Alright working with

' 91 Accord EX
F22A6 Manual trany

Light comes on after about 5 miles or so of driving. Checked for cell code but there is none.

Did a full system check so far everything comes in within specs.

If I turn off the car, wait about 20 sec, do a rolling restart, light stays off for about another 5 miles or so then comes on again.

No jerking, no stalling, no vibrations, no noise, nothing to help inply what the issue might be. Just runs fine, but after about 5 miles engine light comes on but leaves no cell code (engine code).

Confussed

 

I believe that usually indicates an ECU problem... but I would wait for someone else to confirm that.

 

The only thing I can think of that might throw the light but give no codes is that the air/control box under the intake of the A6 is not used. I instead ran the vac line to the intake itself over using the box.
Did not want to run the wire to the ECM for it.

Yes this is an upgrade from the A4 to the A6 motor, but before I did not have this issue as this is the second A6 (last one spun out 3 out of the 4 main bearings).

Miles on:
car 241,000
engine 48,000
Manual trany 241,000

 

when you did the engine swap did you reattach the ground at the T-stat housing?
that ground point is a known troublemaker, clean it up and be sure it's tight.

 

Yes, I ensure that it was clean and on.

I know about the ground issues with Honda's

All grounds are there/clean/tight/solid (most are upgraded with better connections)