Codes P0300 P1313 P1314

I've been trying to figure out these misfires ever since I finished the rebuild. I've ruled out plugs (new), plug wires, CATs (removed), O2 sensors, and coil packs. I checked the reluctor tabs, cleaned the MAF thoroughly, and now replaced all the injector O-rings. It runs well except for these codes. The only time I'd know something is off, is when it very rarely and briefly "hiccups". Have I missed a possibility?

 

Vacumn

 

If the CATs are removed, wouldn't the O2's kinda notice it?

 

Vacuum lines are all new and I've checked them.

CAT delete has made no difference to the misfire codes, and introduced no other codes.

 

Eric, does your truck have AEL ?, they started with that in mid 1997 models.....

 

Yes, it does.

 

I agree with Danny, it may very well be a vac problem......an "Advanced " vac problem..I've been getting random misfire codes & misfire causing excessive emissions codes off and on all winter as well as the dreaded P1447 even though the truck seems to be working well. I'm not completely satisfied that I've cured it yet but I think I'm on to something....for now humor me and just try this........I know you say all your lines are new......but remove the canister purge line where it hooks into the intake plenum ( near the throttle body) and cap off the fitting that sticks out of the plenum with a rubber cap, clear your codes and drive it like ya stole it and see if they come back. if something has gone haywire in the evap system you might be getting a leak through that .

 

If you don't find a vacuum leak (intake) it's usually fuel injectors, usually over fueling. The ECM/ECU cannot correct it. Time to check them out. Leak down test. Because the originals are expensive most modders replace with the Ford SB V8, much less expensive. Same ohm and pound rating. What plugs are you using?

 

I'll try bypassing the AEL. In fact I'd like to remove the whole system.

I've been looking into the Ford injectors. Some recommend the Bosch 0280150556 but Discovery Land Rover Fuel Injectors - Land Rover Fuel Injection - FiveOMotorsport.com recommends different parts. Have you used them?

 

Doesn't give me much hope for my P1313. Was hoping it was wires and plugs and planning for new cats. All of which I need anyway but I'd like to nail it too. At least I don't have that AEL. Eric...it looks like you will reach "better than new" status in the near future.