• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Fiesta ST Forum and Fiesta ST community dedicated to Fiesta ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Fiesta ST Forum today!


Not running right after timing belt change

Messages
49
Likes
26
Location
Richmond, VA, USA
#1
I’ve got a 2016 fiesta st feeling down on power and occasionally the idle gets choppy. Car is making 20 psi of boost but feels sluggish. I don’t have any codes and took it to a mechanic and he found nothing wrong. Had my timing belt rechecked and it was deemed good to go. I did pull the valve covers and vacuum pump etc when doing the timing. Any idea what could be wrong. Not picking up any misfires either.
 


TyphoonFiST

9000 Post Club
Premium Account
Messages
11,828
Likes
8,292
Location
Rich-fizzield
#4
Have you done a boost leak check? As long as the compression is no more than 10-15% between cylinders it is acceptable.
 


OP
R
Messages
49
Likes
26
Location
Richmond, VA, USA
Thread Starter #5
Have you done a boost leak check? As long as the compression is no more than 10-15% between cylinders it is acceptable.
Would boost still hit 25 psi with a leak? Also my short term fuel trim is hitting -25. I think it’s a vacuum leak, could a bypass valve cause this or something under the valve cover?
 


TyphoonFiST

9000 Post Club
Premium Account
Messages
11,828
Likes
8,292
Location
Rich-fizzield
#8
Ran vacuum leak test smoke machine into the vacuum pump and still not seeing any smoke anywhere. Is there anything else in the computer I should be looking for? Maybe low side fuel pressure sensor? What’s it supposed to read at idle
I do believe it should be at idle 70-80psi* for the LPFS and LPFP*
 


Messages
120
Likes
57
Location
Houston, TX
#10
When I had my base model fiesta I had the same issues as you after a timing job. Ended up the timing was off by one tooth so I redone timing and still had the issues. I swapped the camshaft sensors I believe from one side to the other and the issues went away
 


OP
R
Messages
49
Likes
26
Location
Richmond, VA, USA
Thread Starter #11
When I had my base model fiesta I had the same issues as you after a timing job. Ended up the timing was off by one tooth so I redone timing and still had the issues. I swapped the camshaft sensors I believe from one side to the other and the issues went away
I will give that a shot thank you so much! When your timing was off did you have any codes?
 


Last edited:
Messages
120
Likes
57
Location
Houston, TX
#12
I will give that a shot thank you so much! When your timing was off did you have any codes?
When the issues first started I did have codes. After which I redone timing and found it off by a tooth but the issues persisted without codes until I swapped the sensors
 


Messages
120
Likes
57
Location
Houston, TX
#13
If that doesn't work I know it sounds bad but I'd recommend redoing the timing job. It's not as hard the second time around lol especially since you already got the new parts in there. Also make sure you lock the timing and lock the flywheel or it will be off.
 


OP
R
Messages
49
Likes
26
Location
Richmond, VA, USA
Thread Starter #14
If that doesn't work I know it sounds bad but I'd recommend redoing the timing job. It's not as hard the second time around lol especially since you already got the new parts in there. Also make sure you lock the timing and lock the flywheel or it will be off.
Damn unfortunately the cam sensors don’t fit anyway but the right way. I figured if timing was off I’d get a code but I guess I’ll retest it down and retime it just to be a hundred percent sure. Might just wait until my appointment at the dealership on the 21st I’ll post a resolution either way when I have one
 


OP
R
Messages
49
Likes
26
Location
Richmond, VA, USA
Thread Starter #15
So got an update from the dealer today. After 5 hours of diag time they said the cat is completely. Clogged. Im highly skeptical of this being the issue but hey who knows. Not sure why it would take 5 hours of diag time to figure out the cats clogged.
 


TyphoonFiST

9000 Post Club
Premium Account
Messages
11,828
Likes
8,292
Location
Rich-fizzield
#16
So got an update from the dealer today. After 5 hours of diag time they said the cat is completely. Clogged. Im highly skeptical of this being the issue but hey who knows. Not sure why it would take 5 hours of diag time to figure out the cats clogged.
Keep us up to date with the findings!
 


OP
R
Messages
49
Likes
26
Location
Richmond, VA, USA
Thread Starter #17
Keep us up to date with the findings!
I pulled the cat its not clogged it's not even remotely black. I took a leaf blower through it on lowest setting and it blows my hand off the cat. Im calling the dealership tomorrow.. they changed me 950 dollars for a bull shit diagnosis. Does anyone know any solid shops in the richmond va area? Im 2 months into this thing being down and starting to lose patience
 


OP
R
Messages
49
Likes
26
Location
Richmond, VA, USA
Thread Starter #20
maybe when you put the new timing belt you timed it too advanced, were you sure to lock the cams and the tdc pin?
Yes, i would think there would be a check engine light though and none of the three shops its been too seem to think its a timing issue. I locked cams and put against tdc but didnt lock fltwheel. Its not the cat i drove it without the cat and still doing the same thing. Its going back to the dealership tomorrow hoping its fixed before I leave for a few weeks to Japan but doubtful at this point. They said the turbo also might be bad, but in what world does a turbo make full boost when it's bad and there's no oil in the downpipe and minimal in the hot side
 




Top