5EAT shifting issues

I've put nearly 20k on the clock since I bought my beater 05 LGT. When I bought it, the engine was in the trunk partly disassembled. Anyways, I drained what trans fluid was in the pan and did my best to get out everything in the lines. Cleaned out the cooler in the radiator, drained the TC, and replaced the filter in the driver's side fender. Basically I tried to get out every drop I could. Replaced it to the fill level with Subaru HP ATF... the stuff made for the 5EAT. I also rebuilt the engine with forged internals and dropped it in with a stock turbo. Within a few thousand miles I was happy with the reliability, so I threw on a larger TMIC (made by FMS), some PE850s, and an FP20g. I did a rough self tune. Rough may not be the right word. It idles fine, AFR's are dialed in, but I haven't tried leaning it up past stage 2 or messing with the timing that much. I'd be exaggerating to say the car is making over 325whp. A good tuner could easily add 50hp to that, but it suits my needs at the moment. Keep in mind I've put nearly 20k miles on with this tune and not had any problems with the engine.

 

On to the actual problem. The car started having a rough upshift from 1-2, but only the FIRST shift after a cold start. This is as reliable as the sunrise. I get up in the morning, start down my street, rough up shift. The rest of my 50 mile commute no problems. I leave work at 5 and it has a rough upshift before I leave the parking lot and not again after that on the way home. That is only the beginning...

 

I don't drive like an asshat (most of the time), but I didn't drop a 20g in it to drive it like my wife's Odyssey. I can't remember when it started, but basically any decent amount of throttle pressure from 1st resulted into bouncing off the rev limiter until the pedal was released. I'm not talking floor, 40-50% TPS is enough to run it up to redline and bounce off the limiter every single time. It started out as 1-2 upshift only, but has since worsened to 2-3, and is starting to show signs in 3-4. Not sure about 4-5 as I've never had the car up that fast... heck 3-4 shift before redline is over 100mph.

 

Any ideas what actually causes this? valvebody? clutchpacks? I can rebuild a subaru motor with my eyes closed, but have never opened a trans case.

 

I could buy a junkyard trans, but I'm guessing the same thing would eventually happen. Is there any thing that can be done to improve the current situation, even if that means buying a spare trans and having it beefed up in some way. I have another 05 LGT with a built motor going in right now, and I'd really like to run a GTX2876r or GTX3071r on it... at least that's what I'm drooling over right now.

has the tcu ever been reset to relearn? have you rechecked the fluid level since the flush?

Yes and yes. I check the fluids regularly. I had read up a little before posting the question and saw that some people had luck resetting the TCU. I downloaded the open TCU program and reset it with my tactrix cable. No change that I could tell.

I would try to narrow it down, to at least see if it's a valve body issue.

I may have overlooked you mentioning this, but does it do the same thing if you upshift manually? Throw it in manual mode and stay in a high gear at low speed, say 5th at 40mph and squeeze the gas pedal. Can you tell if it's slipping?

If it's holding gears fine and shifting up when you tell it to, I think there is an issue in the valve body.

Then again I would have expected some sort of CEL (check engine light)

Sorry for the delayed response, I've been out of the country.

No check engine light.

 

It will not upshift 'properly' in manual. It will actually shift under decent load, but will not under WOT. It also is a delayed shift from the time I hit the button. The shift itself seems okay though. If I plan on getting around someone, I'll throw it in manual, downshift, give it the gas, and hit the upshift well before I think it actually should be shifted, and with the exception of the delay, it does what its supposed to... as long as I don't go full power.

 

What would it feel like if it's slipping? Back when I was tuning it, I didn't have a trans cooler. I was making a 3rd gear pull after several other 3rd gear pulls and all of a sudden the car started to shudder. I figured that I had overheated the trans fluid and gave it a rest for the night. It hasn't happened since.

 

If it's a valvebody issue, would a true flush help?

I doubt a flush will do anything else for you.

Slipping basically feels like a loss of forward acceleration while the revs are still climbing, basically almost like having the car in neutral.

The delayed shift is normal and just the sucky shift logic from Subaru. It can take as much as a full second from the moment you hit the button to the moment it actually shifts.

Mine also slams the first shift after the car has cooled down.

You're still not clear whether or not it will ALWAYS shift at part throttle. I understand WOT it won't. Does it do this in all gears?

If it slips, it will usually do so in a certain gearshift, not all, unless all are messed up.

When you flushed the fluid, what did it look like? Anything that should not be in it, like a gritty feel or shiny particles?

 

A used tranny last I checked on car-part.com was anywhere around 800 to 2K depending on mileage, warranty, etc.

A new valve body is around 700 bucks. Unless you can find a much cheaper one AND we can reasonably narrow it down to being a vb issue, I would probably just swap the transmission with the same model year.

It has no loss of acceleration while RPMs are climbing. I floor it, the revs go to TC stall speed, and stay there until the drivetrain catches up. Then both engine and car increase speed together. As far as I can tell this is every gear, but I have come no where near maxing out 4th or 5th.

 

If manumatic is that crappy for everyone, I'll look into an aftermarket solution. I am pretty handy with microcontrollers, I've just never taken the time to apply them to the auto industry. It couldn't be that difficult to interrupt a few signals and control the VB directly. Anybody in for a TCU piggyback?!?!

 

The bang when cold doesn't bother me as I just drive very gently until it has made that first 1-2 shift. After that, it won't happen again until I let the engine cool down.

 

If you separate acceleration into 5 steps, 1 being daily driving, 5 being WOT, the following is what I have observed:

1-2 driving style will always shift in a normal manner

3-5 will not shift in the standard automatic mode

3-4 will shift in manumatic with extensive delay

4-5 not thoroughly tested in manumatic. Will try tonight.

 

I never flushed, just an extensive drain and refill when I rebuilt the motor. The fluid was still red, but had a burnt smell to it. I didn't see anything unusual about it at the time.

75% throttle (4 by above scale) it will shift in manumatic, anything higher and it won't. I have not tried it in the 4-5 shift, but seems to be the same for 1-4.

 

The higher line pressure of sport mode, which I've incorrectly called manumatic seems to improve the capabilities. Would a valvebody swap be out of order? Could it be the hydraulic pump? At this point, I don't think any slipping is ocurring.

 

FWIW I don't want to spend too much money here as I'm going to have to sell the car. I bought a Baja turbo 2 weeks ago, and apparently 2 LGTs, a WRX, an Impreza, and a Baja is where the wife drew the line. Sold the Impreza already, and now the Baja or the LGT has to go. I may sell it with the issue, obviously letting the buyer know in advance of the issue, but if I can fix it, I will.

Maybe ClimberD can chime in, he knows more about the ins and outs but I can tell you the valve body doesn't have the pump integrated in it. It could very well be sticky valves or servos. And if you think about it, it's a heck of a lot easier and faster to swap a valve body than the whole tranny. Drop the pan, undo the bolts, drop the valve body and swap. It is worth a shot. I'm just surprised there are no codes.

If it's not slipping then the only thing I can think if is a malfunctioning valve body in all honesty since it's responsible with directing engaging and disengaging of gears.

And the tranny throws a code if the line pressure is either too high or too low.

This issue has been resolved. Got dyno tuned today and the tuner informed me this is an issue with 350Z and G35's too. It has to do with load scaling being altered from factory and the TCU. Brad's tune at Engine Logics 'fixed the glitch.'

Thanks for posting the update! This sheds some light on a question a lot of us have had for years now.

So he reverted back to the stock, or tweaked it?

Please reply to last question I'm having the same issue and even after replacing my trans with a low mileage Trans (23k miles )

"On to the actual problem. The car started having a rough upshift from 1-2, but only the FIRST shift after a cold start. This is as reliable as the sunrise. I get up in the morning, start down my street, rough up shift. The rest of my 50 mile commute no problems. I leave work at 5 and it has a rough upshift before I leave the parking lot and not again after that on the way home. That is only the beginning..."

 

I have the same exact problem but my car is 100% stock. What should I have checked?

laff79 is correct. I still have the hard shift first thing in the morning. I'm not worried about it anymore.

 

BuiltLGT. I answered your question. The issue is that the ECU/TCU are seeing loads that they wouldn't see on a stock car. I thought that was explanation enough. To fix the problem you need to modify your MAF scaling and injector scalar. Then you need to correct all of your tables that are load based. It essentially is a version of the 'MAF hack' that all of the 16bit ECU guys did to get above the 300g/s limit.