First a little background on this car.. It is a 2006 MDX with 130K. I just replaced the engine myself with a new/used 70K engine because the original engine had a burned valve and the rings had been bad for a couple of years. It burned a quart of oil a week.
The new engine went in fine but came with it's own wiring harness and all sensors attached so I just left all that on there and plugged it in to the ECU.
Now I have a hard code P2649 and it won't rev above 3500 rpms. It runs excellent other than that. I had neither of these codes before the engine change.
OK, no problem I thought, it must have a bad VTEC oil pressure sensor so I swapped it out with the one that had been on my original engine. No change. So I swapped the VTEC solenoid and the OP switch while I'm in there.... no change. Great. So then I pulled off the VTEC solenoid casting and cleaned the screen, nope, not dirty. Yes, I have new 5W-20 oil in it with a new oil filter.
So now this little bug is getting nasty...darn it. Off to YouTube- I looked at a bunch of stuff and then found this by KY garage- excellent info: YouTube- PHgsFZYXevw
I metered out the wiring to the VTEC OP sensor and got nothing on the power side and no ground either so I figured the harness that came on the new engine was bad. So I probed the harness from the ECU connector to the switch (BLU/BLK wire) - nothing. Cool. I spliced into the harness wire just out of the ECU connector and ran a new wire to the plug at the switch and a new ground on the BRN/YEL wire and figured I had it nailed. No...... freaking really? No.
So where I'm at today is I probed for voltage at the BLU/BLK power wire and it is showing me 6.94 volts with the switch plug off, yes, not 12V. The P2649 code is a hard code that will not reset - ever. I clear it on my scanner even with KOEO and it just pops back on. How can this be setting this "High" code with the VTEC OP switch either connected or disconnected with the KOEO? I have much lower voltage than I should on the BLU/BLK wire straight out of the ECU. (Yes, I have 12V at the batt)
Do I have a bad ECU?
The new engine went in fine but came with it's own wiring harness and all sensors attached so I just left all that on there and plugged it in to the ECU.
Now I have a hard code P2649 and it won't rev above 3500 rpms. It runs excellent other than that. I had neither of these codes before the engine change.
OK, no problem I thought, it must have a bad VTEC oil pressure sensor so I swapped it out with the one that had been on my original engine. No change. So I swapped the VTEC solenoid and the OP switch while I'm in there.... no change. Great. So then I pulled off the VTEC solenoid casting and cleaned the screen, nope, not dirty. Yes, I have new 5W-20 oil in it with a new oil filter.
So now this little bug is getting nasty...darn it. Off to YouTube- I looked at a bunch of stuff and then found this by KY garage- excellent info: YouTube- PHgsFZYXevw
I metered out the wiring to the VTEC OP sensor and got nothing on the power side and no ground either so I figured the harness that came on the new engine was bad. So I probed the harness from the ECU connector to the switch (BLU/BLK wire) - nothing. Cool. I spliced into the harness wire just out of the ECU connector and ran a new wire to the plug at the switch and a new ground on the BRN/YEL wire and figured I had it nailed. No...... freaking really? No.
So where I'm at today is I probed for voltage at the BLU/BLK power wire and it is showing me 6.94 volts with the switch plug off, yes, not 12V. The P2649 code is a hard code that will not reset - ever. I clear it on my scanner even with KOEO and it just pops back on. How can this be setting this "High" code with the VTEC OP switch either connected or disconnected with the KOEO? I have much lower voltage than I should on the BLU/BLK wire straight out of the ECU. (Yes, I have 12V at the batt)
Do I have a bad ECU?