i have a 93 f350 with a 460 5spd that has been getting the check enging light on so i tested it on it gave me these codes for the KOER test...412(high rpm control),172(right side lean),538(insufficient rpm change). Wouldnt the 172 be the oxygen sensor(hego sensor) down below?


Yesterday i did fix the exhaust leaks and now it sputters. I did have a leak on the left side of the motor to a vacumn with a green and red hose fisttings and the pipe fitting and the passenger side manifold gasket was bad.

I did notice that the oxygen sensor was pretty corroded and brittle around the wires on the top of it..

It has been smelling slightly rich for awhile though as the light has been on for a couple weeks..


Any ideas?

 

DTC 172 can be caused by an exhaust leak. Holes in the exhaust let gases out as well as allow air in. Now that you have fixed the leaks, disconnect the battery for 15-30 minutes. This will reset the PCM (engine computer) back to default settings. The computer has most likely dialed in a bunch of fuel in the long-term fuel scalars thinking you had a lean condition.

Good luck changing out the O2 sensor if it comes down to that. I never was able to break mine loose on my '92 F350. I ended up replacing the entire exhaust because everything else was rusted solid or completely gone.

 

No that's not necessarally an O2 sensor code, it indicates the computer thinks the motor is running lean but if you can smell that it's actually rich then the problem could be elsewhere, check fuel pressure and for a possible faulty fuel pressure regulator(leaking fuel out the vacuum line). If the O2 sensor has not been changed recently then it may be a good idea to put a new one in anyway but it may not clear the problem.

 

i checked and i do have great fuel pressure and you can smell rich exhaust while driving and idieling now. I need to check the cat too to see if it is plugged as it sputters now.

 

so far the truck is extremely fummt to ride in when ot os running, and makes me think something is choking it out, but it does start right up and stay running fine, just sputters while driving, especially in 4 and 5th gears.

 

Change the O2 then and clear the codes.

 

Could you quantify "great fuel pressure"? Even with correct fuel pressure if the regulator has a tear in the diaphragm you will be sucking in fuel just as Paul alluded to earlier. Did you pull the power to the PCM for 15-20 minutes to force the PCM to use default calibrations as I suggested? Did you check to see if there are anymore stored error codes?

 

Change the O2 sensor! As it ages it cannot cycle enough times for keeping fuel trim proper. It gets lazy as we call it. It should be switching rich lean 10 or so times a second. Any kind of an exhaust leak in front of the sensor will give a lean signal and the sensor will be trying to richen the mixture, this in turn will cause a cat failure, as in plugging....................There's no real guidelines on when to change the sensor, but if it has a 100,000 on it, do it. That, along with plugs every 20,000 or so will help your mileage.

 

am i am still new to the fords, and unsure what the fuel regulator and pcm look like.

i got lucky and the o2 sensor came right out as the truck still looks new underneath(60,000mile truck).
Now im going to take the cat off to see if it is plugged.

I did unhook the battery overnight and it was still the same thing this morning.


Is there a way to post pics on here on a couple things to show where i welded on the motor to diagnose what they are called? The one on the left of the throttle body has a green vaccumn line to it, a white cap with a black wire connector on the side of it and a pipe that connects to the back of it to the left manifold. The line broke behind the threaded nut so i rewelded it back on since i didnt want to mess with changing the manifold section as it might break there instead.