Big backfire then 16712 - Knock Sensor signal too high

[Martyn]

Interesting bud, something definately isnt right.

I'd still be tempted to whip the plugs out and have a quick look at em.

 

[YerMother]

Sorted yet mate? It's funny how there is still timing pull off throttle!

 

[Martyn]

Sorted yet mate? It's funny how there is still timing pull off throttle!

Could that be down to a shagged knock censor though?

 

[Feel]

No not done anything yet - cleared the codes in the tried and tested "Hope it'll go away" method, which of course these things never do.

I'm fairly sure that the CF's have always gone up off-throttle on mine

 

[Saul]

they do on overrun

 

[Feel]

So everyone's best guess is plugs, and the fault code was just the knock sensors giving it some "Ouch that's loud" as a result of the misfire?

 

[ZBOYD]

As long as the knock fault has gone for good, it didn't on mine, it came back and you know what happened next

But does seem likely if you got a bad sensor or a bad sparkie or coil, then the misfire will make the knock sensors, say oh hello!!

As long as you not getting any low engine vibration, or tippity tappy sounds under load, that get less when you dip the clutch, it shouldn't be what I had.

 

[Jonzy]

As long as you not getting any low engine vibration, or tippity tappy sounds under load, that get less when you dip the clutch, it shouldn't be what I had.

Like a very tinny metallic pinging under load? Could be mistaken for a small hole in the exahust?

 

[Feel]

Small update - It might be N249/Split Vacuum hose related...

 

[Martyn]

How did you work that out mate?

 

[Feel]

I didn't, dealer did. I have parts on order, but the temp fix they've done has made a difference for sure, whether it's fixed the misfiring when cold I guess I'll have to wait and see.

You never know, they might have swapped the plugs, and not told me, but there was nothing on the job card.

 

[DannyC87]

Feel, any conclusion to this thread at all? Mine is doing similar things with the same fault code

 

[Feel]

It's a while ago now, but ISTR that it was TWO coilpacks in the end - one went and was replaced then another went a week later. It was fine afterwards.

Replacing the split N249 "y" pipe smoothed out the idle/tickover, but I don't think it was to do with the misfire.

 

[DannyC87]

okay thanks feel. I have replaced 3 coilpacks recently so hopefully it is just the 4th one on the way out! I am also getting a fault code related to an implausible signal from my egt sensor, could this be related?

 

[DannyC87]

also, what sort of value of CFs are normal? I have also noticed my AFR is staying around 0.78 for maybe a second after coming off the throttle before going to max (2.0); anyone know if this is normal?