For about 3months now my fiesta stutters/hesitates when i come to a near stand still or when in reverse, the problem is getting so bad now that it occurs almost every time i come to the stop and is preventing me from pulling away onto a roundabout quickly. Diagnostics did not highlight any problem and i have no fault codes popping up. I have changed the TMAP sensor and serviced car (incl replacing all filters), i have checked the wires on the Lamda sensors and they appear OK. I have also noticed a particularly odd hot 'electrical' smell from around the timing belt housing area immediately after the hesitation problem occurs, this has me baffled and i would rather not throw any more money at the problem until i have a better idea of what it may be. Could it be ignition coils/ht leads and if so why? I am still able to get 40mpg on a long run but by efficiency around town is in the 20s. Any help/ideas would be much appreciated please.
​Cheers,
Graham

have you cleaned the throttle body?

Yes, and tbh it wasn't particularly dirty however I also decided to disconnect the crank case breather hose from the airbox to further prevent oil vapour from building up on the throttle body. I did not however spray any sort of cleaner inside the throttle body housing i only cleaned what i could using my hands and a petrol dipped rag. Is it worth buying carb cleaner and spraying it inside the throttle?

So long as there's not a black build up around the butterfly valve it should be ok.

Check the spark plug well for water build up

The mk6 also has frequent problems with coil pack failure

Thanks i will do, i only changed my spark plugs 2 months ago (2000 miles) but will have a look anyway. The strong hot electrical smell that only occurs immediately after the problem has got me absolutely stumped! Thank you for your suggestions!
Graham

Also how can you tell if your ignition coil pack is working correctly/efficiently other than to replace it and see if the car runs better?
Cheers, Graham

you can buy coil pack testers from halfords they plug inbetween the spark plug and the end of the ht lead

Brilliant cheers, it seems to just test the continuity of the coil pack so i imagine my multimeter should do the job! Thanks!

I thought the testers glowed when the coil pack fired? The brighter the glow the better health your ignition system

I don't know to be honest, but I think measuring for continuity using an ohmmeter should prove satisfactory in discovering whether there is a problem or not :) I am about to try it so will update later

So no glow no firing....

So no glow no firing....

Basically yeah

Decided to have a look at my spark plug wells before checking the ignition coil packs, turns out they were once again full of water! only 3 spark plugs well contained water and i dried the wells out and checked the spark plugs. spark plugs were clean and not corroded yet however it was obvious that water had been up to the plastic level (very worrying and not for the first time). Took the car for the test drive and the problem still persist, sigh! :( unfortunately i didn't even get round to checking coil packs tonight :/

Your washer jets are leaking due to no rubber seal or your water cores are corroded

What do you mean by water cores? Cores in the cylinder head? I doubt it would be them as I haven't lost any coolant as far as i can see. I will check the washer jets but i haven't notice any leaks, i will check tomorrow though :) . Thank you for the suggestions!

It leaks through the gap between the jet and the bonnet, onto the airbox and into the spark plug well. Purchase some mist washer jets. These come with a rubber seal to solve this problem :)

Thanks will get those ordered. Now just need to sort my never ending stuttering problem :( ....

The water won't have helped the stuttering. Perhaps it's also worked it's way into the coil pack? Or corroded the HT leads? All things worth checking or replacing

Exactly the water probably caused some shorting/missfiring problems. Yer they are on my to do list but to be honest the HT leads look in good condition and although it may be the coil pack i would rather be more sure of the potential culprit(s) first before i start throwing £100s at the car just to try and rule out the malfunctioning part by trial and error. The most frustrating thing is that i have no fault codes and diagnostics didn't detect anything (took it to two trusted garages a few months apart). What is interesting is that the stuttering/choking appears to occur only once the engine is warm

Have you checked for air leaks anywhere? Have you checked the condition of your air filter? Fuel filter?

I have got a hissing sound from what i think is the fuel return line but i haven't found any obvious air leaks anywhere unless there is one that is hard to find. I have considered replacing the clip on the fuel return line in case it is sucking in air but i thought it was under pressure so is unlikely to do so? I did a full service on my car 2 weeks ago including replacement of all filters, i have contemplated the idea of a malfunctioning lamda sensor(s) but i replaced the pre manifold one last summer.

I wouldn't have thought that would only affect a warm engine though & If you take a picture of the line you mean I'll try help! :)

If you need any part numbers take a picture of what part and I'll have a look on microcat

Thank you I will tomorrow! Thank you for all your help!