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Lack of power-- No CEL and apparently not a boost leak.

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San Antonio
#1
I bought my 2016 FiST brand new in January of last year. Car currently has about 24k on the clock and all maintenance has been done per the manual. Within the last month I've noticed that the power while accelerating through the gears is substantially down (basing this solely on feel as I don't have a way to reliably test this). Car feels like it's being held back higher up in the RPMs and at times feels like it's sort of "bucking" as it accelerates. I've also noticed that the car will idle roughly or the idle will dip a bit sporadically. The car isn't throwing a CEL code. I've gotten the car up on ramps and checked all the boost hoses and everything was nice and snug. Took her to the dealer under warranty and they're saying they can't find anything wrong-- did a boost leak check, etc.

I'm kind of stumped at this point. Wondering if anyone has ever experienced anything like this before. A buddy of mine suggested it could be one of the fuel injectors, however I'd imagine this would throw a code? Any bright ideas or some leads to take to the dealer so they can hone in on some specifics would be greatly appreciated. Thank you all for your time!
 


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Austin
#2
Hey man, im in SA. I can hop a ride as passenger to see what you mean and help poke around.
 


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New Castle
#3
I'm assuming you are 100% stock. The age and mileage isn't that high, but did the dealer check your plugs and coil packs? Outside of that, would need something like an AP hooked up to see some logs on what your ECU is thinking.

You mention maintenance - but hey, it is probably dusty in Texas. Have you changed/inspected your air filter lately?

After that I'm outta ideas on "easy" stuff and into things that hopefully the dealer already inspected and checked off the list (O2 sensor, fuel pump, fuel filter, etc). Speaking of fuel, have you been using the good stuff (93, or at least 91 octane)? If the weather it hot, maybe what you are feeling is the ECU pulling timing to reduce knock. [???:)]
 


alexrex20

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#4
I would pull your plugs and check them first. They can definitely cause the symptoms you are experiencing without ever throwing a CEL.

Sent from my SM-G950U using Tapatalk
 


D1JL

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#5
I do speak with a little experience.
Plugs, coils, or injectors would set a misfire code.
So the first obvious thing I would check is the turbo itself.
I don't believe any codes would set if it stopped working.
If you have a boost gauge that would be the easiest way.
If no boost gauge pull the output hose from the turbo (hot side) and just check for pressure with your hand.
If pressure is there follow it through the intercooler to the throttle body.
there is no way to just guess, you will need to test until you find it.


Dave
 


TyphoonFiST

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Rich-fizzield
#6
I bought my 2016 FiST brand new in January of last year. Car currently has about 24k on the clock and all maintenance has been done per the manual. Within the last month I've noticed that the power while accelerating through the gears is substantially down (basing this solely on feel as I don't have a way to reliably test this). Car feels like it's being held back higher up in the RPMs and at times feels like it's sort of "bucking" as it accelerates. I've also noticed that the car will idle roughly or the idle will dip a bit sporadically. The car isn't throwing a CEL code. I've gotten the car up on ramps and checked all the boost hoses and everything was nice and snug. Took her to the dealer under warranty and they're saying they can't find anything wrong-- did a boost leak check, etc.

I'm kind of stumped at this point. Wondering if anyone has ever experienced anything like this before. A buddy of mine suggested it could be one of the fuel injectors, however I'd imagine this would throw a code? Any bright ideas or some leads to take to the dealer so they can hone in on some specifics would be greatly appreciated. Thank you all for your time![/QUO

Did you do a ride along with a Tech to show them what you were feeling/Encountering? This is the best way to show what you think is going on and to build a paper trail in case of lemon law.[driving]
 


OP
B
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Thread Starter #7
Thanks for all the replies everyone. Work has been crazy-- hopefully I'll get to some of y'alls suggestions this week when I have some free time. I will definitely report back once everything gets sorted out.
 


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#8
Thanks for all the replies everyone. Work has been crazy-- hopefully I'll get to some of y'alls suggestions this week when I have some free time. I will definitely report back once everything gets sorted out.
Bucking? Does it sound like a stutter from the exhaust? That would be a misfire, or a couple misfires in a row. Have had that happen.

I have had nasty full throttle misfires before with out of gap spark plugs. I put a .040" plug in with a turboswap on accident when it should have been set to .026" to .028" aproximatly. In order for the ECU to set a code, you have to have like 5% of the ignitions at high RPMS be misfires. You would have to get a lot of misfires in a row to trigger a code...as the spark plugs would only reliably misfire at full boost. That is actually kind of hard to do if it is only one/two spark plugs giving you major issues and the rest be mediocre. If you have a coil pack issue, it usually pops a check engine light up since a bad coil pack seems to misfire all the time, not just under full power.

I would order a set of NGK Iridium 6510 or Denso ITV-22 Iridium plugs. Both are a step colder, and both are highly recommended on this fourm. I personally recommend the NGKs. You can have a vendor like Whoosh Motorsports send you a pre-gapped set of NGKs for around $45.

The plugs come gapped to like 0.035" or 0.040" so you will have to gap them down to 0.026" to 0.028" to get it right. You need feeler gauge style spark plug tool, the little half-dollar sized coin spark gapper tools will destroy the iridium tips. Get a good $5-$9 spark plug tool if you decide to do it yourself.
 


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#9
I do speak with a little experience.
Plugs, coils, or injectors would set a misfire code.
So the first obvious thing I would check is the turbo itself.
I don't believe any codes would set if it stopped working.
If you have a boost gauge that would be the easiest way.
If no boost gauge pull the output hose from the turbo (hot side) and just check for pressure with your hand.
If pressure is there follow it through the intercooler to the throttle body.
there is no way to just guess, you will need to test until you find it.


Dave
I am positive that a coil pack would throw a code, but I have had spark plug issues from "blow-out" and have no code pop up. Nasty misfires under full boost. Pulled all four plugs to figure out once of them was gapped nearly twice as big as the rest. That was my fault and it was terribly misfiring terribly yet no code. Pretty sure I just forgot to gap one of them. [8]

I am not so sure that one of the fuel injectors would cause a code to pop up either. If it just is really lean on one cylinder, the car might just make the other three richer to bump up the AFRs. That would cause issues without really triggering a code, as it would be (barely) within normal fuel trims if one injector would be a little low on flow. If OP notices a melting plug, that would be a better indicator of a lean cylinder.
 


D1JL

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#11
Sorry, my mistake.
I have and am use to using professional diagnostic code readers, like my SnapOn.
A misfire will always set a "Soft" code when they start happening randomly.
As the problem continues and happens more frequently a "Hard" code will be set.
So it is possible a hard code had not yet been set, therefore no MIL.
Soft codes are also known as "Pending" codes.
In California, a pending code will also cause you to fail a smog inspection.

The bottom line is that I am glad you found the problem.


Dave
 


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Location
Fontana
#13
Just to give you a heads up ish was having the exact same thing as you and ended finding out it was the hpfp was going out. Bucking was lack of fuel, sluggish feeling to compensate for the lack of fuel. I'd check it out, or if it's like me the, Your BMS inline with the positive battery terminal causing the many vital things that are regulated through this piece that was very corroded was throwing a few things off.
 




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