rough idle and stalling during warm weather
 

Hi peoples. I'm new to this discussion board and I have a problem I'm hoping I can get some help figuring out. I have a 93 F 150 with the 5.0. My problem is a rough and surging idle. I don't have the problem as often when the weather is cold. (I live in north east Ohio) Once spring and summer get here the problem gets very bad. So bad that the engine stalls all most every time once the idle kicks down after starting it. If I keep slight pressure on the gas pedal I don't have the problem so I replaced the TPS. Which didn't help. I tested it according to the directions in a Haynes manual and I have the proper voltage, at the right times. My CEL comes on from time to time as well, but only when the weather is warm. I've tried having a friend pull the codes but they can't get their machine to communicate with my vehicle. I'm at a loss. Any ideas on what the problem could be? Maybe an O2 sensor? I read a post on here where someone had a rough idle and an intermitent CEL and he replaced the O2 sensor and his problems went away. Any help would be greatly appreciated. I tow my bass boat with this truck and having it stall at the ramp is getting to be a pain in the you know where. Thanks in advance for any help you people can offer.

Have you cleaned the throttle body recently? When was the last time it had a tune up?

http://fordfuelinjection.com/?p=13

Time to pull out the paperclip.

Congratulations on randomly throwing parts at a EEC IV truck without knowing what is wrong. FAIL.

Pull codes so you know where to start.

I did a "tune up" ( cap, rotor, wires, and plugs) about 14,000 miles ago. Haven't cleaned the throttle body, but I do run fuel injector cleaner through it once a year. I did a KOEO test and pulled these codes. 22, 12, and an 11. According to the codes list I'll check the MAP sensor. (code 22) And I see that the 11 code means the system is OK. But the 12 code has me baffled. What the heck is an Idle Speed Control motor? (code 12)Any help on what the heck that is, where it is, and how to check it would be greatly appreciated. Thanks to everyone for responding, and a special thanks to Skatebro for the web link. I didn't know you could do a self test on the EEC system that easily. I'm a gear head from way back in the days of points and condensers, this electronic stuff is Greek to me.

A code 12 is not part of the KOEO test, you only get a 12 with the KOER test.
If you get a 12 then it means the IAC valve is not controlling the idle during the KOER test.
The IAC is operated by a solenoid and solenoids are not part of the KOEO test.

By the way the KOEO is just a voltage test to see if all the sensors and relays voltages are with in a range (high and low) of given voltages.

A 12 code isn't part of the KOEO test? Maybe I read it wrong then. I used a volt meter and watched the needle move as described in the Haynes manual for 1980 to 1996 trucks. I ran the test twice to make sure I got it right, but evidently I didn't. I'll run it again, maybe I missed a needle movement and it was a 13. I see that, that code will show in a KOEO test. Thanks for your imput. I'll try and get it this time

You most likely have a vacuum leak, a TP sensor flaking out, bad MAP, low fuel press., etc. Hard to say.

It may be easier to watch the CEL then the meter.

When I did this I went to my local auto parts store and bought one of those $30 code readers that beeps and flashes a light. No guess work and it is the same concept as watching the light or the needle.

Just something to think about.

For $30.00 you can get one that reads it out digits.
The EQUUS #3145
http://i54.photobucket.com/albums/g9...CodeReader.jpg

Thanks for the ideas on the code reader guys. It seems a whole lot easier than wondering if you missed a flash or needle movement. Actually I just went to Amazon.com and purchased the EQUUS reader that was suggested. I even ordered the extension wire that came with it. I've had this truck since 97 and I want to keep it around another 12 years. If the body doesn't rust off that is. lol

Once I get the engine back to running right I'll be tackling my front hubs for the 4 wheel drive. I popped one of the automatic hubs this year and at the price the dealer wants for new ones I'm going to be putting some manual hubs on. Other than having to buy a hub conversion kit is there anything else I need to look out for that the repair books don't tell you when doing a swap like this? Thanks again for all your help, and ideas guys. It's very much appreciated! Check back with you later.

Make sure you do all of the tests with it and not just the KOEO.
Read your CM codes, and do the KOER self tests with it.
You can also check all of the solenoids with solenoid test by using the throttle at the end of the KOEO test if you want.
You can also do a wiggle wire test with it.

Haynes manual and a code reader, sounds like you're on your way.

Just don't beleve what the Haynes manual and the on-line code charts say about the codes. As they are not complete for each year truck and are somewhat miss leading.
Post the codes back here and what test they were from and we will tell you what they mean.