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Discussion Starter #1
Hey Guys,

I need your help....

So as the title states, I have a 2JZ-GTE > AEM V2 > Dakota Digital SGI-8D > RX7 oem Tach...

When I rev the motor past 1500-2000 RPM, the tach/SGI-8D drops the signal.

What I have done:

I have cleared any configurations on the AEM V2, reloaded a default config and still does the same thing.

I have removed the AEM V2 and installed an Apexi Power FC that I had laying around and the RPMs stay constant and work throughout the RPM range.

I have installed a different AEM V2 from a friend and it drops the RPM signal.

The RPMs show correctly on the AEM tuning software...

This leads me to believe, that the Dakota Digital and OEM Tach works as it should.

I spoke to Dakota Digital tech support and they advised that there is a possibility the AEM V2 "lowers" the signal enough that the SGI-8D cannot read it....

Can someone advise me on how to manipulate the tach output to fix this issue... If you don't mind, could you maybe walk me through step by step since this is all new to me.....

Buy you a case of beer...your choice? Anybody local in South NJ?

TIA
Chris
 

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i replied in my thread about my fd. it does the same thing. when i had my 1jz in it with the stock ecu it was fine and read just fine. once the 2j went in with the aem it started doing the same thing youre saying. i never bothered to see what was causing it but it does sound like the aem is doing it. i didnt change anything on my setup when i swapped besides the motor and ecu and harness.

mine goes bonkers on deceleration. if i do a pull in a gear then let off my tach jumps all over the place and goes crazy until it reaches about 2-3k rpms then the revs fall like normal. but if i hit the gas the singal just drops and the tack needle goes dead until i decel again
 

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I really appreciate the reply. Your car is what I hope my car will be once finished. =)

I did speak with Dakota Digital and was advised that they have seen this once before and it was the standalone ECU causing the fluctuation. They suggested to use a SGI-17 which amplifies the signal of the ECU. I have not tested this since it was backordered and still awaiting for my unit to come in($35 iirc).

I spoke to AEM and was advised to play with the tach settings, but I do not know enough about it to manipulate. I was advised that "it could" be fixed, but you should not have to do anything.... =/

Im a little disappointed after spending this much on an ECU when my APEXi Power FC is not affected by this at all.



i replied in my thread about my fd. it does the same thing. when i had my 1jz in it with the stock ecu it was fine and read just fine. once the 2j went in with the aem it started doing the same thing youre saying. i never bothered to see what was causing it but it does sound like the aem is doing it. i didnt change anything on my setup when i swapped besides the motor and ecu and harness.

mine goes bonkers on deceleration. if i do a pull in a gear then let off my tach jumps all over the place and goes crazy until it reaches about 2-3k rpms then the revs fall like normal. but if i hit the gas the singal just drops and the tack needle goes dead until i decel again
 

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I got this from a LS1 swapping site.

"Tachometer Signal Wiring...The RX-7's tachometer originally got it's signal from the rotary engine's ECU. The stock rotary engine put out a tach signal that was the same rate as a 4 cyl piston engine. The LS1's PCM puts out a 1/2 rate tach signal for a V-8. Simply using the LS1's tach signal to drive the RX-7 tach will result in a correct reading tach. Connect the LS1 PCM's blue connector terminal 35 (white wire in connector, "tach signal output") to the RX-7's B1-01 ECU plug terminal 2B, a yellow w/ blue stripe wire (formerly the signal input point for the RX-7's tach)."

Not sure if it might help you. So input to this SGI-8 is a 6-cylinder signal, and the output should be a 4-cylinder. Next, make sure your grounds are all good, that includes the ECU , engine, and dashboard.

When under decel conditions, the ECU might shut off the coil and/or injectors, because it does need any power since it is trying to decel. So perhaps the signal you are getting is from a coil rather than the tach-output. Double check that.

Not sure where else to look, since changing the output signal from the AEM appears to be tough.

Also, check out this site. it is for an LS1 swap but it might prove helpful. http://grannys.tripod.com/3LS18.html
 

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It actually isn't that hard to setup the Tach output on the Series 2.

Go to Display -> Display Explorer -> Setup -> Advanced Setup -> Tacho/Speedo Control. Open both windows by double clicking on them. Options and Tacho.

Options - This will be the pin output of your EMS to the Tach. Usually LS7 so make sure you wire your tach to the LS7 pin. No need for the Dakota Digital Signal Interface Unit wire it directly to the Tach.
Tacho Table - This basically says for each rotation of your of your crank sensor. For instance a 24 tooth found on the 2JZ it sends out 6 pulses per revolution. Two teeth "ON = 1" two teeth "Off = 0". Simply change yours to 4 pulses since that is what your tacho wants to see. You can shorten or lengthen the signal to send a more defined signal to the tach. Usually needs 2 teeth "on" 1, but you may try shortening it up to 1 or increasing it to 3.

So for your car I would set it up as.
0 = 0
1 = 0
2 = 1
3 = 1
4 = 0
5 = 0
6 = 0
7 = 0
8 = 1
9 = 1
10 = 0
11 = 0
12 = 0
13 = 0
14 = 1
15 = 1
16 = 0
17 = 0
18 = 0
19 = 0
20 = 1
21 = 1
22 = 0
23 = 0
 

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It actually isn't that hard to setup the Tach output on the Series 2.

Go to Display -> Display Explorer -> Setup -> Advanced Setup -> Tacho/Speedo Control. Open both windows by double clicking on them. Options and Tacho.

Options - This will be the pin output of your EMS to the Tach. Usually LS7 so make sure you wire your tach to the LS7 pin.
Tacho Table - This basically says for each rotation of your of your crank sensor. For instance a 24 tooth found on the 2JZ it sends out 6 pulses per revolution. Simply change your to 4 pulses since that is what your tacho wants to see. You can shorten or lengthen the signal to send a more defined signal to the tach. Usually needs 2 teeth "on" 1, but you may try shortening it up to 1 or increasing it to 3

Thanks for the information.

If it almost directly works for an LS1, it should work for a 2jz-gte. Like i said, double check the Dakota input and output, or if anything, just bypass that and use the AEM to output a 4-cylinder output using 24 teeth. So every 3 teeth, have it pulse up or pulse down.

Stock Supra output is:
A Tooth: 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23
TACHO: 0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0,0,1,1,0

Try doing what rtype16 said by setting the values like this:
A Tooth: 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23
Tacho: 0,1,1,1,0,0,0,1,1,1,0,0,0,1,1,1,0,0,0,1,1,1,0,0.

And double check your wiring, make sure you do use LS7 from the AEM output.
 

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Discussion Starter #8
I appreciate the very helpful input guys! Ill play with it this weekend when I get a chance and keep you guys update.
 
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