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Return of Code 31...

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ckuske

Return of Code 31...

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This post was updated on .

Hi Guys,

I'm still not driving my truck as much as I'd like, but every couple weeks I'll drive it 10 or 15 miles. I noticed last time I drove it that the "hesitation off a stop" was worse, so I broke out my code reader.

I replaced the original computer with a Cardone reman, and the codes went away. Now, code 31 is back (grr)

Code 31 is the only KOEO code, but there is Code 31 and 33 in continuous memory. There used to be a lot more codes before replacing sensors, wiring, and the computer, but still, some aren't good...

I ran the following wiring tests, and the DD6 test is failing.

I also checked resistance of Pins 27 to 40 and 40 to 46 at the EEC connector, and both pairs are reading infinity (so no shorts, unless that is intermittent). I also just for fun (and to double check that I could accurately probe other pins at the EEC connector, I checked continuity between Pins 40 and 60, and that was very close to zero resistance)

I am kind of worried that there is an intermittent short that is killing the computer, since DD6 is telling me to replace it??

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

ckuske

Re: Return of Code 31...

Administrator

I also jumpered Pins 27 and 46 (Sig and Sig Rtn) at the EVP connector, and buzzed out the same pins at the EEC connector. .36 ohms resistance - so looks like the wiring is OK?

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Return of Code 31...

Administrator

It does look like the wiring is ok. But I'm not sure what that means.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

ckuske

Re: Return of Code 31...

Administrator

I’m not either.

Either my reconditioned ECU has gone bad with one of the same codes the original ECU had, I have an intermittent short that is damaging ECUs at those input pins.

I am going to try and do the jiggle test tomorrow with a test light to see if I can get something to happen.

I’ve also ordered another ECU from eBay to compare and contrast but that just adds variables.

It seems like an EEC-IV could be done pretty easily these days on a Raspberry Pi or Arduino, if we had access to the data tables etc. I know it’s not THAT easy, but relying on second hand 40 year old hardware with each example having different potential unknown issues isnt fun, either!

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Return of Code 31...

Administrator

Maybe time to go EEC-V? Would be a lot of work, but...

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: Return of Code 31...

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In reply to this post by ckuske

I am not sure if this will help, but, a friend and I ran into EGR position sensor codes with replacement sensors. They would show a small open position reading with the valve verified closed. If you loosened the sensor to where there was a slight gap, then the closed position value would be in spec.

Our solution was to shorten the plunger on the sensor enough that it came in spec. I seem to recall it was about 1/8" we took off.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

ckuske

Re: Return of Code 31...

Administrator

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...

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

ckuske

Re: Return of Code 31...

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In reply to this post by Gary Lewis

Gary, yes, that is a thought too. I mean... I only have ONE code. But this one code is a bugger.

I found a few more pinpoint tests to run, I think I will try them right at the EEC instead of the harness (measuring resistance between pins) and see if anything is different (it shouldn't be, but you never know...)

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

ckuske

Re: Return of Code 31...

Administrator

This post was updated on .

In reply to this post by ckuske

I posted the link here for the breakout box to ask about it, and someone scooped it up. That kinda stinks but I guess that was the risk I took

I have another EEC coming in tomorrow, I will let everyone know how it goes after plugging it in (just trying a KOEO test to start!)

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Return of Code 31...

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Good luck!

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: Return of Code 31...

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In reply to this post by 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.

Bill AKA "LOBO" Profile

ckuske

Re: Return of Code 31...

Administrator

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.

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

ckuske

Re: Return of Code 31...

Administrator

This post was updated on .

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...

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Return of Code 31...

Administrator

Yippee!!!

Gary, AKA "Gary fellow": Profile

ckuske

Re: Return of Code 31...

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In reply to this post by ckuske

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...

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Return of Code 31...

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Again

Gary, AKA "Gary fellow": Profile

ckuske

Re: Return of Code 31...

Administrator

I will accept any and all good wishes

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

ckuske

Re: Return of Code 31...

Administrator

This post was updated on .

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...

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Return of Code 31...

Administrator

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!

Gary, AKA "Gary fellow": Profile

ckuske

Re: Return of Code 31...

Administrator

This post was updated on .

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...

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

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