99 Mustang CHH3 Transmission issue

Anything about Ford EEC tuning. TwEECer and Moates questions dominate, but there's some SCT and OBD-II knowledge too.

Moderators: cgrey8, EDS50, Jon 94GT, 2Shaker

Post Reply
User avatar
Gear Head
Posts: 33
Joined: Wed Nov 20, 2013 1:34 pm

99 Mustang CHH3 Transmission issue

Post by Montecarlodrag » Mon Jan 07, 2019 4:01 pm


I tuned a 99 mustang with a forged 4.6, single turbo with BA3000 MAF and all supporting mods. Everything went smooth on the engine side.
The transmission is rebuilt with a shift kit. I only changed the RPM shift points and it shifted nice and firm at WOT 1-2, 2-3. At part throttle it works very good without any issue.
However it started to go "neutral" after a long pull, I release the gas pedal and rev it again but the transmission is still in "neutral" (for lack of a better word), if I move the shifter to N then to D again it engages again and seems to be normal.
It won't re-engage by itself no matter how long I wait, I can limp to a complete stop and it will still be in neutral, as soon as I switch the shifter to N and back to D it engages again and works "normal".

It only does it in 3rd or when downshifting 4-3

I have tuned many cars like this and they are all working good with same trans settings. This is the first time I see this behavior. ATF is at correct level.
Is there anything I can change in the tune to fix this? Using BE with a QH, CHH3 ECU, I flashed the tune to the ECU with OBD2 cable to rule out the QH and it still did the same.

Thanks in advance.

Post Reply

Who is online

Users browsing this forum: No registered users and 21 guests