at Wide Open Throttle, Engine seems to pulsate.

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#1
Good afternoon everybody! I have a 2017 fiesta st. Ever since replacing my differential and turbo, my engine seems to pulsate as it goes up the RPM range while at WOT. I notice this happens more at 3rd gear or higher. I had the turbo replaced under warranty, but had the tech throw a new 7psi waste gate actuator on it. While the vehicle was in the shop, I also had him install a M-Factory LSD, new OEM Clutch, and new OEM slave cylinder. Other wise, my modifications include: Intercooler, Cold Air Intake, step colder plugs (20,000 miles old now),motor mounts, turbo back exhaust, coilovers.
I was told that it could be the LSD trying to engage thus putting a heavier load on the engine (bogging it down). Once it catches up in power, the LSD kicks in again causing the Pulsation. I'm not sure how true this is. It does sound a little odd to me because I've never experienced that in a FWD vehicle with an aftermarket LSD.
I was also told it could be the Spark Plugs. I didn't pull them yet, but was told 20,000 miles on an E40 tune for plugs might cause them to go bad prematurely.
Lastly, I suspect the Wastegate might not have been tightened down correctly. Not sure if that would do it or not. I'm hitting peek boost of about 24psi (per my accessport datalog). When I look at the datalog in Excel, I don't see any sort of pulsation in the boost pressure that would reflect the engine rev/pulse.

Any thoughts one what this might be, or any others experiencing the same issue?
 


Se7eN

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#2
run a quick log in economy which will tell you what your preload is. Supposed to be 7psi as per your waste gate. Also are you custom tuned at all?
 


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sdobbs717
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Thread Starter #3
run a quick log in economy which will tell you what your preload is. Supposed to be 7psi as per your waste gate. Also are you custom tuned at all?
i have a custom tune by JST
 


PunkST

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#4
Are your AFR s wandering while its doing that?
 


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#6
Did you replace the flywheel when you did the clutch? If not that could be a factor.
 


TyphoonFiST

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#8
what are your fuel pressures? Any pending codes?
 


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sdobbs717
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Thread Starter #9
I'm not sure of the fuel pressures. But currently, there are no pending codes. I did note that my friend who has a Focus ST has the same issue. According to him, it's done that since he bought the car new.
 


Business6

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#10
Then you might be able to rule out the changes. What's something each car shares one way or another? Shitty engine mounts?
 




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