Hesitation under throttle problem

[erburtt]

I've been an inactive member for quite a while, I kinda stopped caring about performance mods etc. and have just been daily driving the FiST pining for a truck. A problem came up the other day though so I'm back on the forum to try and figure it out.

150,000 kms on the clock, all stock 2014 except a BOV spacer. When accelerating things don't feel right, kinda feels like the wheels are spinning/engine hesitating between 2000k-2500k rpm. Then it seems to pick up again and accelerates faster. I don't really notice it until I'm in third gear, but up from there every gear is missing that low end pull I'm used to. Feels like excessive turbo lag. Passes definitely require downshifts now. I checked/tightened all hose clamps to and from intercooler, and can't hear a boost leak. I also checked the sound symposer tubes and all looked fine. I pulled one plug and it looked alright, but I'm planning on checking the actual gaps on all of them tomorrow when I get my feeler gauges from home. I'm hesitant to blame it on an ignition issue as it still idles smooth. I've ruled out fuel delivery issues as I figure it would be exasperated at higher rpms. I though it could be bad gas too, but again the issue isnt there at high rpms, and it only started abruptly one day about halfway through a tank.

Any ideas or thoughts?

 

[JDG]

I've been an inactive member for quite a while, I kinda stopped caring about performance mods etc. and have just been daily driving the FiST pining for a truck. A problem came up the other day though so I'm back on the forum to try and figure it out.

150,000 kms on the clock, all stock 2014 except a BOV spacer. When accelerating things don't feel right, kinda feels like the wheels are spinning/engine hesitating between 2000k-2500k rpm. Then it seems to pick up again and accelerates faster. I don't really notice it until I'm in third gear, but up from there every gear is missing that low end pull I'm used to. Feels like excessive turbo lag. Passes definitely require downshifts now. I checked/tightened all hose clamps to and from intercooler, and can't hear a boost leak. I also checked the sound symposer tubes and all looked fine. I pulled one plug and it looked alright, but I'm planning on checking the actual gaps on all of them tomorrow when I get my feeler gauges from home. I'm hesitant to blame it on an ignition issue as it still idles smooth. I've ruled out fuel delivery issues as I figure it would be exasperated at higher rpms. I though it could be bad gas too, but again the issue isnt there at high rpms, and it only started abruptly one day about halfway through a tank.

Any ideas or thoughts?

"Wheels are spinning": As in the clutch is slipping?

When was the last time you changed those plugs? Just because the car idles fine, doesn't mean the plugs are a-okay. New plugs are probably in your future if you are still running the OEM units at 93K miles.

Does this happen under partial throttle as well as full throttle?

 

[erburtt]

"Wheels are spinning": As in the clutch is slipping?

When was the last time you changed those plugs? Just because the car idles fine, doesn't mean the plugs are a-okay. New plugs are probably in your future if you are still running the OEM units at 93K miles.

Does this happen under partial throttle as well as full throttle?

it’s not the clutch, I can see the tach sort of pausing as well, I meant more it feels like a sudden drop on pull as if the wheels have lost traction.

I’m planning on replacing the plugs anyway, this just came on so suddenly, where as if it were plugs I figured it would more slowly get worse. I’m hoping I can have a coworker rev it for me and I’ll use a soapy spray bottle to look for leaks.

I did a couple full throttle pulls on the highway today, and it’s actually way better like that, I don’t feel it hesitate at all under full throttle. It’s worst when I’m just driving normally around town and need to accelerate from a dig without revving the crap out of it first.

I don’t have an access port, I wish I had a way to monitor misfires and boost levels.

 

[kivnul]

Could the waste gate actuator (or the vacuum line controlling it) be on its way to dead? Works fine when pegged but may not be closing properly under partial throttle.

 

[CarGuy]

Did you replace the timing belt already? I've heard of higher mileage FiSTs jumping timing with worn timing belts. Although I would think that you'd feel that at all rpms.

Sent from my SM-N950U using Tapatalk

 

[erburtt]

Could the waste gate actuator (or the
vacuum line controlling it) be on its way to dead? Works fine when pegged but may not be closing properly under partial throttle.

I’m not actually sure, would there be any other symptoms to help diagnose if that was the issue?

I should add that I do have a check engine light, but it’s a P0128 code, it’s come on for the past 3 winters and goes away in the summer. I figured it’s either a bad coolant sensor or the coolant not coming up to temp enough with the cooler thermostat installed when I had the coolant tank recall done

 

[erburtt]

Did you replace the timing belt already? I've heard of higher mileage FiSTs jumping timing with worn timing belts. Although I would think that you'd feel that at all rpms.

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nope never touched that, I read somewhere it’s considered a “lifetime” timing belt, I did research it a bit when I passed 100k thinking that it would be due soon. I don’t think it’s timing related though, that would be evident in all running aspects of the car, this is limited to between 2000 and 2500 rpm

 

[TyphoonFiST]

Ignition breaking up? Worn ignition coils....Food for thought

 

[PunkST]

Belt change is at 150k intervals. I suspect you have some very worn coils. ( mine died at 80k miles)

 

[erburtt]

Ignition breaking up? Worn ignition coils....Food for thought

That was going to be the next thought after doing the plugs. I wasn't excited about shelling out for them though. Any other symptoms that would indicate that?

This morning the car was completely back to normal, drove fine, no lag. I'm still going to do the plugs though, just one of those maintenance items I never got around to.

 

[erburtt]

Belt change is at 150k intervals. I suspect you have some very worn coils. ( mine died at 80k miles)

150k miles, so 243k kms. I will have sold the car long before getting there, looking at getting a F-150 in the next month or so.

Did you have any other symptoms or indicators that told you your coils were going bad?

 

[PunkST]

Nothing, no codes, no misfire, just ran poorly and got almost undriveable in wet weather. Which im not sure the new coilpacks 100% solved. But it definitely improved.