TurboAv

iTrader: (6)

Swapped in a TH400 from a six speed. The six speed had a 17 tooth reluctor on it. I put in a 40 tooth reluctor which the 4L60E GTO's come with and the applicable speed sensor. No matter what my tuner puts in for VSS pulses per mile and tire size the speedo stays the same. It reads 105 at an actual 75. The messed up thing is the PCM is seeing actual speed of 75 at 75. The cluster is reading F'd up though. Any GTO tuning gurus out there that can help me out?

TurboAv

iTrader: (6)

Anybody???

rsz288

Did you reflash the ECM with an auto calibration, or is it still stock manual?

TurboAv

iTrader: (6)

It's still the manual tune.

rsz288

If your tuner has switched to 40T reluctor, and adjusted tyre revs per mile/km, and pulses per mile/km, there is a chance that the manual cal is looking for the characteristics of the 17T reluctor.

TurboAv

iTrader: (6)

That's what I said and he told me he couldn't switch to a auto tune since I won't have the TCM and it's not an electronically controlled transmission. I don't see why you can't just delete all the codes though. The other option is getting a 17 tooth reluctor made for the TH400.

NicD

iTrader: (7)

Deleting the codes doesn't help the limp mode characteristics. People have been doing this for years and you really need to run the manual transmission calibration. Only thing I can think of is that the gauges aren't paying attention to the PCM since the PCM is reading the speed correctly and all the tables are filled out appropriately. About the only thing I can think of is to try a 17 tooth reluctor since nothing being changed in the PCM is actually changing the gauge cluster, only the reported speed in a scanner.

rsz288

It may be worth trying the A4 cal back in there just to check whether the speedo does read right. Yes it will raise DTC's, but the objective is to check the speedo right.

TurboAv

iTrader: (6)

Tried calling Gene Culley today and he said they don't make a 17 tooth reluctor for the six speed. He thinks it's built into the output shaft. That sucks for me.

TLewis4095

iTrader: (10)

I did a 04 GTO w/ a T-400 swap and got the speedo w/in 2 mph acording to the GPS. I can send the tune file to you.....

TurboAv

iTrader: (6)

A member on the GTO board with an 05 had the same issue. He said he had to use a Jet Accu-Speed to correct it. I also found a Dakota Digital piece the at does the same thing. Takes the VSS signal and changes it until you get your speedo reading correctly.