280ZX Misfire

S

scoobydoo15775

Forum User
Hi,
Can anyone please help, I've got a 1982 280zx, which when running at low rpm misfires badly, and when running higher up the RPM is running fine, I've changed the plugs and have checked the HT Leads for a spark and they are fine:unsure: so any other ideas would be greatfull, the car has a K+N Induction kit has been prepared for racing, stripped out interior, full roll cage, bucket seats, 3 point racing harness, Knock-On Wire Wheels, uprated suspension, brakes, etc. The car has recently passed the MOT, I'm in two minds weather to sell it or keep it, its just this misfire that lets it down, also needs a respray.
 
I've not seen many race cars with a luggage rack and towbar I must admit.

Suggest you do a compression test. Does it misfire at tickover - try removing one plug lead at a time to see if you have one faulty cylinder. If so and the plugs are ok it might be an injector.

Just guessing really tbh but worth a try.
 
Hi,
The car doesn't misfire at tickover, or when standinf still, only when moving off or the rpm are at the lower end. The towbar and luggage rack where added after the car was used on the track by the previous owner to try and make it more pratical.
Thanks
 
Andy, good info I'm sure but I'm always a bit cautious about testing ECUs with a meter. I was a BT engineer for many years so I understand circuits but electronic components are easily wrecked if you are not 100% sure of what you are doing.
Recently my lad's Pug 106GTi developed a fault, I looked for obvious things but daren't mess with the ECU etc in case I put another fault on. In the end we used a local diagnostics man. He said up front that he would charge 2 hours labour (£70) and although he sorted it in 45mins he did spent the full 2 hours with me, teaching me stuff (he lectures at college on car electronics). We also confirmed that my Haynes diagram was wrong and his Autodata info was too. The correct info for our ECU was found in the 205GTi section.

So just a word of caution for Scooby really. If you know what you are doing then fine.
 
I'm confident on some car electrics but no on ECU's, but I've got spares as well from another car that was broken up, I'll try my spare ECU out that hasn't been chipped and see if that helps. Thanks for the advice, by the way are there any members on the Isle of Wight.
 
Rob/Scooby,
I take your point about testing ECUs but here you don't test the ECU. You remove the plug from the ECU and use a multi meter across the plug pins and then you can test each circuit. With the air flow meter you'll see the resistance change as you manually move the flap. Any flat spots will show up.
Hope this helps
 
scoobydoo15775 said:
I'm confident on some car electrics but no on ECU's, but I've got spares as well from another car that was broken up, I'll try my spare ECU out that hasn't been chipped and see if that helps. Thanks for the advice, by the way are there any members on the Isle of Wight.
Click to expand...

Make sure you're changing like with like, if your spare ECU is from an Auto it won't be the same.
 
Does the ECU you have currently look as if it has been opened up? Not saying it's impossible but I didn't know that these ECU's can be chipped. There was a few piggy back systems for the turbo models but not heard of an NA chipped one so not that common. I'd therefore check for signs of entry as it may just be a standard ecu, which will make your life easier.
 
Hi,

The person who rebuilt the car into what it is now, a sort of racer, got the ECU chipped by a American Company as he bought most of the parts from there for the car, e.g wire wheel conversion, suspension, breaks, etc etc.

Thanks

Paul
 
Not sounding stupid or anything you haven't tested it for an air leak have you. try squirting some WD40 or carb cleaner around various vacuum pipes and manifolds. A change in revs will notify any leaks.
 
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