VN Running rough, ---LONG POST---

[Whiteford88]

Hey guys, this is going to be a very long and detailed post and I please ask that you bear with me through out it

All was running fine in my VN Commodore up until one morning I needed to go to work at 5am. I tried to start the car, it shuttered and shaked violently at no more than 400rpm, miss-firing on easily 2-4 cylinders if not more, then stopped fighting. Cranked her over again, same thing happened, but she kept fighting, and I put my foot down slightly to bring the revs up and it stabilized the motor but it was still missing and running insanely rough. I took my foot off the accelerator and it dropped in RPM from 2,000 down to idle (in a split second.. started firing again at 600 and went back up) and it kept fighting, and stayed fighting. I put the Auto into Reverse, and the pressure as soon as she engaged stalled the motor after getting the car into a slight roll (car was on a flat concrete surface at the time) and failed to start again. When I turned it over, there was an insane power drain (I had my lights on at the time) and it was draining the power ALOT more than usual, all the dash lights were dimming to the point you could barely see them and the high beams went so low it was like they were on parkers. I stopped trying, I didn't wish to hurt the car any more if it was a major internal problem.

Came back out at 10am, and tried to start her again. This time, she cranked over normally, could hear the compression, but no spark. No cylinders were firing. Another 3 - 4 raging, depressed turns of the key and still no boot. I looked at the dash, only to notice no dash lights were activating, at all!
I had no idea what had gone wrong. I've worked as a mechanic for months and have cert II in auto, also have a good idea of electrics but I wasn't going to stuff around with this job (partially because I can't STAND Auto Electrics. Such a f***ing pain!) and hit the local mechanic up for a lift to the Auto Electricians.

2 days later I got a call, stating that they believe the Cruise Control System may be the problem. And I said that's not possible, as the Cruise Control System is not hooked up at the moment as I do not have a fuse for it installed in the vehicle, and I did not want it running straight from the battery. They told me they would take another thorough look over it and get back to me. The next day I get a call saying 'We believe it is your Anti-Theft Immobilizer Switch' to which I quickly turned around and said it has been installed for 14 years without a single problem, and hasn't been touched in over a month as I only activate it when I am in Sydney, as I live so far out rural that the extra security isn't needed.

3 days later they rang me up and told me the car was finished, I got there and they charged me $300. They told me the Ignition Fuse was blown under the dash and my computer was faulty. They then told me the computers in VNs break all the time due to a dodgy fan relay system that frequently blows and overheats the car. (Which I'm sorry, I find to be a load of horse S***!) Not to mention they said there was a crack in the Silicon Board which caused the short and that the computer did not work, but I requested for the unit back and they gave it to me, and it started the car absolutely fine!! I did however put the new computer in they gave me just incase I was wrong, afterall they would want to be for the cash they wanted!

So now I just do not know what to think, the car is running like absolute crap at the moment. It is shaking every now and then when you pull upto the lights or an intersection, it's chewing through fuel like there is no tomorrow, and it feels like I've lost 10kw (it just feels.. sluggish?) I feel like it's got something to do with the fuel injection system, or the coil pack as it looked warped on the side and melted on the bottom, but the auto electritan re-assured me it was a perfectly fine unit.

Recently, there has been a ticking noise (the exact same noise you hear when the blinker is... blinkering.. ) under the dash and it happens rapidly, like a switch relay is violently flicking on and off. My break lights are being temperamental, and I put a fuse in the Cruise Control to try and help with my fuel economy and TWICE the system failed to disengage when I pressed the break and almost sent me flying into the car infront of me if I didn't put it in neutral and slam the breaks. It's getting ridiculous, my beloved VN commodore (Which is in such amazing condition, engine and body that it has kept up with a 2007 XR6 with full zorst and custom ram air) can barely pull up a hill without losing stupid amounts of speed/power.

The auto electrician also hooked my tacho up incorrectly, and everytime you turn the lights on the tacho turns off, so they have unhooked and played around with obv everything in the car.

I don't know what to do guys, and it's shitting me to tears that this auto electric problem is causing so much hurt to my car!
Please help, I love my VN and plan to run it into the ground or use it as a pot plant holder before I on sell it, but for 238000 this VN is still only halfway through it's life!

Thanks in advance, happy motoring!


=== Built with Spanners, not Chopsticks ===

[hi_ryder]

if you think its an electrical problem start there and back track. grab a spare spark plug and individually test each lead end on crank over to see if your getting spark. if not back track. leads, coil packs, ignition module, ect. check all your fuses and relays too too make sure none are blown. the mechanics would have seen you coming dude....

what parts have you changed as well. done spark plugs? leads? let us know.... also if you wanna check error codes theres an open plug on the passenger front kick panel area (near the computer) bridge the 2 with a wire and count the blinks. use this thread too... Checking your Computer for Faults (VN - VP)

Just Commodores - For All Your Holden Commodore Needs

[Whiteford88]

Yeah I have checked the computer for fault codes and got the all clear (12). I have a switch hooked upto it for a quick Diagnosis, it was the first thing I did when I found the engine running a bit rough.

I haven't changed the plugs or leads, ignition module or the coil pack because well I've never needed to. Always ran like a dream. But my guess before I had even taken it to the Auto electrician (the mechanic is a friend of mine and would NOT screw me over, it was the auto electrician they took the car to that were dodgy)

My best guess of what has happened is the coil pack started melting (it's the original VN coil pack for christ sakes! lol!) and that caused a shortage in the ignition system causing the fuse to blow, because the power drain going into the effort to get the system going was to much for the circuit, and it blew the fuse.
The ticking relay under the dash happened about a year ago but only happened for about two weeks on and off and only recently started happening again, but it's not loud and it's minimal, I think I should just change the relay with a new one and see what the hell the break system is doing..

I think the system running rough could also have something to do with the computer they have put in, because I had an SV3800 chip that I got off my Mechanic because he crashed his and he gave it to me, (just the memcal) and it gave her a bit extra kick, but they said they took the memcal out and put it in the new computer.. and if they have gotten it out of a VP (I don't know if you can cross computers like that) and put this tune in, or the computer they have given me is just simply dodgy or they stole my SV3800 chip (wouldn't surprise me) and put in a dodgy memcal/computer combo..

Maybe I should just take the time strip the dash wiring down and re-wire everything myself.. I just hate wiring as it takes so long.. lol

But I am definitely going to put in a new coil pack, leads and plugs and computer, I'm just worried that it's not going to fix it, and I'm going to waste 200+ dollars..

[hi_ryder]

id doubt youll need to rewire anything, thats what the fuses and relays are for to keep your spaghetti from over cooking. also what year is your vn. pre oct 89 run different cam, and memcal to the the later ones. if you run a vp memcal in a pre oct 89 engine, it could be the reason its running like a pig.... get everything back to stock so you can chase down the problem properly.... id say what your going to so should fix it....

[psi3800]

Almost guarantee you have fried your D.F.I. Module under your coil pack. Very common for them to be faulty. If your running the single vn style coils it might be an idea to switch over to the later model triple coil style when you change the dfi..

[Whiteford88]

Thanks for all your responses guys, I took it to my Mechanic today and we worked on the car a bit and he gave me a new computer and she is running like an absolute dream again! He told me that it reminded me of his VN commodore that he had when it was only 3 years old! So I am a bit worried that I might have previously had an engine swap or something done in the car because there is evidence of tampering with engine mounts and the vehicle was assembled on the 10/11/90 and somehow still manages to have a Series I Buick motor in it? Unless for some reason one of those engines found it's way through the factory into my car.. but I thought they stopped putting in those engines after oct 89? Will be posting a topic on this for y'all to comment, thanks again!

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