Anybody know where this plug goes to?

12th July 2021, 22:07

Carbon fuel canister maybe? Just trying to find the cause of a weird misfire and see if it's causing it what's been deleted, thank you

13th July 2021, 20:05

It's for the ABS.

Under what conditions does your car misfire?

13th July 2021, 20:53

Thanks Martin,well the misfire is very intermittent,it won't misfire when driving along or at wot,it will misfire when it sits idleing after a minute or so and the engine light starts flashing,code comes up as random multiple cylinder misfire but it won't always do it,sometimes it will just idle happily no problem.

The thing is nothing is standard and the wiring has been modified to fit all the wiring loom inside the cabin so not really straightforward to sort out,I do have a 8v VTR wiring loom which I can a look at for the most part so that helps a bit.
I've mapped the car like this at Chipwizard and it drives lovely and pulls nicely it's just this misfire issue that annoying but then again it's probably my fault lol.

13th July 2021, 22:48

Quote:

Originally Posted by VeiRoN

Thanks Martin,well the misfire is very intermittent,it won't misfire when driving along or at wot,it will misfire when it sits idleing after a minute or so and the engine light starts flashing,code comes up as random multiple cylinder misfire but it won't always do it,sometimes it will just idle happily no problem.

The thing is nothing is standard and the wiring has been modified to fit all the wiring loom inside the cabin so not really straightforward to sort out,I do have a 8v VTR wiring loom which I can a look at for the most part so that helps a bit.
I've mapped the car like this at Chipwizard and it drives lovely and pulls nicely it's just this misfire issue that annoying but then again it's probably my fault lol.

Hmm yeah if it's intermittent that sounds like a loose connector somewhere or a wire that's breaking down internally. The cores are decent quality so it's probably a fault near or at a plug.

Does the misfire go away as soon as you rev it, or still there when you rev it gently?

14th July 2021, 00:28

No it doesn't seem I can get rid the misfiring by reving it,the only thing that works is turning the engine off and on again and then drive away and it just runs as normal, it's just strange.

14th July 2021, 09:37

Quote:

Originally Posted by VeiRoN

No it doesn't seem I can get rid the misfiring by reving it,the only thing that works is turning the engine off and on again and then drive away and it just runs as normal, it's just strange.

Sounds like an internal ECU fault, my 3 plug VTS used to do that.

If you have a way to look at live data, I would look at the value for short and long term fuel trim when its running normally, and then check it when it's misfiring. It could actually be a faulty lambda sensor or a small exhaust leak before the sensor.

14th July 2021, 11:45

Hmmm it really shouldn't be a ECU fault, before mapping I bought a new unlocked VTS ECU just to rule out an ECU fault,I actually bought a brand new BOSCH front lambda sensor before mapping, exhaust leak there really shouldn't be as I've assembled back everything with plenty of paste but I will certainly have a look.
To be honest the after cat lambda is not fitted to anything and tucked away in the engine bay but then again I wouldn't think that would affect running and it was also mapped like that.

I need to get the Launch diagnostic at work again one day and have a look the live data.

14th July 2021, 14:03

Quote:

Originally Posted by VeiRoN

Hmmm it really shouldn't be a ECU fault, before mapping I bought a new unlocked VTS ECU just to rule out an ECU fault,I actually bought a brand new BOSCH front lambda sensor before mapping, exhaust leak there really shouldn't be as I've assembled back everything with plenty of paste but I will certainly have a look.
To be honest the after cat lambda is not fitted to anything and tucked away in the engine bay but then again I wouldn't think that would affect running and it was also mapped like that.

I need to get the Launch diagnostic at work again one day and have a look the live data.

the after cat lambda doesn't really affect anything, I'm sure it only exists to check if the cat is working.

It'll be something daft I'm sure of that hahaha

15th July 2021, 17:09

Quote:

Originally Posted by MartinObviously

Does the misfire go away as soon as you rev it, or still there when you rev it gently?

I lied, today it did again while driving along the motorway,engine light was on (because I unplugged the carbon canister relay,my mistake) was not flashing but it was bogging down and sounding like I lost a cylinder,however after 30 seconds I was just able to rev it out of it and drove just fine afterwards.