Catostrophic Misfire fault - Solutions please

[arg_carra]

Anyone else had this problem? My ph1 172 has the EML light displayed. Is showing catastrophic misfire as the diagnostic fault but is running spot on. Both lambda sensors have been replaced but the fault will not clear. Car isn't used daily but I haven't noticed it using more fuel than normal. The emissions are very high though. Any thoughts?
Cheers, Al

 

[bloke]

injector. can also show up as destructive misfire.

 

[arg_carra]

Ruled that out unfortunately but thanks anyway surely that would cause bad running anyway?

 

[Russ_16v]

Spark plugs - are you running the correct plugs? The official time is 72k, but I do them every 40k (I have had 2 sets fail around 50k)

 

[arg_carra]

I am indeed, were changed at the last major service about 10k ago.

 

[arg_carra]

I have had knock sensor suggested by Dave. Seems like a shout the more I look into it?

 

[bloke]

what did you read the codes with?

 

[arg_carra]

I have no idea. The workshop at work did it.

 

[Russ_16v]

IMO the usual culprits are:

Plugs
Leads
Coil
Injectors

Could be knock sensor, but that doesn't usually cause that code

 

[DannyR]

It's very strange for an engine light to come on on the Ph1. It would be worth trying lambda sensor too if the above don't sort it.

You've also got MAP sensor which could cause problems with over fuelling/misfiring.

 

[JamesBryan]

Destructive misfire means it's putting unburnt fuel into the cat i think.

If you've had new spark plugs, then i'd say it was the coilpack.

 

[arg_carra]

Destructive misfire means it's putting unburnt fuel into the cat i think.

If you've had new spark plugs, then i'd say it was the coilpack.

Thanks for the replies folks. I'm guessing the above wont do the cat any good either? Strange how its running completely fine.

 

[DannyR]

So it hasn't actually got a misfire? Sure it's not an old code?

 

[arg_carra]

So it hasn't actually got a misfire? Sure it's not an old code?

No misfire at all nope. Don't think it's an old code as it was reset after an injector failure last year. Light came on randomly and failed mot emissions.

 

[JamesBryan]

Thanks for the replies folks. I'm guessing the above wont do the cat any good either? Strange how its running completely fine.

If it is putting fuel into the cat then you should be able to smell it.

 

[bloke]

need to know what the code was read with, then clear the code and take the car out for a good hard drive and then read codes again. you can have a faulty injector without a misfire, they can overfuel easy enough. did you read live data from the front lambda?

 

[MicKPM]

I'd want to see the live data/misfire detection analysis to. Sounds ignition based though.