Lugging at speed/No power at WOT

[ratdude747]

Looked at the 1985 5.0 EEC book... overlaying my test results on the follow though (skipping any EFI steps), both come down to replace/recalibrate the ECU. Not a good test since anything feedback carb specific wasn't tested... but more evidence the ECU is the problem.

ECU grounds appear to be on pins 20/40/60 (Black-Light Green) and 48 (Orange). Oddly enough, the Ground locations listed don't match my truck; The former is at least partially the cable I redid when I replaced the battery ground (C449 replaced with insulated spade terminals). The latter is shown going to the O2 sensor; there is an orange wire attached to the block ground, but it's no where near the O2 sensor; such doesn't have provisions for a ground???. Looks like we have a suspect (and perhaps there actually was supposed to be an O2 ground wire!!!)... All I have to to is find such ground, verify the identity/continuity (probe through check), and figure out how/where it was supposed to be grounded. The schematic says that ground is "In 12A581, Terminal grounded to EGO (O2 sensor)".

Good thing I have spare orange wire... which was part of a long-removed hillbilly circuit I pulled from the truck when I bought it (and used part of such for the radio/CB power wiring). Full circle?

I want to punch something here... and (edit) maybe consider swapping to a 3 wire heated O2 and wire up a heater circuit since such already has sensor grounding provisions. I happen to have a spare 3 wire O2 sensor (suspect old one that came off my ranger (stock Ford) but I sort of suspect wasn't actually bad)... but I'm not wanting to have to fuss with harness mods beyond what I've done (connector swaps/replacements). Not to mention with my mainfold threads being half chowdered it might not be a reversible swap (I think such has more threads though, which would help!). Hmm...

[ratdude747]

Found the old Ranger O2 sensor... I now remember that it seemed cooked at the time (erractic data), although I later got more erractic data which ultimately was worn to death spark plugs causing a random cylinder 4 misfire. Either way, I was keeping it for the pigtail (in case the wire ever got snared and I wanted a cheap way to fix it). Also, it's a 4 wire... which isn't a bad thing. Also has seemingly more threads, which for me, is also a very good thing. If I were to use it, I'd get a mating plug; the plugs used on the ranger were good to work with and that means I have plug and play ready replacement.

For those playing at home, this ranger O2 i have is part number F48F-9F472-BC. Seems to be a somewhat common part. OE'd by Bosch. I feel cheap for considering using it... but heck, I have the part in hand, and it's probably fine... but it is an old part from 1994/1995. Hmm...

Edit: Regarding the heater circuit: Y'all think the 1.5A or so of heater draw is OK to add to the EEC Power relay output? It's powered off a fusible link to the battery.

Also, The matching connector is available locally for $20 (not at the store I have a $20 credit though :( ) or at rockauto for $7 + shipping.

I'd prefer to fix the ground the OE way if possible... this heated O2 idea is my plan B (which isn't too terrible considering I happen to have a used "compatible" sensor in hand).

Much later edit: Another idea: Pull-A-Part a sensor and plug... with lots of wire. $11 for the sensor, and the plug they might even toss for free? (if not , add $2-$3). I'd have to get the afternoon off to give me decent time to look for stuff (and to get the tool box packed)... but given my 15 hour self-imposed marathon yesterday, I'll have a shot.

[Gary Lewis]

Wow!  So many issues.  What is your plan then?  Pull-A-Part?

I do think the relay will be quite adequate to heat the O2 sensor.

[ratdude747]

Went to pull-a-part yesterday... Picked up the plug (with 12" of wire). Also found a 1986 F150 with 300. ECU was easy pickings (harness and cluster cover gone), so I nabbed it. Can't remember if it has an automatic or manual tranny; the ecu is a newer 1985 part number. Had I brought wrenches and not been out of time, I would have also grabbed the carb... although between the burnt feedback wiring (down to raw copper), smashed electric choke can, and being filthy and sitting open with no hood, I'm not calling it a huge loss. I can always come back and pull it later this week if it's worth getting another carb core to rebuild.

Wired in the O2... had to retape a lot of the engine harness (due to the O2 GND wire moving to a different branch). Luckily there was a EEC power wire for the Feedback solenoid and an ECU ground for the Bowl vent solenoid in the branch I was in, so I actually had to use zero additional wire!

That said, no change in performance or self test results. KOER 23 and 41... Will have to see if the O2 is working... and I have the spare ECU to swap if I want. Did they have different ECU turnings back then? Any likely issues if I try the 1986 ECU? (came from a "sport" package truck, if that matters).

[Gary Lewis]

There were different part numbers on the ECU's, so there were differences.  But I can't tell you what they are.  However, the pinouts didn't change, so I think it would be safe to try the other ECU.

[ratdude747]

Tried the '86 ECU for kicks... She's fried. Several burnt tracks... that burnt feedback solenoid I noted took out a power diode in the driver circuit (blew and shorted). Replaced the capacitors and blown diode, and bodged the tracks together... and it actually worked! Sort of. It was doing things (and was entering test mode on command), but no codes to the reader. And when I shut her down, I smelled magic smoke... I'll return it under warranty tomorrow if I get out of work on time.

I also did a quick test on the O2 sensor... nothing. She's DEAD. Oh well. I'll fetch a new one and repeat the test.

[Gary Lewis]

You are having so much FUN!  WOW!

So the O2 sensor is dead?  That might be a problem.  Did it get fried?

[ArdWrknTrk]

I know you like to repair electronics but have you ever considered getting a relay, an HEI and a YF clone?
You'd probably be all in for $150, and ALL this would be in your rearview mirror as you motored away.

[ratdude747]

Honest answer:

Yeah, and so does "everybody". It's kinda why I'm not a huge 302 fan (or heck, the freaking LS!) for the most part... been done so many times that "special" doesn't exist any more. Not that (in both cases here) it's bad, or doesn't work, or isn't a good option for some people, but it's not my style or desire. I enjoy building things that aren't the usual trendy thing.

No offense intended... I get flack like this on pretty much every build I do for similar "it would be easier if you did X like everybody else" rationales. Not just trucks... computer builds and even my choice of homes (and how I chose to furnish/adorn it) has seen such at one point or another. I'm weird!

If the electronics were already stripped or there was some reason that it absolutely wouldn't work... then fine, back to the stone age we go. Although at that point, I'd probably be saving up for an offy intake and 4 barreling it. I've read it can match a 351 if built right (4 barrel + better flowing exhaust) while keeping most of the 300's fuel economy. This isn't merely a form of essential transportation, so I'm not inclined to do something just to make it run...

[ratdude747]

Fried? Nope. Remember that it was in the junk pile... I think I do remember the sensor going completely dead and that's why I replaced it. I kept it for the pigtail apparently.

Not a huge loss. I would have grabbed one or both O2's off the explorer I got the plug from (both upstreams were virtually new looking)... but I wasn't able to get them out and I hadn't thought of removing the studs of the Y pipe or chopping it with a hacksaw. Maybe I'll fetch them when I return the ECU? The tranny was already pulled so I had good access (but a floppy tippy engine that I couldn't torque on)

[ArdWrknTrk]

I understand, and I'm not giving you "flack"

We here are all about 'Make it Yours', and do our best to be supportive of that position.  

But the feedback system was sketchy when it was new, and NOS parts are challenging to find.
Many convert to the DSII system, and some -that are doing it on a shoestring- go with the path of least resistance.

Oh, and I want to correct my previous post.
The $65 HEI I was looking at was for the car I-6, the one that fits the 240/300 is $110.  

Do you have the catch code from your original module?
Maybe one of us can turn one up?
David seems especially good at that, and he has a deep knowledge of these engines.

[ratdude747]

I know a lot of people do DSII... again, one "hobby" of mine is trying to make rejected "overcomplicated" technology work. My AV rack at home has S-VHS, Laserdisc, and HD-DVD included (and a beta VCR in the garage) if you want another example.

I'm not going condemn the ECU until I have a verified working O2 sensor...

[ArdWrknTrk]

You sound like you'd really enjoy the Technology Connections YouTube channel.

[ratdude747]

"Traded" the bad ECU for the carb off that truck and one of the upstream O2's off the explorer I got the pigtail from. The carb is for parts; it's a bit rough (lots of loose screws the intake was full of water and rusted the bottom of the throttle plate) and has no TV cable provisions.

The new O2 sensor is working and at idle I'm getting 0.88V between the O2 signal and ground (RICH!) at the ECU plug... but KOER is still giving me 23 and 41. Something isn't happy with the ECU; Almost seems like an analog input issue (since both faults are for analog sensors), but I'll need to do more debugging on the ECU board itself to see.

The 1986 and 1984 ECUs had very different packaging and board designs; the 1986 was cased in cast aluminum (better heatsinking) while the 1984 is cased in stamped sheet metal. The 1986 was OEM'd by motorola, while the 1984 one didn't have any OEM marks that I remember (edit: it's probably OEM'd by toshiba, as most of the chips are made by them. They and motorola were the 2nd sources for the Intel 8061 controller made specifically for EECIV, so this makes sense). Hence the different part numbers.

1984 ECU stickers:

[ratdude747]

Pulled the board... did some reverse engineering.

Still no ID on the mystery chip... although I have a rough idea of what it does... and found an issue. The issue is that the chip is powered off the 5V supply inside the ECU (the V ref used by a lot of sensors), but is grounded through the O2 ground. Since the O2 ground isn't tied to the main ground any more (Unless the O2's case is internally bonded to the sensor ground), that chip isn't able to get power. I'll probe my O2 sensors to see what's up. If it isn't bonded, I'll need to jumper the heater ground to the sensor ground at the plug (for noise rejection reasons, the jumper needs to be as close to the sensor as possible, why a separate ground exists in the first place); if it is, then my trashed threads in the manifold are probably causing a weak connection, which is likely the issue I've been fighting all along. Yay helicoil... and/or I'll bond the grounds at the plug anyway. I don't like creating ground loops (again, signal noise reasons), but if that's what I need to ensure I have solid grounding, so be it.

Edit: Not case grounded. Looks like I have more harness work to do...

[grumpin]

Good find!

[ratdude747]

We'll see...

In the mean time, I've hit another snare. went to unplug the O2, and it popped out of the manifold. No more good threads that the sensor can access :(

The good news is that repair kits exist. The bad news is they're wicked expensive. But I did find this:

https://www.ebay.com/itm/Helicoil-4833-Oxygen-Sensor-Thread-Repair-Kit-M-18-x-1-5/164233766665?epid=1368619882&hash=item263d186709:g:A7cAAOSwztRe2sAD&autorefresh=true

Threw an offer on it, but honestly I should probably pony up and nab it while I can. Edit: Found this: https://www.amazon.com/Thread-Kits-1218-500-Repair-Kit/dp/B0025PQITU. I get free 2-day shipping through my wife's prime account... If the offer fails, I'll hit that instead.

Beats replacing the manifold... that EGR tube is likely to be a PITA, and I'd have to redo the choke tubes again.

[85lebaront2]

I've run into that on the 4.9L FBC and 1985-86 5.0L EFI engines, damn cast iron gets very weak after years of heat/cool cycles, Thread is same as a 14mm spark plug and can be Helicoiled.

[ratdude747]

It's the same as M18x1.5 spark plugs. Which is what those kits are for.

The threads got messed up beyond what a thread chaser could fix when I replaced the O2 sensor last year. Tried tapping it, which didn't help... but there was one thread left that the stock type sensor could reach with the copper washer removed. That thread popped today.

---

Was able to set the sensor in hole and test it at least... getting around 1V at idle (not fully warmed up, so richer is normal?). Another KOER test still gives 23 and 41... Either the ECU has an internal issue I'm half helpless to fix without an ECU replacement, or I am doing something terribly wrong.

[ratdude747]

The plot thickens.

Poking around the calibration lists on the site (my cal sticker had faded to white when I got the truck, and was removed when I painted the valve cover).

From what I can tell, the correct ECU was one the "ZB" ones... mine is a "ZA" (a Z1A, to be exact), which only shows on the list as a 1985 part (number 440, the "ZB" is also listed as a valid number).

Very odd... either this ECU isn't original, or ford's cal lists are lying (or it's a weird transition between years build?)

Edit: Rockauto (via cardone) lists the ZA and ZB as the same thing... one common part, which they have in stock ($125 after core return).

Edit: From what I can see, the E5DZ 12A650-VB from 1986 (300 AOD RWD normal emissions, list #471) is also compatible to some degree. The only other different part on the list is the carb itself... and from what I see on my 1986 carb, there isn't much different.