No Start, hacked up ecu harness

The car's harness has been cut up by every person in arizona

With that being said, the car was sitting about 5 months while I very slowly installed a new turbo. Go to start and only the car only cranks

Spark good
Compression good
Fuel pressure good

played around with the car for days, she finally started with a quick wiggle of the ecu harness, but will die with another wiggle.

Ive replaced some of the afro-engineered harness with solder and heat shrink. This is as far as my electrical experience goes. I just ran to walmart and bought a decent mufti meter and am ready to dive into this project.

What I am looking for is a good starting point? What should I test first? Does anyone have a list of what pins should have in terms of voltage with key on, cranking and off?

Any help would be much appreciated.

 

here is where i am.
No power to pins 107 or 102.
CHecked for continuity between 63 and pin 8 of the mpi relay, its good.

I grounded pin 8 of the relay, still no power to pins 107 or 102.

Im assuming at this point bad relay.

When pin 8 of the relay grounds, what sends power to ecu? pin 4, 5 on relay? Im not seeing power on either.

to rule out possibly of ecu being bad can i jump power from battery backup(pin 103) to pins 107/102 to see if boots up? or could this cause issues?

 

[rdomeck]

Check your ecu fuse in the engine bay. I ran into this problem a couple of months ago and dove into checking a bunch of wiring. Turned out to be the fuse was blown. I found a wire that was rubbed through causing it to short out!

 

[Struc]

Also check the reading for the ECU's coolant temp sensor. Car will start really hard without that working properly.

 

Ill double check the fuse.

I doubt the coolant temp sensor has anythign to do with it. when it did start it starts quick and idles perfectly. I dont think the coolant temp sensor would kill power to ecu.

 

[496of2000]

Check the MPI fuse.

 

[Xcelerate]

Try jumping a power directly to those terminal. Check your can sensor and wires to make sure their good, the ecu will not send those voltage till it sees the cam sensor turning. And yes the coolant temp plays a big role on starting so make sure their operational. There's a different trim/tune in variable temp reading, so make sure all your major sensors work (coolant temp, THrottle sensor, can sensor)

 

[Xcelerate]

There's also a ground next to the ecu screwed in to the metal of the center console, trace all those wires and make sure their good and solid and grounded properly

 

[mitsu90]

I fought this exact same problem for over 4 years.I was never able to locate the problem, I ended up replacing every plug going to the ECU. It was a long tedious job but the end result was worth it.

 

[IncorpoRatedX]

Quoting fivesfe:
Ill double check the fuse.

I doubt the coolant temp sensor has anythign to do with it. when it did start it starts quick and idles perfectly. I dont think the coolant temp sensor would kill power to ecu.




I can tell you from direct experience that if the wiring to the coolant temp sensor is screwed up, it will start great when the connection is good and wont start at all when it's not. I had to use starting fluid to get the car going, 4 or 5 times until the engine would get itself warm enough to begin idling poorly on its own. when the connection was good, the car would start up, idle fine and run smoothly. try getting the car running 5 or so times with starting fluid, spray it in a vacuum port on the intake tube after the MAF to avoid harming the MAF sensor. If it will run and idle after that, i'd start tracing those wires.