Mini-update:

Unplugged the CMP and was still able to replicate the drivability issues above. Also checked MAF 1 and 2 readouts and they seem to be about equal (UG manual doesn't say what they should be), and respond quickly to changes.

So with my MAF working fine and with continued power loss at default engine timing, I'm assuming that the problem is not the sensor, but somewhere else...possibly downstream? Or does the fact that continued problems after removing the sensor confirm that it's the culprit?

During power-loss conditions the computer is still trying to pull out fuel, so I can't imagine it's a deficiency in the fuel pump or filter (new filter on the way anyway).

Air filter is new, rechecked connections from the intake to the MAF and to the plenum and they're all tight...so I'm assuming enough metered air is getting into the intake. O2 sensors are both reading similarly, and not sluggish in response so I don't think they're driving the bus (if they were and I'm getting lean readings from them I'd expect the computer to start adding fuel rather than subtract it). I think that clears any upstream/intake issues.

I guess my next step is to hook up a vacuum gauge and look for a leak downstream.

Any other thoughts or faults in my logic?

 

Here is the little that I can contribute, if you suspect a sensor is bad and you remove that senor from the equation and the symptom is the exact same then odds are that sensor is bad.

I do not know if your cam sensor is the problem or not.

 

Thank you, that helps a lot, actually.

 

The truck will run with CPS disconnected, on fall back data. So like Spike says, if you don't see a change, then maybe it was bad to begin with.

 

Thanks. I'll be crawling under the engine to check out the wire harness to see if there's any interruption.

Anyone know how well the truck is supposed to run on default timing? I understand that the CMP is supposed to assist with running, but it's straight up hobbled with the sensor unplugged. I'll be checking my MAF and checking for vacuum leaks in the meantime. Thanks everyone/Buzz/Spike.

 

Yet another update. I think I've made some progress. I cleaned off the CMP sensor connector and plugged it back in; also hooked up a vacuum gauge and took her for a spin. Rather than just flooring the engine until it flooded and failed, I had a nice leisurely 2-3 mile drive after the engine warmed up and the power loss came on again.

What I noticed is that I got P0340/P1158 pending codes...they cleared. Then a few minutes later I just got a standalone P1158 ("Oxygen Sensor indicates rich fault - Bank 2") pending code. I also noticed that the short term fuel trims on bank 2 stayed locked at 0.00 and would not change once the engine decided to stop using trims; the other bank kept going rich (STFT on bank 1 got up to 25%).

So this time I have the same engine problems, but now I have rich codes and not just some random camshaft position sensor error. I'm hoping that will at least get me down the "rich code" troubleshooting path rather than worrying about everything else?

For the vacuum gauge I teed into the intake plenum between between the fuel pressure regulator. Readings I was getting there was about 15 inches of mercury at idle, with good response under throttle. I didn't notice any wide pressure swings, or "ticking" of the needle while under moderate load so I'm guessing my exhaust valves are working fine. I'm hoping that's enough to rule out an exhaust leak. I wasn't able to get the RPM's high enough to try and see if there was too much exhaust back pressure, though.

And with my MAF readings concurrent with everyone else's, I think that's clear too.

So...gone are the random camshaft codes, and now my bank 2 O2 sensor is reading rich with the same power loss. Any comments or thoughts?

 

Ooooooh-kay. Finally had some time to give the truck some attention.

- Changed air filter (old one didn't look that bad, until I saw the new one);
- Verified no exhaust leaks with vacuum gauge;
- Changed out all four O2 sensors ($75/ea from Will)

Lo and behold she runs beautifully. I haven't had a chance to get her on the roads more than going up and down the block, so I hope I'm not declaring this issue fixed before it really is.

Kind of makes sense...drivability was fine until the engine/O2 sensors warmed up, and then that's when everything went haywire. I think the CMP codes were throwing me off, and probably my fault for flooring it and trying to make things worse when the engine was hesitating...thought it would help bring out a code faster (oops).

 

Until warmed up, fueling was open loop, depending on fall back data and "best guess" of what would be good. Once closed loop begins, the O2s are in control. Glad it is fixed.

Time to motor up to OBX for some fun in the surf. Zodiac optional.

 

Just when I was about to load up the surfboards on the way home from a shakedown run...BAM! P1313 and P1314 (Misfire Fault Catalyst Damage Bank A, Misfire Fault Catalyst Damage Bank B).

Had about 10-15 minutes solid driving, then significant drop in power but was able to keep limping home. At idle seemed to be running smoothly (to my ear at least), with negative STFT (-5%) on both banks.

From another post (Savannah)
From a post over on Dweb (Chris-StLouis)
http://www.discoweb.org/forums/showt...ht=p1313+p1314
The CEL was flashing before going solid...
- Fuel filter: have it on the shelf just in case
- Vacuum: no loss of vacuum throughout, nice even needle responses, no stepdowns or loss; all hoses in place and intact
- VSS: New, shop replaced in December
- Plugs/wire: Kingsborne 8mm, Bosch 4+ replaced last month.
- MAF: have an extra on the shelf
- Air Filter: replaced yesterday

Waiting for it to cool down to recheck my O2 sensor connections and make sure I didn't crimp something when I moved the coilpack out. Wonder why it's still running rich with negative STFT's. Maybe this really is a fuel pressure regulator/injector issue now that I've sorted some of the other random issues out. The saga continues...

 

P0340 Trouble Code

What does that mean?
This indicates that a problem was detected in the camshaft position sensor circuit. Since it says circuit, that means the problem could lie in any part of the circuit - the sensor itself, the wiring, or the PCM. Don't just replace the CPS (camshaft position sensor) and think that will definitely fix it.

Symptoms
Symptoms can include:

• Hard starting or no start
• Rough running / misfiring
• Loss of engine power

Causes
A code P0340 could mean one or more of the following has happened:

• a wire or connector in the circuit could be grounded/shorted/broken
• the camshaft position sensor may have failed
• the PCM may have failed
• there exists an open circuit
• the crankshaft position sensor may have failed

Possible Solutions
With a P0340 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

• Visually inspect all the wiring and connectors in the circuit
• Check for continuity in the circuit wiring
• Check the operation (voltage) of the camshaft position sensor
• Replace the camshaft position sensor as required
• Check the crankshaft position circuit as well
• Replace circuit wiring and/or connectors as required
• Diagnose/replace the PCM as required