Pulled a code 311 ( thermactor air system inoperative ). Does anyone know if this could be the reason that my truck runs bad.

 

Yes, I know. No, that's not the direct cause. It indicates other problems, many of which might cause it to run "badly".

If you'll put your truck's specs in your signature &/or profile, and describe the problem more thoroughly, we MIGHT be able to help. We assume it's a Ford F150, so you can omit that. Engine size, transmission model, miles, mods, repairs, trim level... Details. If you don't know them all, read this caption:



And "inoperative" is about as vague as possible, so look up that code on several other lists, and post every definition you find so we can compare them. It helps to understand them when you see them worded several ways. The caption of this diagram contains a link to a couple of code lists.

 

Thanks steve83 for the response. It's a 1993 f150 4x4 xlt supercab wb-155 5.0 302 vin-H automatic I believe it is the E4OD trans. Here is my problem. The truck stumbles and misfires through the air box when accelerating or under a load. even if i am cruising at 40 mph and back off the gas for just a minute as soon as I get back on the gas it will stumble and then clear out. In the morning when cold it will start and then stall immediately, or idles down fast to an almost stall. if it stalls it starts right back up and stumbles idling funky for about a minute or two before leveling out to a somewhat decent idle. As soon as I hit the gas to pull out of my driveway it will stumble, pop through the air box and take off. Sometimes It will run as if a cylinder is dead and then clear out. Here is the kicker, it does not always run like this, sometimes it will run good until I shut it down, when it restarts it runs crappy. I put a new fuel pump in the mid ship tank that went bad but made no difference. I also put in a new map sensor that went, ignition coil, plugs, wires, cap and rotor within the past month. I have a manual and checked the EGR valve and position sensor, the new map, iac,tps and iat all are working.I keep checking for codes and keep coming up with nothing. The truck it self has over 200000 miles on it and supposedly has a rebuilt motor in it. It does not smoke, burn or lose any oil between changes, and when I changed the plugs they were all in great shape and look like they are burning identically. Any help would be great. I really like the truck and would hate to get rid of it.

 

H is NOT the VIN code for a 5.0L.Did you read the caption of that first diagram? It gives 2 ways of IDing the trans, and there are others. What are the positions in your shift indicator (PRNDL)? Does your shifter have an O/D OFF button?That's a backfire; not a misfire. They're different, and have different causes. What's the base ignition timing? Read the emissions sticker under the hood for the procedure to set it. Pull the Red vacuum line off the FPR at idle & check for the presence or odor of gasoline.

There are many possible causes for those symptoms. Use a 3' piece of garden hose as a stethoscope to listen all around the idling engine for vacuum leaks. Read these:

. . . . What about the ECT, PIP, TFI, coil, HEGO, & MLPS? Does the TPS respond within these specs?

. . What method are you using to check for codes, and are you saying you get NO code at all? Did you read the link in the 2nd caption?

 

vin-N is what it is. The trans code is E = E4OD/4R100 (gas) there is a OD off button on the shifter and the indicator reads PRND21. You are right it is a backfire through the air box, A loud pop, it also pops through the cats. I pulled the vacuum line to the fpr and there was no smell. I am going to check for codes tomorrow with my ford code reader again and go over all the sensors again. I started reading through the material you sent me, what a big difference from my Haynes manual. Thanks for the material. and help. I will post my finds tomorrow.