Built a340e, Torque Converter Lockup, not shifting into 2nd under WOT?

[Supra0089]

Hey everyone.

Last year I had my motor built, installed an AEM EMS, and removed the 7m ecu.

The AEM, for some reason, can only control the torque converter lockup and nothing else. So as it sits, I have to manually shift the transmission between gears (which is no biggie).

When I first started driving it (during motor break-in), the torque converter was constantly locking & unlocking cruising around town. My tuner suggested we set the AEM to keep the converter locked while under 40mph. This took care of the problem.

After driving the car for the 3k break-in (yes I went a little more than you need to), I got it retuned etc etc. Then I took it out on the road and for the first time, did some WOT 1st, 2nd, into third pulls. What I noticed is that the tranny refuses to shift from 1st to second under WOT...you have to completely let off the gas and then give it a little gas, then it will shift. Shifting between 2nd and 3rd is not an issue.

What I'm wondering is, why does it stick in first gear? Does anyone think it could be the fact that the converter is programmed to stay locked under 40mph, since 1st gear runs through about 37mph? Or could it be something else?

My tuner is about 2.5 hours away from me, and he books out about 2 months, so it's been less than convenient for me to bring it over to him and try adjusting the lockup. I also store my car during the winter. I just wanted to get peoples' thoughts as I'm thinking about investing in a Suprastick tranny piggyback to address this issue.

Thanks in advance.

 

[Nick M]

Hey everyone.

Last year I had my motor built, installed an AEM EMS, and removed the 7m ecu.

The AEM, for some reason, can only control the torque converter lockup and nothing else. So as it sits, I have to manually shift the transmission between gears (which is no biggie).

AEM has no control over the transmission. The trans ECU needs various signals from the TCCS or AEM to function properly.

When I first started driving it (during motor break-in), the torque converter was constantly locking & unlocking cruising around town.

That is normal, to a point. And, how do you know this?

My tuner suggested we set the AEM to keep the converter locked while under 40mph. This took care of the problem.

Are you using an AEM for a different car? Or a universal unit and not the plug and play that is now discontinued? Toyota has a seperate ECU for the transmission that gets signals from the TCCS. It controls lock up and shifting.

After driving the car for the 3k break-in (yes I went a little more than you need to), I got it retuned etc etc. Then I took it out on the road and for the first time, did some WOT 1st, 2nd, into third pulls. What I noticed is that the tranny refuses to shift from 1st to second under WOT...you have to completely let off the gas and then give it a little gas, then it will shift. Shifting between 2nd and 3rd is not an issue.

The Toyota ECU isn't getting signals from the AEM. Some people have wired it against AEM's recommendation. However, long as you do it right, then the the Toyota ECU can control the trans like it is designed.

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=106

What I'm wondering is, why does it stick in first gear?

It doesn't know what to do. Unless you hardwired the trans ECU from the AEM.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=AT&P=4

Does anyone think it could be the fact that the converter is programmed to stay locked under 40mph, since 1st gear runs through about 37mph? Or could it be something else?

The converter is not supposed to lock until about 37 mph or faster, depending on TPS.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=AT&P=8

Does he schedule sooner for his comebacks? That is a screw up. I don't think your trans ECU is getting the signals it needs. But I can't see it from here, I am only guessing based on your description.

 

[Supra0089]

Thanks for the response. It's pretty much made up my mind that I need the Suprastick.

When I first started driving it (during motor break-in), the torque converter was constantly locking & unlocking cruising around town.
That is normal, to a point. And, how do you know this?

-Because...I can hear it...

Are you using an AEM for a different car? Or a universal unit and not the plug and play that is now discontinued? Toyota has a seperate ECU for the transmission that gets signals from the TCCS. It controls lock up and shifting.

-On AEM website there is a PDF that shows how to hook up the torque converter to the AEM.


It doesn't know what to do. Unless you hardwired the trans ECU from the AEM.

-This makes sense...


The converter is not supposed to lock until about 37 mph or faster, depending on TPS.

-This also makes sense...

Does he schedule sooner for his comebacks? That is a screw up. I don't think your trans ECU is getting the signals it needs. But I can't see it from here, I am only guessing based on your description.

-He does...but he's literally the only guy in NH that does tuning that's reputable. He's also a pilot, which is where the huge waits come from. He's in Europe a lot doing MVP piloting...and I do think all the problems are related to the fact nothing is controlling the tranny.

 

[Tony]

Had the same issue with my auto. One of two things. Clogged filter.... or time to rebuild tranny. Had to rebuild three times. Installing r154 this time.