Fiesta MK7 ST idle misfires and poor performance.

[JarnoV]

2 weeks ago i took my ST to a Ford dealer to get the timing belt replaced. Since then the car is idling very rough and it is clearly misfiring. I don’t get a single DTC. The acceleration under 4k revs isnt as fast as before. I posted a threat about it and most of the people suggested the timing was of.
So i went back to the dealer and they have redone the work and proved me the timing was correct. They made a video where they showed how they put the cranckshaft to TDC with the locking pin, you can clearly hear the click and then they putted the brace in between the camshaft with the marks at 12 o’clock. Everything seems to be fine with the timing i checked it myself in the ford manual.

I did a compression test and the resulst were
155 - 157 - 154 - 154 on a cold engine. The gauge i used is reading a lil bit low (5psi) because of the long extension i had to use. I changed the sparkplugs and coils, tightend all the turbo hose clamps and cleaned the MAF sensor and air filter. The car is stock except for a K&N airfilter. The car has 107000 km’s

Does anyone have an idea what the problem could be because i am really clueless at this point. What could they have done wrong with the timing belt?

 

[DEss]

2 weeks ago i took my ST to a Ford dealer to get the timing belt replaced. Since then the car is idling very rough and it is clearly misfiring. I don’t get a single DTC. The acceleration under 4k revs isnt as fast as before. I posted a threat about it and most of the people suggested the timing was of.
So i went back to the dealer and they have redone the work and proved me the timing was correct. They made a video where they showed how they put the cranckshaft to TDC with the locking pin, you can clearly hear the click and then they putted the brace in between the camshaft with the marks at 12 o’clock. Everything seems to be fine with the timing i checked it myself in the ford manual.

I did a compression test and the resulst were
155 - 157 - 154 - 154 on a cold engine. The gauge i used is reading a lil bit low (5psi) because of the long extension i had to use. I changed the sparkplugs and coils, tightend all the turbo hose clamps and cleaned the MAF sensor and air filter. The car is stock except for a K&N airfilter. The car has 107000 km’s

Does anyone have an idea what the problem could be because i am really clueless at this point. What could they have done wrong with the timing belt?

Maybe check the simple stuff - electrical connectors are all clicked in properly, battery connections are tightened, and ground is good. G'luck

DS

 

[koozy]

compression is low, I got ~180 when I checked mine.

https://www.fiestastforum.com/threads/koozys-st.5536/page-22#post-370785

 

[koozy]

Even though the timing marks lined up, I would confirm that the piston is indeed TDC by removing the sparkplug and making sure. The fact that the car runs rough, low compression and mis-firing indicates something is a miss. Could be the compression stroke is timed, but not actually at TDC. Makes one wonder if the tech actually timed everything correctly before removing the belt or moved something before the new belt was put on.