1G Can somebody veryify that 90, 91, and 92-93 power transistors are different? Part #??

[90 GSX]

I thought I had a 91 ECU but I never checked the p/n on vfaq. Apparently it's a 7/92-5/93 and I have been using a 91 power transistor for over a year!!!!!!!!!!!!!!!!!! It works but I have been trying to solve this intermittent miss and stutter I have. I also have unexplainable knock counts without a single boost leak, 2g timing maps with base timing at 2*, complete fuel system including regulator and -6an lines and banjo bolt eliminated.

Can somebody please verify for me that the power transistor I need for my ECU is different than the 7 pin 91 PT I have in my car right now. Can you also verify that the 92-93 PT's have 8 pins. And lastly, does anybody have a part number for the 92-93 PT. I have CAPS but I don't have a 92-93 vin number.

 

[steve]

The change was between the 90 and 91 cars where the PTM went from a 6 pin to a 8 pin part. The 91+ PTM includes the tach gate signal and power where the 90 PTM doesn't and the tach gate is on the coil pack.

Using a 91+ PTM is one of the ways to solve the tachometer errors on 90 cars with 91+ ECUs installed. You leave the stock tach attached to the stock tach gate signal and install a 91+ PTM to provice the ECU with a signal on pin 109.

Are pins 6 and 14 in the ECU connector swapped like they should be? Those two pins switched position on the connector between 90 and 91.

Steve

 

[90 GSX]

I went to 4 junkyards yesterday. Every single 91 that I have seen, including the diagrams in my hayne's and chilton's manual is a 7 pin module missing pin 5 not 8 pins. The 1990 has 8 pins and the 92-93 has 8 pins as well but they are impossible to find. I can't believe that nowhere on this entire site (I searched back as far as it goes) has any mention of an 8 pin power transistor except for maybe one post.

The ECU pins are switched. I did the entire conversion - eliminate noise filter, gauge cluster, coil, PT.

 

[steve]

I'm not surprised about the confusion because even the 91 FSM shows the incorrect connector while showing the correct pin numbers.

CAPS says that ther are different PTM used on 1G DOHC 4G63's.

From 8903.1 to 9006.1 uses MD127742 (90 model year)
From 9006.2 to 9405.1 uses MD149768 (91-94 model years)

I have a MD149768 in hand and it has 8 pin connector (counting the missing key at position 5). Perhaps that's part of the confusion, you do count the missing pin.

The older MD127742 has one less pin.

The PTM needs clean power and ground. I also use heatsink grease betwwn the module case and the mounting bracket after cleaning any corrosion since the bracket is the heatsink.

Steve

 

[90 GSX]

My PTM has never been removed from the bracket and it has all 3 mounting bolts holding it on to a clean intake manifold and block surface. I also have a dedicated 4 gauge power wire grounding the coil pack straight to the battery (not the PTM). I also swapped a known working PTM in and it didn't make a difference.

Every manual I have seen says that the PTM or the wiring itself is different between 90, 91, and 92-93 cars. Is it possible that mine is wired wrong or something??? There MUST be some difference that I have overlooked if you test the PTM for different years using different pins. Do you happen to have a PTM wiring diagram or something? Or tell me what pins are switched around between 91 and 92-93 PTM's???

I used this link for the wiring diagram by the way:

http://www.ecanfix.com/users/mdhamilton/images/1990ignition/1990to1991.jpg

Thanks.

 

[steve]

You keep saying that the 91 is different from the 92-93 but the information I have says there are only two different power transistor modules. The one used on the 90 cars and the one used on the 91+ cars. If your refering to a Chilton or Haynes manual, they aren't very good sources.

I have been mistaken about the pin count on the 90 PTM. I forgot about the additional power wire on the 91+, so the 90 PTM only has 5 wires in a 6 position connector with position 4 being unused. (Corrected)

The guys that make the manual CD are kind enough to provide some usefull extracts from the factory service manuals. the 91+ 1G circuit diagrams are one of them http://www.ecanfix.com/users/manualcd/gift/dsm/1g_circuit_diagram.pdf
Note that the diagram for the B-15 connector is wrong and was cortrected by a later TSB for the manual but the pin numbers and wire colors are correct as far as I know for the 91+ cars. Note that the pins used are 1-8 not including 5. The actual signals are also molded into the PTM. The primary difference between the two versions of the PTM is the addition of the tach gate signal (white) into the later module and a 12v power lead (black/white).

I can't read the pin numbers for the 90 wiring off this.
http://www.ecanfix.com/users/mdhamilton/images/1990wiring/ecupinouts.jpg
the NT version looks a little clearer.
http://www.ecanfix.com/users/mdhamilton/images/1990wiring/ntecupinout.jpg
Those are the only 90 MY references (ATM) beside the 1G tech manual I've found.

It looks like the early PTM uses different pins for the other signals
1 Yellow/Green OC1
2 Yellow - IB1 (cyl 1 and 4)
3 Black - GND
4 NC
5 Yellow/Red - IB2 (cyl 2 and 3)
6 Yellow/Black - OC2

Where the 91+ is wired

1 Yellow/Black - OC2
2 Yellow/Red - IB2
3 Black - GND
4 White - Tac
5 NC
6 Black/White - Vb
7 Yellow - IB1
8 Yellow/Green - OC1

I also have a dedicated 4 gauge power wire grounding the coil pack straight to the battery (not the PTM).

You can't be grounding the coil pack. It doesn't get grounded except by way of the PTM ground. It gets power from the ignition circuit IG1 terminal.

I hope this helps

Steve

 

[90 GSX]

If the PTM is not different then the wiring must be different. Maybe the pins are switched around so they are numbered differently or something... I will look over those wiring diagrams.

I found this thread searching, the guy (Quasimodo) came to the same conclusion I did:

http://www.dsmtuners.com/forums/showthread.php?t=126762&highlight=transistor

He said that he checked the manuals and there is clearly a difference in the 91 and 92-93 wiring even if the PTM is the same. There must be something different... do you have a haynes or chilton's you can look at to compare.

I thought the coil grounded through the body... another tidbit of false information I acquired searching the board. Thanks for the info steve, I appreciate the help. I'll fix that.

 

[steve]

I see he came to the same conclusion based on the same bad manuals.

I double checked the pinout against the 2G which uses the same module in a different bracket and it matches what I listed. Remember I compared that to a actual PTM so I'm pretty sure of my 91+ data. I don't have a 90 module here to double check it.


Steve

 

[90 GSX]

Okay so then the transistor is not the problem with the car is what you are saying. I have no idea what else it could be. Tell me this Steve, is it possible that the power transistors are the same, but the pin numbering on the harness changes with year? The pinouts you gave me are the pinouts for the actual PTM module. But it is possible that the pins are changed between years on the connector right? Do you know about that or would it take more research.

I have a random misfire at idle, sometimes it's bad sometimes it's not, but I think that may be because I have no aircan or cold air on my car since I put on the intake pipe and 2g MAS. But how can I explain the stutter. I feel it even more when the car is cold, like the spark is really weak or something. While cruising at light throttle it feels smooth, but if I give it some load even at a low rpm it will occasionally stutter. Under boost sometimes it misses pretty hard before the car starts to really start moving and accelerating smoothly.

I just got home right now from driving on a cold night and the knock started out at zero and as I did more pulls I got more and more knock. But regardless, the car felt hesitant most of the time. It seems like an ignition problem but honestly I don't know what else it could be. Do you have any suggestions for checking or improving the stock ignition system.

 

[steve]

Okay so then the transistor is not the problem with the car is what you are saying.

I'm not saying anything about your problems other than you are operating under several questionable pieces of data that may lead you to the wrong conclusion.

Is it possible that the power transistors are the same, but the pin numbering on the harness changes with year? The pinouts you gave me are the pinouts for the actual PTM module. But it is possible that the pins are changed between years on the connector right?

No it's not possible for the pins to change between years on the connector without the physical part also changing like it did between 90 and 91. Wire colors could change, different harnesses could be made with different parts numbers but the signals/functions on each pin are dictated the the actual part.

Steve