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Old 03-22-2010, 08:38 PM   #1
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Default Link ECU has me scratching my head.

This one is odd.

I have a 94 wiring harness in my car. I bought a used ECU from flying Miata (its a link) and I have wired it all in on the weekend.

Nothing too serious. I turned the key first time and it all came to life and appeared to work.

Today I went to start it and it loads, fires and dies.


What has me scratching my head is :
My knock sensor works but yet the MAP value shows 8. The book says to look for 100 as a rough number. This means the sensor isnt working.
I checked my wiring twice and all work.

My conclusion- The map sensor is toast . Anyone know how i could verify ?

The second problem is that the intake air temp sensor reads 100. If I disconnect the 1 plug (i believe, whichever one it plugs into) the number goes to 14. Its about 50 degrees in my garage so that could be right but it has me scratching my head.

Oh and that one is a brand new direct wire that crimps between the sensor lead and the other end goes in the ECU.

This one I have no conclusion.. Im stumped!

Anyone have an idea? All help is appreciated!

(and no.. I dont want a Megasquirt)
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Old 03-23-2010, 01:43 AM   #2
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Open the map/knock box and make sure that you have +5V at the sensor (across the cap between pin 2 & 3). If you do check the voltage on pin 1. It should be ~1.8V when the car is off at sea level.

Regarding the temp sensor, make sure that the wires aren't broken/loose where the meet the pcb the sensor is mounted on.
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Old 03-23-2010, 02:12 AM   #3
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heya, i have the same ecu for my 1.6L so it may be different

Air temp sensor reading 100 = bad sensor / Bad ground in 99% of cases this is covered in the installation pdf ( or maybe its the tuning pdf ) try a different ground.remember this reads in celcus not farenhight so arround 50f would be arround 10c, it saying 14 would be pretty accurate in the engine bay as its a little hotter in there then ambient.

"Today I went to start it and it loads, fires and dies."

Make sure ur turning the car on correctly ( lol ) turn the key to the on position and u will hear the fuel pump prime and then a click under your dash, after that click ur right to start the car. what u say above is exactly the same as when u just turn the key on without letting hte ecu boot correctly.

if your not hearing the fuel pump prime and the relay under the dah click ( about 5-7 secoonds wait) try different things with the ribbon cable from the ecu. Latly ive had issues with it. EG

Ribbon cable plugged into serical converter and serial converter plugged into laptop = at key on fuel pump doednt turn on and car wont start OR starts for a second then stalls from no fuel

Ribbon cable plugged into serial adaptor but serial adaptor not plugged into laptop edu boots fine and car runs

Ribbon cable unplugged = edu boots properly and car runs

Just throwing ideas out if the above doesnt work, not sure but if ur map is under 20 u will be under the MAP overrun ammount ( default is 20 ) so it would start then just stall cause the injectors have been shut off, what does this mean? NFI just something to think about. you could try lowering your map overrun setting and see if that helps, but not sure it would be fixing the issue. Also check the vacum hose your using, probibly not it but its an idea.

Good luck hope this helps
Oni
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Old 03-23-2010, 06:40 AM   #4
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You should double check your grounds(the two grounds from the ecu to the block... But I have a 1.6L setup). I had an incorrect map reading and assumed it was the map sensor but it was a bad wire. GL, ihate electrical shiet!!
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Old 03-23-2010, 01:07 PM   #5
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Thanks to everyone for the replies.

I checked the wire that plugs into the map.
On #1 (or #5) i get 13v
On the others I get nothing.

Nothing on 2-3 or 3-4.
Any idea what that means?
Again massive thanks for the help
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Old 03-23-2010, 01:25 PM   #6
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And since I cant let things go I went back to play on it.

I checked every pins connection between the ECU and the connector. All checkout perfectly.

So im almost thinking now that the ECU is fubared and not sending out signal?

I attached a ground strap to the ecu and still not dice
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Old 03-23-2010, 01:28 PM   #7
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Quote:
Originally Posted by TurboRoach View Post
Regarding the temp sensor, make sure that the wires aren't broken/loose where the meet the pcb the sensor is mounted on.
Checked and there is continuity which makes me doubt it. The number on my meter isnt 000 so i am doubting its a short because thats what i would usually see if the 2 wires are directly touching
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Old 03-23-2010, 04:25 PM   #8
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Quote:
Originally Posted by YeboGoGo View Post
Thanks to everyone for the replies.

I checked the wire that plugs into the map.
On #1 (or #5) i get 13v
On the others I get nothing.

Nothing on 2-3 or 3-4.
Any idea what that means?
Again massive thanks for the help
I meant on the actual sensor inside the box across C5. You should only see +12V on the connector that plugs into the box. The rest are either ground or signal wires.

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Old 03-23-2010, 05:04 PM   #9
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I checked at that sensor too. No dice. :(

Nothing shows up.

I notice that one has a plug like a 90-93 model. Mine doesnt (if that matters)
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Old 03-23-2010, 05:08 PM   #10
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Does the circuit look the same?
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Old 03-23-2010, 08:34 PM   #11
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Quote:
Originally Posted by TurboRoach View Post
Does the circuit look the same?
It does

so i did a software reset again and now i get 5v on 2 and 3. I also get 2v on 1 with the car off.

Is that a good thing?

I did notice 2 lines on the circuit board have been cut. Is that normal ?
https://www.miataturbo.net/forum/att...1&d=1269387234

I know 1 is.. is the other??
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Old 03-23-2010, 08:47 PM   #12
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Quote:
Originally Posted by YeboGoGo View Post
It does

so i did a software reset again and now i get 5v on 2 and 3. I also get 2v on 1 with the car off.

Is that a good thing?
Yup that means the sensor itself is mostly likely fine.

Quote:
Originally Posted by YeboGoGo View Post
I did notice 2 lines on the circuit board have been cut. Is that normal ?
https://www.miataturbo.net/forum/att...1&d=1269387234

I know 1 is.. is the other??
I don't think so. The only cut trace I know of is the one for the wideband. I would email FM about that second trace. Is it actually cut or just scratched?
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Old 03-23-2010, 10:23 PM   #13
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Quote:
Originally Posted by TurboRoach View Post
Yup that means the sensor itself is mostly likely fine.



I don't think so. The only cut trace I know of is the one for the wideband. I would email FM about that second trace. Is it actually cut or just scratched?
firstly thanks for your help!

It looks cut. There is definitely no continuity between the 2 parts :(

This thing isnt doing very well so far
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Old 03-23-2010, 11:03 PM   #14
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No problem.

Definitely solder a bit of wire to reconnect it. I just found the pic of another pcb.
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Old 03-23-2010, 11:22 PM   #15
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Quote:
Originally Posted by TurboRoach View Post
No problem.

Definitely solder a bit of wire to reconnect it. I just found the pic of another pcb.

I think thats probably going to happen. Ill call FM tomorrow and see if it would void any warranty i may have (if any)

If I cant get this damn thing to work by friday im going LS1
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Old 03-23-2010, 11:33 PM   #16
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Shoulda got a megasquirt.....
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Old 03-24-2010, 10:24 AM   #17
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anyone know how long FM usually takes to respond to emails ?
I'm hoping to have this working by the weekend
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Old 03-24-2010, 03:17 PM   #18
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Quote:
Originally Posted by YeboGoGo View Post
I did notice 2 lines on the circuit board have been cut. Is that normal ?
https://www.miataturbo.net/forum/att...1&d=1269387234

I know 1 is.. is the other??
DO NOT "REPAIR" THE CUT TRACES!!! THEY ARE SUPPOSED TO BE THERE!

I went through the exact same thing:

https://www.miataturbo.net/forum/t30883/

Both of these circuits are necessary for the 90-93 Link that uses the same circuit board. For the 94-95 cars they are supposed to be cut.
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Old 03-24-2010, 04:01 PM   #19
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You beat me to it, but indeed, do NOT reconnect those traces. Having owned a couple of Links, I can confirm that both cuts are supposed to be there on the 1.8 Link.
TurboRoach you should be careful about giving advice like that.
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Old 03-24-2010, 04:09 PM   #20
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Well didnt try it. Also no reply from FM yet :(

Guess ill just wait and see what happens
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