AJP V8 Misfire

[Shanksy87]

Hello TVR community, I come in search of help once again.

Took the car out at the weekend, was running fine then whilst pottering through town I noticed it started running rough, 4 maybe 6 cylinders at best. It will idle but only just and has no power.

By spraying a little water on each exhaust I can see 1, 3, 4, 6 are running cool. I've recently change both coil packs and have confirmed the injectors are working correctly. The coil pack wiring seems solid. After pulling all the plugs the odd bank seems between good and rich, even bank is rich which can be seen clearly from the exhaust gases.

My diagnostic software seems to give spurious readings so I'm a little stuffed there right now. There has been no MIL.

My first thoughts are to replace the plugs and leads but I have a feeling this will not be the issue. I will also do a compression check as the plugs seemed a little too oily but part of me choses not to consider a head gasket, the financial bit mostly.

What would the next recommended steps be after this? Throttle pots and lambda came to mind but I would have expected to see a MIL.

[sonnylad]

First i would double check the leads are actually fitted home correctly on plugs, especially the 2 rear ones.

In fact on mine i cut about 5mm of the end of the plug lead so it push in the hole easier.

Edited by sonnylad on Thursday 26th February 20:04

[Byker28i]

if you think you've a dodgy throttle pot then the car will run on one, so you can pull one to be sure, but to be honest it'll show easily on the diagnostics. Same with the Lambdas

[Jabbah]

Shanksy87 said:

My diagnostic software seems to give spurious readings so I'm a little stuffed there right now. There has been no MIL.

How spurious? The wrong serial lead or connecting to the wrong COM port can cause this.

[jamieduff1981]

1 & 3 and 4 & 6 share a bank, a coil pack and locality with each other but I can't think of any real reason for the two pairs to 'happen' together.

The wet plugs could just be fuel to be honest so I wouldn't worry too much. I can't imagine both head gaskets would fail at the same time.

I'd start from the plugs and leads and take it from there. Magnecors were the root of all my recent problems. On Jools' advice I got ones for half the price from Racetech Direct which sorted it. After I fitted them. Apparently just removing the Magnecors and trying to run it doesn't solve it completely...

[coetzeeh]

jamieduff1981 said:

Apparently just removing the Magnecors and trying to run it doesn't solve it completely...

- must make a note of that bit of advice, thanks!

[gruffalo]

coetzeeh said:

jamieduff1981 said:

Apparently just removing the Magnecors and trying to run it doesn't solve it completely...

- must make a note of that bit of advice, thanks!

Well not immediately it won't as the adaptives in the ECU will be all over the place.

Change the leads and run around for 50 miles or so and she should sort her self out.

[Shanksy87]

Thanks for all the advice chaps. Unfortunately I'm still having no luck with new plugs and leads, with only a few hours a week to try and route cause I'm about to give a specialist a call. Very annoying as I enjoy spannering on cars but electrical gremlins are beyond my patience!

I will update this in future to add to the Cerbera problems wiki that this forum is so useful for.