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Discussion Starter #1
So, I've been getting a P0306 code, miss fire detected on #6 cylinder. It was due time for plugs, wires, cap, and rotor. So I did all of that. Engine starts and runs fine. Code came back. I figures to move on to the fuel system. Replaced the fuel injectors (270,000 miles and I think they were original) and put a noid light to the #6 . Noid light test showed the circuit working just fine. Well code came back. Tried moving the fuel injectors around to see if maybe I got a bad one. Nope, code came back on #6 . So I ask, am I missing something here?
 

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does the truck still have power. I'm in the same boat, but my code is for Cyl #4 . I'm also experiencing lack of power and poor drivability with mine though. Hopefully we can bounce idea's off one another, to solve this issue. My truck only has 99K on it, but it has been sitting for almost a year in my garage while I rebuilt/ modified it. Try looking into the cam sensor in the Distributor as well. Good luck, and I'll check back to see if you've solved your issue.
 

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Well I just got done rebuilding and putting a shift kit in the transmission valve body because the governor solenoid was messing up. I found the front band all out of wack and the accumulator spring broken. With all that fixed the truck has great shift and power. I also has the ignition coil short out on me, replaced that. Yet I am still getting the P0306. The cam sensor might be worth looking in to. I am curious to know how the OBDII figures a misfire. Maybe if I knew the variables, I might be able to test better.
 

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Did you ever get this figured out? The code is a "generic" code so it is common to many other vehicles - even from other manufacturers. I have a Chevy full size 1/2 ton from the very late 1990s. I had the same code for cylinder 5. I discovered that carbon build up on the plugs shut the cylinder off. it actually shuts off the fuel injector. Cleaning the spark plug resulted in the code going away. reconditioning the cylinder heads resulted in (both curing a water leak and) the fault not returning. This is a "funny" fail safe I am told. Once the computer senses the misfire, it does not reset itself. If you have a higher end code reader that captures live data, you may be a ble to try and reset the code while driving the vehicle. You could then see if, once the engine is in operation, it continues to run without the fault returning.

So, if replacing the high voltage electrical components and the injector itself did not fix it, I would do a compression test and look for a low cylinder pressure. I am also told that the engine senses "proper" power pulses through the knock sensor . I do not know if that is actually the truth though.... But there has to be a way to actually detect a misfire somehow. Now, the low compression does make sense if it is electrically sensed. The coil will not build up enough voltage and, thus, resistance while jumping the spark in low compression environments. I always assumed that was what the computer sensed.

If you ever played with spark plug testers, the application of high air pressure would cause the spark to not jump. In high school auto shop class, we would do tune-ups on "customers' " vehicles. We would take the used spark plus, use the plug cleaner and the test them. If they would keep firing at anything over 200psi, we would "purloin" them and re-use them in our own cars. :smile:
 

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old thread I know... had the P0306 on my 01 Durango w/a 360 ("5.9") After going thru all the tuneup, noid light checks, injector swaperoo, compression test, etc it still was there. Mine wound up being the injector driver itself within the computer. I sent it in, I guess the solder joints on the circuit board worked loose, sounded like a common issue on these according to the computer repair place.
 
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