Following........

5.0L V8: 1986–87 Truck and Van - z To adjust idle speed:

1. Disconnect the battery for 3 minutes to erase the current idle control program from ECA memory. Turn the throttle stop screw in (clockwise) 1 turn.
2. Reconnect the battery, place the transmission in neutral or park, and run the engine at
1800 rpm for 30 seconds.
3. Place the transmission in drive (AT) or neutral (MT) and let idle speed stabilize.
NOTE: i Adjustment must be completed within 30 seconds after returning to idle.
4. Back out the throttle stop screw (Figure F050-17 on page F167) to adjust idle to 600 ±20, (AT) or 700 ±20 (MT) rpm.
5. Stop engine and repeat steps 2, 3, and 4 to verify minimum idle speed.
6. Stop the engine and disconnect the battery for at least 3 minutes

http://beta.askatech.com/askatechliv...track/f050.pdf

"Vacuum/EGR leaks don't pair well with a good idle."
"Always perform scheduled maintenance prior to troubleshooting"

These trucks are so old and usually have not had all the parts replaced they should have in accordance with the maintenance manuals.

O2 sensors can start to fail at 30k mi. – I suggest you replace it, the ECA uses that voltage reading from the O2 sensor to make decisions for controlling other devices.

 

O2 sensor is new, but I'm considering replacing it incase I got a bad part. I appreciate the info!

 

You might be ok with it, but you get what you pay for with sensors for the most part.

I wouldn't put 100% faith in those early 80's computers either. Best of luck.

 

Update again:
Played with the timing some. Got the truck running better, has a lot more power now.

Truck is still running rich and throwing a lean code.

Truck is randomly dying, but restarts immediately. And is throwing a CM code 18.

I'm working on both issues, will update when I have a solution or more info.

 

Any others in KOEO or KOER?

 

It's throwing a code for always lean (can't remember the number) KOER, but nothing KOEO.

 

My Bronco had been sitting up a while before purchasing. I went thu all kinds of problems trying to diagnose why it didnt run right. Every time it thru a code with something else not working, thought that fixed it.

Your description above caught my eye. "running rich and throwing a lean code" That was one I got over and over. Already swapped out ecm's changing sensors, nothing worked.

I have a Jeep Comanche with old renix on the 4.0 motor. It was also doing the same thing. One common thing between both of the motors is the idle was not consistent. They both shared the same Bosch style injectors. In fact I had swapped out the renix to Bosch style from one of my Bronco projects earlier hoping that would help out of the Jeep.

So then I had the old injectors from Bronco above in the Jeep. I replaced the Bronco injectors with a set from an HO 5.0 sitting in storage.

Long story short, I finally removed injectors and borrowed a SnapOn pulser from a mechanic I know.

I pushed lacquer thinner under pressure thru the injector while pulsing until it had a nice high sounding buzz and the dirty gas varnish was washed out.

You will know the sound injector is supposed to make when its working correctly.

Did this to the Bronco and Jeep. It fixed everything. Motor fires right up without any delay and idles down in a few seconds. Neither had done this before. Got rid of any hesitation and all codes were gone.

Dirty injectors can cause major issues that will throw all kinds of different codes that changing every one of the sensors will make no difference at all.

I remember getting a code " Bank 1 lean". That was the tell tale the injectors were the problem. Sticky sluggish and restricted injectors are not going to diagnose from throwing codes. But clean working ones will stop a lot of codes.

One other thing that bothers me. Mud and water in the ecm is a red flag too. You need to trace each wire from the pin out to where ever it goes and check for continuity. Especially the grounds.

 

Post that code number when you get the chance.

 

Code was 41 KOER, 18 CM.

Swapped the wiring harness, showing same codes.

Ran it down the road some (it died twice), when I got back to the house it was throwing code 44 KOER, 18 CM, and system pass KOEO.

 

Understand, did you swap the O2 sensor? Did the code change, when the sensor was changed?

Have you adjusted idle per instructions?

Check your hoses for leaks on your smog pump hoses, check your Diverter and Bypass valve vacuum connectons. Do you have a vacuum gage? Check the EGR vacuum, you should only have vacuum at the EGR when your RPMs accelerate after the engine is warmed up. Should be no vacuum at idle at EGR vacuum connection. You will get about 5 Hg at the EGR at about 2K RPMs at the EGR vacuum connection.

Your engine should be pulling a steady 10-15 Hg, have you checked your engine vacuum?

 

"wiring harness' What harness are you speaking of?

 

I replaced the wiring that goes from the computer to the engine. I had a spare wiring harness, figured I try it.

Truck is idling fine, has plenty of power driving down the road. Not throwing a lean code anymore, but is glowing the mesh inside of the cat like it is still running rich.

Only codes I am getting is 44 KOER (which is the smog pump if I'm not mistaken, and it's not hooked up)

And 18 CM after the truck dies. It isn't dieing as often as it was when I started.

. I've replaced the ICM multiple times to no avail.

My plan for the time being, is probably to tear the wiring harness I took out apart and check for bad wires/connections and fix them.

 

Ok, i must have missed where the smog pump was no longer connected.....

 

I told you this in Post #2 last January, dude, that CM 18 is a serious error... you may have gone down that path already the past 6 months and it's maybe contained in this thread,I don't remember exactly where this all stands (just that it's taking a long time) and that CM 18 is a big deal!

That's the Ignition Diagnostic Monitor, it runs on Pin #4 at the computer harness and connects the computer to the ICM at the distributor:





It's got a 22KΩ resistor in it, too, and THAT needs to be there, too.

That is an extremely critical wire, it's how the computer controls the ignition module and necessarily must be in correct working order for the computer to be able to talk to the ignition.

I cannot say definitely that this is your ONLY problem, but it is A problem that necessarily MUST be fixed before trying to diagnose any further - too much fuel, whatever's causing your cat-burning symptoms.

 

I see also last February I had questions about this being the right computer for the truck... where do you stand on all that? I didn't go re-read 4 pages and six months worth of posts.... but all this stuff is critical if you want to have it pass emissions and make it drivable on the street.