I searched around on here and it seems there's a few potential causes/solutions to ST170 engines misbehaving when cold. Just wanted to run this past you guys to see if I'm missing anything.

Here's my symptoms:

56k mile 2003 ST170
From cold, if I just turn the key, the ignition will fire, but the engine won't catch. After 5 or so minutes of trying repeatedly, eventually the engine will catch and lurch/splutter into life. I have to hold on the throttle at higher revs to keep it alive. Once it's running I come off throttle but then (still stationary) after about 60- 90 seconds when the idle speed drops, it will suddenly run out of puff and stutter, almost stalling and misfiring before eventually recovering.

If I'm moving then in that 60 - 90 second window, I lose power and the car stutters almost on the point of stalling before recovering.



Once warm and running the problem disappears e.g. if I stop after a journey then come back, the car will restart perfectly first time which makes me conclude it's absolutely something to do with temperature - either components not warm enough or something not responding correctly at the appropriate temperature or some sensor not providing the right temperature data.

The car has brand new OEM battery, sparks and HT leads. Ford dealer has also replaced fuel filter at first attempt, but the problem is still occuring and they seemed a bit clueless as to what might be the next plan of attack.

From similar-ish posts on here, fuel pump or ecu reset seem to come up - what else could be going on?

 

Does it only happen if you have less than a quarter tank of fuel?

 

I'd like to say no as it's been happening frequently enough over last few months that it must have been at a variety of fuel levels - but haven't really been watching the fuel level to be definitive about it.

 

I only ask as a lot of st170's seem very temperamental at under a 1/4 tank.
Most people end up swapping fuel pumps over with varying degrees of luck.

 

Other cause maybe coil pack, do you know anyone else with a happy running zetec engine you can borrow one off?

 

Something else, could be crank sensor?