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really? did your ze have a plate covering the knock sensor? or was it all open?

projectzemx3 wrote:that would also work as well. but it would mean taking my intake off again and the timing belt to get at that coolant neck to switch it back over.

Hmmm that's definitely more work than you want to have. I would try see if the guys chipping can get around the need to use 2 coolant sensors.

Heaps of people have 1994-5 MX3s so I can't understand why hardly anyone has the coolant sensor problem. Maybe some chips do eliminate the need. I know that my chip didn't.

RX8SE3P wrote:

projectzemx3 wrote:that would also work as well. but it would mean taking my intake off again and the timing belt to get at that coolant neck to switch it back over.

Hmmm that's definitely more work than you want to have. I would try see if the guys chipping can get around the need to use 2 coolant sensors.

Heaps of people have 1994-5 MX3s so I can't understand why hardly anyone has the coolant sensor problem. Maybe some chips do eliminate the need. I know that my chip didn't.

Heaps if people dont have swaps in there 94+ mx3's. Look in the worklogs, you will see there are only a few.

As for the chip, it has nothing at all to do with the coolant temp fans. The ecu itself is the one that controls the fans going on or off. So if you chip the ecu that came with the car (k834 or another type that is used in a 94+ model) then you will not have a issue. If you chip a k801/kl01 and put that into your 94+ then you will have fan issues because the problem still remains that the ecu doesn't know why there is a missing sensor.

Not sure about that. I got a socket installed into my 1995 K8 ecu, so I can easily swap chips in and out. The fans came on and stayed on with the KL31 chip in it. With the K8 chip back in, it only looked for one coolant sensor and never turned on.

Also, I then used the K8 ecu, with a DE chip (OEM, was desoldered from a 1993 KLDE ecu, not flashed or anything) in my MX6. It looked for two coolant sensors, if I took either sensor off once the car was warm, the fans came on and stayed on. With both plugs in, the fans worked normally. This ecu with the K8 chip only looks for 1 sensor. But as soon as it had the 1993 DE chip in, it wanted to see 2 sensors.

I tested this pretty thoroughly with a friend too, who was having the same issues. So I think it may be related to the eprom chip.

I was under the impression that the chip only controls the fuel mapping/timing and VRIS. I hope that when my ecu comes that it will recognize the fan situation, otherwise i will just have to live with the fans going all the time haha.

Let me know how it goes. I'd be interested to hear what happens with your chip and fan situation.

The chip does control the fans. Probinator chip is made for pre-94 2-sensor motors, and even if you chip your 94 ECU, it'll look for the second sensor, and will run the fans. I'm in the same boat. If I put the original chip back into the ECU, my fans function properly, but with Probinator chip they run all the time. I just have them wired to manual switches for now. I've had this discussion with Ryan couple years ago, and he said there's not much he can do about it.

I think at some point I'm gonna try and get the plug for the second sensor off an older car and maybe wire it into the ECU directly...

I hear it's not too good to run your fans all the time, because the motors will burn out.

I wonder how they can wired into the ecu? I have a spare harness here with the correct plug...

Yeah, I'm not sure about that part, but it seems RX8 has done it, so maybe he can shed some light on it.

The pins on the back can come out. It's not too hard, you sort of unclip the ecu plug itself. Have a look, you can actually pull out any wire you like. All you need to do is buy a little connector just like the ecu connector has, connect a wire to the little connecter, put it in the right spot and then run it to the coolant sensor. That's how I got mine working and my car is a 1995.

I might put some pics up just so what I said actually makes some sense LOL.

Well yeah, but what IS the right spot, then? That's the main question. Post pics, that'd be awesome.

Also, what of the actual sensors? I think the dual sensor setup uses different ones, since it's different resistance for on and off.

If I can get this sorted, then I'd be back to norm.

Correct, as the later model uses one sensor only, it is actually different.

You can get them from a wrecked car though. They are rarely faulty.

Here's a pic of my wire. I can make a post of how to get the connector to open up, so you can slot in a wire+connector if you need. The wire that's been added is the one by itself. You can see it's not loomed up with the rest.

Also the pics of the wiring for a 1993 probe. The pin you need is 2G if I remember correctly. Look at where my wire is and also look at where they are on the diagram, I think that matches up. Remember the diagram shows the plug facing you, in my pics the plug is in the ECU, so it's not facing us, just so no one gets confused.

I bookmarked this page. If I have any questions I will PM you.

Awesome. This is good info. I'm gonna try this as soon as I can get my hands on a correct primary sensor and harness plug. I already have the other sensor (black one), since I'm using the ZE coolant neck, and never took the sensor out.

Thanks a bunch.

projectzemx3 wrote:really? did your ze have a plate covering the knock sensor? or was it all open?

Nope. No block off plate either. I bolted the K8 EGR valve to it to seal it. I will have to make a block off plate for it.