leglessmedic

Greetings, and I hope i may find some sage advice here.
2004 Honda Civic Hx

My son's vehicle. Unfortunately he ran the engine oil low and the Check Engine Light came on with a code of P2646. His description of the issue running like crap above 3K rpm, would IMHO indicate the vehicle went into a "limp" mode.

History of the Vehicle. 190k miles. New "used" motor about 10K miles ago, (used engine probably about 20k to 40k miles based on the condition of the piston heads, cams etc. All new gaskets everywhere during the engine swap.)
VTECH module is from the old motor (190,000 miles,) with new gaskets during motor replacement.

Vehicle was brought home on a roll back.

Attempted fixes / Work done to date (this issue)

1. Oil Changed with 5w-20 (per spec) & Lucas Oil Treatment
2. NAPA Gold filter.
3. Valve assembly and mounting rods disassembled and inspected, Re-gaped at 0.07 to 0.09 on Intake and 0.09 to 0.11 on exhaust.
4. VTECH removed and cleaned (really cleaned!!!)
   • Piston inside moves freely on spring, all the little holes cleaned and blown clear with compressed air.
   • Gaskets and screens cleaned and inspected.
   • Actuator on top was cleaned and bench tested (simple circuit test that activates the mechanism that would move aforementioned piston.)
   • Oil Pressure sensor was removed and cleaned, tested open circuit normal and by blowing compressed air into sensor, circuit closed. (or the other way around...)
   • Oil ports to and from the VTECH were cleaned.

Reassembled everything and test drove, after about 10 miles Check engine light returned with "limp" mode activated and Error Code P2646.
In attempt to isolate the oil pressure sensor it was disconnected and immediately error code P2647 occurred when starting the engine.

Next in the list to repair / replace in the VTECH Oil Pressure sensor. Thinking is that the sensor, while testing okay, might not be activating with the engine's normal oil pressure and using a burst of compressed air was the equivalent if breaking a door down with a battering ram.

Any other ideas?

sdaidoji

iTrader: (1)

wiring problems?

leglessmedic

Hopefully not. Been combing through the forums to find where / how to check continuity to the ECM.

I did strip down the wiring harness were the VTECH connects to the main wiring body. The individual connections were sound (as far as I could trace them there) so if there is a short, it's somewhere else in the wiring trunk.

I did see somewhere else on here about the VSS being somehow connected to the VTECH system, at least electrically. However, I am uncertain if the vehicle has VSS...

Slumpertcivic

Your “VTEC” spool solenoid has failed or is not getting energized.

The codes P2647 P2646 coming up on your testing means your oil system is working and your oil pressure system is working.

You can clean a failed solenoid all day long and get “movement” on the bench all day long but it can still fail when doing the job it needs to do. As you said it’s 190,000 miles old.

If your handy with a multimeter, helper, and 20 foot of lead wires, you can unplug the vtec, hook meter up to the engine harness connector, run the wires into the cabin and take it for a test drive.

Have the helper watch the meter when you hit “88 mph” ( no wait that’s for a Delorean) “3000-3500” rpm to see if trigger voltage is actually making it to the vtec.

Cwaite487

can you just Rev the car to 3500 and see if voltage changes? Or does engine need a certain load. Even if it needed load would a had Rev create enough engine load?