Greetings! First post here.

I'm the proud new owner of a 1991 Ford F250 4x4 5.8L Automatic Extended cab! Yay! Estimated to be around 220k on it.

Anyways, I have been having some issues with it, which is probably why I got such a good deal on it.

When it's cold it runs like a champ. When it warms up, it dies on idle or when pulling to a stop. Let it sit for 2 hours and it's good to go again. Weather here is 30's to 40's. There is a slight hesitation when accelerating, especially from a stop. Hit it hard while cruising at 40 and it almost sounds like it's pinging, but more on the minor side with more hesitation. It will cruise at 70 just fine.

Intermittent check engine light. Ran codes off the dash just now and here is what I came up with:

334
(O,R,M)
EVP sensor is/was high – EVR

171
(M)
Oxygen sensor not switching – system was at adaptive limits – Single, Right or Rear HO2S – Fuel control

172
(R,M)
Oxygen sensor not switching – system is or was lean – Single, Right or Rear HO2S – Fuel control

181
(M)
Fuel system was lean at part throttle Single, Right or Rear HO2S – Fuel control

337
(O,R,M)
EGR feedback signal is/was was high – EVR

Before I pulled the codes I replaced the ignition module. I cleaned the IAC, but didn't replace it. No change.

I was thinking of replacing the IAC next, but don't wan't to throw money at it like I'm in congress for a solution that might not work. I'm willing to buy parts for it, but would prefer some more experienced input.

Any help would be awesome!

Happy trucking!
Alex

 

I noticed today once it warmed up my idle was around 500RPM. Any ideas?

Alex

 

Have you measured your vacuum off the intake? Have you checked for Vacuum leaks using some type of spray, like carb cleaner? The O2 sensors on both banks are telling you it's lean. I doubt both O2 sensors are bad, so that leads me to believe the system has too much oxygen. Could be a fuel issue, but i'd tend to head towards vacuum leaks first.

Also could explain a some what higher idle, though I'm not sure it would push it all the way to 5000 RPMS.

EDIT: Just realized I misread your post as 5000 not 500. Please disregard that last sentence.

 

Code 171 and 172 are for the one and only O2 sensor on this model year truck. Both indicate the engine is running lean or there is an exhaust leak upstream of the O2 sensor.

Code 334 and 337 indicate the EGR valve may be sticking open or blocked from closing completely. This could explain your lean codes....

As far as the idle RPM goes, seems counter-intuitive to having a vacuum leak. Usually the idle goes too high. I would start by inspecting/cleaning/replacing the EGR valve before going any further.

 

Randy has much more time in diagnosing these things. I would listen to him before me first!

 

You posted some good input. Just a little clarification on my part.

 

Thanks a ton guys! Cleaned the EGR Valve today (just sprayed the heck out of it with carb cleaner) and it ran flawless today. I will add it too my little book of tricks. Learn something new every day!


I even towed home a new project. This one is going to be a bit more complicated. (transmission is toast.)

 

Thanks for the feedback and auto ****!

 

Nice looking truck! I see you are removing the side trim. What are you using on the remaining glue and do you intend to replace the molding, leave it white or paint on a stripe? I removed my molding and some of the paint came with it and there is lots of glue remaining that I can't get off. I am planning on sanding everything smooth, spraying a little high build primer, sanding again and applying 4 inch wide dark Grey vinyl tape I bought off ebay.

 

Yes, my goal was to completely debadge the sides but I'm having a difficult time getting the factory trim off without taking off the paint.

There were also aftermarket "chrome" strips on it (on the very bottom which is still there and in the "groove" up top) which I just hated- and it came off relatively easy. You can see them in the 1st picture. I used two different sprays. Goof Off and 3M adhesive remover. One worked better on foam remnants, the other on glue residue, cant remember which was for which. Used carefully cause I did feel like it was taking paint off too, just in thin layers. But the aftermarket stuff came off without too much problem. I will do the lower sections as well. Follow it up with a good coat of wax.

There is also some rust on the rear drivers side section under the extra cab window all the way on the bottom. Doesn't seem to be anywhere else. My thought was to bondo it up, and then spray the whole section from the trim line on down with a bed liner type material. Probably wont go with a profressional system, just a DIY. It's an old truck. I'm not going to spend as much as I did on the entire truck for two black strips.

If anyone has ideas on what exactly to spray it with I would be all ears. I'm going for a cleaner look.





Removing the chrome trim





Before trim removal

 

The glue on my truck softened the paint and much of it came off with the molding. I guess 24 years in the desert sun will do that. Surprisingly the paint overall is in good condition on the rest of the truck. Today I began sanding off the glue and soft paint. I will primer and paint just where the old molding was and then apply a nice 4 inch wide grey vinyl tape stripe. I got 150 feet of the stuff on ebay and for now this will be the solution. In a couple years I will paint the truck and fix a couple of dings. You have a nice looking truck by the way.