Misfire only over 6000rpm on my VTS

[Christian555]

Hi, I've got a misfire on my ITB'd VTS. Weird thing is that it only occurs above 6000rpms. Makes it something that hasn't forced me to stop using the car but I'm struggling to find out why its doing it.

So far i have:
Replaced coilpack
Replaced injectors
Tried different ECU

Still doesn't like high RPM's. Anyone got suggestions what to try or do next? I've just purchased a new knock sensor for it & I will change spark plugs soon.

Also, i've searched loads on here & other forums. I think it may be a bad earth somewhere or even a vacuum leak but I'm unsure tbh.

[stevo67]

Why a new knock sensor,is it pinking?

[Chipwizards]

Check fuel pressure at the top end.

[Chipwizards]

Or check delivery from the return line. You need at least 20cc/second.

[BUMMERS]

Fueling or spark.


Could be coil/plugs/leads/earth.

[Christian555]

Ok, cheers for the help so far. I have just replaced the fuel pump & fuel filter. I also changed the coilpack & spark plugs for a final time.

Went out for a test drive & problem still occurs but here is the thing....It only occurs when I'm flat to the floor at over 6000rpm.

If I am half or two thirds throttle, It does not occurs & revs right up.

I'm going to take the car to a garage soon because I'm off Nurburgring on the 29th April. I will ask them to look for the 20cc/second (cheers Wayne) because I'm not sure what to use or how to do that.

By the way, the knock sensor I haven't checked, just read it on another forum. Caused some guys Subaru to misfire at high revs.