Ph1 172 misfire

[TommyPh1]

Hi lads
I've got a misfire on my PH1 172. I done a trackday at Lydden Hill back in September and the car was fine all day. It wasn't until it had sat while I watched the last few sessions the problem arose. I started it up to drive home and noticed the misfire. Since getting it home I've changed the injectors, plugs, leads and coil pack, none of which have solved the issue. Ive also discovered that when I disconnect the injector on the far right as you look at the rail it makes no difference to the idle, where as all the other 3 it does. I've checked all the wiring to that plug and it's fine.. Anyone experienced anything like this or can suggest what to try next?
Cheers, Tommy

 

[KitsonRis]

If you have unplugged an injector and the idle is no different then it's a dodgey injector. Have you tried to swap an injector around - swap this "bad" one for a good one and do the same test. If the problem still exists on the same cylinder then I would say it's the loom/wiring/things to do with that cylinder. If the problem moves then it's the injector.

Have you plugged a fault code reader into it?

Are you sure it is misfiring in idle and not under load? As my pre cat lambda needed replacing and it was like I had a misfire when I was accelerating.

 

[oVerboost.]

As above, injector issue. Any warning lights on the dash and do you have access to an OBD scanner?

 

[TommyPh1]

Thanks for the replies. I've tried switching the injectors round and still the same. Have also checked the wiring and no problems with that. The engine light is flashing on the dash but haven't got an obd scanner unfortunately. Will see if I can get hold of one

 

[KitsonRis]

Thanks for the replies. I've tried switching the injectors round and still the same. Have also checked the wiring and no problems with that. The engine light is flashing on the dash but haven't got an obd scanner unfortunately. Will see if I can get hold of one

Same as in what....the missfire is still on the same cylinder or the missfire moves?
IIRC there is potential for the fuel rail gaurd to clamp the injector wires if not in the correct place so this could be an issue.

 

[TommyPh1]

Same as in what....the missfire is still on the same cylinder or the missfire moves?
IIRC there is potential for the fuel rail gaurd to clamp the injector wires if not in the correct place so this could be an issue.

Misfire is still on the same cylinder. Yea I've read that, have checked that and all seems fine. Wires are all free moving and traced it back to find no problems.

 

[KitsonRis]

Have you checked the wires going to the coil pack? As it looks like mine have been trapped, probably by the inlet manifold, at one point as there is a small repair on them.
Also is it just a mussfurecat idle or over the entire rev range?
Could try and see if there is a spark on this cylinder or if there is a fueling issue.
Just some ideas to explore.