Turbo 'flutter' during low rpm / high gear acceleration...

sholxgt · September 11, 2016, 06:10:57 PM

Wow! Surprised that I hadn't seen this thread before now.

My car is driving me nuts. Stock it is only mildly annoying, but with either of my SCT based tunes, it is unbearable. The stutters that happen between 1300 and 1600 rpm under load are just incredibly annoying because I live in the mountains.

I had decided that mine are converter related, but this has me wondering. For some reason, the stutter is significantly worse when tuned than when left stock. I keep running a tune for a few days at a time with the idea of getting a data log, but end up going back to stock after a few days because I can't stand the way it drives.

I don't think it's the tuners, but something that is wrong with the car that gets exacerbated with the tunes. Dealer can't replicate because it's mild untuned and I don't want to tell them that it's tuned for warranty sake.

John Miller · September 12, 2016, 02:09:59 PM

Mine was driving me nuts and was certainly worse with tune. I tried plugs, cleaning the oil out of the CAC, Etc. Dealer couldn't replicate it when stock - like you said, it was too mild.

But, again, Livernois's tune took it out. Been gone for months. This was not placebo - the change was very obvious. And I'm not a Livernois homer - I have my critiques too of them. And this was obviously an accident that their tune did fixed it, but who cares. It worked.

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sholxgt · September 23, 2016, 02:32:11 PM

Small bit of data...

The wife took a mechanic buddy for a ride today. He watched a ton of parameters while she drove and found one odd thing...

The amp reading for Shift Solenoid C goes up each time the car stutters. Next step is for him to research to see if it's related.

Fingers crossed that they find a fix. It's not so bad stock, but becomes highly annoying once tuned.

SHOdded · September 23, 2016, 02:34:59 PM

Possibly a weak solenoid then, interesting! Fix would be either a new solenoid body assembly, or new PCM. Good time to replace the TSS & OSS sensors too!

Shift Solenoid A (SSA), Shift Solenoid B (SSB), Shift Solenoid C (SSC), Shift Solenoid D (SSD) and Shift Solenoid E (SSE)

Five shift solenoids are used for electronic shift scheduling. The 5 solenoids are located in the solenoid body. SSA , SSB , SSC and SSD are Variable Force Solenoid (VFS). SSE is an ON/OFF shift solenoid. Shift solenoids SSA , SSB , SSC , SSD and SSE provide selection of 1st through 6th gears and reverse by controlling the pressure of the shift valves. SSA and SSC are normally low-pressure solenoids. Pressure increases as the PCM activates the solenoid. SSB and SSD are normally high-pressure solenoids. Pressure decreases as the PCM activates the solenoid. SSE is normally closed and opens when the PCM activates the solenoid. The solenoids are activated by the PCM controlling current flow at the solenoid ground circuit, this is known as ground side switching.

John Miller · September 23, 2016, 04:22:41 PM

SHOLXGT - not sure if you have the logs from the mechanic's diagnosis but, if so, check out my logs posted a couple pages back. See if there are any similarities

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sholxgt · September 23, 2016, 04:54:03 PM

We seem to be having the same exact symptom happening under the same conditions...under load, light throttle, going up hill, 1400 or so rpm, but seem to have different reasons possibly.

The most noticeable things in my logs are the fluctuating rpm and fluctuating converter lock percent. The rest of my logs look normal to me, but I'm no expert.

Here's some logs from my SCT. Car is stuttering between 0 and 5 seconds.

SHOdded · September 23, 2016, 06:08:11 PM

Dont forget the PTU is also a candidate under those conditions.

John Miller · September 23, 2016, 06:37:33 PM

If it was a mechanical issue, I don't think the Livernois tune would have fixed it for me the way it did.

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SHOdded · September 23, 2016, 07:07:46 PM

I am glad it worked for you, John

I hope it is a cure in sholxgt's case also, but keeping options open is needed at this stage.

John Miller · September 23, 2016, 08:59:53 PM

Just sharing my experience and talking through the logical conclusions, if any. Take it or leave it.

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sholxgt · September 23, 2016, 09:18:00 PM

Agree with all here!

My basic plan is to see if the dealership can fix it first, since there is a problem stock. Mechanical? Tune? Not sure which, but I'll let them try first.

If unsuccessful, I'm open to the idea of a Livernois tune. Especially if they will cut me a take back deal like they did for you. In the end, I just want my "not cheap" car to run decent. It should not run the way it does. I was very close to buying outside of the blue oval for the first time in a long time when I got the MKS. I'm starting to think that I should have.

MeanKS · October 28, 2016, 08:17:26 PM

i think my car may be experiencing this. i feel a surging sometimes cruising at 1500 rpm and my gas mileage has gone down to below 13mpg.

any new answers?

SHOdded · October 28, 2016, 08:44:32 PM

Checked codes and all the usual trouble spots? MAP sensors, intercooler, pooling oil, cracked hoses...? Oxygen sensors and fuel injectors would be next. Then possibly a sticking wastegate.