Return of Code 31...

[85lebaront2]

Thanks Bill! I've seen that post as well. That is on the list of things to try, but the resistance between pins at the EEC is what has me worried (DD6 on the image I posted above).

With that resistance, I'm thinking a trace on the board is partially blown, a new bad cap on the processor board, etc. I don't think the two would be correlated, but I'm not assuming anything at this point!

I'm not sure if a BOB is really needed, but since we are geeking out on EEC-IV, this seems like a good deal, doesn't it?

https://www.ebay.com/itm/296017000421

I think everything is there as far as cables/adapters...

I have an EEC-IV breakout box, you can borrow it for the cost of shipping. I can probably ship in the case it is stored in.

[ckuske]

I have an EEC-IV breakout box, you can borrow it for the cost of shipping. I can probably ship in the case it is stored in.

Thanks! I appreciate the offer.

I will give this new (to me) ECU a try for the next couple days. If/when something manifests itself again, you will hear from me.

Thank you for the offer Bill, this is what makes this forum so great.

[ckuske]

Thanks! I appreciate the offer.

I will give this new (to me) ECU a try for the next couple days. If/when something manifests itself again, you will hear from me.

Thank you for the offer Bill, this is what makes this forum so great.

Ok, so I have a confession to make. I actually ordered two ECMs. A "cheapie" from eBay (as-is, not listed as a reman etc), and one reconditioned one from BSE via Autozone.

I just plugged the eBay one in, KOEO is clean! (Code 11) The Autozone one is coming today as well, I'll try that one next with the KOEO test.

Then I'll start the truck up. I'm being very methodical from this point forward, I'll update each test in a new reply in this thread...

[Gary Lewis]

Ok, so I have a confession to make. I actually ordered two ECMs. A "cheapie" from eBay (as-is, not listed as a reman etc), and one reconditioned one from BSE via Autozone.

I just plugged the eBay one in, KOEO is clean! (Code 11) The Autozone one is coming today as well, I'll try that one next with the KOEO test.

Then I'll start the truck up. I'm being very methodical from this point forward, I'll update each test in a new reply in this thread...

Yippee!!!

[ckuske]

Ok, so I have a confession to make. I actually ordered two ECMs. A "cheapie" from eBay (as-is, not listed as a reman etc), and one reconditioned one from BSE via Autozone.

I just plugged the eBay one in, KOEO is clean! (Code 11) The Autozone one is coming today as well, I'll try that one next with the KOEO test.

Then I'll start the truck up. I'm being very methodical from this point forward, I'll update each test in a new reply in this thread...

The Autozone/BSE one came in. That one is passing KOEO as well.

Then just because I'm a glutton for punishment, I plugged the Cardone one back in. The first time, it passed KOEO as well! I was both shocked and annoyed. It was failing 100% of the time (about 20 tries lately). I turned the key off and waited 10 seconds, turned the key back on, then ran KOEO again and it went back to failing with Code 31. I didn't notice that I didn't hear one of the solenoids ticking (I'm not sure which, but it normally does this) when it failed. I'm not sure what this means, if anything.

I then put the BSE back in again, and a clean KOEO. I'm going to leave it like that for now, and start it up. I'll keep the eBay (unmolested Ford EEC) one in reserve to be reconditioned if/when the BSE one fails. And I'll keep the Cardone for now as the backup to the backup.

As an aside, I disconnected the negative battery cable between unplugging/plugging anything in.

Hopefully this resolves it for now! Gonna start it up and see what happens...

[Gary Lewis]

The Autozone/BSE one came in. That one is passing KOEO as well.

Then just because I'm a glutton for punishment, I plugged the Cardone one back in. The first time, it passed KOEO as well! I was both shocked and annoyed. It was failing 100% of the time (about 20 tries lately). I turned the key off and waited 10 seconds, turned the key back on, then ran KOEO again and it went back to failing with Code 31. I didn't notice that I didn't hear one of the solenoids ticking (I'm not sure which, but it normally does this) when it failed. I'm not sure what this means, if anything.

I then put the BSE back in again, and a clean KOEO. I'm going to leave it like that for now, and start it up. I'll keep the eBay (unmolested Ford EEC) one in reserve to be reconditioned if/when the BSE one fails. And I'll keep the Cardone for now as the backup to the backup.

As an aside, I disconnected the negative battery cable between unplugging/plugging anything in.

Hopefully this resolves it for now! Gonna start it up and see what happens...

Again

[ckuske]

Again

I will accept any and all good wishes

[ckuske]

I will accept any and all good wishes

Ok, so today was a mixed bag (mostly bad)

I plugged the BSE ECU in, it passed KOEO still. Started the truck, and it immediately had bad behavior. It started at 2000 RPM (good) but the engine was "missing" like when my original ECU went bad, randomly oscillating between 1000 and 2000 RPM, with steps in between. I tuned the engine off within 30 seconds or so of that.

I plugged the eBay (original Ford) ECM in. It passed KOEO. I started the truck and it behaved well, unlike the BSE ECU. It let it warm up for about 5 minutes, then ran a KOER. With my code reader, it didn't display the cylinder count (4 pulses, for an '8'). Some things cycled as usual, and I got the 'Goose' code (10). I punched the throttle and got a batch of three codes I had never seen (cant remember right now, first one was 41).

Unhappy with the KOER test, I then turned the truck off and ran KOEO. Code 31 came back, after not touching ANYTHING. I got disgusted and decided to walk away for a little bit... after everything cooled off, I just ran KOEO again. Now it is passing again.

I've decided that I am going to try and run new wire for the Sig/Sig Rtn wires either straight from the ECU or as close to the firewall as I can get, and also put a new connector pigtail on for the EVP sensor, its almost as possibly something in the wire is intermittent, sometimes based on temperature???

Tomorrow I am first going to also remove the EVP sensor from the EGR to test Bill's theory that maybe the pintle is too long. If it's removed from the EGR and that theory is correct, Code 31 would go away. This wouldn't jibe with the above statement about the issue being temperature related, but I have two things to try.

The new pigtail and wire comes Sunday. I will be stewing until then...

[Gary Lewis]

Ok, so today was a mixed bag (mostly bad)

I plugged the BSE ECU in, it passed KOEO still. Started the truck, and it immediately had bad behavior. It started at 2000 RPM (good) but the engine was "missing" like when my original ECU went bad, randomly oscillating between 1000 and 2000 RPM, with steps in between. I tuned the engine off within 30 seconds or so of that.

I plugged the eBay (original Ford) ECM in. It passed KOEO. I started the truck and it behaved well, unlike the BSE ECU. It let it warm up for about 5 minutes, then ran a KOER. With my code reader, it didn't display the cylinder count (4 pulses, for an '8'). Some things cycled as usual, and I got the 'Goose' code (10). I punched the throttle and got a batch of three codes I had never seen (cant remember right now, first one was 41).

Unhappy with the KOER test, I then turned the truck off and ran KOEO. Code 31 came back, after not touching ANYTHING. I got disgusted and decided to walk away for a little bit... after everything cooled off, I just ran KOEO again. Now it is passing again.

I've decided that I am going to try and run new wire for the Sig/Sig Rtn wires either straight from the ECU or as close to the firewall as I can get, and also put a new connector pigtail on for the EVP sensor, its almost as possibly something in the wire is intermittent, sometimes based on temperature???

Tomorrow I am first going to also remove the EVP sensor from the EGR to test Bill's theory that maybe the pintle is too long. If it's removed from the EGR and that theory is correct, Code 31 would go away. This wouldn't jibe with the above statement about the issue being temperature related, but I have two things to try.

The new pigtail and wire comes Sunday. I will be stewing until then...

Wow! I understand the stewing.

Obviously something is wrong somewhere as all of the ECUs find issues, although not the same one nor seemingly under the same conditions.

So making some changes is probably the right thing to do. Good luck!

[ckuske]

Wow! I understand the stewing.

Obviously something is wrong somewhere as all of the ECUs find issues, although not the same one nor seemingly under the same conditions.

So making some changes is probably the right thing to do. Good luck!

I'd even be fine with bad results, if results were consistent... but this is crazy!

I think the first wire to replace will be the EVP Signal wire that goes straight to Pin 27 on the ECU via Wire 352. There are no splices with other wires for that portion of the system.

I'm pretty sure VRef is good as the 5 volts seems consistent. It comes from connector 260

The Sig Rtn is like a shared ground between two other sensors, and I'm not getting errors from any of those. That's at Splice 255.

I need to check these visually, I've just been looking at the EVTM. But, Wire 352 seems like a good candidate besides switching out the connector and the pintle experiment...