XF 250 carby bad misfire on cold startup...slight misfire on idle?? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

Extreme_2020 · 07-28-2003, 21:53

Hey all,

the XF has had an ongoing problem where on cold startup in the morning it has a violent misfire at idle...shaking the whole engine almost off its mounts! You can feel it through the entire car...after about 2 minutes of running it settles down...but when warm there is still a misfire at idle..but not as bad...also when cold there isint really any power...and it hesitates to accelerate for the first minute or so of running...when warm the car runs fine except for the miss at idle...im stumped??
its had a reconditioned 250 put in...but the exact same thing happened with the old engine...the carby has been adjusted and some air leaks fixed...the dist cap/rotor/plugs were changed a few months back...although the old engine was burning coolant...so i suspect the plugs may have become damaged...i replaced the ignition leads again today with some new bosch ones and it hasnt really helped...

Where should i start?? The problem is driving me up the wall!

Thanks

Extreme

xdc351 · 07-28-2003, 22:08

Sounds like it might be overfueling or the dizzy has sh*t itself to me.

Does it ever go away?
If not i would lean towards the dizzy, if it does, check the choke is working.

HTH

xdc

Extreme_2020 · 07-28-2003, 22:27

It dosent miss under load (well that i can tell)..but it always misses at idle...just very violent on first startup...then when warm its a very slight miss..still shakes the entire engine tho...

its had a slight miss since i got it...but in the past 4 months or so its gotten worse..

hmm...could be dizzy...that hasnt been checked!...its a EST model so it has no vacumn pickups or anything like that to fail...and the timing has been checked and adjusted to factory spec...

Thanks

Extreme

Extreme_2020 · 07-29-2003, 17:17

Ive had a thought...could the base plate and hall effect device inside the distributor be worn in such a way that when cold it causes the misifre...but when warm settles down?

Id like to check it but it looks a tad beyond me to dismantle the distributor to get to it...maybe get my mechanic to look?
Anybody know how much a replacement dissy is for a XF EST Model?

Thanks

Extreme