Are ecu’s always rebuildable?

ChaseRoads

do I need to lube this area?
Oct 29, 2020
202
71
38
midwestern america
Buddy finished up the manual swap on my car. Repined the o2 harness for use with an A9l , ran into a bunch of issues with poor idle , running rich , and acting up, engine light.

Disconnected the o2 harness and it ran better but had an engine light. Tried a different a9l and it ran fine. Temp solution was to repin for the a9p. Runs perfect with the a9p. I’ll have the car back this week and can dig in and diagnose myself.

All signs point to a bad ecu. Is there any extra testing I should do? Anything i
Should check on the ecu before sending it off?

Car is a factory 91 5.0 auto, now a 5 speed .
 
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rednotch

Founding Member
Aug 14, 2000
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south jersey
did you pull any codes before swapping the harness and ecu back. Crack it open, remove the board and look at the trace on the back side., the majority of the time when the he 02 harness wiring was is issue it just kills the Sig return trace on the board, should still be plenty of pics on the net how to jumper it.


Not all are repairable, some boards get killed when a capacitor pops and causes a serious short blowing threw the board, but the majority are.
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
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Massachusetts
Not always. Some of the components are obsolete.

Transistors and caps seem to be the most common things to go and those can be replaced. Burned traces can be repairs. There's a post on this page showing a burned out 8-pin IC that would need to be replaced and it comes down to finding a modern equivalent.
 

ChaseRoads

do I need to lube this area?
Oct 29, 2020
202
71
38
midwestern america
Yeah we pulled codes and got a bunch of them, none of the codes predated the trans/ecu swap so we cleared codes and did it again and got 22 and 34. Before he tried a spare map sensor he tried a spare ecu he had laying around, after that worked I asked him to repin the harness to use the factory ecu. That’s where we left off. I’ll have the car back in my possession this weekend and I’ll open up the broken A9L and go from there.
 

Specracer

Active Member
Nov 24, 2020
67
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SE MA
Ironically I came across this today. Fox Resto in NC is doing ECU's

 

rednotch

Founding Member
Aug 14, 2000
518
214
73
south jersey
Ecu exchange is the only one I've seen that repaired more then bunt traces, caps and transistors, though I haven't opened many other rebuilds besides cardone/ bluestreaks. Think there $130 now on ebay.. Either way take pics before ya send it in so you can see what all was replaced.