Buzzmanb12

iTrader: (11)

A4 Overdrive Issue

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I swapped my M6 trans to an A4. Why can't I get it to go into overdrive all the time? It feels like it shifts just fine 1-3, but when it hits 4th the rpms don't drop off like they should. I can feel each gear change and see the tach drop. It has shifted into 4th a handful of times like it is supposed to, I think it does anyway because the rpms drop about 600-800 less than 3rd. What would keep it from acting right. I have done the: "Drive down the road in D at about 50 mph and ride the brakes and gas to see if it's coming out of overdrive." check, with no change in how the tranny acted. the car is an 04' GTO. Any help?
Thanks
Buzz

DannoWS6

iTrader: (5)

I'm not 100% sure what you are feeling is 4th gear or the converter lockup. Maybe you are not getting lockup? Are you using the PCM to command the Tranny or some kind of piggy back system? I would just data log the car and make sure it's hitting all gears. is it a used tranny? What converter? Make sure the VSS is hooked up.

Gilbert@Ace Racing

Is this a new unit that you installed?

There are two ways to definatively know if it is in 4th gear. One is to utilize a scanner and watch the command and rpm's. The other is to get it up to speed presumably in 4th and then manually downshift it into 3rd and then back into 4th. If it responds, then you know it is in 4th.

It is possible that you are feeling lock-up. Not likely, but possible.

Feel free to give me a call, wouldn't mind discussing it with you a bit this afternoon.

g

Buzzmanb12

iTrader: (11)

You may be right about the lockup being felt, the pcm is doing all the work. It was bought used (4l60e) and then totally gutted and rebuilt by my tuners shop with all the good stuff and reputible guys. The converter is a PTC 10" lockup 36-3800 stall, not quite sure. What is the VSS?

Just got off work and will try to call. Thanks.
Buzz

Gilbert@Ace Racing

VSS is the Vehicle Speed Sensor.

Based on our conversation I am sure it is hooked up and working fine.

Run through those checks we talked about and get back to me.

g

Buzzmanb12

iTrader: (11)

We did the tests and did some logging and the results are:
The converter is not locking up in 4th gear and there is something in the pcm causing it/not letting it lock. WTF? We are at odds as to what it is. We are going to try putting in a stock converter to see if that works and go from there.

DannoWS6

iTrader: (5)

That's kinda what is sounded like. So is the PCM actually commanding the lockup? You're tuner should be able to force lockup if he can't than it's probably mechanical.

Now what about codes? is the dash light on? Things like Misfires or a selenoid slip code will remove lockup even though everything is ok. Also suspect the TCC valve and the PWM selenoid, those would also throw a code.

Now it's possible the clutch could be shot in the converter or infact maybe a bad seal. Worst case you don't have a lockup converter. If you have no codes than changing the converter is probably what I would do.

Gilbert@Ace Racing

Thanks for getting back to us Buzz. Glad to see you doing those things we talked about. Now we know!

As mentioned there are several issues that can and will inhibit Lock Up. Misfires are the #1 cause of this, then we see things like exhuast hitting the floor creating an implied detonation, detontation itself can inhibit lock up. Those are just a few.

What you want to do is to see if indeed any of those conditions exist and correct them, I would recommend talking to a Tuner here in the Forums to see what they would do.

I think that replacing the converter is a bit premature, and seems awfully invasive to me at this point in the game. I don't remember the stall speed of your converter.. reresh my memory please. Also, if there is a way for you to inspect the front cover of the converter... the engine side... you are looking for a dark looking discoloration that runs the circumfance (sp) of the unit itself. If you can see this discoloration then the converter clutch has been slipping... if that is not readily apparent I suggest focusing on the tuning.

One thing I would like to know is the TCC enable tables... is there a way for you to convey that info to me?

I will be in and out all day... if you would like to get me on the phone try to do so this afternoon or evening. I'll be happy to discuss this with you again.

Good Luck.

g

Buzzmanb12

iTrader: (11)

The following is cut/paste from another forum. We used these to correct my lock-up issue. Everything works like it should now.

I would like to thank the few of you that took the time to respond, give me more avenues to check and helped over the phone. THANKS VERY MUCH!

Buzz

One of the misfire tables wasn't desensitized enough causing the TCC to unlock at low loads when the PCM detected "misfire".
Used the Misfire.cfg to find it...

You can turn off misfire detection as a diagnostic. Then if the TCC locks and stays locked it's just a matter of adjusting the misfire tables for your engine

DannoWS6

iTrader: (5)

Awesome bud, glad it worked out and it was an easy fix.

Gilbert@Ace Racing

Congratulations, Glad to see you got it worked out. Sometimes problems on todays Hot Rods can be elusive. Don't hesitate to call if you need anything again in the future.

g

Buzzmanb12

iTrader: (11)

^^ok man thanks again.