For those with 7AT smoothness and driveability issues
09-25-2012, 01:06 PM
#1
For those with 7AT smoothness and driveability issues
.... clean your throttle bodies!
I've had the 7AT reprogram for a while and it did get rid of the nervousness and hesitation to jump down (or just into) a gear as it was described to... but I've had a growing issue with a lack of smoothness with upshifts and downshifts, and was thinking I may need to get a trans flush to address this. But, at only 19k miles I felt this just didn't make sense.
Well, on Sunday I got bored and cleaned my TB's for the first time, as well as the plenum port (as far as I could reach inside). The throttle is considerably more sensitive to inputs now, particularly off-on transitions, which I feel is what has contributed significantly to restoring an as-new transmission driveability.
I think what happens is the trans ECM expects a certain level of responsiveness from the engine, but doesn't get it, and can't compensate for it automatically. By restoring this responsiveness in throttle sensitivity, the transmission's commands to the ECU are properly carried through by the TB butterfly, and the smoothness in shifting returns.
It's easy to do, so go do it and reap the benefits immediately!
I've had the 7AT reprogram for a while and it did get rid of the nervousness and hesitation to jump down (or just into) a gear as it was described to... but I've had a growing issue with a lack of smoothness with upshifts and downshifts, and was thinking I may need to get a trans flush to address this. But, at only 19k miles I felt this just didn't make sense.
Well, on Sunday I got bored and cleaned my TB's for the first time, as well as the plenum port (as far as I could reach inside). The throttle is considerably more sensitive to inputs now, particularly off-on transitions, which I feel is what has contributed significantly to restoring an as-new transmission driveability.
I think what happens is the trans ECM expects a certain level of responsiveness from the engine, but doesn't get it, and can't compensate for it automatically. By restoring this responsiveness in throttle sensitivity, the transmission's commands to the ECU are properly carried through by the TB butterfly, and the smoothness in shifting returns.
It's easy to do, so go do it and reap the benefits immediately!
09-25-2012, 01:46 PM
#3
You missed where I said early on that I did get the TSB (I used the word "reprogram" so maybe it didn't jump out).
On its own, the TSB didn't help the smoothness issue, only the hesitation. The TB cleaning all but eliminated the smoothness issue.
On its own, the TSB didn't help the smoothness issue, only the hesitation. The TB cleaning all but eliminated the smoothness issue.
09-25-2012, 02:23 PM
#5
Essentially a new transmission firmware to improve shift logic and electronic throttle behavior to address complaints of hunting, long delays and hesitation to downshift (and apply throttle), and a few other characteristics.
There's a long thread about it here.
There's a long thread about it here.
Trending Topics
09-25-2012, 04:43 PM
#8
One thing I do want to add that I find strange is why cleaning the TBs helped this much, given that they essentially stay open pretty much the whole time the engine is running, unless the VVEL fails.
That's correct, isn't it? Are there times when the TBs close under normal VVEL operation?
Maybe it's just an airflow turbulence/resistance thing.
That's correct, isn't it? Are there times when the TBs close under normal VVEL operation?
Maybe it's just an airflow turbulence/resistance thing.
09-25-2012, 04:49 PM
#9
Registered User
Join Date: Sep 2012
Posts: 34
Likes: 0
Received 0 Likes
on
0 Posts
Only problem I've noticed is a hard downshift into first and lag in regular drive mode, think this would fix that or should I get the TSB? As far as cleaning the TB's, just pop off the intakes/MAF sensor and get in there with microfiber?
09-25-2012, 04:53 PM
#10
My post-TSB symptoms were harsh downshifts into any gear, because the rev-matching wouldn't bring the revs up far enough to reduce the driveline shock. Also had a little hesitation when modulating the throttle at low RPMs. Both of these went away with the cleaning.
What will not be affected by this is any kind of shifting lag as that's totally computer controlled. That may be remedied by the TSB, assuming your car falls into the applicable category (look up the TSB for it and compare your VIN against the applicable list).
As far as cleaning TBs, I followed this DIY posted here. It took me less than 30 minutes and I was really taking my time.
What will not be affected by this is any kind of shifting lag as that's totally computer controlled. That may be remedied by the TSB, assuming your car falls into the applicable category (look up the TSB for it and compare your VIN against the applicable list).
As far as cleaning TBs, I followed this DIY posted here. It took me less than 30 minutes and I was really taking my time.
Thread
Thread Starter
Forum
Replies
Last Post
coachdave2001
Newbie Corner
5
09-21-2015 12:05 AM
