Gti6 Misfire At 3.5/4K

[Paul_13 212 1 Cars]

This is now really starting to piss me off!

 

90% under all conditions I'm getting a misfire when climbing the Rev range. No matter if I'm at part /full throttle!

 

I've so far changed:

 

Map sensor

All the coil packs

Cam sensor

Fuel pump

Alternator is putting out the correct voltage

Tps

 

Haven't done the spark plugs yet, which I might do tonight.

 

Now I wondering if the reground cams are causing this issue and the map on the standard ecu is throwing a wobbler!?

 

I also reterminated all the earth and positive cables to eliminate that as well.

 

Any ideas anyone?

What would cause it to misfire at exactly just under 4k?

[petert 586]

Could be a lean misfire I guess? But given it's at various throttle openings it suggests not. You'd need to put a wide band O2 sensor on it to confirm.

 

Does it go further through after the misfire?

 

Take the vacuum off the fuel pressure reg. This will increase fuel pressure slightly at part throttle, giving a richer mixture. It won't help WOT however.

Edited June 10, 2013 by petert

[camgti 56]

ICV? They can play around with what your describing.

 

Was there a miss before the cams were installed?

 

Cam

[Anthony 1,003]

Now I wondering if the reground cams are causing this issue and the map on the standard ecu is throwing a wobbler!?

Didn't it initially run fine on the cams for a few hundred miles after we fitted them? If it was a cam issue not working with the ECU map, I'd expect it to have been a problem from the off, not only to have appeared after a few hundred miles.

 

Have you tried a different ECU, as I'm wondering if one of the ignition drivers is starting to fail or something similar? Certainly on 8v and Mi16's a ~4k misfire is normally the ignition amplifier dying, and that's built into the ECU on a GTi-6.

[welshpug 1,657]

Were all those parts new?

 

As Anthony suggested, its unlikely to be the cams, the PH2's run perfectly fine with my standard ecu.

[Paul_13 212 1 Cars]

Could be a lean misfire I guess? But given it's at various throttle openings it suggests not. You'd need to put a wide band O2 sensor on it to confirm.

 

Does it go further through after the misfire?

 

Take the vacuum off the fuel pressure reg. This will increase fuel pressure slightly at part throttle, giving a richer mixture. It won't help WOT however.

I've just disconnected the vac hose, yet to test bit will be driving it shortly so will report back. Once it gets past 4k it screams round As the Rev range. It's almost a hesitation issue but isn't if you know what I mean

 

ICV? They can play around with what your describing.

 

Was there a miss before the cams were installed?

 

Cam

no misfire before the cams were installed, I've changed the icv to solve another problem and the misfire has been there through out

 

Didn't it initially run fine on the cams for a few hundred miles after we fitted them? If it was a cam issue not working with the ECU map, I'd expect it to have been a problem from the off, not only to have appeared after a few hundred miles.Have you tried a different ECU, as I'm wondering if one of the ignition drivers is starting to fail or something similar? Certainly on 8v and Mi16's a ~4k misfire is normally the ignition amplifier dying, and that's built into the ECU on a GTi-6.

I think it came in after a few hundred miles. To be honest I'm not too sure. It's fine when it's cold but when it warms up it's not happy. I've got a brand new ecu temp sensor in there, but that might be f***ed as well.

 

Were all those parts new?

 

As Anthony suggested, its unlikely to be the cams, the PH2's run perfectly fine with my standard ecu.

Most of them were known working sensors.

[Paul_13 212 1 Cars]

Still doing it with vac pipe disconnected

[dcc 855]

do you have a downpipe with a 'split' in it?

 

Can you swap your fuel pump? I had a friend with a very similar problem who had a dead/dieing fuel pump. After changing it the car was a different beast.

[Paul_13 212 1 Cars]

There's no "split" post in the downpipe mate and I've swapped fuel pumps and it was still doing it.

 

But I think I've found the cause. Another dodgy MAP sensor. I had one lying about in the silver car and it's back to its normal self?!

 

So I now have 3 dodgy MAP sensors

[dcc 855]

bin them

[Jemehan 3 1 Cars]

I have this issue on my s16, got a new edu with map built in but it is locked. Anyone know how to get an ecu unlocked?

[laldy875 6 1 Cars]

I had this- check fuel pressure with a gauge. When I was driving it was like hitting a limiter briefly. The grommet in the fuel pump had a hairline crack.
Worth a shot before you buy all the sensors like everyone else does

This is the thread: http://forum.205gtidrivers.com/index.php?showtopic=147191

[Paul_13 212 1 Cars]

I should of updated the thread but I found out what it was

 

[welshpug 1,657]

how the funk does one manage that?!

[Paul_13 212 1 Cars]

No f***ing idea mate

[Jemehan 3 1 Cars]

Well ill be having the full intake off when I get home.... Thanks for posting!!!

[Anthony 1,003]

how the funk does one manage that?!

Never under-estimate Paul's ability to break the normally unbreakable in bizarre and inexplicable ways...

[welshpug 1,657]

I was thinking that

[petert 586]

Lean misfire it was!

Edited July 17, 2013 by petert

[jackherer 543]

how the funk does one manage that?!

Tightening one fastener fully before even engaging any of the others.

[Paul_13 212 1 Cars]

Which I never do

[jackherer 543]

Sorry, I didn't mean to imply you had done it, I was just answering Welshpug who asked how "one" could do something like that.