28 replies to this topic

[becksta1234]

my ford fiesta 2004 make keeps cutting out when i turn engine on in cold weather have to rev engine for bout 5 minutes to warm engine up then the car works fine , have had fault code test and says catalic converter and speed sensor errors have been told those wont be causing the problem, what could be the problem ive had new spark plugs fitted didnt change anything , confused had loads of different answers from various people including crank shaft sensor , lumber sensor , petrol pump , help !! 

[btmaldon]

Were the spark plugs gapped correctly. If not it could be the cause of your problems.

[wase16ll]

first thing that springs to mind would be ecu coolant temp sensor, cheap and easy fix, but tbh, needs to be properly tested/checked otherwise its just throwing money in hope.
you mentioned codes for cat and speed sensor, were those codes cleared and if so, did they come back up again or not.

few more details might help....such as what model, wether you notice any other problems once its running, if the engine light flashes up or not.

[becksta1234]

not sure about spark plugs need to ask my dad as he done them haha ,yea code were cleared and engine light came straight back on ,lights been on for months and had it cleared a few times and comes back on all the time , a zetec model 

[becksta1234]

also once the cars warm and starts up its fine drives like normal once engine stays on 

[becksta1234]

had to get break down people out other day as can normally get the car warm  and rev engine for a bit then engine starts fine but this time tried the usual but got no revs or anything just wouldnt start at all

[wase16ll]

any idea of the actual code numbers

[becksta1234]

the po500 and po420 

[wase16ll]

could still be that temp sensor, laymans terms, that sensor sets the choke for cold start

[wase16ll]

ill just look those codes up, back in a mo

[becksta1234]

ok

[wase16ll]

P0500 speed sensor
although i have never had a bad speed sensor cause starting problems, its not impossible...the fact the code keeps flagging, it needs to be tested.
P0420..cat system efficiency below threshold
this is most probably a problem with the oxygen senor, which may be causing an overfueling, so could be related to your problem.

need to add, codes are a clue, not a reason, so faults could lie elsewhere but causing these sensor to flag up....plus sensors themselves could be fine, maybe a wiring fault or ecu fault for eg.

has the engine light only been coming up since starting problem, or did this occur before [or after] problem started

[becksta1234]

the engine light came on and the problems started 

[wase16ll]

right, definitely related then..
if you fancy a gamble, i would try changing the ecu coolant temp sensor, cost should be under £3o, its situated under the coil pack on right hand side of cylinder head, as you look from front..

this sensor could be working within its set parameters, which is why it doesnt flag its code up, but still fool the engine into believing the engine is warm, when its actually cold...this in turn could confuse the oxy sensor, which is why this code is coming up...
the speed sensor is the one throwing me..

ideally, you need to get somebody that can read and understand live data, that will show where the fault lies, but expect to be charged at least £40 before they even find the fault.

[becksta1234]

ok thanks ile give that a go , thanks for your advice