Multiple codes P0300, P0308, P1314, P1314

[cdkarp]

1999 DI 126,000 miles

Truck starts and runs fine after 18-20 minutes the CEL light flashes and truck starts to misfire.

I pulled the codes P0300, P0308, P1314, P1314.

 

[WILL.TILLERY]

If the light flashes then turn it off.

Check your plug wires first ... may be a broken one.. .. Multiple misfire codes there.

 

[cdkarp]

Checked and cleaned my wires (magnecor 30,000 miles) today they look fine, no crack. Changed my plugs (Champion plugs gapped to .035")

Drove on highway for about 20 minutes and and regular streets for about 45 minutes. No misfires or loss of power. Shut the truck off for about 15 minutes and CEL started to flash after about 2 minutes of driving.

Pulled the following codes P0300, P0304, P0308, P1314.

Cleared the codes and drove around for 20 minutes, it was fine.

 

[The Fourth Amigo]

Mine has been doing the same thing. Can't figure it out. Only happens when it's really cold out. Not an ignition problem.

 

[WILL.TILLERY]

Now you have a misfire on 4...

try swapping the 4 and 8 wire with two of the others...

I am leaning towards a cps at this point but do not want to jump the gun.

 

[muger80]

Mine is doing the same thing, except that it was calling for a P0306 instead of the eighth cylinder so far, I've changed wires, plugs, no change, I tested, compression and #6 on mine has low compression, about 30# lower than the rest, I've seen threads about head gasket, etc, but so far I'm on the same boat that you are, I actually added a bottle of MMO on the oil, hoping that the low compression is due to some sticky valve on the cylinder, and have cleared the codes, so far they haven't commed back and it has been driving just fine, since I'm not losing any antifreeze I'm assuming the issue of the sticky valves on the 4.0 engine due to poor fuel management, I also notice, that before the MMO the trim used to run a bit in the negative percentage, but since then I've been running more in the richer side, I'm not saying that's your problem but is worth the try.

 

[cdkarp]

Switched the plug wires around last night drove for about 30 minutes and truck ran fine. Parked for about an hour started up and within 5 minutes CEL came back on P1314 & P1314.

After paying attention to what the circumstances are when the CEL light comes on or flashes. It seems to be after driving for awhile and starting the truck without letting sit for an hour or less. If the truck sits for a few hours and completely cools down it seems to run better.

 

[WILL.TILLERY]

Ok..Before we start spending any money.. You swapped you wires.. What happened to the misfires on the cylinders that were coming up before...

My thought is they were random and there are more misfires than what the scanner is reading just yet.


Without running my own test at this point I am lead to think your Cat/s have failed.

 

[cdkarp]

I did not get any misfire codes yesterday just the 1313 & 1314 codes. I drove it this morning for 30 minutes to work and no codes.

 

[seventyfive]

like Will said. do your cats rattle at all? crawl underneath the truck and tamp the cats with a deadblow, do they rattle when they're cold? when they get hot the substrate swells up and the rattle will subside, a little. unfortunately, real time data doesn't help much with these trucks, even bosch motors.
for example, on a bosch (d2) motor if you get 1171 and 1174 with a trans fault for 4th gear it is always a mass airflow, even if you read about 8 gps, even if you watch the o2's switch properly, in real time.