1987 F-150 XLT Lariat 4x4 302

I have been having some idle and power under load problems. I ordered a code reader last week and it come in yesterday. I pulled the codes when I got home from work this afternoon and here are the results.

KOEO - 11

CM - 29, 33

KOER - 13, 33, 41

Where do I start with the KOER codes?

 

Possible vacuum leak for the EGR, which would leave the EGR inoperative and the idle high.

 

Thanks for the response Sean.

I was thinking it might be a vacuum leak and will start checking hoses.

 

Replaced most of the vacuum hoses, cleaned the EGR. Unhooked the battery last night to clear codes. Drove it to work today and pulled codes when I got home. It is running a little better. Here are the codes from to day.

KOEO - 11

CM - 29, 33

KOER - 13, 44

 

Still seems like a vacuum problem. Is the idle high?

 

Yes, real bad at start up. It seems to have a low idle after it gets good and warm, but then again, I don't think I have ever heard it idle right since I have had the truck.

It still has the surge/skip problem (not as bad as it was), and the power seemed to be better under load.

I still have some vacuum hoses to replace this weekend and I need to find a replacement air filter inlet tube so I can get the vacuum hoses hooked up to my air filter box.

For the code #44, I just replaced the smog pump two weeks ago, so I don't think that is the issue. I do have to replace the vacuum line going to the the air bypass valve on the smog, so maybe that will fix that.

 

The computer doesn't see the thermactor or the valves that operate it. The only thing the computer sees that gives thermactor codes are the control solenoids.

 

After replacing all the vacuum hoses, my truck is almost running normal. It still has a very small skip in it some where.

Anyway, I pulled the codes again after doing a test drive of about 15 miles this afternoon when I finished.

KOEO - 11
CM - 29, 33
KOER - 12, 13, 41

Questions:

1. Would I not get the code 33 in the KOER test if its in the memory? I had the neg battery cable off since yesterday while replacing the vacuum lines, so the CM should have been cleared.

2. How can I have a Low idle (code 13) and a High idle (code 12)?

 

See if you are getting any vac flow from the EGR regulaor to the EGR valve at idle. there should be none. If there is, it is keeping the EGR valve from closing completely (#33) & causing an always lean (#41).

Your code behavior is kinda wacked. C/m's should have cleared. If anything, the #33 should have cleared in c/m, & returned as an active.

Noted in c/m & not active suggests that sensor input is locked out. But should have reverted to an active & no longer a c/m after the KAM was cleared.

12 & 13 in the same scan is wacked too. Was the engine idle surging?

When 02's pooch, it's usually on the "always lean". How many miles on yours?

When you disconnect the battery, carefully remove the positive cable. Wait 5 mins. & momentarily touch the loose pos cable on the neg terminal/post, before reconnecting.

 

I will check this in the morning


It might have been surging a little. I don't pay to much attention to the idle when running codes because the reader will idle up the motor when it starts in test mode.


Over 300,000 - I am sure the o2 needs to be replaced, I was just trying to clear up the other codes before hand.

I am going to clear the codes again tomorrow and run them again after a short drive. I will post the findings when I get them.

One other thing, I did notice that my exhaust is leaking before the o2 sensor. Would this cause any of my problems?