It Was Just A Matter Of Time...

BGstang

BGstang

New Member
Jun 19, 2012
21
0
2
#1
I got my SCT SF3 earlier this week and tuned for 87 octane (cause the tank still had 87 in it) and was able to set for 4.10 gears. The car was 100% better and funner to drive just with these settings.

I was waiting for the tank to go low so I can fill up with 91 and tune for it. The gas gauge is broken on the car and always shows E (and the low fuel light is always on) so I was going by mileage. I got to 210 miles when the car started bogging down on me on the freeway so I exited and was luckily able to get to a gas station (I could have sworn the car would die on the way). I found it odd that I was already out of gas at 210 so I was expecting the worse that it may be something worse than just an empty tank. I filled up with 91 and only was able to put in 12 gallons. Now I was sure it's worse because I thought I had a ~15 gallon tank. But I started her up and made it all the way home without any issues.

Well, I took out the SCT and tuned for 91. Took her out for a few minutes and she felt just fine (I really can't tell a difference between 87 and 91 tune...so I might just go 87...we'll see). Then I got a little adventurous and decided to play a little with the tuner. I wanted to see what would happen if I up'd the "Shift Press" by 5% through all the gears. That's when it started. My O/D light started flashing and the car wouldn't shift out of first. So I put the "Shift Press" back to zero...light still flashed. I put the tune back to stock...light still flashed. Brought her home on first gear (luckily I was just a couple blocks away) and disconnected the neg on the battery in hopes resetting the ECU. After 20 minutes, I plug her back in and cross my fingers. SUCCESS!!! I put the tune back to 91 and set my gears and drove around for 20 minutes with no issues. Even got on the throttle hard at some stretch of road and it felt strong.

Question:
Why did my car bog down when I should have had 3 gallons of gas left? Could it have something to do with my gas gauge not working? I am getting DTC P0460 also.
Why did my O/D flash when I set the Shift Press to 5%? When the light was flashing, I did see the DTC code from the SCT but didn't write it down. Figured if the battery reset didn't work, then I'd jot it down and get some help from you guys.

Definitely got my first scare with the car but I'm glad everthing's back to normal.
 

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#3
Yeah I'm pretty sure it's a 13-15 gallon tank. I typically put in about 12+ if I'm driving to the filling station with the low fuel light on, and can even get a receipt as proof that I've put in more than 13 gallons sometimes.

sounds like your car went into a limp mode or something. I don't even know if our cars have that, though. It could also have been fuel slosh or an ignition failure at that COP or plug that's starting to die.

Call SCT?
 
#4
Gas tank is 15.9 gallons. You wont really run the tank "dry", there's usually a little fuel left when your gauge is reading "E".

I agree if you were real low, the sloshing gas could have allowed the pump to suck some air.
 
#5
and btw, my low fuel light typically comes on around 175-180, so unless you're getting much better mileage than me (with an auto? not likely) you probably were legitimately running out of fuel, as most cars have about 30-40 miles after the light comes on (which yours probably doesn't due to your dead fuel gauge.)
 
#6
Looks like the car's not back to normal. Took it out for a little ride tonight and after going about 14 miles, the O/D light started flashing again. So I pulled over at a big parking lot and had my wife come bring a wrench and the tuner. When she got there, I pulled the following DTC codes:

P0753, P0758, P0750, P0755

I started it up without doing anything else and the O/D light wasn't flashing. So I went ahead and drove it towards home but O/D started flashing about after 2 miles so I pulled over again. Pulled the negative out for 10 minutes, started it and O/D was still flashing. So I tried the negative off for 20 minutes and that worked. I then put the stock tune back on and drove home without any issues.

Anyone have any ideas on this?
 
#9
P0750 Shift Solenoid A Malfunction, P0753 Shift Solenoid A Electrical, P0758 Shift Solenoid B Electrical, P0755 Shift Solenoid B Malfunction. Does the 91 octane tune increase the shift pressure?
 
#10
All shift pressure were set to zero when I tuned for 87 and 91. There wasn't a noticable difference when I went from 87 to 91 so I'm assuming there isn't a difference between the two tunes (in terms of the shift pressure).

Should I put it back to 87 (with the 91 gas still in it) and see if that makes a difference? Think I need to replace the solenoids?
 
#11
A couple things I would like to point out (I'm guessing you have the SCT SF3 with 3 tunes, by the way).

The "Street" and "Performance" tunes have the same Automatic Transmission tuning. Only the "Race" tune is different in this aspect.

When changing to a higher octane gas, it's my understanding that you should empty 2 full tanks of the higher octane gas before installing the higher octane tune. So as to remove all of the lower octane gas from the system, and eliminate the risk of detonation.
 
#12
Penguin - yes you're right, i have the SCT SF3 with 87/91/93 tunes.

I will tune down to 87 and use up 2 full tanks and go back up to 91. However, would that have anything to do with the tranny issue I'm having?
 
#13
No, I don't think the gas octane had anything to do with your transmission issues. I would think your adjustment of the "shift pressure" was the start of your problems.

But you can also check all of the wiring from the solenoid to the transmission control module, to see if anything is corroded/loose.

If everything checks out there, I would probably replace the solenoid.
 
#14
If it drives just fine on the factory tune then it sounds like its the tuner. I would do as mentioned as well as contacting SCT about a replacement tuner or at least an email update.
 
#15
Is the shift solenoid located on the steering column? As mentioned on another post, I've been reading the Chilton's repair manual and the only place a shift solenoid is mentioned is in the Body and Trim section where it talks about removing the Instrument Panel.

Does that mean in order to get to the solenoid, I have to remove the steering wheel and lower the steering column? Or am I way off on this???
 
#16
You're pretty far off. Apparently they don't want you messing inside the transmission, so it's left out of the books.

It's inside your transmission. You'll be going into it. See if you can find a youtube video or something that details the removal and installation.
 
#18
Found this diagram on the JMOD site. So if I'm seeing this correctly, i just have to drop the pan and I should see the shift solenoid. I might as well replace trans fluid and filter while I'm at it since I don't know when it was last done. Anything else I should do while the tranny pan is off? Shift kit perhaps? Been reading up on performance valve body vs shift kit debate and perhaps I may go with a valve body replacement since it seems easier to install than the shift kit.

Am I missing anything here?

View attachment 146894
 
#20
Also, I would contact Bama and find out if they've had this type of situation before. At least ask them about the "shift pressure" increase. Maybe someone has already gone through this, and you could benefit from the resolution.
 
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