89maf to 92map created error 24
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Junior Member
Joined: Oct 2004
Posts: 7
Likes: 1
From: Illinois
Car: 89 gta
Engine: stealth rammed 360chevy
Transmission: 700r4 modified
89maf to 92map created error 24
I've got an 89 gta with a 350 and I've recently converted to SD using a 730 ecm and by following the info here on TGO (http://www.eecis.udel.edu/~davis/z28/ecm_swap_730/) The car has an automatic and I'm using an AUJP bin. with TunerPro RT v4.12 and the proper memcal that I bought new. The conversion article states that the prom needs a vss change for bit 6 which I have no idea how to change in TunerPro or if it is actually necessary. My car is running fine, the speedo works accurately, the cruise works, but when I accelerate hard and then let off fast the ecm stores an error code 24. My car has a gear driven vss(no cable just wires coming out). I believe it to be a magnetic vss version from what I've read in the message boards, which leads me to these questions:
1. Do I need to change the prom with this combination since I do not have an optical vss?
2. Should I wire my vss directly into pins B9 and B11 on the 730, if this is possible?
3. Is the pin out diagram the same for a 1986 tpi 165 ecm as it is for a 1989 tpi 165 ecm? (my chilton manual shows no difference for the vss input on A10, both are buffered inputs per their diagram)
4. Are the ppm values the same for a 89 165ecm as they are for a 92 730 ecm since I have what I think is a magnetic vss?
Any help from people with the proper knowledge would be greatly appreciated as I'm trying to get away form the nightmare that was the original maf ecm, thanks!
1. Do I need to change the prom with this combination since I do not have an optical vss?
2. Should I wire my vss directly into pins B9 and B11 on the 730, if this is possible?
3. Is the pin out diagram the same for a 1986 tpi 165 ecm as it is for a 1989 tpi 165 ecm? (my chilton manual shows no difference for the vss input on A10, both are buffered inputs per their diagram)
4. Are the ppm values the same for a 89 165ecm as they are for a 92 730 ecm since I have what I think is a magnetic vss?
Any help from people with the proper knowledge would be greatly appreciated as I'm trying to get away form the nightmare that was the original maf ecm, thanks!
Supreme Member
Joined: Sep 2003
Posts: 1,409
Likes: 1
From: Texas
Do an item search in TP for address 018.
Then look for the item that is VSS related or something w/ the#6.
Then look for the item that is VSS related or something w/ the#6.
Code:
L8018: .byte 0xD8 ; AFR OPTION WORD 3, 1101 1000
; DRef: 0xD542,0xB05B,0xB12A,0xD7D1,0xCFF8,0xBEEE,0xCF57,
; 0xCA45,0xD036,0xBF7F,0xDFF8,0xE0D6
;----------------------------------------------
; b7, 1 = CCP WHEN OUTPUT ENRGIZED
; b6, 1 = MAGNETIC SPEED SENSOR INSTALLED, B9 & B10 Connect
; 0 = OPTICAL SPEED SENSOR(5V Square wave) uses Pin "C6" 7730
; b5, 1 = INT RESET WHEN BLM CELL CHG
; b4, 1 = OPT INV MAT Lk Up
;
; b3, 1 = UNLOCK TCC IN DECEL FUEL C/O
; b2, 1 = CPU Auto Ratio Sel, 1 = CARS, 0 = TCC
; b1, 1 = INT RESET WHEN Accel Enr IN WORK
; b0, 1 = COOL FOR IDLE SPEED TIME OUT 
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
There are two methods of correcting this issue. The easiest (and what I would do), is to wire the original '165 ECM VSS signal to pin C6 of the '730. Most likely this is a brown wire. It originates from the 4-out buffer box.
Then change the option bit to 'optical' (set it to a zero). This is in location $18 as shown by Z69 above. The reason your speedo and cruise work is that the VSS signal goes to the buffer box first. The VSS pulse trains are then fed to the cruise and speedo. Just need to get one going to the ECM.
The other method is to remove the 4-out buffer box, wire the VSS directly to the ECM, and wire the speedo and cruise to the ECM. In this case the ECM buffers the VSS and creates the pulse trains for the other devices. This will also work but entails additional wiring changes.
RBob.
Then change the option bit to 'optical' (set it to a zero). This is in location $18 as shown by Z69 above. The reason your speedo and cruise work is that the VSS signal goes to the buffer box first. The VSS pulse trains are then fed to the cruise and speedo. Just need to get one going to the ECM.
The other method is to remove the 4-out buffer box, wire the VSS directly to the ECM, and wire the speedo and cruise to the ECM. In this case the ECM buffers the VSS and creates the pulse trains for the other devices. This will also work but entails additional wiring changes.
RBob.
Thread Starter
Junior Member
Joined: Oct 2004
Posts: 7
Likes: 1
From: Illinois
Car: 89 gta
Engine: stealth rammed 360chevy
Transmission: 700r4 modified
I found the location of the place to change the vss setting in TunerPro RT v4.12. Using the Super_8dm2.ecu for viewing the AUJP bin., the 018 location is listed as "Switch 18" in the "Flags" list where the vss bit 6 switch is either set with a check mark in the box or unset w/o a check mark. It doesn't say anything about optical or magnetic in it and it is normally checked so I unchecked it, and haven't had an error 24 set for two days now.
I'd also like to say thanks gentlemen for the fast and correct answers that helped me fix my car, this is how things should be instead of a bunch of misinformation which I usually spend hours reading through just to get to one simple answer.
I'd also like to say thanks gentlemen for the fast and correct answers that helped me fix my car, this is how things should be instead of a bunch of misinformation which I usually spend hours reading through just to get to one simple answer.
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