I'm going to think about that an re read the thread. Unplugging the MAF should not prevent you from driving. I've done it and drive all over without one. Did you unplug it with the truck on? If so, do you still have both hands?! Haha.

 

I like this idea. I've never experienced this on a D2, but years ago I saw a mid 80's 300zx come into the shop I worked in that had running issues. It had been to every place in town and no one could figure it out. It had all new ignition and tune up stuff, but still ran like crap, like it was missing under load. Voltage checked fine everywhere.

The boss had just purchased a fancy new snapon device, basically just a big multimeter, but it could graph your output and had a pretty high refresh rate for the graphing. Once that was hooked up we could see that when the thing was running, the voltage was no longer 12 or 13 volts, as a steady line across the screen, and instead was a big thick up and down graph going as low as maybe 3 volts, but a normal multimeter would still show full voltage. We went back and double checked all of the stuff we check before (that all had good voltage) and we found a fuse that was green and corroded in the fuse box, that was the power to the ignition. We cleaned up the fuse box and installed a new fuse and everything was good.

 

The truck has always run, started and driven just fine with no hesitation. I certainly don't feel the misfires and neither did the shops who have looked at it. If it were not for the check engine light coming back I think the engine is running well.

 

I was just telling a story about how checking the power might not be a bad idea. I don't think your vehicle needs to replicate all of the symptoms of a 30 years old Nissan for that to be true.

ULEV emissions are very sensitive, to earn that rating. I don't doubt that you don't feel anything at all. If the misfire was bad the shops would have already found it by now.

The only other things that come to mind are the wiring to the cranks sensor and the notches that the sensor is reading.

I'm thinking finding a shop with some advanced diagnostic tools might be required. Probe the cranks sense near the engine and see what the wave looks like compared to a engine that doesn't get codes. Probe near the computer. Compare the results. If those are good, perhaps check secondary ignition. Just thoughts. no warranty with my guesses.

 

Is that P093 code new? Just noticed that in the last message on the first page. That's an indicator of a drop in fuel pressure. I know you've replaced the fuel pump, but have you tested the pressure at the rail?

Also, I think it's time to start considering "out-there" possibilities that might be related to the previous owners "rebuild" of the engine. Is a knock sensor loose/damaged, causing a false positive? Is an engine mount loose and rattling causing false knocks? (I just found the 2 large bolts missing and the small bolt hanging in by a thread on one of the mounts on my "new" 2003) Have you done a diagnostic with a vacuum gauge to test for exhaust restriction, etc?

 

I stopped at a friend's BMW repair shop yesterday and asked his opinion. He mentioned a few things that have already been suggested and also asked about the gas I am using. I have only ever put in premium (91 octane here in CA). As an experiment, he suggested trying higher octane fuel. The tank was just over 1/4 full and a station near me sells race gas (100 octane and $9.39 a gallon ) so I put in 5 gallons. I drove a few miles and stopped and cleared all the codes. It was getting late so I only drove about 15 more miles and went home. No codes yet. I will take it on some longer drives this weekend and see what happens. I know that octane rating is another one of those hotly-debated issues not to mention you would go broke running a D2 on race gas!

I agree that the "out-there" possibilities need to be checked out. It was getting dark when I got home but the knock sensors look OK and were tight. The motor mounts look fine but I will give them a more thorough inspection with better light. I borrowed a fuel pressure gauge to check the pressure over the weekend.

 

Wow; that's amazing.

I've put pure gas (no ethanol) in mine (usually from gas stations near lakes) and mine ran like a scalded dog. Instant response, smooth running.

But I have also put 87 octane in mine and it was little sluggish, but no misfires.

Outside the box thinking, indeed! The MAF thing is still haunting me. For an experiment I unplugged mine this morning and drove all over town. It wasn't happy but it sure didn't quit.

To me, that points to your knock sensors, but, like you, I have never seen anything that led me to believe that a knock sensor could go bad or that you could tell it was bad, unless you get a code. Land rovers are fickle beasts.

 

Knock sensors aren't used to register misfire codes, the crank sensor is.

 

Use http://enginecodemaster.com
Might help

 

So after about 50 miles the check engine light came back. Codes are P300, P303, P304, P306, P307, and P308. P93 code did not come back. I checked the fuel pressure at the rail and it was 45psi according to the gauge I borrowed. Even though I am fairly certain they have nothing to do with the problem, I replaced both knock sensors (one did have some minor damage and replacements were inexpensive). Both motor mounts look new and the bolts are tight.

I was in touch with the independent Rover shop that got it smogged in CT prior to my purchase. The owner said they were able to get all 8 drive monitors to reset with no check engine light but it did take a while. He suggested the exhaust valves were sticking due to carbon buildup or tight valve guides. This doesn't really make sense to me since he was able to get it to pass (I have the CT certificate) and I was able to drive it over 500 miles without a CEL. Any thoughts on this idea?

The truck still starts, runs and drives well. Any more suggestions, even crazy ones? I am beyond frustrated with this vehicle!!