Hi, I have a 52plate ST170 which runs fine when cold but once the temp goes up to normal it starts to run rough .
the rough running is really bad, to get it to go you have to rev then back off of the accelerator then it will go slowly ..

i have changed lamba sensors checked for air leaks , new plugs and HT leads , havent changed the coil pack as i don't want to spend the money unless i am sure its faulty .

Any ideas ??

thanks
Bamp

 

Coil pack, then fuel pump

 

When was fuel filter last changed ?
tabetha

 

turns out it was the cam shaft sensor ..

thanks guys

 

Mine runs lumpy at idle but clears when rev's are raised, how did they find the sensor problem?

 

Try what i said cuz , if that dont work then we can look at something else

 

Laptop says "Running lean" Lambda sensor one!

 

And my problem has returned , cam sensor seemed to fix it for a bout a week now the problem is back.

Is there away of testing the Fuel pump?
Main stealer wants roughly £250 so i would like to be sure before i fork out all that wonga ,,

thanks

 

the fact it runs fine when cold suggests the pump is in GWO, very uncommon for a fuel pump failure.

 

Sounds the same as the problem I had. It was diagnosed as the fuel pulp control module under the rear west carpet on drivers side.

 

because this system uses the pump as a fuel pressure regulator and has no return pipe, correct?

 

Correct

 

do you have any other suggestions ? i have run out of ideas and money .... i wil try almost anything now ..

 

Hi
Not much help after all this time i know, but mine ran like a bag of knackers when hot or cold.
After putting new cheapo MAF sensor off ebay on the ST, problem was still there. After lots of substituting other bits it turned out to be cheapo MAF sensor at fault. Full price £130 jobbie sorted problem a treat.
Cheers
Kevin