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Major Fallout
Original Poster
4,085 posts
100 months
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Every car I have ever owned has had a misfire its the bain of my life! And because of my lack of knowledge of electrickery its always electrical.
But this time I'm running out of ideas.
It is at its worst at 40mph in 4th gear, somewhere between 1'000 rpm and 2'000 rpm on light throttle.
I cant quite make out if it still does it when it goes full loop, but it does feel down on power.
All plugs are black with carbon, not oiled up.
Up to now I have changed:
Plugs
Leads
Rotor arm
Dizzy cap
lamba sensors
ECU temp sensor
Cleaned the idle control valve thingy and made sure it moved.
Im thinking of looking at the injectors next?
Any ideas?
Would the ECU fault reader thingy help me?
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edo
12,567 posts
134 months
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Major Fallout
Original Poster
4,085 posts
100 months
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It looks brand new, is there a way of testing them? as its an expensive part.
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Quietlybonkers
3,177 posts
13 months
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? Ministry of Agriculture and Fisheries?
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mb450
369 posts
68 months
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rigga
3,039 posts
70 months
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carsy
1,274 posts
34 months
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rigga said: shunting ..... Yes my initial thoughts aswell. Does it miss at 3,4,5K rpm.
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Kitchski
2,155 posts
100 months
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If it's definitely not shunting I'd go TPS.
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davep
418 posts
153 months
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Having replaced all those parts I would do a quick check on ignition timing and verify that the mechanical advance is working OK. Also ECUMate or RoverGuage would show up any TPS faults.
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EGB
928 posts
26 months
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Black plugs suggests its running rich. Or a weak spark from coil and ignition module not helping to burn off the carbon on plugs. Check all leads are passing a good consistent spark. A good spark should be 8-10mm. A shot of injector cleaner in the tank could help.
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edo
12,567 posts
134 months
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Mine was running rich and hesitating around 2.5k.. A new MAF sorted it.
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Major Fallout
Original Poster
4,085 posts
100 months
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I did think it was shunting at first but its been getting worse, now it defiantly feels and sounds like its running on 7 at times. I have tried an injector cleaner. Would it be the worst thing in the world to unplug the MAF and try it down the road? And if I did what would it tell me? If it still had the problem then it might be an air leak, or a spark problem. Thanks for your help guys, I'm very quickly getting over my head with the electrics. 
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Major Fallout
Original Poster
4,085 posts
100 months
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Just gave it a go and it was a lot worse.
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Kitchski
2,155 posts
100 months
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The AFM can go out of range without actually failing completely (telling the ECU white is grey rather than black etc), so unplugging it totally will tell you nothing.
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del 203
12,727 posts
118 months
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Where are you based ?
Borrow one to test...
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edo
12,567 posts
134 months
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Bring it to Goodwood tomorrow assuming you dont live miles away!
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Major Fallout
Original Poster
4,085 posts
100 months
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Thank you but yes I'm miles away.
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Major Fallout
Original Poster
4,085 posts
100 months
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Well after lots of head scratching I have given it to someone else to try and fix.
They are used to modern cars so maybe they will have more luck. Fingers crossed!
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blitzracing
3,294 posts
89 months
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A lot of TVR plugs run black- especially if the cars are round around town all the time, it could simply be a case of running a slightly hotter plug to allow the carbon to burn off- This is nothing to do with the spark at all, its down to how quickly the plug tip conducts the heat away during the mixture burn period. If the engine is genuinely running rich for any reasons like an AFM being out of spec' the either RoverGauge or the ECU mate will show the lambda's are not switching as they should, but these ECU (fuel only) tools cant really do much with the ignition side of things. The ignition system really needs an old fashioned Crypton tuner with a display of the HT voltages on a scope if you want any meaningful data. If its a nasty snatch under light engine load at around 1700 rpm in higher gears, that goes the moment you give it more gas- that sounds like shunting.
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Major Fallout
Original Poster
4,085 posts
100 months
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Been doing a bit of reading and it does sound a little like the shunting problem.
But I'm sure it wasn't doing it before, and its quite a bad misfire/shunt. Its bad enough cause drivetrain damage.
I think I need someone with a Chimaera to drive mine and tell me if its the dreaded shunt.
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