Hi guys anyone got any ideas on what the problem could be.

Cars ok for a short time with new plugs.

It`s got new leads, dizzy cap, coil, battery,rotor arm,

need help.

 

What car?

assuming its the cossie; it could well be the blue sensor at the back of the head on inlet side

 

ECT sensor..... Maybe giving the ECU wrong info when hot. Worth a try Ł9 from Matt Lewis.

 

Mines doing it now........ except not all the time.

 

yup; could well be

MSD do a sensor kit which does the whole lot in one go; i think its circa Ł90, but well worth it IMO

 

I've had exactly this just recently on a 2WD Cossie. Hard driving for a short while and no problem, then when turbo is hot, 4500 rpm misfire and won't rev any higher. Weirdly enough mine got slightly better on right and slightly worse on left hand bends.

Rolling road diagnosis told me that all the sensors are fine and the electrics are fine we now believe it is fuel related - pressure is good but fuel flow isn't great. So have flushed the tank, got new fuel filter on. Also checked fuel lines for proximity to hot exhaust.

Charlie

 

as soon as i change the plugs it`s fine for a short time then back to the usual after a while. It`s a 3 door mk1 sierra cosworth. thanks for your help so far guys.

 

Possibly the CPS connector, this is a fave, had it myself, tried tweaking the female part iof the termianls to grip harder, then ok for a few days then same again.
I think the pins in the housing lose thier tight grip as they weaken over the years, as when I later put a nerw connector on it was ok.
tabetha

 

what is the CPS sensor and where do i find it ?

 

CPS = Crank Position Connector, just follow the lead from the sensor located about the
7 o'clock position around the crank pulley up to it's connector, they are white, will possibly be in a metal bracket on side of engine just pop out.
Try mr wiggles test first when it is running as this may cause it to fluctuate/conk out refuse to start, but at least you'll have defo found the problem!!
tabetha

 

thought it was but wasn`t sure. I`ll give that a try and will let you`s know. cheers