I need help from you wonderful guys! Any advice will be an absolute God send.
Right my 91 GTO kept misfiring before dying on me, had the air filter checked and all relevant pipes checked out and all came back okay. A diagnostic check showed a fault with the coil pack. Soooo, new coil pack fitted and still the same problem. Told it could possibly be the crank sensor, new one of those and still the same. ECU has been checked and not a problem there. Its not the PTU as it does actually start.
Now the only thing that’s really left is the timing belt, but because my wrong diagnostic the garage focused on the coil pack. They’d had a quick look briefly beforehand and said everything had looked okay.
Has anybody had anything like this before? Or any other ideas as I’m getting to my wits end with the car. If the belts jumped a tooth what damage am I looking at? Thank you in advance for any insight, please excuse me whilst I go put my head through a brick wall.
Woah! hold on, you’ve mentioned nearly all the things that cause these babies to misfire/not start/run rough etc. As you say, it starts. A mates would run, tick over, but that was it, the rear cam was out. So the timing is the way to go. When I took everything apart on mine there were so many white dots for timing marks I used the pointers on the back of the cam wheels against the markers on the cam covers. Rob suggested this and was spot on. Jack up the NSF and take off the wheel, remove the cover for the access to the bottom pulley. Using a long bar and socket turn the engine over, make sure you do it the right way as the belt could come slack from the tensioner, turn the engine over until the front cam gears marks start to line up with the marks on the cam cover, remember the engine will turn twice to the camshafts once. Once this is achieved check the piston, by removing the front plug, that it is at top dead centre (check with a very long screw driver, gasp, or a long piece of coat hanger) then check the back gears. If all line up further investigation is needed. If the piston is not at TDC but the cam gears line up could have jumped a couple of teeth on the crank pulley. Damage, you could be lucky and not get any, that there seems to be a lottery whereby some have a big job to repair, others have put a new belt on and timed it up and carried on.
Good luck,
Any further questions, like where are you, or everything you’ve said is ok, means you’ll have to ask the brains on here.
Gave it my best shot
Hi, does it misfire all of the time or occasionally? on boost? off boost? when did it start to happen? what were the circumstances when it started? cold/wet/engine hot/cold? you said a coil pack had been replaced? did you have all 3 coil packs replaced or just one? a faulty PTU can cause a misfire so I wouldn’t rule that out just yet. have you had anything else replaced? plugs/ leads/ or changed any parts recently for new/upgraded?
have you had a compression check done as part of the diagnostic check?
I had the same issue end up chaging every single thing but at the end it was timming belt!
Car use to start fine then dies straight after unless u put foot on accelerator but coukd see missfiring .
Timming belt was loose beacuse of the hydroclic tentionar
Took it to Eurospec
Labor £250 + vat
New Timming belt and hydroclic about £300+ vat could get cheaper else where but then no gaurante was given
So ended up paying about £800 quid in total
Some great advice tendered already. Thing is not to panic or get desperate. From what I’ve read so far I’d take a look at the belt timing as Just Cool has mentioned. It won’t cost to take a look at least. If those little dimples on the cam sprockets (take the cover off to see them) line up opposite the casting pointers, and the crankshaft pointer lines up at the TDC marker on the crankcase, then the belt hasn’t slipped. I don’t know how far out the timing has to be to begin to cause a collision between valve(s) and piston(s), but the odds are, from what I can gather, that you’re only having a minor timing issue, and nothing more serious than that. Obviously it’ll need realigning and tensioning rechecked if so, and some investigation as to why it slipped in the first place. Ultimately it’s likely that the belt and its ancillaries ought to be replaced. If the timing markers appear to be aligned, then checks to the PTU and leads would be my next course of action.
Good luck with the fix.
My PTU allowed me to drive the car as long as I kept it below 2500 rpm or wot to get to +3000 and beyond. Hover around the 2.5 mark and you could feel the car hesitating. I replaced both the PTU and the coil packs and now runs well. Just have to take the PTU back off and do a Marty conversion.
All’s well.
does the car run and idle, or just dies straight away?
had a prob with mine, it would take a while to start and then would randomly cut out. it got to the point where it would not start at all. I eventually tracked the problem down to a corroded multi plug in the wiring loom located under the air filter and behind the drivers side headlight.
if you need any more info I have some pics and a diagram on how to test the wiring harness to see if theres a fault.
if you can find that multi plug and it is at fault it should be very obvious to spot.
hope this helps
Thanks for all your help guys, after diagnosing a fuel problem we decided to change the fuel injectors. Bought some new ones and when the garage removed mine, that’s when they discovered sugar residue. Could not believe it. I’ve clearly pissed someone off!
A second hand fuel tank, pump, filter, lines blah blah blah and I’m finally up and running again! Apart from now the speedos playing havoc. But I’m happy to have it back for a few days til it goes back in
