Interesting airbox relocate. Anticipating some deep water crossing?

Hoping this will solve the problem. Good luck!

 

That's actually the stock airbox and location for the 86. I probably shoud've pulled the 87+ airbox and the 95/96 topper for it, but was too worn out that day to bother.

So far the IAC cold start up issue is definitely gone (THANK GOD) and the stall that often happened immediately after a warm start is also gone.
I've got a bit of rough running, some missing, and some idle flutter, so I need to dig into that a bit before I can decide if my issues are fixed. On a good path, though!

 

So I'm doing pretty damned good, and I think I can claim that the issue is SOLVED!

Just to sum up for anyone killing themselves with the same issues:

For the Code 41, the problem was that my larger exhaust and aftermarket headers would not let my 86's UNHEATED oxygen sensor heat up enough. The fix is to upgrade to a three or four wire HEATED oxygen sensor. This only takes a little while to do if you already have a KOER 12v fuseblock set up for accessories.

For the lack of power, especially on the freeway, I suspect my big issue was that my AOD throttle valve cable going to the transmission was not set correctly.
It had about a 1/4"-1/2" of slack in it, which I think was causing the transmission to keep my RPMs a little too low. Since correcting it using the method below, I find that the transmission holds the gear a little longer and doesn't put me into that 302 pocket of no power (~1200rpm).

The MAF swap definitely feels good, I can't claim hard numbers for power/MPG but taking it for a test drive last night felt great. Definitely more power. BIG changes are throttle response is much better (although that might also be the AOD getting fixed) and that crazy rev startup problem I had are gone. I also don't have the stall immediately after a hot start. I don't know if I had an issue with my old ECU but I'm real happy now.

My last issue is I have a Code 311 (thermactor system inoperative) and a Code 332 (EGR - insufficient flow). I had the thermactor one before the swap, and I've read that the 332 can be a symptom of the 311, NOT necessarily a separate issue. But that's an easy one, relatively speaking.

 

I have the code 41 as well. Mine does the same annoying cold idle high rev, A quick blip of the throttle will bring it down if I dont wanna wait for it to come down on its own. It will stall sometimes when going from reverse to drive or from either to neutral. It will also hold a bit of a higher idle on warm restarts and will eventually taper down. It has plenty of power and seems to run fine otherwise, But it drinks gas and I mean bad. I'm getting ready to install some shorty headers so I'll attempt to deal with it then. It needs valve cover gaskets and the lower intake resealed, it's seeping oil out the front. I'm doing a double roller timing chain and possibly a very mild cam while its apart. If it aggravates me to much I'll carb swap it right now.

 

Yep, same here - blip to bring it down, the stalling, all that.
Odd thing is mine only started doing it only after I got a new engine put in (and continued with the new engine's replacement too). I assume it's something that wasn't hooked back up, but damned if I can find it. Swapping to MAF fixed it, and seems to be a smart upgrade if you're planning on other mods anyways, so I definitely recommend it. If you do your research you can probably put a MAF kit together for less than $200, but I found the fiveology kit really well put together and it was worth it for me not to drag the project out. The documentation they provide is also very well done.

 

Checked out that Fiveology kit. Looks pretty straighforward and reasonable value too. MAF EECIV stuff just does not happen in the salvage yard very often.

Interesting that you are getting 3 digit trouble codes. I assumed the Fiveology kit would use something like an A9L ECU, which is a bit old for 3 digit codes. It's my understanding that anything before about 1991 only supported 2 digit codes. You wouldn't happen to know which ECU the Fiveology kit is using?

My favorite set of EECIV code retrieval instructions and code list is at this link.

EEC IV Self Test hookup

Anyways, always glad to see a happy ending. Enjoy your Bronco!

 

I'm not sure which computer is in there, I'll check the documentation today when I get home. I get electric fan unglugged codes and can-p unplugged codes, neither of which is on this Bronco, so I suspect it's a Mustang or similar. 563, 564, and 565.

Only real code left is 332, EGR insufficient flow. Rough idle too. Everything in the EGR system checks out perfect except the EVP. The circuit is good and the EVP fails resistance tests so I'm replacing that today. Kind of annoying since I replaced it in 2016 with a Motorcraft unit for $86! I'm not cheap when it comes to my truck, but I sure hate throwing money away.

I decided to run down to the junkyard and pick up an 87+ airbox after all since I'm not super happy about the amount of adapters needed to make it work with an 86, nor the big bend in the flow.

Franklin, can you change the title of this thread to "Code 41 - SOLVED!" to make it a better resource for others?

By the way, thank you both for your excellent input on this. I've done LOTS of reading and I betcha this turned out to be the best Code 41 resource around.

 

I am not moderator of this forum, so I can't change the title.

For your EGR problem, are you sure the ECU you are using is for the EVP type system? Ford used another system also, where it measured the back pressure in the steel line to the EGR. These commonly fail also when a free flow exhaust is used, since there is less back pressure and the EGR doesn't have enough flow to work.

 

But I am, and I did.

 

Thanks.

I figured that one out. I am using an EVP ECU, confirmed via 94-95 diagrams (It's the TCM0).
I found one big thing that wasn't covered in Fiveology's instructions. What I've found is that the 1986 has two EGR solenoids. One for "control" (vacuum to EGR) called the EGRC. The other for 'vent', called the EGR Vent (I think). On the 1994 Mustang, which is what my new MAF EEC is, there's only one EGR solenoid, called the EVR. Fiveology said nothing about this.
Here's the mustang EVR next to the Bronco EGRC and EGRV.


On a hunch, I installed a 94 Mustang EVR in place of my EGRC, and the 332 code is gone!
In detail, here's the steps:
"I removed the old Pin 33 Vent Solenoid, then moved the EGRC Solenoid line from Pin 52 over to Pin 33, which is where the Mustang EEC wanted to see the EVR Solenoid. Then I pulled both of the old solenoids out (EGR Control and EGR Vent) and put the new EVR Solenoid in the place of the EGRC. Didn't even need to change the connector. Cleared codes, drove her for a bit, pulled codes again, bam! Code 332 (EGR Flow Insufficient) totally gone. I really wish Fiveology included that in the documentation because I wasted a bunch of time troubleshooting the EGR setup. The solenoid swap took all of five minutes."
I suspect that I might have been able to just reuse my old EGRC in place of the EVR and make the necessary changes to the EEC connector, but I'm not positive and to be honest just don't have the goddamn patience at this point.


I also installed a Canister Purge (CANP) valve between my fuel vapor carbon canister and the throttle body. Most Fords have them, but the 1986 doesn't. The new 1994 EEC was expecting one, so I pulled a CANP solenoid out of an explorer or something at the jnukyard and wired it in. One side goes to KOEO positive, the other side goes to Pin 11 on the EEC.
Installed, codes pulled, and my code 565 "CANP Failure" is all gone. I think it cost me $3.


I'm down to one important KOER code (311, thermactor system fault) and I had the 86 equivalent of the same code before I started this process (Code 44). Currently working on that one but I'm just about stumped. I'll start a new thread for that one for the sake of organization. (link here)
I also have a code 452 (VSS Fault), which so far seems to be due to the fact that I have 8.8v on the VSS harness with the sensor unplugged! I'm assuming it should be 5v. What's odd is my reference voltage pin on the ECU is 5.0v bang on. I gotta inspect for shorts or anything in the line.

 

Andrew, I give you a lot of credit for what you have done to get the codes gone.
If that was me I am pretty sure I would not gone that far to fix it.
I guess a lot has to do with not fully understanding that system?

Nice job
Dave ----

 

Thanks Dave. Hopefully the steps help someone unlucky sap in the future. I will say that I started off not knowing nearly this much... Never tested O2 sensors, never messed with the ECU harness, etc. Necessity is a great teacher.

 

You went through some of the same stuff my son went through on his 1986 F150 5.0L AOD 4WD. part of his issue was an aftermarket TPS that would not go below about 1.1 volts, at this point the EGR system kicks in, vacuum valve opens and then the vent valve opens and the idle would go up and down almost constantly. The AOD throttle adjustment can be very touchy on these as I found out on both my son's truck and my Lincoln Town Car. I had actually acquired two extra 1986 EFI harnesses due to the crummy condition of his, and built a little bank fired LED monitor so it blinks as the two banks are pulsed.

 

Oh that's a great idea. I wish I had some solid indication as to what the solenoids are doing while I'm driving, this would definitely help. In my case I had issues with them, they passed all of the Ford pinpoint tests, electrical, vacuum, etc., as did the ECU and harness. I swapped the solenoids anyways and I think the issue went away (still gotta pull codes again). Super frustrating.

 

abaldwin, can i tell you that you are my hero! i'm having problems with no power going up hills in my 1990 ford e350 econoling 5.8. i'm not quite done with all of you and notenoughtrucks comments yet but dang, you guys are good. i'm struggling along because i'm not a mechanic but i've learned a lot in last month and finding this post was gold. i know this was a couple of years ago but i strangely feel like i now know you guys and hope you're doing well. much love))-barbie