4G swap in a 3000gt?

[bradrs]

Well, this isn't as easy as I hoped. The rpm pin on 3S ecu is not used at all in AEM 3S ecu. (It is however used as the rpm signal in a DSM ecu). So, I'll have to de-pin and switch it to another low side output. I "think" it should go on a low side ground driver, but since the 3S AEM EMS isn't actually made to send a tach output I have no idea if there are resistors and "crap" that should be in the EMS box to make it work. Waaay out of my knowledge base here.

Did you look inside the 3S version to see if it isn't wired up? It seems like the DSM has it ready, and it just needs to have the settings changed.

It might be easier to use another lowside ground driver from 3S EMS. That 3/2 ratio could be a pain to do outside of the ECU.

Since you used the 3S EMS, what power transistor and coils are you using, 3S or DSM?

[familyMAN]

3S PTU and built a patch cable from coil plug on wire harness to DSM coils. I could wire in the DSM PTU I have for the same result but this was a lot easier than chopping up two plugs on the 3S engine harness to wire the one plug for DSM PTU. (thanks donnie for the time saving suggestion)

I didn't open the AEM box, since it's new and don't want to void the warranty. I selected the LS7 option that you would use on a DSM box or any other AEM for that matter (except 3S damn it!) and it didn't work. The AEM instructions for the 3S box don't even list the LS7 output anywhere on the pinout. I can try playing with the options again, but I'm not hopeful anything will happen without moving it to another pin.

I still wonder if a DSM tach wouldn't just plug right into the instrument cluster.

[familyMAN]

Stock 3S tach connections

Attachment 6788Attachment 6789Attachment 6790

This is what I found on dsmtuners.....


and a random pic from internet of a 2g dsm cluster....

[bradrs]

Doing the tach swap might be simpler then, since the AEM doesn't seem to support it. Looks like it is mechanically correct. It would make sense if they were the same electrically, with only a change in scaling. But I'd probably still want to at least do a pin out and make sure I wasn't shorting something to ground or going to accidentally damage the cluster or tach.

I just looked up the EMS instruction sheets, and the relevant pin (58 on the 93- ECUs) is not wired according to their instructions. Not even to a spare output.

The reason I was asking about the coil/PTU is you could still use it to trigger the tach since you kept the stock one. If you hook up a coil(just to test it) to the 3rd channel then get the AEM to fire that channel, it should get the correct pulse generated back to the tach. And if that works, then remove the coil and swap in a small inductor. That would basically be a tach adapter, like many CDIs use to work with the OEM ignitions.

[familyMAN]

Doing the tach swap might be simpler then, since the AEM doesn't seem to support it. Looks like it is mechanically correct. It would make sense if they were the same electrically, with only a change in scaling. But I'd probably still want to at least do a pin out and make sure I wasn't shorting something to ground or going to accidentally damage the cluster or tach. I'm going to search craigslist and see if I can get a 2g tach to inspect.

I just looked up the EMS instruction sheets, and the relevant pin (58 on the 93- ECUs) is not wired according to their instructions. Not even to a spare output. Yep, that's what I thought when looking at the instructions also.

The reason I was asking about the coil/PTU is you could still use it to trigger the tach since you kept the stock one. If you hook up a coil(just to test it) to the 3rd channel then get the AEM to fire that channel, it should get the correct pulse generated back to the tach. And if that works, then remove the coil and swap in a small inductor. That would basically be a tach adapter, like many CDIs use to work with the OEM ignitions. Lost you there

comments above

[familyMAN]

I believe a WTB craigslist ad found me a local 2g instrument cluster. Will update after I get a chance to pick it up and compare.

[bradrs]

Lost you there

It's a bit complicated. It simulates the 3rd coil to get the tach corrected.

Depending on how easy it is to get to the tach and swap it, that is probably easier. If that doesn't work, I could explain the other method better

[MDoe8]

Make it easy on yourself.
Universal Tachometer Signal Interface

[familyMAN]

Figured I could update this thread for once. Need to buy that tach adapter sometime. Keep forgetting about it.

Quick 1st gear stab tonight that apparently a friend was videoing when I left his house.


Short, 3rd gear pull on flat ground with new wastegate springs vs an uphill pull (basically meaningless) with an 8psi spring. Yeah, it moves pretty good so far (and boost creeps up top). EBC will be next for some more fun.


....but it's only a 4cyl in a 3S, it must be so slow and can't even move out of its own way

[familyMAN]

Nothing to see here....


Same stretch of road. Two different directions. Need more pulls to determine if it's completely flat, but I would guess the red pull is slightly downhill since I don't think it's making that much HP (auto trans may be affecting VD also). Touching 600hp seems like it could be true. I pulled between .5*-1.5* from 6500-8500 in the blue pull to see if it affects so knock voltage. May try some more timing from 7500-8500 to level out the hp and do some runs this weekend. Definitely need to lean it out some up top.

Looks laggy because it's just WG pressure yet, and then creeps up top. Actual boost control would get to 30psi much sooner.

Logged a 0-60 run with the lower timing. It was uphill and with a little wheel spin shifting to 2nd....3.2sec. Not bad, considering it's below 20psi half the run without a boost controller.