i have a bit of hesitation / misfire just before the car comes on boost, this only seems to happen when cold.

so far i have done the following

Magnecor leads
New MAF
all new boost pipework and cleaned the solenoid
Reset the ECU (no fault codes)
Previous owner replaced the oxygen sensor just before i bought but it looks to be a non genuine one fitted (is this likely to cause the symptoms i have?)

i am sure this is worse since i washed the engine bay, i did dry everything with an air line afterwards.

 

you really dont want to be boosting etc when the car is cold.
if its fine when it warms up then its not a problem.
if its cold it will be on choke etc and not up to temperature so wont run the same as in its normal conditions i.e. warm

 

while that is sound advice, you are kind of missing the point, i always let my cars warm up properly before they are driven hard but this is a uk car with a td04 so boost starts building around 2k rpm so the hesitation / misfire is apparent when driving normally

 

but is it ok when the car is up to normal operating temperatures?

 

A friend of mine has a similar problem, he was advised to change the spark plugs, an if that doesnt solve it yhen it could be something to do with the 4th fuel injector, so we changed the plugs problem is still there but not as apparent as it was previously, so looks like were going to change the 4th fuel injector. Dont if that helps but thought id just say.

 

yeah seems to

 

Start the car up and leave it to warm up for 5 mins before you drive it, problem solved

 

i want to find the cause of the hesitation because i want to make sure my car is running perfectly before i take it for a remap, plugs, oil and filters will be done next. I am wondering if the oxygen sensor could be to blame as it looks like a non genuine one fitted

 

My money is on the lamba whats the mpg like?

 

The MPG seems ok, the lamba has a heater element to get it upto temp, I am wondering if his the issue, I have a spare that came in my down pipe, will fit it and see what happens

 

its a trait of the MY99/00 UK cars. its feels like its hesitating, holding back on partial throttle between 2-3krpm?

 

Several people said it was normal and I should live with it but I refused to believe that and the culprit was indeed the lambda, the one fitted didn't have the correct plastic housing fitted so had let water corrode the terminals, I had a spare lambda so swapped the plastic plug housing over and cleaned up the terminals and all hesitation hot or cold has gone, in fact off boost performance is dramatically improved and so will fuel economy I am guessing, it's so smooth to drive now

 

Good stuff! Nice to know tat you have resolved the problem nw.

 

I was about to say the same thing, my MY00 Classic does exactly the same thing, but perfect when warm.
I will now check the lambda, Cheers!

 

+1...checking tomorrow