Don’t have much history on the car but...
2002 accord with f23a/mcja. It has a delayed/hard downshift from 2nd to 1st and engage in reverse. And a code P1607. Could these be related?
I disconnected the pcm checking connections and found a small amount of oil in the blue connector. Cleared code. And it resets before starting the engine.
Will a solenoid problem cause a low/reverse shift issue?

 

P1607 is ECU failure code. It is detecting some kind of circuit failure inside the ECU that is throwing the code. In your vehicle the ECU and TCU are the same unit so they could very likely be related.

 

If you are getting a P1607 then it most likely is a PCM failure if the code came back pretty quickly.
If the PCM is flooded with oil/water you might be able to open it up and dry it out, and the PCM may work again.
Diagnostics are simply clear code, turn off, turn on, wait for any codes to pop up. If they do replace current PCM with known good one and retry.

 

I opened up the PCM. No oil inside, only in the connector. No visible signs of damage. I’m sure it has a oil sensor or solenoid (VTEC or trans) that is leaking and following the insulation to the pcm. A wiring schematic for the pcm would be helpful. Maybe it will lead me to a failed part??

 

If it really is a 1607, and not a 1706, code then you need to locate another PCM and retry. The diagnostics for 1607 are brutally simple. If the code comes back after removing memory/power then the PCM is probably goobered.

 

Update on the trans issue.
removed and cleaned and tested all solenoids. No change. I will start a new thread with only the transmission symptoms.

 

If the PCM is toast, working on the trans is going to do **** all.
Fix the PCM first, then move on to the trans if the problem persists.

Transmission functionality is greatly affected by engine tune. And since the PCM is ballox'd the trans is gonna shift like ****.
Fix the PCM first.

 

Replaced PCM and repaired CEL with code P1607. Transmission issues remain unchanged.

 

Verify fluid is good, and take the car for a proper drive.
With the new PCM it will have a clear memory. Drive it for a bit and see if it will chuck a code.
This generation of PCM will not set a CEL/D4 lamp even if there is a problem, you will need to check for codes with a scanner/code reader after your drive.

If no codes are set, you will need to have the pressure readings on the trans checked to verify that the various gear circuits are working at the proper pressures.

Commonality with delayed R and 2-1 shock is defective Solenoid Valve C and/or foreign material inside separator plate orifice.
There could also be separate issues that are causing the problems, which are another dozen issues to check.

Verify that the gear selector and gear selector lamps all line up correctly, this would affect shifting.
Verify the transmission itself has no leaks. Check the solenoids and pressure switches are not leaking.

 

No codes after 20 minute drive. Will do fluid flush this week. Solenoid c is the lowest one on front? It clicked soundly when bench tested with 12 volts. Is there a spool that can be removed or cleaned?