1G 1990 RPM'S wrong on SAFC Neo and factory tach doesn't work

[DallasN2O]

I have read the VFAQ and the wiring diagram that comes with the neo. They point to two entirely different wires for the rpm wire. I have tried both wires and can not get the neo to display RPMs. It just stays at zero.

I have tried changing number of cylinders and all that. No luck. My car is a 90 model Laser. Is there a special place I need to tap into to get an RPM signal to the AFC?

Someone please help me.

 

[DallasN2O]

What if I ran the green wire from the afc and tapped into one of the wires on the power transistor? Anyone know which wire would work?

I know I'm not supposed to bump but I really need help on this guys please?

 

[Siral3x]

AHhh...I don't have a wiring diagram infront of me but I think it's the white wire on the coil pack on the 90 models is the tach signal wire. Not the wire with the white stripe...the WHITE wire

 

[DallasN2O]

So is that the only way I can get an RPM signal is wiring into the coil? I've tried 4 different wires on the ECU harness and cant get it to read anything at all. 4th wire from the left, 4th from right, and even 2 others on the middle plug. I'm so frustrated.

Ok, looking at the VFAQ 1g ECU pinout diagram. I have hooked the green SAFC RPM wire to the following wires:

21, 16, 54, 56, and 109 (I believe 109 is the same white wire as on the coil)

I haven't gotten the RPM gauge on the SAFC to move at all. I have tried changing the number of cyls to every different setting. I am extremely frustrated as I paid lots of money for all this crap and something so stupid as this keeps me from making progress.

Wisemen pls help me. Is there a test I can perform on the AFC to see if its defective? Any other suggestions? Thanks.

 

[spaugh]

Ok i searched and found something that works, but i was wanting to know why if i put it as a 2 cylinder the rpm's are right but on vfaq.com it said to set it at 4 cylinder. Also what could cause my factory tach not to work? I have tried two diff. clusters.

Well, the only gauge that works right is my speedo, the temp gauge starts at 0 but goes all the up after a few min, gas gauge reads full all the time does not move, and the oil pressure doesn't move what so ever stays at 0.

Thanks for any help with this

it is a 1g by the way

 

[ROOKIE1]

Have you checked all fuses ? Did you install tha safc ? Was the green rpm wire spliced into or cut and wired . Have you checked your oil sending unit ? Temp sending unit ? could be a bad install .

 

[spaugh]

I have check all fuses. I just installed the SAFC today and i tapped the wire for the rpm's. I have not checked the oil sending unit. For one i dont know where it is and i thought that since none of the gauges work the i might be one thing causing all of them not to work. Its odd the turn signals work on the outside but not in the cluster they did not work in either one of them. I just got the car a few weeks ago and i keep finding more small stuff wrong with it.

 

[TurboAnything]

I think on 1990 Dsm's the Safc needs to be set on 2 cylinder. I would remove the gauge cluster and make sure the connection is good they just push in.

 

[spaugh]

I have check those before i switched out the cluster for another one. Something that i just thought of i have a 91 TSI AWD when i got it had a bad ECU and i one from a 90 GSX laying around. So i put it in it. Would that cause any problems?

 

[rb25det510]

I think on 1990 Dsm's the Safc needs to be set on 2 cylinder. I would remove the gauge cluster and make sure the connection is good they just push in.

when i had an afc in my 90 galant gsx i had to set it to 2 cylinder also, i had it set that way for probly about a year and since have had no problems. knock on wood...

 

[steve]

The S-AFC manual tells you to install the RPM wire to the wrong place on the ECU. They have you connect to one of the leads to the power transistor so that the S-AFC only see half the ignition pulses.

Either connect to the CAS or pin 109.

 

[subie22]

its true you have to set it on 2cly on the safc. Dont mean to highjack the thread, but i figure it may help also. I noticed that the safc is usually 200 rpm higher then the mechanical gauge is that normal.

 

[vettesmoker]

to do a ecu swap from 90 to 91-94 or from 91-94 to 90, you must swap ecu pins #6 and #14 to get good rpm signal. 90 is unique from all dsms.

 

[steve]

to do a ecu swap from 90 to 91-94 or from 91-94 to 90, you must swap ecu pins #6 and #14 to get good rpm signal. 90 is unique from all dsms.

Those pins have nothing to do with the SAFC getting a good RPM signal.
It's true that they have to be changed in an ECU swap but that's not why.

I explained why the SAFC reads half the RPMs in post 7. There is nothing else involved WRT the S-AFC.

1990 Tach's not working could be due to a bad/missing/disconnected noise filter that unique to the 1990 cars or sometimes a 1991-1994 ECU installed in the 1990 car.

 

[DallasN2O]

I'm still having this same problem. I have a 1990 model and I'm trying to get my S-AFC NEO to read RPMs. I need to know if the AFC Neo is looking for an RPM signal that the 90 ignition system doesn't provide. I know the 90s are different than the rest of the 1g's. Have any of you installed a S-AFC II or Neo on a 90? Do I need some kind of signal translator? Please help.

I have a 1990 model and I'm trying to get my S-AFC NEO to read RPMs. It is currently connected to the 109 wire on the ECU and I'm not getting ANY RPM readings. What could be wrong?

 

[steve]

It is currently connected to the 109 wire on the ecu and I'm not getting ANY rpm readings. What could be wrong?

Does your tach in the car work? What color is the wire in pin 109?

What color was each of the wires you tapped into? Far too many people mix up the pin numbers since they don't understand what the diagrams are showing them.

 

[DallasN2O]

Yes the stock tach works fine. I know for sure I tapped into an all white, an all blue, and an all yellow. I was attempting to tap into the black wire directly from the CAS last night and broke the wires coming out of the bottom of my old 90 CAS. I guess now I'll try and put my blacktop CAS on it and try to find a signal to tap into there.

The color of the wire for 109 is blue if I'm not mistaken. I'm still at work or I'd look. Pretty sure it's blue though.

 

[steve]

The point of me asking was to make sure you have the right pins. If you don't want the help...

If it's blue you have the wrong one.

 

[Dewayne Waldron]

The S-AFC manual tells you to install the RPM wire to the wrong place on the ECU. They have you connect to one of the leads to the power transistor so that the S-AFC only see half the ignition pulses.

Either connect to the CAS or pin 109.

there ya go, also set it to 2 cylinder. should fix your problem

 

[DallasN2O]

What? What gave you the idea I don't want the help? I was just telling you what colors the wires were by memory bc I'm at work away from the car.

 

[steve]

Thank you.

Since your the eyes and ears for me I need you to be as specific and precise as possible or I can't help because I can't answer the questions that lead to the next steps.

 

[DallasN2O]

ok. I just got through tapping directly into the black wire coming from the CAS and splicing it into the green wire on the s-afc neo. I just ran the wire through the passenger window for testing purposes.. I get absolutely no rpm reading at all. Not even a twich. The factory tach is working flawlessly. Is it possible that the optical signal isn't recognized by the s-afc? Would I have to switch to the hall-effect style CAS to make this work? How can I test to see if my neo could be not functioning correctly? If I put a volt meter on the black wire coming from the CAS, what should I see? I tried it and the voltage rose with rpms so it looks to me like that is the correct wire.

 

[DallasN2O]

Suggestions?

 

[gobagheera]

Hey, just saw this thread when I was searching for the RPM wire for my Zeitronix and noticed that you were getting nowhere.

Upon my research, you tap your green RPM wire from the AFC to pin 58 (white) on the ECU based on the Zeitronix install. No need to tap all the way from the coil. Hopefully this helps.

 

[steve]

Upon my research, you tap your green RPM wire from the AFC to pin 58 (white) on the ECU based on the Zeitronix install. No need to tap all the way from the coil. Hopefully this helps.

Pin 58 on a 2G is the same signal as pin 109 on a 91+ 1G. Both are the ignition pulses from the power transistor. On a 90 that signal comes from the tach gate on the coil bracket.