Missing At High Revs

[KTASTRPHE]

Im getting all out of ideas, but Im sick of having to take my car in to ford for days at a time for them to fix stuff. Ive done a search in here with quite a few key words and not had any luck. Anyways, its an 03 manual XR6T, upgraded clutch, APS phase II running 14psi.

Pretty much any time I give it a squirt, not even full throttle, there is some noticeble miss under boost.

Now I had new valve springs put in a couple months back under warranty - they used FPV XR8 springs apparently - and it ran shyte for the first 5 kms or so when I got it back, but then went sweet. well, for a couple weeks... so Im thinking its not springs.

So far I have put new plugs in at 0.89mm gap, checked all the hose clamps on piping, cleaned the air filter and put a new fuel filter in, and they have definately improved things, but the miss is still there. Any idea what the problem could be? It hasnt been retuned since the valve springs were done - could this be the problem?

thanks guys.

[Turbo6man]

At 14 psi I would suggest the plug gap is still a bit much - bring it down to 0.8 or even less if it still doesn't fix it. You might have to go as low as 0.7 because the Ford coils apparently aren't very strong on spark after you get over 12 psi.

[ZAP]

I would suggest a retune as Ford may have flashed the ECU and upset the Unitchip tune.

You also might find your fuel pump is at the limit of fueling your car.

[KTASTRPHE]

thanks guys.

I specifically asked ford not to reflash my computer because they did that last time I went in and I had to get it retuned.

Might try the smaller gap - the problem is it used to run fine with normal premium fuel and at 0.9mm gap... now it doesnt.

[RAP1D]

I gapped mine to .75 as per cappas recomendations, it was missing at 5000 on 10psi on the standard gaps, all good now

[KTASTRPHE]

Ill give it a go then. thanks again guys.

[xr6 typhoon]

Ill give it a go then. thanks again guys.

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If you dont fix it soon you could have a KTASTRPHE

[FPV TRANNY]

The xr8 springs do fail aswell.Ask Sutty as he had the same problem and dismissed springs as he had them done but it ended up being buggerd valve springs(XR8)

[Jacobcurtis]

Hey guys, my car misses just like this, only under boost and just blow a crap tone of black smoke out the back like the waste gate is just dumping all the built pressure when it spoils, done coils and plugs, going to do fuel filter, replaced turbo with direct replacement. How do I shorten the spark plug gap?

[k31th]

The spark plug gap is unlikely to be at fault if you've replaced the plugs, but if you do want to modify the spark plug gap, it's a matter of lightly tapping/bending the electrode arm on each plug until it's the desired gap (measured by a feeler gauge).

 

The symptoms themselves could be an engine problem, though... I'd be doing a compression test to ensure that the engine isn't hurt.

 

good luck.