the coils, one near the battery and a few on the engine .... looks like a small wire bolted to the engine. Check if they are rusty or dirty.

[Changa]

Ok thanks for that

[paulsautoelec]

how is yor harmonic balancer looking i have seen this before where thehamonic balancer was running that far out it was chewin up the crank angle sensor on a car with similar symptons to yours

[Changa]

Yeah it has a tiny bit of wobble but I think that is normal. I havent checked the crank angle sensor as I have no idea how to know if its stuffed or not. But I am fairly sure it has to be an ignition problem, hence either the DFI module, coils, leads or plugs. Went to a mechanic he said it cant be the plugs with the symptoms described and I have checked the leads and coils which just leaves the DFI module. But I have heard a stuffed crank angle sensor can do similar things.

[Changa]

Hey guys thought Id say I have fixed this problem, ended up being my own fault. I purchased a new modded memcal tune from delcowizzid and after taking mine out I started removing my stock chip to send back to him as its an exchange. But his first chip was buggered so I had to resolder in my stock chip back in, I thought it worked fine but it did drop out occasionally (half stall once it fully stalled). When I got a new chip from delcowizzid the problem vanished. Hence the way I came to the conclusion that I had either incorrectly soldered in the chip or I damaged it with the heat of the soldering iron.