Auto transmission issues please help!!!
 

Hi guys, I have a 2015 AT and I am having severe transmission issues. I would appreciate some help.

Current mods I have is Weir's 4.88 fd, jdl catless uel, catback and OFT stage 2 tune.

I had a track today and it confirms my transmission or tune is 100% fucked.

Ever since getting Weir's 4.88 fd installed I've been having some issues with the tranny and possibly the ECU/tune.

Transmission Issue:
First, the issue is mainly for first, second and third gears. During regular city driving, when switching back and forth between manual mode and auto, the car would sometimes rev freely when I gas it as if it is in neutral. The gears would not be engaged, and sometimes redline if I gas it hard. Sometimes it does shift but it feels like power is cut majorly.

Turning the car off and restarting it temporary fixes the issue.
Also, when I downshift into any of these gears and rpm is at like 4k rpm, it suddenly drops down to 1k and revs freely like I previously described.

It is similar to this guy but mine drops completely to 1k rpm:
[ame="https://www.youtube.com/watch?v=hBZQbFU2s-g"]Scion FRS Transmission Issues - YouTube[/ame]

I have not experienced this with the taller gears in the highway (4-6).

This issue has been apparent and continuing since installing the gears one month ago. The fluid has been changed during installation.

When the car is working it feels great. Pulls very nicely and strongly and I enjoy it when it does not have these issues.


ECU/Tune:
I logged for the first time since I got the headers installed and tuned with OTS stage 2 tune with JDL tables I found somewhere in the forum. The only other changes is a quiet cold start and AT throttle map from Wayno.
I have not switched tunes after installing gears.

I remember logging many times after flashing with the stage 2 tune and concluding it was running fine. IAM at 1, no major FLKC, under 4% fuel trims.

Today I logged on the highway after experiencing transmission issues around town, and the IAM was between 0.54-0.9. Non-zero values of FLKC (usually below -1) and KC learned. Fuel trims were +6% sometimes. I fueled up with Shell like always before hitting the highway. It sounds like a really shitty batch of fuel but I didn't know it would be that bad. I was almost at the track by the time I logged this, so I didn't turn around and went to the track.

At the track the car managed 1 clean lap with no issues in automatic mode. 2 more as a complete shit show the moment I tried to change gears myself.
Same tranny issues and major cut in power throughout the higher rev range. I had to stop as the car did not run properly at all.

On my way home I babied it and left it in automatic. Did not experience free-revving issue but I can feel a lack of torque and power in the lower range just driving around town.

I am not sure what the issue is. I feel like the tune issue is just for today with the very shitty batch of fuel. The transmission issue has been happening very often.

Any ideas on how to approach these problems??

***UPDATE***
Emptied the god awful remainder of Shell 91 gas and fueled up with Esso 93.
Data logged and IAM is back to full time 1 and non-existent FLKC.
Haven't pushed it yet but I fear the tranny issues may return. No transmission issues since battery reset though.

Have you considered flashing back to the stock tune .......??


humfrz

No I haven't, but if the fuel is bad the tune won't matter anyways right? AFAIK the OTS tunes run better than the stock tune so I didn't bother trying the stock tune.

On the plus side I reset the battery today and I did not experience transmission issues for a short drive.

Can't be completely relieved yet..

I would think it would be tough to "tune out" bad gas.

Well, the transmission may not think the OTS tune is better ..... :iono:


humfrz

Definitely sounds like a tune issue. The transmission ECU has set speed limits for shifting in each gear which can be found in the factory service manual. The 4.88 FD messes with these by decreasing max speed in lower gears.

Its likely more of an issue between 1-3 as the percent change in speed over the stock set point is greater than in 4-6. Edit: (I think, but not positive.)

I've read that this will only affect the gear number shown on the dash but it seems to me like it's also affecting the tcu logic as well. Try going back to the stock tune just to see if it changes anything. Pretty sure you can solve this issue with an ECUtek tune as well.

I see. I'll flash back to stock now. I should have done some logging after installing the fd, what if I damaged the engine the whole time since I got it?

Then you bring it into the dealer under warranty and they'll fix it. :D

But seriously...I was just about to do the 4.88 in my car and in all the reading about prior installs, this never came up before.

The ecu and tcu are both flashed separately. Your tune would not affect anything in transmission.

I'm running a 4.88 for about 8 months now. I drive it hard and have had no issues.

You might just have a bad transmission.

I flashed to stock and the issues haven't replicated yet.. so far..
What should I DO...?

The TCU receives input from the ECU so changing certain ECU tables can definitely affect how the TCU operates.

Good to know you haven't had issues though. What tune are you running?

So after looking through the manual again the shift speed limits are just for reference when assessing transmission function. Here are some screenshots from the manual for reference. Do you have a check engine light and if so what are the diagnostic codes? Also if you haven't already you should take ecu datalogs while driving.

I did not get any check engine lights.
One day after a full day of poor running, I did get the stability light and abs light come on simultaneously till I turned the car off.

It's flashed to stock right now and it's been running alright.
I'm tempted to sell the OFT and get it dyno tuned..