Hello,

I've had this issue for a few months now, I thought it might be a mapping issue but my recent 165 upgrade hasn't fixed it. Basically my ST is quite rough on idle from cold (doesn't do it any other time). I'm thinking misfire, so potentially spark plugs/leads. I have Denso iridium plugs fitted around 2 months ago, so it could possibly be a dodgy plug?

I've upped a video, please ignore the knocking, as the engine is moving slightly the lid on my airbox is being hit slightly. So just listen to the engine itself.

http://www.youtube.com/watch?v=sRdJIvsDvQA

Anyone got an ideas on this? I'm thinking HT leads myself, I've had a quote off Ford and they want £81+VAT for them :o

I would get some Magnecor ones if I were to pay that.

im at work mate so cant watch video unfortunately.

mine is a pre facelift ST and would struggle now and again to start, although this is normally after short journeys rather than cold.

however, since i had the 165 fitted shes been fine (touches wood), only time she has struggled was after she hadnt been moved for a week.

im probably not much help to you im afraid

Left mine for 3 weeks and it started as it normally would... Sounds like a damp issue... Poor ht leads coilpack

From past threads similar to your issue, members have taken the Throttle Body off and gave it a good clean which sometimes cures the fault

I listened to that very carefully, quite a knocking noise, if you had this exactly before MT then we can rule that out, did sound like the K&N was hitting the top of the CAIS - which they do ! Can turn it slightly to avoid and I my CAIS is soundproofed so the carbon lid is protected from damage.
Anyway, it didn't sound internal to me, does sound misfire-ish or something blowing.
Have them plugs out again and, poor starting and idle sounds like TB, so check that out and clean.

Thanks for all the input guys, I will grab a video of the rev counter tomorrow so you guys can see it moving about. The car starts first time everytime, it's just this rough idle I want sorting.

Easiest thing to check then is the throttle body but I would've expected the mechanics to clean it quickly when fitting the kit

I cleaned it a while ago, say 2-3 months? It wasn't too bad. How often to HT leads need changing anyway? I think I'm going to order some and see if it does the job, can always send them back for a refund if they don't?

can you do a vid of the exhaust at the same time

I can yes, got another camera I can use. Will update the thread tomorrow afteroon with them. Thanks again guys!

hi mate have exactly the same problem as you and im still in the process of fixing it.

i've tried new spark plugs

my old HT leads

new MAP sensor

different fuel

old Throttle body

and still does it

im going to order a new ignition coil pack and if that doesnt fix it im taking it into a garage and likely the engine will be tested and if they cant find the problem im going to get it taken out, and wont be able to drive it until i can afford to put my cosworth engine back in.

other than that i think one of many sensors that records temperatures is knackered.

Ah, that doesn't sound good

Someone mentioned head gasket, this doesn't sound like that? Not losing any coolant and I've got no crap in my oil.

Idle control valve or throttle position sensor? Not 100% sure if the ST has them?? Common Ford failure. I would gap check your spark plugs ( cheapest and easiest thing to do yourself possibly). I know the densos are pre gapped but best to be sure if they were fitted recently and so is the problem.