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Not running right after timing belt change

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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

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#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
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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

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#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*
 


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#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
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Location
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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:
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Location
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#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
 


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Location
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#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
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Location
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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
 




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