[Mk2] [Turbo] Misifre when on boost? Rev3 Turbo

[jwarren2k2]

Hi all,

I'm after some help/advice please!

To help you out, mods are as follows:

Usual bolts on...
air filter, uprated intercooler, EBC, decat, exhaust and a forge actuator.
I've also recently purchased a hks f con v ecu.

The problem...

Last night it was raining, I was in 3rd gear, on standard boost setting (it wasn't fuel cut), I overtook someone on the dual carriageway and when I put my foot down, I came on boost for the first time in my journey and as soon as it came on boost, the car just suddenly stuttered/misfired. It was like hitting a rev limiter, except I was at about 3500-4000rpm. The car kind of held back and the exhaust sounded like a fireweork crackling all the time it was 'missing'.

I lifted off and put my foot down again, and it did it straight away.

On my return jhourney, I disconnected the hks ecu, thinking this could be the problem. This didn't fix it, except when it did it, it was extremely mild on standard boost, but when I upped the boost a bit, it got worse again.


Things on my 'To-do' list:

Check...
Diagnostics error codes
see if vacuum pipes are ok and still connected
Check spark plugs condition to see for running lean or rich etc.
ignition systems doesn't have any water ingress, give it a clean and spray with wd40 to improve the connection (HT leads, Dizzy, rotor)
See if there are any oil deposits anywhere
Check sensor connections
Compression test.


Any help, advice or thoughts will be very helpful.

Thanks

James

[jimGTS]

alot of people are getting this recently...

check out the coil and map sensor....

ive taped up the map sensor connector, and im going to do the same with the coil to avoid these issues as a ton of people are getting it.

someone mentioned to be maybe the pim wire maybe grounding out (due to the damp), car uses this to know how much fuel/timing etc etc to run.
this is a wire on the map sensor that also splices somewhere along the line and sends a signal to the stock boost gauge.


just a suggestion.

[jwarren2k2]

Thanks for your help, Jim.

This may sound silly, but I've not heard of the "pim" wire before? Do you know appriximately where I'll find it too please?

Thanks.

[jimGTS]

Sorry I should have said the pim wire is one of the wires that goes to the map sensor. Perhaps this is grouding out.

Am not sure where it goes exactly, would guess in the harness strap across the fuel rail, then obviously the ecu. But I'm told it does splice at some point and sends signal to stock boost gauge.
Stuartthefish over on the OC said he cut this wire that leads to the gauge and hasn't had problems since.

Like I say, just a suggestion.

[jimGTS]

And by cut I just mean on the line that goes to the gauge somewhere.
Not the pim wire completely, still needs signal from map sensor to ecu.

[bobhatton]

Have a look here, same sort of problem.

http://www.imoc.co.uk/forums/viewtopic. ... highlight=

Bob

[jwarren2k2]

Thanks for your help guys.

Going to give it a look over tomorrow.

If it's the coil being cracked, as suggested in the other thread, where would I get one? Do general motor factors do them for the turbo? Or are n/a ones the same? I suppose I should ask the same question of the coolant temp sensor too.

I'll give an update tomorrow as to how I got on with all my checks.

Thanks again,

James

[Odin_S]

Could also be a simple thing (like what happened to me) of one of your HT leads not stuck down

[jwarren2k2]

Right, just a quick update!

On Sunday I did a diagnostics check and it was all clear.

I then disconnected the HT leads and king lead (both ends) and the MAP sensor and gave them a squirt of wd40.

I also took a look at the plugs but they looked perfect which was encouraging!

I drove the car this evening for the first time since Thursday when the misfire developed and it ran really well.

I didn't have look at the coil in the end, mostly because it was pretty cold and I didn't have a lot of time. If the misfire re-appears, then I'll take a look at the coil.

I'm hoping that what I've done hasn't just temporarily fixed the issue. I'll give the car a drive next time it's wet to see if it was down to the wet.


Thanks for all your help and advice, and if anything else happens, I'll update this thread.


Thanks again,

James