4g61t.org

Holy rats nest, can you take a pic of the harness under your dash so we can take a look at that?

It's pin 4 on that black connector at the passenger kick panel above the ECU. It's a solid white wire. All you gotta do is run a wire from that tach filter on the coil pack directly to that wire and your tach will work.

what about an aftermarket tach? all I need to do is run it to the tach filter?

Are there any other alternatives to the 90 coil pack filter?? Can you find just the filter from a parts store? Its getting hard to find the 90 coil packs with tach filters. Just wondering if anyone else has found a different way that doesnt add another aftermarket tach to the dash.

Hey Jason, I'm trying to figure out what I can do here. I have a 91 coil pack and I don't have a tach filter. What should I do in this situation?

Junkyard? They should have one.

Ebay? I might have an extra one.

Robert, read this entire thread. to4garrett schools us on how to get it working correctly.

http://forum.4g61t.org/viewtopic.php?se ... 49&t=22217

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93 Mitsubishi Expo LRV 1.8/manual
95 Eagle Summit DL Coupe 1.5/manual
01 Mitsubishi Mirage ES Sedan 1.8/manual

Thanks LILEVO for the instruction manual, it helped a lot today.

I just modified my 90 Colt hach last weekend, from 89 N/A 4G61 ECU and wiring, to 91 4G63T coil, power transistor, TPS, MAF, DSMlink ECU, and the extra solenoids and knock sensor. I have the turbo throttle body on there but I still have the N/A engine in it. I just wanted to work out the bugs electronically before I drop my $10,000,000 freshly built 4G63T in there. So the ISC was shot, for anyone wondering the 89-90 ISC WILL fit on a 91 engine.

Anyways to the point, my tach stopped working as well and I worried it was some kind of disasterous compatiblity problem. My fears were put to rest after I read this link: http://www.lilevo.com/turbo/tach/body_tach.html . I put my 89 coil pack with the tacho interface back on the car, retained the 91 PT, and put the 4 wire coil plug back on my engine harness.

The shortcut I found that may be helpful to anyone reading this thread, was to run the yellow wire (fourth wire from the coil pack), from the tacho interface, to the noise filter for the original 89-90 tach. It's already mounted on/near the manifold on the 89-90 CSM's. Assuming you still have that part of the wiring from your original engine harness, you only have to run the wire a few inches instead of going through the firewall.

There should be a small rectangular metal box about an inch long by a half inch wide, screwed to the manifold or the bracket underneath it. That's the tach filter. Two wires come up from it and go to a two blade plug like what's on your purge or wastegate solenoids. On the 4G61 and 4G63 engines wiring, it plugs into the harness right behind the fuel pressure regulator.
Simply cut the side of that pigtail which splices into the (Power Transistor to ECU) tach signal wire, and connect that side of the plug to the tacho interface wire from the 89-90 coil pack. The other end of that pigtail that comes OUT of the filter should already go directly to your Tach and DOES NOT not pass the ECU nor does it collect $200. Thanks again for the pointers and the pictures. Now that that pain in the rectum is finally over with, I can move on to the next stage of my build.

my tacho works but when I start it up the needle is at 2k still runs fine with normal idle at 800-1000. It sometimes pulses also, I've link a direct wire from the tacho at ecu to tacho filter.

It settles down (real idle) after I've driven a bit as well. I also adjusted the sensitivity on the tacho circuit to max because if I don't it doesn't sync with response time (lags).

would a tach filter like this work also?
http://www.bobsgauges.com/servlet/the-3 ... ter/Detail

It may be an alternative to trying to find '90 coils with the filter on them.

I don't know if this contributes to the thread or not, but when I got my 90 Laser, the factory tach had been disabled, hacked, whatever. So I found a different cluster but it was from a 91-94. To get the tach to work, I simply tapped into the white wire by the transistor and ran it inside into the stock harness right behind the cluster. It still didn't work because I had a 90 car and a 91-94 cluster. So I opened up the cluster and swapped the chip that's inside with the one in my old hacked cluster. Worked perfect.


Just thought it might be some usefull info. 1g dsm's and 3g csm's are really close right? I would imagine the tach setup inside the csm cluster uses the same components?

Hi all,

I have a 89-90 wiring harness and coil pack w/ filter on 4g63t w/450cc.
Run great with 89 csm turbo ecu/maf.

When I put my 94 dsm turbo ecu/maf, tach is bouncing at 5000 rpm.

I read a lot about puting a 94 coil pack/harness in 89 csm. But isn't really my situation.


What I have to do for my tach/ecu work properly and see real good rpm signal?

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Colt92t: 12.71@107mph/ 1.8 60' on 22x8x15' slicks, 4g63t, 16g@15psi, FMIC, 3" TBE, K&N, EcmLink

Wire in a 91-94 power transistor/ignition module in place of your 89-90 one. You will find that the 91-94 one has an extra pin. That's the tach signal you want to use for your ECU. The signal from your coil tach interface should only go to your tach via the filter, and the one from your 91-95 ignition module goes directly to your ECU.

FYI: The "Filter" and the "Tacho interface" are two seperate parts.

I think is the 89-90 that has 4 wires plug and the 91-94 has 3 wires plug.

http://www.4g61t.org/forum/viewtopic.ph ... 7&start=15

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Colt92t: 12.71@107mph/ 1.8 60' on 22x8x15' slicks, 4g63t, 16g@15psi, FMIC, 3" TBE, K&N, EcmLink