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Major Fallout

Original Poster:

4,549 posts

118 months

[news] 
Friday 5th October 2012 quote quote all
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?



edo

14,581 posts

152 months

[news] 
Friday 5th October 2012 quote quote all
MAF.

Major Fallout

Original Poster:

4,549 posts

118 months

[news] 
Friday 5th October 2012 quote quote all
It looks brand new, is there a way of testing them? as its an expensive part.

Quietlybonkers

9,171 posts

31 months

[news] 
Friday 5th October 2012 quote quote all
? Ministry of Agriculture and Fisheries?

mb450

382 posts

86 months

[news] 
Friday 5th October 2012 quote quote all
There are some instructions on how to check the meter on the rpi website
under
"Setting Air Mass/Flow Meter & Throttle Pot"
On this page http://www.v8engines.com/carbs-2.htm
Advertisement

rigga

4,681 posts

88 months

[news] 
Friday 5th October 2012 quote quote all
shunting .....

carsy

2,093 posts

52 months

[news] 
Friday 5th October 2012 quote quote all
rigga said:
shunting .....
Yes my initial thoughts aswell. Does it miss at 3,4,5K rpm.

Kitchski

3,187 posts

118 months

[news] 
Saturday 6th October 2012 quote quote all
If it's definitely not shunting I'd go TPS.

davep

628 posts

171 months

[news] 
Saturday 6th October 2012 quote quote all
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.

EGB

1,674 posts

44 months

[news] 
Saturday 6th October 2012 quote quote all
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.

edo

14,581 posts

152 months

[news] 
Saturday 6th October 2012 quote quote all
Mine was running rich and hesitating around 2.5k.. A new MAF sorted it.

Major Fallout

Original Poster:

4,549 posts

118 months

[news] 
Saturday 6th October 2012 quote quote all
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. thumbup

Major Fallout

Original Poster:

4,549 posts

118 months

[news] 
Saturday 6th October 2012 quote quote all
Just gave it a go and it was a lot worse.

Kitchski

3,187 posts

118 months

[news] 
Saturday 6th October 2012 quote quote all
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.

del 203

12,727 posts

136 months

[news] 
Saturday 6th October 2012 quote quote all
Where are you based ?


Borrow one to test...

edo

14,581 posts

152 months

[news] 
Saturday 6th October 2012 quote quote all
Bring it to Goodwood tomorrow assuming you dont live miles away!

Major Fallout

Original Poster:

4,549 posts

118 months

[news] 
Sunday 7th October 2012 quote quote all
Thank you but yes I'm miles away.

Major Fallout

Original Poster:

4,549 posts

118 months

[news] 
Monday 8th October 2012 quote quote all
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!

blitzracing

4,091 posts

107 months

[news] 
Monday 8th October 2012 quote quote all
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.

Major Fallout

Original Poster:

4,549 posts

118 months

[news] 
Tuesday 9th October 2012 quote quote all
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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