'94 EEC removal ?
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Senior User
Joined: Aug 2008
Posts: 108
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From: Barrington, Il.
You've got to have a broken wire or short somewhere in the TPS wiring. Check the connector for corrosion, and trace back as much of the wiring as you can. The passenger side is tough to follow because of the upper intake, but see if there's anything obvious. The wiring harness runs along the side of the valve cover facing the intake. Also re-check the connector at the EEC for contamination or loose wires.
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Senior User
Joined: Aug 2008
Posts: 108
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From: Barrington, Il.
Got a pair of MK VIIs, '89 Blass and my '90 SE project, 347 stroker, T5, spring suspension, 'stang GT master (no more ABS), A9L, 2 1/2" exh., GT40 int., 24# inj. Scary fast. 
The long block I had done, everything else, including all the re-wiring, I did myself.
The long block I had done, everything else, including all the re-wiring, I did myself.
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Senior User
Joined: Aug 2008
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From: Barrington, Il.
My 1st was a '66 Coupe', then '69, '72,'75,'79,'83,'86,'94, and then the MKs. Great rides 1 and all.
Post Fiend
Joined: Mar 2002
Posts: 19,402
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From: Bonita Springs FL
I've had the EEC out, and pinned out everything looking for shorts. The replacement EEC I tried was a non-starter (literally). Thinking about ANOTHER replacement, or maybe looking @ FFInj. for a 'stang unit with MAF and 4R70W application. Just really frustrated @ this point.
Mountain Pass
Joined: Aug 2005
Posts: 140
Likes: 1
From: Seattle
These computers have a short circuit test mode you can put them in where you can wiggle wires around and if a short is detected by the computer it will beep, that is if you have one of those cheap code scanners hooke up. I forget what you do to put it in that mode, but it works great. I used it to find a couple of shorts a while back, would have been near impossible to have found it otherwise. One of those after market manuals will have the instructions on how to put the eec in short test mode.
Best of luck!
Best of luck!
Thread Starter
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Senior User
Joined: Aug 2008
Posts: 108
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From: Barrington, Il.
These computers have a short circuit test mode you can put them in where you can wiggle wires around and if a short is detected by the computer it will beep, that is if you have one of those cheap code scanners hooke up. I forget what you do to put it in that mode, but it works great. I used it to find a couple of shorts a while back, would have been near impossible to have found it otherwise. One of those after market manuals will have the instructions on how to put the eec in short test mode.
Best of luck!
Best of luck!
The contradictory codes, tps voltage too high / too low and HEGO too rich / too lean have me stumped, especially the HEGO saying bank 1 for both when there's only 1 O2 sensor.
I'll have to look at doing the wiggle I guess.
Right now, running decent again, seems a little underpowered, and only 11.2 mpg.
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Mountain Pass
Joined: Aug 2005
Posts: 140
Likes: 1
From: Seattle
One thing I have run into with HEGO sensors and a bad running engine is that after a while if the engine is running really rich it will produce enough soot and heat to ruin the sensor. When this happens, once you correct the problem that caused the rich condition the HEGO sensor will still indicate the engine running out of optimum range. I ran into this situation a couple of years ago. Even though there is only one sensor I believe the EEC does have a pin for each bank and the signal goes to both. On a mass air equiped vehicle they added the second O2 sensor.
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Senior User
Joined: Aug 2008
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From: Barrington, Il.
One thing I have run into with HEGO sensors and a bad running engine is that after a while if the engine is running really rich it will produce enough soot and heat to ruin the sensor. When this happens, once you correct the problem that caused the rich condition the HEGO sensor will still indicate the engine running out of optimum range. I ran into this situation a couple of years ago. Even though there is only one sensor I believe the EEC does have a pin for each bank and the signal goes to both. On a mass air equiped vehicle they added the second O2 sensor.
Both of my MKs were originally SD and had 2 O2s, but thanks - it's something I hadn't thought of.
Even tho the tailgate has a sticker on it from a downstate IL dealer, and CarFax showed it only in IL, I wonder if it might have been built for Ca. CARB stds.
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From: Barrington, Il.
The "wiggle" test was a bust - I'd have been better off taking a couple of the GKids to SEE the Wiggles.
If I could keep it from going closed loop, maybe I'd actually be able to find out what's going on.
From cold start, it's great for ~ 1 minute, then the codes kick in.
I heard today @ www.fordvschevy.com that Ford is discontinuing 5.0 support, and liquidating parts thru racepartsdirect (I'm not sure that's the right site), but THEY {RPD} ARE ALSO folding their tent, so I might look for an N.O.S. engine harness.
Too much time and $ tied up in this POS now to walk away.
When it's good, it's very good, when it's bad it pisses me off to no end.
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joachim1340
1987 - 1996 F150 & Larger F-Series Trucks
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Jan 24, 2011 08:26 AM
