In my exhaustive search to find a high stall speed converter for our automatic trannies (the F4AC1), I found these answers to some questions that we've seen before.

1. A lot of us have been discussing the difference between racing in DRIVE and putting it in 1ST. When you leave the AT in 1ST, it bounces off the rev-limiter of 6500 controlled by the TCU. When you have the AT in D, it shifts just a hair before 6500. This makes sense because we've seen approx. -0.1 seconds in 1/4 mile times when leaving it in 1st.

2. There is a slight difference in the AT and MT ECUs. You don't have to change out the ECU when doing a tranny swap though. The AT ECU reads a couple of tranny sensors and gets some info from the TCU to adjust idle when switching from PARK to a drive gear.

Just thought I'd share the info. Later...

>1. A lot of us have been discussing the difference between
>racing in DRIVE and putting it in 1ST. When you leave the
>AT in 1ST, it bounces off the rev-limiter of 6500 controlled
>by the TCU. When you have the AT in D, it shifts just a
>hair before 6500. This makes sense because we've seen
>approx. -0.1 seconds in 1/4 mile times when leaving it in
>1st.

Really? Mine never bounces off the rev limiter, it always shifts before redline. I get the same times whether in D of in 1st, and it feels the same to me too. Since our trannies automatically shift, it's not like other cars. Like my mom's accord will bounce off the rev limiter continuously until you shift to 2nd, and it's a really weird feelin and crazy sound as it is in vtec hitting the rev limiter. I don't think that our autos shift at different rpm whether it is in 1st or drive though, or at least I visually cannot tell.

________________________________________

2004 WRX - WR Blue Pearl
1997 Eclipse GS - Royal Sapphire Pearl

Well it's not the rev limiter that's on the main ECU which is the same for all AT and MT ECUs. It's a rev limiter set at the TCM and it's the rev limit of the tranny. Furthermore, it will not cause a fuel or ignition cut... just an upshift. When you leave it in drive the TCM follows it's normal shift routing which is set to shift slightly before the tranny's rev limiter.

I hope that helps further explain. It sounds like your mother's Accord is hitting the engine's rev limiter, but our cars have one in the TCM too.