93' Explorer Sport, Low, Bad Idle, Runs Rich, Smells of Gas - ECU!?!?

[CreepingNet]

Hi, so I've been researching a lot this week to figure out what's been going on with my 93 Explorer Sport 5-speed. I've already posted some about this but this is a legitimate thread as I have some questions now.

Not to rehash too much but I limped it like this halfway home from work and had it towed to the shop near my apartment when the traffic was just too thick to safely drive it. They took a look, checked the FPR as I mentioned that as a possible cause (been researching since this happened - hardcore), FPR was fine, they said I had air leaks in the airbox and near the throttle body, and that's where I should start on it myself. They said they don't understand OBD-1....well, at this point, I do, not much different from BIOS Beep Error codes for a PC (I work in I.T.).

So this morning I picked it up and limped it home with the MAF disconnected because they said it would not start with the MAF plugged in. This was a red flag.

So took the truck home.....checked all the following....

- Oil is full, needs changed, smalles like gas
- half full and clean coolant
- Air filter is surprisingly clean for being a year old
- The original MAF has a Burn mark on one of the filiments (taller one)
- The Throttle body was nasty
- leaks in the Airbox due to missing bolt anchor
- leaks in intake tube due to bad gasket at throttle body end

What ensued after this was a trip to NAPA for throttle body cleaner and MAF cleaner. Cleaned the MAF, cleaned the throttle body, cleaned the tube up, basically, if it was dirty, it was cleaned - and when done, everything looked brand new, except the MAF where the taller filament had burned up on one side somehow. The IAC looked like the inside of an uncleaned coffee grinder - black stuff pouring out of it. Cleaned it up real good.

Next, a trip to Pick N' Pull for a good MAF to test with, maybe a backup IAC in case the current one is seized, and grab all those parts Precision Tune lost all those years ago. So I nabbed a nice looking MAF from a 93' XLT (clean filaments), snatched up an IAC from a 4.0 Ranger that looks brand new inside and out, pulled a very nice gasket from a 94' limited for the Throttle Body, and a bolt anchor from a damaged airbox for my airbox.

So I did all this
- replaced gasket on TB
- replaced missing screw anchor on airbox
- replaced the throttle cover (not relevant, but it was missing because P.T.)
- replaced MAF - a little bit of a change, seemed to start with less hesitation but still runs terrible
- replaced IAC - seemed to clear up just a little more

Ran KOEO and KOER Codes - I believe I have these right as I verified them from - Aerostar Van/Wagon – Bronco – Econoline/Club Wagon – Explorer – F-Series – Ranger (1992 – 1997) – TroubleCodes.net - I actually did this before the above but did not "decode" things until I got into the house to post this.

KOEO Codes

117 - Engine coolant temperature (ECT) sensor below minimum voltage
122 - Throttle position (TP) sensor -below minimumvoltage
112 - Intake air temperature (IAT) sensor belowminimum voltage
513 - Engine control module (ECM) -internal voltage fault
565 - Evaporative emission (EVAP) canister purge valve 1 -malfunction
556 - Fuel pump (FP) primary circuit

KOER Codes

998 - ECU Hard Fault Present
112 - Intake air temperature (IAT) sensor belowminimum voltage
117 - Engine Coolant Temperature (ECT) sensor below maximum voltage....

that's when it stalled and started repeating the codes from the KOEO test.....

So that explains why the truck was having trouble idling - seems the management computer is doing jack. But the big question is where do I go from here? Should I test the main electrical system for any issues, because it seems fine other than struggling a little with my heater motor going - which I don't need as it's the summer? Or should I look to the ECM. I'm trying to get this running this week so my wife does not need to drive me to and from work on Thursday as she has an interview that day.

If it's look to the ECM, that does not scare me at all, seems they're not that expensive, and also, I might be able to fix mine if it's caps/bodge wires/. I have done motherboard repairs on vintage computers, including....fun fact.... a 1993 NEC Versa Laptop that once belonged to a Ford Motor Company employee around the time the 1st Gen Explorer was in production.

 

[ChildIdenticant]

Possibly some internal resistance on on the pcm/eec relay switch? Try swapping the pcm relay with the abs relay.

 

[CreepingNet]

Possibly some internal resistance on on the pcm/eec relay switch? Try swapping the pcm relay with the abs relay.

Tried that. No change.

 

[CreepingNet]

Ok....fixed my problem, turns out the EEC-IV needed a recap, plus some busted traces fixed. After a couple tries and a lot of nitpicking over the PCB and components, I got it all fixed, for free, just 2 47uf caps and 1 10uf cap I had laying around, and cleaning the board with Acetone. Just took it for a test spin, and after some rough idle at first it started to run like it's supposed to - 1500 RPM from cold start, drops down to 600-700rpm, and holds there VERY Strongly now. So it looks like replacing the MAF and fixing all the leaks in the intake trued up the idle quite a bit as well. One spin around the block threw a CEL but no real signs of true trouble as it was gone afterward and seemed not to come back.

Still throwing codes on KOEO and KOER, but not as many. I'll be looking into those myself since they don't have to do with the main problem - which was the EEC-IV's leaky caps. Now I just need to do an oil change and get rid of that gas-ridden oil.

 

[ChildIdenticant]

Ok....fixed my problem, turns out the EEC-IV needed a recap,

Take any photos of the internals? Never had to open one up yet and haven't seen any pics posted so far. Was it actually leaking cap, or moisture? I'm assuming they are electrolytics? Would be nice to have photos from all years. The boards for the speed amps in the '91s look hand drawn compared to the later ones. Goodonyou for repair.

 

[donalds]

What did YOU do to your Explorer today?

Finished clutch, flywheel, master and slave cylinder and line replacement today just to have the starter not turn over now :/

www.explorerforum.com

 

[CreepingNet]

Yes, took pictures.....here they are...

Actually, the EEC-IV module appears to have a certain type of rubberized coating that they use on modern high end kitchen appliance circuit boards, like the Cuisinart Blender we owned a few years ago. So It's probably more prone to that now than it was before. Most of the damage you see is the Electrolyte leaking out of the capacitors - which eats the traces and appears to attract some kind of carbon build-up.

One thing that surprised me when I was removing the module is how you remove the connector. All the pictures online looked like it was just going to be a simple pull operation but it actually is guided on by a bolt. Actually one of the easier large scale connectors on a digital device I've had to deal with.

Lucky for us this thing is only a 2 layer motherboard (some actual computer motherboards can have 3-6 layers). You can actually see the traces through it, so no worries about damaged vias breaking continuity on internal layers.

 

[ChildIdenticant]

Thanks for the photos. Definitely nasty caps.