Ben King

Hey

For a while now ive had an issue with my st170 when accelerating it can be extremely hesitant and stuttery after dropping a gear or keeping my foot planted to the floor it goes back to normal. It happens with any amount of fuel in the tank. What I have noticed is that it happens mainly after I have been stuck in slow moving trafdic or coasting at 60mph in 6th gear and then go to accelerate and there is nothing there. I have changed fuel filter and all plugs. I also have no error codesDoes anyone know what could be the cause. I have trawled the forum for a few days and cant find anything the same. Found a few similar but they all relate to being higher up the rev range. Mine happens at any rpm.
thanks
Ben

The Loumiester

Have you checked the air filter? Check the MAF sensor while your there.

Mike@8BallTuning

What code reader did you use? as not all show up faults.

There is a common fault about 2200rpm, is this too high to when you experience it?

I would unplug the MAF and see if it makes the problem better or worse

Ben King

thanks for the reply, When i unplug the MAF the engine just dies out.
I used a code reader at My dads friends garage. I have also had it on one of those cheapy bluetooth readers off ebay. Would a air leak around the intake manifold cause issues like this? only i get what i would describe as a hissing noise coming from that area when i turn the engine off. it seems to happen at any RPM but mainly lower down but have had it at 4000rpm but then it doesn't happen all the time, maybe once or twice a week.

Thanks

Ben

jdance

Hi Ben,

I've had my standard ST170 for a couple of months now and have noticed that it hesitates at certain rpm's. Having looked on the forum, it seems that this is common and something to do with the ECU mapping as standard. Mine sounds a bit like yours and gets better the higher the rpm. In a way its typical of an engine with a degree of 'tune' and way back when I used to tune Escorts and similar generation Fords you always accepted the more it was tuned, the more 'highly strung' they become!! The ST has fueling suited to wide throttle openings and I suspect yours feels much better above 4000 rpm.

I would recommend investigating the hissing though as any air leak on the manifold side of the engine is not good and will affect the running of the engine. Spray some carb cleaner around the hissing area with the engine at idle. If the engine speed increases you have an air leak or split hose that needs sorting. You could also take the MAF sensor out and have a look at the fine wire inside - do not touch it but you can spray a bit of carb cleaner onto it.