Rough acceleration and vibration

[jinx099]

2019 Mustang GT PP1, 6 speed manual, 27k miles

Since yesterday, I noticed something strange when accelerating, even lightly. There is a noticeable vibration, kind of rough through the power band. Also I'd get occasional ticks, rattling like sound (maybe pinging??). I thought maybe I got some bad gas, so I filled it up (I always use premium). There was no immediate change, but after several miles while driving back home, it started to feel a little better. Then I kept driving, doing a little bit of a road test, and it seemed like it was back to normal.

I thought that was that, and went out again tonight. At first, still seemed like all was well, but then after ~30 minutes of mostly cruising, it started getting kind of rough again with the vibrations, and occasional tick noises during acceleration, while seeming mostly fine during cruise. Drove it back home after grabbing dinner, and it was the same, though it seemed to possibly get slightly better, and then slightly worse as I got closer to home. So it's not totally consistent, even feeling totally fine for a period today.

What is this, cam phasers maybe? Also of note, possibly related, I got my car back from the dealer 4 or 5 weeks ago for repair on TSB 19-2140, which was an issue with the timing chain tensioners, and the symptom of that was a chirping noise at idle. That is fixed, no more chirping noises noticed since, but mentioning it since the shop was recently working in that area...

I'll likely be taking it back to the shop regardless as I'm still under the powertrain warranty for a couple of months still, but any guidance would be greatly appreciated.

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[horsepower addiction]

Try running some flush through the engine then change the oil. If it’s still there, get some boss tensioners.

 

[jinx099]

This is kind of driving me crazy. I took it to the dealer for a diagnosis, and they said it's the dang typewriter tick and also they couldn't reproduce the vibration. I don't think they are right about the typewriter tick, I have heard other cars that had it, and I've never noticed that on mine. My tick does NOT happen at idle, only while driving with a little load on the engine.

I do believe them about not being able to reproduce the vibration, because that issue has been really intermittent since I first noticed it, though it seems to be getting more consistent.

It's been a few more days and I've dialed in on the symptoms a bit, and have some theories. Here are the 2 main symptoms.

1) Metallic sounding tapping noise, most apparent and reproducible when the engine is cold, and when starting from a stop and light accelerating/light load. When this happens, its just a handful of taps, then it's gone. No tapping noises whatsoever when idling.

Sometimes I can hear the tapping noises at high loads, intermittently across the RPM range, but seems less loud, or maybe just less noticeable over the exhaust sound. I think it might be the "2k rattle" type of sound, but I get it at many different RPMs instead of the "typical" 2000-2800 RPM that I think that is consistent with. For example, if I start, I may hear "tap tap tap tap" somewhere 1000-1500 RPMs, then if I stop on it, I might hear tapping intermittently 2000-2800 RPMs, then gone, then hear it come back around 3000 then gone again, then hear it again 4000 or so.

2) The vibration, it's weirdly intermittent. One day I'll go out, and it will seem gone, or almost gone. Then go out that same evening, and it vibrates a lot. The past day or 2 it's been pretty consistent, but the severity of it doesn't seem any worse, maybe even slightly better from when it first started.

This vibration under any amount of load, but doesn't happen under no load. It will not vibrate if I am coasting, and if I push the clutch in and rev it doesn't seem to vibrate either. In gear, accelerating even slowly it with vibrate, a little bit, enough to let you know that something is wrong, not enough to prevent you from driving, but just enough to prevent you from really getting on it and enjoying the car. The vibration does not depend on road speed, it will happen at very slow speeds, just starting, and higher speeds as well. If I have the car in a lower gear revved a bit higher, say 3500RPM or so, and then step on it, it will still vibrate, but less so. It's a bit more noticeable at slow speeds, just driving around like a normal person.

One theory I have is I had some bad gas, and an injector is a little clogged, and I might be getting some pinging, or its making the injectors more noisy than usual, and maybe leading to incomplete combustion leading to the vibrations.

Some other info that leads me to this theory is that a couple of days before any of this started happening, I was filling my car up and it was almost full, when suddenly every single pump at the gas station stopped and went "out of service". Maybe the gas station ran out of gas... and I got a little bit of crap in my tank, I'm not sure. The car ran totally fine immediately after this so I didn't think too much of it when it happened. I have run some Iso-Heet and an octane booster through it, and it seemed to help. I ran the tank pretty low and re-fueled with Shell 93 (I always have used premium anyway), and it seemed to be running better after that, but could have just been an intermittent coincidence. I have some Redline SI-1 fuel system cleaner that I'm going to run next time I need to fill up.

The next theory I have is motor mounts. I've never actually experiences a motor mount failure before, so I'm not really sure, but from what I have read it will lead to vibrations, and maybe could be somewhat intermittent like I am experiencing. Maybe this also explains the metallic tapping, as in there is something literally rattling instead of noisy injectors or pinging.

I don't know, any other ideas?

 

[sms2022]

I have a bad vibration/miss at idle when hot. Going to dealership Monday morning will let you know what they say.

 

[sms2022]

Dealer thinks maybe a dirty or clogged injector. Says the DI engines are pretty sensitive to that at idle

 

[HKusp]

Do you have the ability to do a crank re-learn? If you are noticing a pinging it could be it needs a crank re-learn done. The real issue, to me, would be the tensioner job you just had done, though. It seems to me like what you are hearing is chain noise and pinging could certainly be due to the timing not being exactly correct if the tensioners aren't working properly, allowing the chains to be sloppy and the timing is of because of it.

 

[jinx099]

Dealer thinks maybe a dirty or clogged injector. Says the DI engines are pretty sensitive to that at idle

Good to know. Mine is totally smooth at idle. In fact, it seems smooth when I put the clutch in and rev it too. That said, I just added the Redline SI-1 to my tank and filled up last night, so we'll see how it goes.

Do you have the ability to do a crank re-learn? If you are noticing a pinging it could be it needs a crank re-learn done. The real issue, to me, would be the tensioner job you just had done, though. It seems to me like what you are hearing is chain noise and pinging could certainly be due to the timing not being exactly correct if the tensioners aren't working properly, allowing the chains to be sloppy and the timing is of because of it.

How do I do a crank re-learn?

Also, I am starting to wonder if this is a clutch, flywheel, or transmission issue. I didn't think so at first because clutch engagement seems totally fine and normal, and shifting is totally fine and normal, but could something have gotten out of balance somehow? If I'm driving and it's vibrating, and I put the clutch in and rev, it seems smooth, though also the engine is not under any load in that case either.

 

[sms2022]

Good to know. Mine is totally smooth at idle. In fact, it seems smooth when I put the clutch in and rev it too. That said, I just added the Redline SI-1 to my tank and filled up last night, so we'll see how it goes.


How do I do a crank re-learn?

Also, I am starting to wonder if this is a clutch, flywheel, or transmission issue. I didn't think so at first because clutch engagement seems totally fine and normal, and shifting is totally fine and normal, but could something have gotten out of balance somehow? If I'm driving and it's vibrating, and I put the clutch in and rev, it seems smooth, though also the engine is not under any load in that case either.

My car is still at the dealer. Apparently it’s turned out to be a fairly complex problem. I know you’re having a different but similar issue so my only advice would be take the car to the dealer if it’s under warranty. I’ve built engines and do 99% of the work on my cars but All the tech on these engines is crazy.

 

[HKusp]

Good to know. Mine is totally smooth at idle. In fact, it seems smooth when I put the clutch in and rev it too. That said, I just added the Redline SI-1 to my tank and filled up last night, so we'll see how it goes.


How do I do a crank re-learn?

Also, I am starting to wonder if this is a clutch, flywheel, or transmission issue. I didn't think so at first because clutch engagement seems totally fine and normal, and shifting is totally fine and normal, but could something have gotten out of balance somehow? If I'm driving and it's vibrating, and I put the clutch in and rev, it seems smooth, though also the engine is not under any load in that case either.

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