Truck running rough. -- Breaks my heart. I can't stand to drive it in it's present condition. Need to fix it and trying not to take it to the dealer. '93 F150 302 4x4 SC, Codes read 311 - smog system problems. Will this system cause my truck to run bad? Do I even need the pump and related equipment for the truck to run OK? Tried to research this on web and in manual but could not find a definitive answer. -- Thanks Ed

 

I can't say for sure if you don't need the smog stuff, but I just bought my 88 F150 last month (5.0EFI/C6) and all the smog stuff has been removed, the truck runs great.

 

I would think that you might have a clogged cat. If the O2 sensors downstream from the cat are not getting the right reading (hence clogged or bad catalytic convertor), the computer tries to adjust for that by leaning out the mixture, retarding the timing, etc.

How many miles and do you know how old the cat is?
Does the cat get red hot(it will actually start to glow I have been told, but I've never seen one)?
Also, you could check the O2 sensors, as I think that is the first step.

Remember, codes are caused by a sensor somewhere, and just because a code says "TPS bad", O2 sensor, smog, that isn't necessarily where the problem is.

Check HERE if you need help testing O2 sensors, etc.

Good luck and keep us posted

 

The cat is original and and at least one of the O2 sensors are original, I don't even know how many there are. I bought the truck new. It has 113,000 miles. Thanks

 

I would highly recommend replacing the cat with a high flo (can be cheaper than factory replacement) and the O2 sensor(s). I think you have 2 of them. One on the down tubes from the manifolds and one behind the cat. Not sure on that. Check out that site, it's very helpful.

 

Your code states that you are having probs with the smog system. The 93 to 95 F150 ,,5.0 and 5.8 are set up the same way you should have one (1) o2 sensor located prior to the cats and you may have dual cats. There are two styles of o2 sensors for the 93 to 95 f series If your problem is in your smog system best to check all your hoses for decay. Take your truck to a muffler shop have them do a back pressure test on the cats..

I had a plugged cat and my truck idled rough and I lost pick up at highway speeds the computer did not even pick it up. If you need a cat look at www. proficientperformance.com look for part number BAS-50150-3 this is the cat (high flow for 86-95 F-150 with 302) and it bolts right up to the factory headers. I would recommend that if you have to replace the cat do the whole exhaust system. I would give you the cat back but I have a super cab and not sure what you have. The smog on your truck is computed with the balance of flow into the intake.

As jbalestri has stated codes just direct you to a problem and may or may not be the problem. the tps is governed by many factors smog pump ,,canister,,egr,,,map,,,check your hoses and connections and start eleminating componets. you may just have a bad tps sensor. most componets require a simple test with an Ohms meter.

hopefully this info helps you out.


Jack 1995 F-150 super cab With 302

 

I have a Super Cab also, please post cat back # also. Thanks for the help.

Ed

 

I saw a cat turn red on the 84 that we sold last week. Problem was that 5 of the 8 spark plugs were fouled and the unburned gas was burning very slowly in the cat causing it to turn red. Check your spark plugs and ignition system.

 

edwarded : check out www.proficientperformance.com for the rest of the system there are different options that can be installed into your truck. i used the bassani exhaust.