L'il Help From The Techy People?

[scouk]

Ok.. Just how on earth do you go about dianosing a cylinder misfire?

On way in to work this morning.. Noticed that every so often the car would jolt slightly as though it was missing a beat.. THis was just runnign at 60mph with a light throttle to keep the speed. Happened again down at lower speed in 2nd gear.. again just keeping constant speed.

On way home from work, all felt ok.. But then CEL started flasshing then a minite later stayed on! Got home and got the codes read from the ECU

Cylinder 1 Misfire

Cylinder 3 Misfire

Yoiks!! Where do you start diagnosing such a thing?

No tubes/connectors loose anywhere.. No signs of oil spurting from strange places..

Only recent changes to the car recently was a air intake resonator removal a couple weeks back.. Is this likely to give me this problem?

Any help appreciated!!!

Really don't wan't to drive it until I can find what's wrong...

Thanks,

[Big 'D']

Ok.. Just how on earth do you go about dianosing a cylinder misfire?

On way in to work this morning.. Noticed that every so often the car would jolt slightly as though it was missing a beat.. THis was just runnign at 60mph with a light throttle to keep the speed. Happened again down at lower speed in 2nd gear.. again just keeping constant speed.

On way home from work, all felt ok.. But then CEL started flasshing then a minite later stayed on! Got home and got the codes read from the ECU

Cylinder 1 Misfire

Cylinder 3 Misfire

Yoiks!! Where do you start diagnosing such a thing?

No tubes/connectors loose anywhere.. No signs of oil spurting from strange places..

Only recent changes to the car recently was a air intake resonator removal a couple weeks back.. Is this likely to give me this problem?

Any help appreciated!!!

Really don't wan't to drive it until I can find what's wrong...

Thanks,

I would get your neutral position sensor in the gearbox checked out mate, it is a common cause for this fault.

Cheers Iain

[dipsy]

Its not the fault of the mapper you use . Pulling your leg

Edited April 6, 2009 by Dipsy

[scouk]

Its not the fault of the mapper you use . Pulling your leg

LOL If it is.. He'll be getting his friggin legs broken!

Thanks Iain... Any easy way to test the sensor rather than swap it out?

[RA Dunk]

perhaps a compression would be an idea as well

[the squiggle]

Plugs?

When were they last changed?

[thefastone]

Grant beat me too it! first thing that I thought of....

[scouk]

Plugs?

When were they last changed?

Good chance of it... Twould have been my first guess too but though best to ask unless it could be something obscure.. No idea when they were last changed.. Long overdue methinks.. I've not changed them since I go thte car 24k miles ago : was hoping AWD would be kind enough to do them at next service

Had a fiddle around, checked MAF and few other electrical plugs and tubes.. Northing obvious.. Did notice that the air intake into teh wing was a bit loose so re-seated that.. Re-set the ECU and went for a leasurely 20 minute drive.. SO far so good.. Will check again tomorrow morning see if I ge teh same sort of symptoms.. Was colder than normal.. thought maybe condensation in the intake... Strange it was at cruising speed, no load/heavy throttle..

Hmnn.... Don't like unknowns...

Edited April 6, 2009 by ScoUK

[Big 'D']

Honestly the neutral position switch on the gearbox causes this 'Misfire' fault code to appear it is very common. I believe its made of plasic and gets worn or something (I have never had it happen to me yet - touch wood) it can be sorted by removing or fitting a washer (I am not sure how easy it is to get to either), I will see if I can get the info on it for you, it will be at first a very intermittent fault but as the switch wears it will become a constant feature

Cheers Iain

[scouk]

Admitedly I didn't physically check it as it means whipping off the intercooler and stuff.. But did check the signal from the ECU and it seems to be toggling as expected.. But yeah.. coudl be intermittent...

Curous though.. As to how a Neutral position sensor can result in a misfire? Is that because the ECU detects the switch flicking to neutral and buggers up the timing?

[Gee Wr1]

Honestly the neutral position switch on the gearbox causes this 'Misfire' fault code to appear it is very common. I believe its made of plasic and gets worn or something (I have never had it happen to me yet - touch wood) it can be sorted by removing or fitting a washer (I am not sure how easy it is to get to either), I will see if I can get the info on it for you, it will be at first a very intermittent fault but as the switch wears it will become a constant feature

Cheers Iain

Iain might have hit the nail on the head there, i mind a wr1 on the owners forum had similar problem ages ago & after much scratching of heads it was found to be the fault. Yes it is made of plastic & can wear down, its starts intermittently then gets progressively worse. Thats why it took a while to diagnose as every time he took it to the garage it was fine.

[Big 'D']

Admitedly I didn't physically check it as it means whipping off the intercooler and stuff.. But did check the signal from the ECU and it seems to be toggling as expected.. But yeah.. coudl be intermittent...

Curous though.. As to how a Neutral position sensor can result in a misfire? Is that because the ECU detects the switch flicking to neutral and buggers up the timing?

That is basically it mate, it gives a signal that the ECU does not expect to see, when you are driving along the ECU will get the false signal from the neutral position switch will result in the misfire as the car is still in gear under load and moving and the ECU expects the car to be in a gear change/parked in neutral situation.

Cheers Iain

[scouk]

That makes sense.. & worth looking into

Thanks guys!

Will report back if I find anything!