WOT with new Diff hit the REV limiter
08-01-2022, 07:34 AM
#1
Instructor
Thread Starter
WOT with new Diff hit the REV limiter
So I swapped my rear Diff from 2.73 to 3.15 then I brought it over to a local guy to update the computer.
Later in the day the guy calls me and asks what gear did I install the.................... PCM has it as 3.42………..?
I told him I removed a 2.73 and installed a 3.15 and 3.42 was not an option for a A4. (at 81 mph with the 2.73 I am turning 1900 RPM in 4th ) he said ok I will call you when its ready.
There is a noticeable change in acceleration in a good way but, at (wide open throttle 1st to 2nd I hit the REV limiter.) I went to the highway and at 80mph slam it to the floor and the car down shifted to 2nd and back to the REV limiter around 98 MPH.
The guy told me he used HP tuner and all he did was check off 3.15 in the option section and that was it.
Two questions
1. What did they miss when updating the CPU for the 3.15s ,before the swap when I had the 2.73 the car seemed fine.
2. How could the sifting have seem fine but the computer option was checked off 3.42 it should have run real strange with 2.73 in the Diff.
The car is going back I would love some info so I can understand what could be going on.
Later in the day the guy calls me and asks what gear did I install the.................... PCM has it as 3.42………..?
I told him I removed a 2.73 and installed a 3.15 and 3.42 was not an option for a A4. (at 81 mph with the 2.73 I am turning 1900 RPM in 4th ) he said ok I will call you when its ready.
There is a noticeable change in acceleration in a good way but, at (wide open throttle 1st to 2nd I hit the REV limiter.) I went to the highway and at 80mph slam it to the floor and the car down shifted to 2nd and back to the REV limiter around 98 MPH.
The guy told me he used HP tuner and all he did was check off 3.15 in the option section and that was it.
Two questions
1. What did they miss when updating the CPU for the 3.15s ,before the swap when I had the 2.73 the car seemed fine.
2. How could the sifting have seem fine but the computer option was checked off 3.42 it should have run real strange with 2.73 in the Diff.
The car is going back I would love some info so I can understand what could be going on.
08-11-2022, 02:13 PM
#3
Nice with the cam and headers my stock 3.15 99 does 80-90mph on the highway at around 2200rpm+ Id prefer some 3.73s-4.10s to get it around 70mph. Easy to get caught speeding same 80mph the 6 speeds do stock with or without a cam.
The dynotuner told me a gear change wouldn't require any additional funding would be changed for free but changing the injectors at 96% duty cycle would require a whole dyno retune. I dont think its too hard if you ask me yes i think shift points have to be scaled to certain mph my stock auto with cam, headers stock 3.15s they left the shiftpoints stock 6k rpm and 6200 rev limiter. Im trying to switch the 3.15s to a 3.73-4.10 gear if i ever get that far.
The dynotuner told me a gear change wouldn't require any additional funding would be changed for free but changing the injectors at 96% duty cycle would require a whole dyno retune. I dont think its too hard if you ask me yes i think shift points have to be scaled to certain mph my stock auto with cam, headers stock 3.15s they left the shiftpoints stock 6k rpm and 6200 rev limiter. Im trying to switch the 3.15s to a 3.73-4.10 gear if i ever get that far.