Help! After Mods My Zf If Hitting The Rev Limiter In 1st Gear And

[pulonium]

I think I may have overdone the mods a little (custom tune, 10 psi, injectors, air, exhaust), 1st gear shoots by so fast now that occasionally the ZF (in auto mode) can't change to 2nd gear in time and the stupid rev limiter kicks in and I get thrown forward in my seat.

I can change it in manual mode ok but it's really dicey, spending too much time focusing on the rpm.

Has anyone else had this problem? Can anyone think of a way to work around it?

I thought of a couple of options in theory, not sure what's involved, who I could get to do them or if they are even possible....

1) Removing the rev limiter?

2) Port the wastegate or add a new bigger one so the gasses can escape and prevent overboosting?

3) Can the ZF be programmed to change gears any quicker? )Was also wondering if changing the transmission oil etc might help speed the change a little, it does seem a tad slow than I'd expect)

4) Making the 1st gear ratio a little taller from the 4.17 to a 4.10 or 4.0? (Personally I think the 1st gear ratio in the ZF is a little too short at 4.17)

5) Bigger wheels on the car, bigger wheels give a taller gear ratio from memory?

Thanks!

Edited 04/10/08 10:28 PM by pulonium

[ravenhard]

I'd choose option 4. Go back to who ever did you custom tune tell them the problem and get them to fix it

[trevs]

take it back to the tuner and get them to fix it

Edited 04/10/08 11:33 PM by trevs

[ravenhard]

did I say option 4? man it must of been too early for me. I meant option 3 the shift can be edited.

[Cashie]

Let me know how you go with this, I have the same issue...

[pulonium]

well thanks for the advice guys, it sounds as though the conscientious is I take it back to the tuners and see if they can fix it (hopefully by tweaking the ZF's gear changes)

I took it for a drive today with the cool weather it's hitting the rev limiter pretty much all the time :(

will let you know how I go.

[EZ2CME]

Is it hitting the rev limiter because of wheel spin and it can't change up in time or is it hitting the rev limiter without wheel spin?

[pulonium]

it's hitting the rev limiter without wheelspin, esp on or off traction isn't an issue.....

I have a couple more ideas now:

1. Get the tuner to increase the pressure in the auto lines so the gears change quicker

2. Check the actuator is not over tightened/sticking

I'm still reading a little about porting the wastegate in helping the overboost, it sounds feasible.

[pulonium]

did I say option 4? man it must of been too early for me. I meant option 3 the shift can be edited.

Update -

All fixed, due to one or all of the following (I decided to do them all at once rather than trial and error):

- Increased the pressure in the transmission lines by 10%

- Changed the 1st gear shift point in ECU

- Replaced auto transmission filter and oil with a premium synthetic oil

it's changing oh so sweetly now even at 10psi!

[PSYCHO XRT]

Good to hear mate. Now go an enjoy it. :]