Well a couple of weeks ago my car started feeling odd at high RPMs. Usually in the 6500-7500rpm range, it would randomly lose a lot of power for short moments. Very intermittent, and still had some power (but not much).
I knew it wasn't misfiring because it wasn't as jerky as a misfire would be. Also when it would be not-at-full-power for longer periods (like several seconds) it could still accelerate, but not well.
I figured it could be one of several things, but what really narrowed it down was two items...
1) I tried just cruising at a steady 5500rpm, and I could actually hear my VTEC solenoid clicking on/off randomly.
2) After doing #1 for a while it threw a CEL & went into limp mode.
The CEL code is 22 / P1259, which is "VTEC pressure switch circuit or VTEC solenoid valve circuit" and that agrees with the click happy solenoid I heard/felt.
So bust out the Helms...
VTEC Control System, Troubleshooting Flowchart
Check VTEC control system:
1. Reset the ECM
2. Start engine
3. Let it warm up
4. Do "road test" which consists of driving at 6000rpm for at least 2 seconds. Repeat two more times if no CEL.
I got the CEL again, moving on...
Test VTEC pressure switch:
1. Turn ignition off
2. Disconnect VTEC pressure switch connector
3. Check for continuity between VTEC pressure switch connector terminals.
There is continuity, pressure switch OK, moving on...
Test VTEC pressure switch wire:
1. Turn ignition to oN (II)
2. Measure voltage between switch terminal 1 and body ground
I got battery voltage, wiring OK, moving on...
Test VTEC pressure switch wire:
1. Measure voltage across switch terminals
I got battery voltage, wiring OK, moving on...
Test VTEC Solenoid Valve:
Well this part of the process has to do with checking oil pressure reading, however I can't really do that right now as I don't have the necessary gauge & adapter to attach it. So I'll say that it is likely to be okay as I always do regular oil changes, am using synthetic oil, the level is within spec, and it has a reasonable number of miles on it. But, to be safe, and assume that it's not, the action to take is "Inspect VTEC solenoid valve" which I did do and it looked fine from what I could tell -- the valve moves freely and the filter screen isn't dirty.
Moving on...
Test VTEC pressure swtich:
1. Turn ignition off
2. Reconnect VTEC pressure swtich connector
3. Start engine
4. Connect battery + terminal to VTEC solenoid valve, measure voltages at ECU connectors.
Got battery voltage over 5000rpm as expected, moving on...
Test VTEC solenoid valve:
1. Turn ignition off
2. Disconnect battery + terminal from solenoid
3. Check for continuity between solenoid connector terminal 1 & ground.
Is there 14-30 ohms? No, mine reads about 40 ohms. Action is to replace the VTEC solenoid valve. So I got a brand new one right from an Acura dealer, which measured about 15 ohms...much better.
Well after replacing that, things are a little better, it doesn't click on/off like it used to. However, it still cuts out sometimes, so there is still a problem!
Test VTEC solenoid valve wire:
1. Check for continuity between VTEC solenoid conector terminal 1 & ECU.
Got continuity, moving on...
Test VTEC solenoid valve wire:
1. Check for continuity between VTEC solenoid conector terminal 1 & ground.
No continuity, moving on...
At this point, the only other thing it suggest is swapping out the ECU itself!!! Well I don't have a spare ECU just laying around, and damned if I only know one other person who has a compatible one...I'll have to see if I can convince him to let me borrow it for a bit.
So now that I've typed up this novel, and you've read it (wow!), I guess the point is that I am really running out of ideas as to what the problem could be. I'm interested in what suggestions others who are more versed in the internal behaviors of the VTEC system might have to offer.
I knew it wasn't misfiring because it wasn't as jerky as a misfire would be. Also when it would be not-at-full-power for longer periods (like several seconds) it could still accelerate, but not well.
I figured it could be one of several things, but what really narrowed it down was two items...
1) I tried just cruising at a steady 5500rpm, and I could actually hear my VTEC solenoid clicking on/off randomly.
2) After doing #1 for a while it threw a CEL & went into limp mode.
The CEL code is 22 / P1259, which is "VTEC pressure switch circuit or VTEC solenoid valve circuit" and that agrees with the click happy solenoid I heard/felt.
So bust out the Helms...
VTEC Control System, Troubleshooting Flowchart
Check VTEC control system:
1. Reset the ECM
2. Start engine
3. Let it warm up
4. Do "road test" which consists of driving at 6000rpm for at least 2 seconds. Repeat two more times if no CEL.
I got the CEL again, moving on...
Test VTEC pressure switch:
1. Turn ignition off
2. Disconnect VTEC pressure switch connector
3. Check for continuity between VTEC pressure switch connector terminals.
There is continuity, pressure switch OK, moving on...
Test VTEC pressure switch wire:
1. Turn ignition to oN (II)
2. Measure voltage between switch terminal 1 and body ground
I got battery voltage, wiring OK, moving on...
Test VTEC pressure switch wire:
1. Measure voltage across switch terminals
I got battery voltage, wiring OK, moving on...
Test VTEC Solenoid Valve:
Well this part of the process has to do with checking oil pressure reading, however I can't really do that right now as I don't have the necessary gauge & adapter to attach it. So I'll say that it is likely to be okay as I always do regular oil changes, am using synthetic oil, the level is within spec, and it has a reasonable number of miles on it. But, to be safe, and assume that it's not, the action to take is "Inspect VTEC solenoid valve" which I did do and it looked fine from what I could tell -- the valve moves freely and the filter screen isn't dirty.
Moving on...
Test VTEC pressure swtich:
1. Turn ignition off
2. Reconnect VTEC pressure swtich connector
3. Start engine
4. Connect battery + terminal to VTEC solenoid valve, measure voltages at ECU connectors.
Got battery voltage over 5000rpm as expected, moving on...
Test VTEC solenoid valve:
1. Turn ignition off
2. Disconnect battery + terminal from solenoid
3. Check for continuity between solenoid connector terminal 1 & ground.
Is there 14-30 ohms? No, mine reads about 40 ohms. Action is to replace the VTEC solenoid valve. So I got a brand new one right from an Acura dealer, which measured about 15 ohms...much better.
Well after replacing that, things are a little better, it doesn't click on/off like it used to. However, it still cuts out sometimes, so there is still a problem!
Test VTEC solenoid valve wire:
1. Check for continuity between VTEC solenoid conector terminal 1 & ECU.
Got continuity, moving on...
Test VTEC solenoid valve wire:
1. Check for continuity between VTEC solenoid conector terminal 1 & ground.
No continuity, moving on...
At this point, the only other thing it suggest is swapping out the ECU itself!!! Well I don't have a spare ECU just laying around, and damned if I only know one other person who has a compatible one...I'll have to see if I can convince him to let me borrow it for a bit.
So now that I've typed up this novel, and you've read it (wow!), I guess the point is that I am really running out of ideas as to what the problem could be. I'm interested in what suggestions others who are more versed in the internal behaviors of the VTEC system might have to offer.