How do you tell if your ECU is bad? I just put my stock engine in 98 civic DX and my car has been idleing funny. Replaces Throttle body and Throttle body gasket, I checked my IACV, Check coolant lines. And then someone told me my ECU might be bad. The car drives perfect except for that anoying idle. Keeps going up and down up and down at a slow pace. Anyway i can tell if its the ECU?
thanx

 

A bad ECU could cause that to happen. Have you had the ECU chipped recently? Checked for vacuum leaks?

 

Check Engine light will not flash when you check the codes. It has to do with the vacuum, same thing was wrong with my friends car and our friend Cortney fixed it, I can't remember exactly what he did though, he capped off some lines on the Intake Manifold.

 

my check engine light does flash when i check for codes. I havent messed with the ECU never chipped never even taken apart. It just sat in my tool box for about 6 month and thats it. Ill check for some vacuum leaks today
thanx for your help