Acceleration Lag and ECM Calibration

[BayAreaPilot]

I purchased my 2005 Solara used last Monday. Soon I noticed an annoying lag between pressing the gas pedal and actually having the car accelerate in certain situations. That's followed by an equally annoying lurch when the car finally decides it's time to downshift and accelerate.

I found TSB TC006-05 and thought that would solve the issue. So I took my car into the dealer, described the symptom, and asked them to check TC006-05. The dealer checked my car and said it already has the latest ECM calibration.

Here's where things get interesting. I found another TSB, EG037-06 issued June 15, 2006, which applies to 2004-2006 V6 models. This TSB says the new ECM calibration ID after the update is 30642100, 50621100.

I didn't see any more recent ECM-related TSBs for the Solara, so I presume 30642100, 50621100 is the latest rev.

I've read other posts where 2006 owners are complaining of acceleration/downshift lag and the fact that TSB TC006-05 doesn't apply to 2006 models. Unless I'm missing something, EG037-06 seems to be saying that 2004-2006 V6 models are now on a common ECM rev, namely 30642100, 50621100. Is there anyone else on this ECM rev experiencing lag?

This is my first throttle-by-wire car, so maybe my expectations need to be reset. But I haven't really been pushing the car, I noticed this in just everyday around town driving. I guess I need to keep it in S and train myself to downshift on my own. Do Toyota's ECM programmers ever actually drive the car?

[MCOjerry]

PXL, where are you?

He has major lag issues in his 06.

Me, not so much.

[Sebas007]

If you read the EG037-06 TSB you'll see that it is to fix one specific thing. It is like adding a monkey proof line in the ECU saying...when the guy is reving high in 3rd gear for a long time...put it in 4th plz

This will not fix anything useful...but nice updating !!

[Down2TheC]

One thing you might try is resetting the ECU by disconnecting the battery for >30 min. The previous owner might have been a 85 yr old grandma who never gunned it. The ECU adapts to your driving style.

Also the Doc John Mod (see Tutorials) gives the engine more air in the 1k-3krpm band. Might not effect the lag, but couldn't hurt.

Lastly, I recall from my lag days that a smooth fast acceleration is faster than dropping it to the floor and waiting on the lag. It seemed to pick up the need to shift quicker that way.

[PXLpainter]

First of all - I just gotta tell you that I appreciate your thorough research and articulate writing. So refreshing on this board!! Thanks!!

Well... what Sebas007 says is true, the TSB EG037-06 you mentioned only provides a "safety" feature for folks who aren't paying attention and going 80 in 3rd for an extended period of time (Sport Shift mode always defaults to 3rd gear when engaging from D).

Unfortunately, still no fix for '06-ers, but you're the first '05 owner that I've heard that has the first TSB TC006-05 and still has the lag issue.

As you'll discover when you read through the various threads on the subject, we've all tried everything we can to try to lessen the affect, from modifying the OEM airbox/plumbing to 3rd party CAI Intakes and more... to no avail. Doing what Down2theC says will reset the ECU alright, but won't help the shift lag issue you're experiencing unfortunately.

This is not a simple issue of throttle-by-wire as the dealer will try to sell you on that line of BS... I've had 2 other Toyotas with TBW (02 Camry and 01 Tundra) that didn't have ANY lag issue, so I don't buy it!

Two things you can do for now is:

1) Call The Toyota Customer Experience Center 800-331-4331 and complain about the issue and state that its actually dangerous - hopefully Toyota will have a real fix for us soon!

2) Learn to ALWAYS drive in the S (Sport Shift) mode to try to control as much of the shifting as possible.

Best of luck to you - and thanks again for your articulate post!

[Mandarinsolara]

how exactly does the ecu adapt? i searched a little bit, but didnt come across anything.

[BayAreaPilot]

Well, here's the thing. The ECM calibration ID after TC006-05 is supposed to be 30642100, 50621000. After EG037-06 the ID is 30642100, 50621100. That looks to me like the EG037-06 update is the most recent and would include the update in TC006-05. I assume it's like other types of software, a new release is expected to have all of the features and bug fixes of previous releases. So if a 2004-2006 owner gets the EG037-06 update, they should implicitly be getting the TC006-05 update as well.

I guess another possibility is that the EG037-06 update doesn't include the TC006-05 update. I would hope Toyota's QA process includes regression testing, though.