missfire/hesitation on boost

[tubbyG]

back with another issue...

I am experiencing a missfire/ignition cut if I go full throttle :scratch: its as if the rev limiter is cutting in early. I get to 10psi @ around 4krpm and it happens.

Half throttle is ok, and boost builds fine, but the second I plant my foot it begins again.

I thought I may have disturbed the wiring causing a short to the rev limiter so I have checked/repaired and rechecked wiring under the car i,e starter power cable.

disconnected the rev limiter completley from the coil, checked the knock sensor and even disconnected that to see if it solved it.

removed plugs, and cleaned them up and re-routed ignition leads incase they were being fouled under harsh acceleration. But still the same!

Any suggestions where to look next?

I have not got the o.e "overboost" sensor fitted, but where should the wiring for it come from and I will see if there is old reminants of it causing probs

[Logg]

Have you checked to see if the fuel regulator reference pipe is still connected or leaking?

Or if you've cut your TDC sensor wire that the bullet/spade conetors haven't come loose?

[tubbyG]

:agree:
I hadnt thought about the fpr refence, im off to work shortly so I will check it over while its warming up

thanks

[Matt@CodeRedMotorsports]

Still got a knock sensor on it?

[tubbyG]

Yes still got the knock sensor attached.

I had even disconnected it to see if it had any effect but was still the same

[Benjer182]

Mine had a similar problem it went when the boost safety pressure switch thing was un plugged so I gad it all set up on a rolling road and they said it shouldn't do it but if it does unplug it

[tubbyG]

had a quick look on my break at the fpr reference pipe and it looks ok from what I can see at the top but below I have no idea if its cracked or not. I have some spare hose in the garage so will change it and see if it helps.

Is there a minimum i/d for the hose or will any do? I think the hose I have is 3mm i/d :scratch:

[tubbyG]

Mine had a similar problem it went when the boost safety pressure switch thing was un plugged so I gad it all set up on a rolling road and they said it shouldn't do it but if it does unplug it


I dont have the over boost sensor fitted, but could you tell me where the wires go to/look like so I can find them (if there still there) to see if they are shorting on something

thanks

[Markey Mark (BD)]

If you got those Silicone HT leads try a standard king lead, also try new set of plugs in there sounds like something is breaking down on hard acceleration. Had this many times before

[tubbyG]

Thanks Mark, i think you are definitely onto something.

I re-routed the king lead for my journey home and now the issue is intermittent. I've got a cppl of old king leads in the garage somewhere so will get them on tomorrow, hopefully that cures it

Thanks again

[Tony Walker]

my king lead snapped once hard braking and downshifting, i stuck it back together with a sticker lol got me home :D (it does sound like a plug,dissy,lead ignition missfire)

[andybond]

I had exactly the same symptoms as you when my FPR reference point has a hairline crack in it. It was underneath as well so couldnt see ..

[tubbyG]

new(old) king lead went on this morning and the misfire went away

now I can tear about like a hooligan again :burnrubber: :laugh:

thanks fella's for all the input... after all that fannying about it was something relativley simple :agree::agree: