1G Using a 90 ECU with other year parts

[Noranuzoki]

If you look closely, you'll see I say it goes to the ECU and gauge cluster.



No you can't, you still need the 90 style Tach Gate driver on the coil pack to operate the 90 gauge cluster. The whole reason for the swap like this is to fix the problem with the tach in the gauge cluster acting up when a 91+ ECU is swapped into a 90 car.

The solution is to continue feeding the tachometer gauge with the original circuit from the coil pack and use the new signal from the power transistor to feed the ECU what it expects.

So is there anyway to retain the 90 ECU or must it be swapped as well? I'm assuming that if you don't then the car won't be able to communicate with the 91+ hardware installed.

 

[1990TSIAWDTALON]

The 90 ECU can be used in 91+ but you have to switch the pins 6 and 14. Almost ALL of my DSMs are 1990s. Finding the tach filter is the key to using the 1990 cluster and having the tach read. 91 and up did not use that.

I am sure I am using one in combination with other ignition components BUT.....let's ask @steve .
Can you confirm or correct me?

 

[Noranuzoki]

The 90 ECU can be used in 91+ but you have to switch the pins 6 and 14. Almost ALL of my DSMs are 1990s. Finding the tach filter is the key to using the 1990 cluster and having the tach read. 91 and up did not use that.

So I can get away with retaining the 90 ECU in my 90 car with 91+ PTU, coils, etc? I understand the tach part of this. I just need to know about functionality/driveibility.

 

[steve]

I'm not sure I understand what the question is other than it's not about putting a 91-94 ECU in a 90 car and such we should move this discussion to a tech post.

It sounds more like using a 90 ECU with other year parts is the issue to be discussed so I'll move what we have so far and then let me know in that thread if it's something else.

 

[Noranuzoki]

I was wondering if a 90 ECU (in a 90 DSM) could be used for a 91+ CAS, PTU, Coil Pack, TB (TPS) setup. I have this setup and I'm trying to eliminate some things that could be contributing to a problem I have.

My 90 GSX has issues idling. I have mostly new equipment excluding the IPS sensor since you can't seem to find those anymore. Anyway, the car starts up just fine, every time. But it dies shortly after. My ECM logs read that it shoots up to 1900RPM then immediately drops after a few seconds. If the pedal is lightly pressed then it just dies. If the pedal is blipped a few times then it might stay alive but the input is delayed.

My thought process is that it might be a TPS or CAS problem. But both of those are new. Sorry if I'm kinda changing the subject again. I'm just a little lost trying to get this fresh rebuild to idle so I can drive her.

 

[steve]

Yes it will work but there are several things that can cause problems.
To run a 91+ TB on a 90 requires swapping fuel rails so that the TPS fits.
The 91+ TB uses a different connector so the harness needs to be modified.
The 90 vs 91+ ISC is wired differently and you need to make allowances for that by making sure the ISC coils are in the correct order.
The 90 ignition is different than the 91+ so you have to again make harness modifications for the 91+ Power Transistor, 91 Coils, and the Tach wiring. I usually suggest saving the 90 Tach Gate and the 90 Noise filter and use those to feed the ECU and gauge cluster when you have 90 gauges. The Tach Gate attaches to the 91+ coil leads like it did on the 90 coils.
The 91+ CAS is also different but that's a simple harness modification side the 91+ CAS has a connector on it vs the pigtail on the 90.

Then there is the whole issue of making sure you have a good FIAV, have the coolant lines routed to the TB and don't have any vacuum/boost leaks

 

[Noranuzoki]

I'll try and make this condensed.
On my swaps I have done ->
- TB Swap: fuel rail, TPS, wiring (bought plug and play harnesses from OHM Racing)
- ISC: OHM Racing harness
- I'm unsure what ISC coils mean. I know what the ISC does but not of the internals
- Coil Pack Swap: have not done tach gate or noise filter. Unsure of their location. Have done wiring for PTU & coil pack (followed previous forum info & wired according to pinouts) Tach Gate is black rectangle on coil? Noise filter where?
- CAS Swap: new unit, black top, OHM Racing harness

 

[steve]

- I'm unsure what ISC coils mean. I know what the ISC does but not of the internals
- Coil Pack Swap: have not done tach gate or noise filter. Unsure of their location. Have done wiring for PTU & coil pack (followed previous forum info & wired according to pinouts) Tach Gate is black rectangle on coil? Noise filter where?

Pictures of the inside of the early metal ISC's that are so prone to the coils shorting.

2G - Is it normal for the ISC sensor to have oil in it?

Is it normal for the ISC sensor to have oil in inside?I have two brown ISCs, one from my 95 talon TSI and the second from a spare intake manifold that came with the car when I purchased it.I’m getting idle surge between 1500-2000 so I started looking into a new ISC. I opened the ISC from...

www.dsmtuners.com

Lots of pictures of the noise filter and tach gate in this thread. https://www.dsmtuners.com/threads/tach-question.532812/ and https://www.dsmtuners.com/threads/tachometer-works-on-and-off.536493

I can't tell from the pictures at Ohm Racing if their 90 to 91+ ISC adapter cable swaps the two pins for the ISC.

1G - Using 91 ISC in 90 TB?

So I know 2 pins are switched (4 and 6) and the polarity is reversed but is it possible to rewire the pigtail to to be compatible? I've read that it will bolt up but work in reverse. You must be registered to see element.Came across this in a thread "The ISC is a little more complex since the...

www.dsmtuners.com

GVR-4 - ECMLink ISC live data

I am running maft+ 3 inch gm maf ecmlink, the thing is that I'm trying to tune the idle but I don't see the ISC live data, also can't addISC position Learn idle valueWhy?You must be registered to see element.

www.dsmtuners.com

 

[all black 4G63]

the 90 idle sw is located at a different pin vs the 91-94 harness. if you use a 90 ECU on a 91-94 harness it will have massive idle rev due to the throttle opening, but the idle sw not opening due to the pin location is now on the ambient temp i believe

 

[Noranuzoki]

Pictures of the inside of the early metal ISC's that are so prone to the coils shorting.

2G - Is it normal for the ISC sensor to have oil in it?

Is it normal for the ISC sensor to have oil in inside?I have two brown ISCs, one from my 95 talon TSI and the second from a spare intake manifold that came with the car when I purchased it.I’m getting idle surge between 1500-2000 so I started looking into a new ISC. I opened the ISC from...

www.dsmtuners.com

Lots of pictures of the noise filter and tach gate in this thread. https://www.dsmtuners.com/threads/tach-question.532812/ and https://www.dsmtuners.com/threads/tachometer-works-on-and-off.536493

I can't tell from the pictures at Ohm Racing if their 90 to 91+ ISC adapter cable swaps the two pins for the ISC.

1G - Using 91 ISC in 90 TB?

So I know 2 pins are switched (4 and 6) and the polarity is reversed but is it possible to rewire the pigtail to to be compatible? I've read that it will bolt up but work in reverse. You must be registered to see element.Came across this in a thread "The ISC is a little more complex since the...

www.dsmtuners.com

GVR-4 - ECMLink ISC live data

I am running maft+ 3 inch gm maf ecmlink, the thing is that I'm trying to tune the idle but I don't see the ISC live data, also can't addISC position Learn idle valueWhy?You must be registered to see element.

www.dsmtuners.com

Thank you. Ill let you know after I get home. I checked the inside of the ISC before installing it and didn't notice anything major but I also didn't really know what to look for.

the 90 idle sw is located at a different pin vs the 91-94 harness. if you use a 90 ECU on a 91-94 harness it will have massive idle rev due to the throttle opening, but the idle sw not opening due to the pin location is now on the ambient temp i believe

Do you know the pin outs of those 2 pins? I'll check the previous thread I was on for the pin outs because I believe he might have labeled them but let me know if you know where these pins are.

 

[steve]

the 90 idle sw is located at a different pin vs the 91-94 harness. if you use a 90 ECU on a 91-94 harness it will have massive idle rev due to the throttle opening, but the idle sw not opening due to the pin location is now on the ambient temp i believe

The only Ohm Racing 90 TPS adapter cable I found was one that uses a 2G TPS so it doesn't have a wire to connect to a 1G IPS (Idle Position Switch). That also means you need to watch to make sure the IPS switches close to the 0.5v point that a 1G ECU wants for a TPS Voltage.

If you use a 91-94 TPS with that adapter you won't have a IPS.

 

[all black 4G63]

Thank you. Ill let you know after I get home. I checked the inside of the ISC before installing it and didn't notice anything major but I also didn't really know what to look for.


Do you know the pin outs of those 2 pins? I'll check the previous thread I was on for the pin outs because I believe he might have labeled them but let me know if you know where these pins are.

1990 ECU connector C-57 pin 6 (idle switch) pin 14 MAF voltage compare circuit.
91-94 ECU Connector C-66 pin 14 (idle switch) pin 6 MAF voltage compare

Assuming this is turbo AWD manual

 

[steve]

1990 ECU connector C-57 pin 6 (idle switch) pin 14 MAF voltage compare circuit.
91-94 ECU Connector C-66 pin 14 (idle switch) pin 6 MAF voltage compare.

If he's using a 90 ECU in a 90 car with the 90 MAF he doesn't need to touch those.

It's only when your mixing ECU vintages and cars (wiring harness) that you need to move the two pins on the ECU that changed location at the ECU between 90 and 91.

 

[Noranuzoki]

The only Ohm Racing 90 TPS adapter cable I found was one that uses a 2G TPS so it doesn't have a wire to connect to a 1F IPS (Idle Position Switch). That also means you need to watch to make sure the IPS switches close to the 0.5v point that a 1G ECU wants for a TPS Voltage.

If you use a 91-94 TPS with that adapter you won't have a IPS.

I have the IPS spliced in via the orange wire (they made note of that on the site unless I just misunderstood). The TPS doesn't have a prong for it to connect to. But it still goes to my car. So it doesn't actually connect up with the TPS but rather goes straight to the ECU...to wherever that goes. I used the 90 TPS as a reference for wiring the IPS in as well but I could be wrong.

As far as the ISC, I was using this new $30 ISC I bought off rockauto and it seems like its not up to the task. Based off the photo of the plastic melting/degrading. Last night, I switched to the metal ISC that came with the TB. That one looks alright to me but again. Not sure what I'm looking for. (Pictures below)

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[Noranuzoki]

1990 ECU connector C-57 pin 6 (idle switch) pin 14 MAF voltage compare circuit.
91-94 ECU Connector C-66 pin 14 (idle switch) pin 6 MAF voltage compare

Assuming this is turbo AWD manual

Oh yes. I switched those pins a few different times and it didn't really seem to make any difference. They have since been switched back. But I'm guessing its necessary to have 6 and 14 switched? I did however note that when they were switched ECMLink could not see throttle position. Not sure if thats a ECMLINK setting issue or if thats what the ECU is actually seeing.

@steve also. Im using a 2g MAF.

 

[steve]

The ISC wiring mentioned earlier is to account for that fact that the 90 ISC pigtail works differently than the 91+ ISC connector and because of that you have to swap 6 and 4 in the adaptor cable.

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On the TPS adaptor the orange wire would be the IPS wire.

I mentioned the 90 MAF only because the MAF reset pin on the 90 harness runs from ECU pin 14 to pin 1 on MAF Connector. It's the pin location at the ECU side that changed from 90 to 91.

 

[Noranuzoki]

The ISC wiring mentioned earlier is to account for that fact that the 90 ISC pigtail works differently than the 91+ ISC connector and because of that you have to swap 6 and 4 in the adaptor cable.

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On the TPS adaptor the orange wire would be the IPS wire.

I mentioned the 90 MAF only because the MAF reset pin on the 90 harness runs from ECU pin 14 to pin 1 on MAF Connector. It's the pin location at the ECU side that changed from 90 to 91.

Ill try switching the ISC pins in the OHM Racing harness and see if that makes a difference.

So another words, youre saying my TPS and IPS sensors are wired in correctly?

 

[steve]

I have the IPS spliced in via the orange wire (they made note of that on the site unless I just misunderstood). The TPS doesn't have a prong for it to connect to. But it still goes to my car. So it doesn't actually connect up with the TPS but rather goes straight to the ECU...to wherever that goes.

So another words, youre saying my TPS and IPS sensors are wired in correctly?

Nope, I can't follow what you posted before and the picture showing something plugged into the IPS. If your tap into the orange wire doesn't run to the spade connector on the IPS it isn't connected correctly.

Ill try switching the ISC pins in the OHM Racing harness and see if that makes a difference.

Much better to get out the multimeter and measure them to see how they are connected. If their are wrong, then change them.

Still trying to figure out what happened to your new ISC. The pintle looks both burned and covered with oil mixed coolant.

 

[Noranuzoki]

Nope, I can't follow what you posted before and the picture showing something plugged into the IPS. If your tap into the orange wire doesn't run to the spade connector on the IPS it isn't connected correctly.



Much better to get out the multimeter and measure them to see how they are connected. If their are wrong, then change them.

Still trying to figure out what happened to your new ISC. The pintle looks both burned and covered with oil mixed coolant.

To answer your concern, yes the spliced in wire is a spade connector that goes to the IPS. It just doesn't connect with the TPS.

I'm unsure what happened to the black ISC as well. I just dumbed it down to it being cheap. But who knows.

Here are some better photos to clear any confusion:

1st photo:
90 ISC (left) - you can see where I've taken the IPS connector off

OHM Racing harness (right) - I soldered the IPS connector to orange connector on this harness.

2nd photo:
Shows the colors that correspond with the OHM Racing harness on the TPS. The 3rd color down is black, it was just hard to draw it black in this photo and have it be seen. Notice how the orange connector doesn't connect to the TPS itself.

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[steve]

I see. Do you have anyway to datalog and tune like DSMLink?

 

[Noranuzoki]

I see. Do you have anyway to datalog and tune like DSMLink?

Yes sir! I have ECMLink V3 (DSMLink).

 

[steve]

Good, I think it's time to post a log of the problem you mentioned in post #5.

 

[Noranuzoki]

Good, I think it's time to post a log of the problem you mentioned in post #5.

I could't figure out how to attach files directly on the site so I just made a google drive file.

Things to note: I my coolant temp sensor does not work (connector needs replaced), my oil pressure sensor doesn't work either (also connector issue). I'm unsure if that effects the driveability of the vehicle.

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[19Eclipse90]

For future reference: How to load a DSMLink "Log" to a thread.

 

[Noranuzoki]

here