Re: help! 96 f150 fails emissions test

> i think it all comes back to a lean mixture... weak fuel pump?clogged fuel > filter? > any ideas?

Sounds like it. But I doubt it's the pump or filter. Otherwise all cylinders should be doing it. I'd take a good look at the EGR as a matter of course, and then injector flow, etc...Make sure your engine is not "carboned up". That will cause this problem due to the semi clogging of the injectors, and higher compression due to the carbon in the chambers. Also carbon can soak fuel vapors, and cause a lean problem. I'd run a can or two of techron fuel system cleaner through it, and do as much stop and go driving as possible. IE: get the truck hot, and then shut it off and let the techron heat soak the injectors and chambers, intake valves etc. Do that over and over if possible. Running injector cleaner does nothing for a running engine. All the "work" is done on each heat soak while the engine is hot and sitting. This is the same way the carbon and gunk builds up in the first place. Anyway, you do sound lean, but it's just a guessing game without seeing it. I'd check everything emmision related including temp sensors, O2 sensors, the whole ball of wax. Being it's on random cylinders, I'm guessing towards some carbon, and semi clogged injectors. You might be able to visually verify if you can locate a borescope. We had the same problem on a camry recently. MK

Reply to
Mark Keith
Loading thread data ...

Your 96 (and newer) vehicles are OBD 2. You have 02 sensors before and after the cat converter(s) teh computer reads both 02 sensors and calculates a) emiisions performance, b) cat converter function.

In your case, the cat code indicates a problem. In most cases, the Ford tech will follow a diag chart based on the code(s) present and perform other tests (is 02 sensor reading, etc). sometimes they reprogram the computer to calculate differently. Most likey you need a cat converter, sorry.

you could try Midas, Meineke, etc and save some mony that way.

chris

Crispy

Life is hard. Life is harder when you're stupid.

Reply to
Chris P

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.