143 replies to this topic

[Dan r]

Cheers Paul.

[Dan r]

Damaged injector wire now sorted so idles perfectly again but still have the same problem. I've now got opcom on the laptop which I'm impressed with for £20. Been playing with the live graph which has flagged up the map pressure increasing when the misfire occurs if I hold that condition for a second or two. I can't spot anything else a miss, it did flag up a fault code p0300 - 0 multi cylinder misfire which was pretty useful! I now think its more likely the cat having broken apart could cause this, I'd have thought it would have been felt more steadily as the mass flow increased but maybe not with a supercharger? I assume I'll need to remove this to check it as a borescope will surely be impossible to reach the cat and only being able to see the downstream side won't be conclusive? Its a gullet 2.5" with 100 cell cat I think and is about 7 years old. Bearing in mind the fault first occurred while flat out on a straight road at about 6krpm in top, so would have got pretty warm by the time it got there! Also is it normal for the first lambda sensor to be so unstable at idle, around 50 to 800mV jumping from lean to rich constantly? Its seems fine while cruising? Thanks chaps. Dan

[smiley]

P0300 has been reported earlier as a defect coilpack.

 

[Dan r]

Thanks, looked into possible causes and it does point to this along with other things: Faulty spark plugs or wires Faulty coil (pack) Faulty oxygen sensor(s) Faulty fuel injector(s) Burned exhaust valve Faulty catalytic converter(s) Stuck/blocked/leaking EGR valve / passages Faulty camshaft position sensor Defective computer I've tried three spare coil packs and it does exactly the same thing each time, I could do with taking a good one off a sc car to check just to rule it it completely still.

[Dan r]

Plugs replaced and gap set to 0.7mm I cant rule out the injectors as they haven't been tested or replaced however its likely only one injector would be at fault so code would be a cylinder specific code? Fuel filter changed. The lambda sensors appear OK on opcom but I'm not sure if the primary one is meant to be so unstable at idle? A burned exhaust valve would effect running across rev range so not worried about that. I'll check the cat this week hopefully. Egr is blanked off and tied to side of head at moment. CPS has been changed and no errors shown on opcom, Would have thought I'd notice something wrong on opcom if the ecu was faulty? Any thoughts??

[Bargi]

Buy or loan a working injector and swap it accross the injectors one by one and see if there's a difference . Sent from my GT-I9305 using Tapatalk

[Dan r]

Thanks bargi, but I thought the error code would be specific to a cylinder, ie the number on the end would be 1 - 4, this has a zero which is a multi cylinder misfire, so an injector shouldn't be at fault? Be interested if anyone can answer my question about the lambda output at idle? Thanks

[CHILL Gone DUTCH]

Lambda idle I think should be 1 v

[CHILL Gone DUTCH]

think idle should be 0.5v

take no notice of the above message 

 

have seen it go to 0.8 at times 

[Dan r]

Thanks chill, its very unstable, cycles between 0.05 and 0.8v constantly but seems stable while cruising? Just thought that seemed odd, I'd have thought it would move about a bit but it idles perfectly?

[Bargi]

Thanks bargi, but I thought the error code would be specific to a cylinder, ie the number on the end would be 1 - 4, this has a zero which is a multi cylinder misfire, so an injector shouldn't be at fault? Be interested if anyone can answer my question about the lambda output at idle? Thanks

What you say makes sense. Just if you've exhausted the obvious options it's about the only other thing I can think of. You'll get there eventually and it'll be something obvious.l

[CHILL Gone DUTCH]

im beginning to think there could be a compression issue with this one 

[Dan r]

Think I'll pin my hopes on the cat at the moment as the only thing I can work with is seeing the map output increase as the misfire occurs. The cylinders were pressure tested a couple of years ago and all were fine, I realise something could have happened since but i cant understand the way it runs so well until the point of misfire at high speed. Be good to understand why you think it might be this? Can borrow a compression tester easy enough. I'll try getting hold of an injector to swap over as that's a quick easy one as well.

[oakmere]

Lambda should jump up and down if it stays the same its not working. This is for the std narrow band sensor.

[Dan r]

Thanks oakmere.

[mark moyz]

When i had a sticky injector it would throw two codes dependant on when it stuck. Stuck open would create a general misfire code and stuck closed created a cylinder shut down code. But mine started out as fine on idle and low to mid speed but misfired at high revs/speed then it gradually got worse over a couple of months and would send the car into limp mode at anyghing over 2k revs

[Dan r]

When i had a sticky injector it would throw two codes dependant on when it stuck. Stuck open would create a general misfire code and stuck closed created a cylinder shut down code. But mine started out as fine on idle and low to mid speed but misfired at high revs/speed then it gradually got worse over a couple of months and would send the car into limp mode at anyghing over 2k revs

That's interesting, how did you know if it was stuck open or closed? I've only had the mil light on the dash come up twice and only been able to see a code once.

[mark moyz]

When the injector was stuck closed i got a cylinder shut down code specific to the cylinder but when it was stuck open it had loads of unburnt fuel spitting out the exhaust and i got a general misfire code. But like i said this was what the original misfire under load developed in to.

[Dan r]

Thanks Mark, it does stink of fuel when it misfires so could well be sticking open. Would an injector not stick open or closed rather than always stick open as it did with yours Mark? Also why would it then start working again by dropping the revs? I'm going to look at the cat today or tomorrow though as I've got it in my head that its mass flow related due to it always misfiring at around 3500rpm at high load and the lighter the load the higher it seems to rev before misfire. I've also spotted the MAP increase at (or possible before) the misfire point. I'll get a new injector if the cat looks fine. Cheers Dan

[Sutol]

Injector cleaner??