90 gsx ecu issue

[Chris25]

OK so ive been slowly but surely cleaning up all the issues from the previous owner so I recently took the ecu out (was told it was from a 91 wired into a 90 and that's why my tach is all screwy) and after searching the ecu code found out its a 90fwd ecu not a 91 my ?s is he's has alote of wires swapped as if he was putting a 91 ecu in car runs and drives but has a weird idle at times should i swap the wires he changed back ?

 

[Fehrion_sit]

my 90 also has a butched wiring job, i feel your pain; what other electronics are in the car? careful not to mess them up. i would check the noise filter first before you blame the ECU for the tach, i was on the same thought train as you until i ohmed out my noise filter and got OL ... just my .02

good luck, gotta love the 90s

 

[DSM1G90]

It's a very tedious job, but first : Disconnect the battery completely-you don't want stray current floating around down there.

Cut apart all of the splices, as clean as you can and remove all of the "spider's nest" that the previous owner added.

Do your best to match up the wire's color codes (white/black, red/blue -for example) from the clipped ends and resolder them back together.

I did this to one car that was vandalized - someone broke into the car and had fun with wire snips to the main harness under the dash - by resoldering everything back together to get the vehicle to run again.

Good luck - DSM

 

[Chris25]

Ya I'm going to get in their tomorrow and resolder everything back together and clean it up. Where is the noise filter located at

 

[Fehrion_sit]

http://www.dsmtuners.com/forums/articles-electrical-wiring/414636-how-fix-1990-dsm-tach.html

 

[Chris25]

Thanks I really appreciate that

 

[steve]

The big electrical tape wraps look like the factory covering for the shield braid on the O2 and knock sensors. Leave that alone. What pins do the other two run to? It looks like they are the Green and Green/White for the IPS and MAF reset you swap but the focus isn't great.

 

[Chris25]

Also found this mess going to the cam angle sensor

 

[Chris25]

Ya their the green and green and white wires

 

[steve]

Also found this mess going to the cam angle sensor

Let's see the CAS. I'm expecting it's a 91+ CAS and this is to add the connector for it.

 

[Chris25]

Here's the cam angle sensor

 

[steve]

As I suspected.

 

[Chris25]

Is that an issue having that cas

 

[Chris25]

On a side note got my rpm gauge working again with the male connector mod.

 

[steve]

Is that an issue having that cas

No. The 90 CAS have wires coming out of it and the insulation gets cooked and breaks off shorting out the CAS. The 91+ style doesn't have that problem are are easier to source. As long as it's working it fine it's not a problem. I don't care for the typical sloppy DYI crimp connections but again if it works it can wait.

 

[Chris25]

Ya I just soldered all the connections together. Still trying to figure out what the hell he did to the ecu it looks like the two white wires you where talking about he switched around

 

[DSM1G90]

Yea, those DYI crimp connectors are not the golden answer since they're just not the strongest spice that can be made.

Actual soldering and cover with shrink tube is the way to go.

I had to do what Steve mentioned on when I had to replace my CAS and it does hold true about wire insulation getting all cooked up shorting out the unit:

I did get a replacement '90 CAS, but took the existing wires and surrounded them with shrink tube to re-inforce the existing wires, but in doing this, I have a small tool that extracts the pins out of the connector so the placement of the shrink tube over each of the wires was simple. Then to add in reinforcement, I zip tied the wires to the small bracket that supports the end of the throttle housing to definitely secure the wiring loom so no more breakage is present due to wire stress.

-DSM

 

[Chris25]

Ya well its all soldered up but i noticed some oil that looks like its coming from behind the cas so im assuming he didnt replace the oring when he swapped it.

 

[Chris25]

My ? Is if the two green wires are swapped how is the car still running.

 

[Chris25]

Trying to figure out what these ground wires belong to

 

[Chris25]

OK now I'm really stumped I swapped the green and white wire and green wire back to where they should be and the car would just spit and sputter and die

 

[steve]

You never provided the date on your ECU or showed us the board to validate what you had. As you have discovered various owners have bastardized these cars and that includes putting different ECU boards in different cases.