Hi all,
I hope you can help me here. My truck idles high and smells rich. In addition it goes through a tank quit fast and has little bottom end power..
1993 f250 5.8 180,000 miles.

I did the koeo test amd had to replace the TPS only. No more codes.
I did the koer test and have the following codes
311-
(R)
AIR system not working – Single, Right or Rear HO2S – Air Injection

332
(R,M)
EGR did not open/respond during test or if memory code, did not open intermittantly – EVR or PFE

These are over my head it seems. Any help here is greatly appreciated. How do I proceed?

 

I found another thread about 311 that told about vacuum hoses. I found 1 hose melted. I tried to find out where it went to no avail. It did not have any vacuum pull on it at all and came directly from the intake right behind the throttle cable. I took one of the big hoses off but the intake connection barely had enough vacuum on it to hold my finger to it. I also have a brake light on so I wonder if this low vacuum pressure has any correlation?

 

Vacuum leak would explain your high idle. I wouldn't try to isolate a specific rich cause until you address the egr code.

An absolute crucial tool to have for these trucks is a vacuum tester, which are available at pretty much any part store at an affordable price. You hook the tester up to every line coming off the intake to isolate a leak in the system.

What you can also do with the tester, is check functionality of the egr valve and sensor. Hook vacuum directly to the vac port on the egr valve and confirm it holds vacuum.

There's more to the egr story but I don't want to say a thousand things at once...

 

ok i got the 332 fixed. The previous owner just plugged vacuum lines anywhere they would fit. I found a vacuum diagram and re routed everything to the correct place. Now working on the 311 code. Found that the TAD valve was in two pieces. Got that fixed and the vacuum line was melted so I replaced the line to the TAD solenoid as well. Idle is a lot better. It now idles at around 800 or so for some time then after driving it a bit it idles at 1100 or so until I shut down and re start. Then back to 800 Weird!! Still smell gas but I went from 8 mpg to about 12 mpg so It is improving. I sprayed carb cleaner at every vacuum connection, around the intake bolts, and almost everywhere I could think of but no change in engine rpm. Still testing. Waiting on a vacuum pump tester to arrive.

 

The egr code typically causes drivability issues, so once you get that figured out you'll be in better shape.