Hi, Im looking for some advice please.

My 52 plate st170 has started stalling on me when slowing down to a stop. The problem first started a couple of weeks back when I noticed that the engine seemed to be misfiring when started up from cold. I changed the plugs and fuel filter which seemed to improve the situation but now things have taken a turn for the worse. Originally when I fired her up she would rev high for a few seconds and then would suddenly drop low resulting in the engine sounding like it was misfiring. The next time I started her up she would run smooth until sat in traffic and the revs would drop low again when idling. Now when accelerating I noticed that the engine was holding back and with very erratic performance. On my way home from work last night everytime I slowed down to a stop the battery light would come on and the engine would cut out completely leaving me with no brakes or steering which was a complete nightmare. I have done the self test diagnostics and no codes were logged.

Any suggestions would be greatfully received before taking it to the garage to get stung!

 

hi mate
when you changed the plugs did you use genuine ford plugs ?? if not change them to the ford type as the ST170 don't run on after market plugs also change your leads to the ford spec ones had this problem with my ST170 a few years ago and the same with my now focus rs put genuine ford parts on both problem solved

 

Thanks for the reply.

No, a reputable dealer put champion EON plugs in for me but only because the symptoms that I posted were becoming more severe. I seem to think that it might be electrical as the car is running sweet and then all of a sudden the revs drop off when idling to the point where I have to accelerate to get back above 1000rpm before it stalls. Even then tho the car starts to perform very erratic as if there isn't enough fuel getting through, hence the fuel filter change. I also noticed that the oil pressure gauge needle rises and falls when accelerating when stood, is this normal?

Cheers

 

the oil pressure gauge is fine mate they work that way nothing to worry about
as said put the standard plugs/leads back on the car also have you checked the coil pack as these also brake down

 

Split/Perished PCV hose I would bet. Exactly the symptoms it would display. Also check your PCV valve that it isn't stuck. Both the above would not log a fault code either.

 

if its a coil pack a fault code will come up and the EML will come on
did so on my mates ST170 last week

 

Cheers

I will have to take it in and have it checked out as no longer able to drive the car. Thanks for your suggestions, I had a look about under the bonnet but nothing obvious so gave in. Might look at trading it in for a newer St if I start having more and more problems as really need to be mobile and this car has been so reliable up to now.

Thanks again.