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Discussion Starter · #1 · (Edited)
super huge mystery and super long story, please bear with me.

the head was recently replaced on my stang due to bent/broken/leaky valves. he ran great afterwards. had to replace the radiator (hole got accidently poked in it). after the battery went back on the stang was idling (to relearn). was good at first (like 10 min approximately) then he started idling for crap, wanting to bog down and die. when driving he has no power.
stang is in the shop and they are stumped.
they checked the head job, it was good, the timing is perfect. after about 3 days the CEL finally came on. it spit out about 20 codes for the sensors having low voltage. so they checked the sensors (mas, iac, tps, ignition module, crank sensor) and individually they are working fine. egr, coils, battery, and alternator were also checked and they also tried switching all of them out and no change. the fuses were all checked and were fine. so the eec4 was checked (no hard fault code), but they tried switching it out with 2 different eec's and the stang wouldnt even stay started. when the original eec was put back in, it would start, but behaved just as crappy as before. they checked all the grounds and even double grounded a few they thought were iffy. the wiring was ohmed (i might have spelled that wrong) from each sensor to the computer, and came up fine. they said that at the sensors, they were only getting .03 ohms (i think it was ohms, my notes smudged where i wrote that part), when its supposed to be .07. (this is all direct from the mechanic, i dont know wiring or electricity in general for crap, part of why i took it in in the first place.) the only thing that hasnt been replaced is the ircm (after the new parts din make a difference the mechanic returned them. he cant return an ircm so he hasnt tried a new one.)
i'm not sure if this is related or not, but this morning they pulled the battery again. after it was out of the car for a couple hours, somehow my fan caught on fire and burned up some of its wiring. how does that even happen with no battery in the car??

:?:any ideas what else can possibly be checked???:?:

this is just screwing with all logic. i really need some help here because i'm out of ideas.
 

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well first off a fan that has no voltage to it will not catch fire unless set on fire. this shop you have it sounds a little off. checked wires for ohms is ok to check for open i circuits but depending on gauge of wire and how long it is will have diffrent ohms readings. i hope they checked wire harnes with everything unhooked from that circuit. some sensors can be damaged by checking that way. is the timing correct? if it off by one tooth can lead to alot of running problems and set alot of codes. what codes is it setting right now?
 

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Hum. Fire no battery really odd.
What year Mustang?
Wiring diagrams for Mustangs here.
www.rothfam.com - /svo/reference/
What codes getting list?
Ford Bronco EEC IV Codes
I guess done compression test and leakdown test? People do mess up.
Now low voltage to sensor. There are several wires that are common to all sensor. Sends voltage out to them [or comes back on them I forget] and what is returned tell computer what to do. The wire from computer to before 1st splice can be bad. Look harness over real good for bad spot. Pulling head if they were not careful broke wire. The 2 major ones are VREF and Sig Return.
Now to check sensors that get code from. Check with volt meter at sensor.
http://www.rothfam.com/svo/reference/sensors.pdf
If not there check at the computer. You can run these car with computer in the floorboard so can test. Get more info on year and codes and will try to help more. Maurice
 

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Read this. Check on it.
Ford Fuel Injection » No Codes?
Especially check grounds at computer. While on that subject there should be a braided ground cable from intake to body. Check on it. If not there just decent size wire from upper intake bolt to body will do.
This checking 2 wires I mention. Cut and past from link.
•Turn key to ON with engine OFF and computer removed. Measure voltage on pins 1, 37, and 57. Must be above 10.5 volts and within 1.0 volt of each other.
•Replace faulty wiring between computer and battery if not.
•Turn key ON with engine OFF and computer reinstalled. Measure voltage between Pin 26 and 46 (voltage reference and signal return) must be between 4.0-6.0 volts. [my notes if ok. check voltages at sensors on these 2 wires for same. If not check harness. ]
•Replace faulty wiring and sensors.
•Measure resistance between Pin 46 and Pins 40 and 60 at the computer harness, must be less than 5.0 ohms.
Maybe some of this will help. Maurice
Edit harness do go bad and wires break. Found them in mine, the SHOVert project, [turbo17's harness]. Some minor some major. Make sure to solder and heat shrink them. Also look at backside of computer wiring. The plastic retainers break and wire slide out and don't make good connection. I got several in mine now. I just used 2 part epoxy glue to retain them. Maurice
 

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Discussion Starter · #5 ·
wow, i dont believe i forgot to put my year down. i am really not all there lately.

its a 1991 2.3 ranger engine, 1992 2.3 computer and wiring (almost all of the wiring is brand new).

i'm gonna pass along what all has been posted so far. my eternal thanks, and please keep any and all ideas coming.
 

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tip with the soldering, sometimes this will work but if the voltage is really low, (milivolts) then its a bad idea to solder, because it can change the resistance in the circuit and also cause problems. just a tip :bigthumbsup
 

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Discussion Starter · #8 ·
just wanted to update everyone. i was gonna yesterday but just got busy and forgot, sorry. still checking out everyones ideas to see if any of that is what is making my stang sick. good lord i do sooo hate electrical problems.

ok, here are the codes it was making:
koer-
172 lack of o2 sensors indicates lean
327 evp circuit below minimum voltage
411 cant control rpm during koer low rpm check
koeo-
122 throttle position sensor circuit below minimum voltage
157 maf circuit below minimum voltage
327 evp circuit below minimum voltage
334 egr closed valve voltage higher than expected
566 3-4 shift soleniod circuit failure
629 converter clutch control circuit failure

i need to note that the 566 and 629 codes have been there since i switched my trans over a year ago, so i really doubt theyre related.

and an update; this morning the guys went to hook the battery back up and now nothing in the car has power. i may not know much about electrical things, but i think its safe to assume that i have some kind of wiring gremlins in my stang. let me know what you all think.
 

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Discussion Starter · #9 ·
well first off a fan that has no voltage to it will not catch fire unless set on fire. this shop you have it sounds a little off. checked wires for ohms is ok to check for open i circuits but depending on gauge of wire and how long it is will have diffrent ohms readings. i hope they checked wire harnes with everything unhooked from that circuit. some sensors can be damaged by checking that way. is the timing correct? if it off by one tooth can lead to alot of running problems and set alot of codes. what codes is it setting right now?
honestly, human error cant be ruled out with the fan, or even the wiring, but this shop has been good to me and the few times theyve made a mistake theyve always been honest and told me and fixed the mistake at no cost. so either way, if any of this is their error i do trust them to make it right. and a giant thanks for the ideas to fix my mustang!:bounce2:

I hear you. Things for me been nightmare also. With the heat etc work has been busy. Maurice
Edit 91 wiring diagram.
http://www.rothfam.com/svo/reference/90-91Mustang.pdf
92-92 diagram
http://www.rothfam.com/svo/reference/92-93Mustang.pdf
Say most of wiring new. I assume used parts or new makes little difference. I assume wiring connection solder and heat shrinked. Those crimp slicers are a nightmare just to cause problems. They corrod inside and cause problems. Maurice
yea, the evil hot sticky weather was a PAIN in the rear. up here at least were having nice pleasant weather, hope you are too. the wiring diagrams have been a big help, thank you buddy :bigthumbsup.

tip with the soldering, sometimes this will work but if the voltage is really low, (milivolts) then its a bad idea to solder, because it can change the resistance in the circuit and also cause problems. just a tip :bigthumbsup
a good tip. thank you for sharing it. :shiny:
 

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Nothing works including lights. If lights work check ignition switch. No lights check fuse links etc at the solinoid. I am going to look at wiring diagram and see if can help. Sounds like a common wire problems. Check those fuse links near the solinoid. Maybe corroded. Maurice
I wish I had this car in my driveway.
I remember Tom mentioning a ground under the solinoid that can cause problems. Make sure grouns good at computer. Seems like common thing is 37,57 power, 26, and 46. Look at diagrams vs codes and can see what I mean. I would check the maf with testing from link I gave vs voltages at it and then at computer. I think if solved one it will solve rest. Like you said ignore the last 2 I get them on my car also. Maurice
 

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Discussion Starter · #11 · (Edited)
excellent ideas, theyre being checked out as i type.

another update, the guys put a new battery in the stang, (the old one was tested and came up good, but it could be just that side of good) and now the lights and power windows work (have manual locks, not even wired for power locks, just fyi in case it matters.) they havent tried starting it, thats gonna happen first thing tomorrow. the CEL came back on, codes are getting pulled (again) tomorrow. i'll post to let folks know if theres any change or not.
thanks again for all the help :bigthumbsup
 

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Make sure the grounds on the computer are good. If remember correct. Some go to ground near computer and other ground goes near battery as mention. When solved let us know. Maurice
 

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Discussion Starter · #13 ·
so the mustang turns on now and idles a bit better than before, and then it dies. weird. it just decided to do it on its own, all that was done was the battery switch. nothing has changed with the codes its throwing. i swear that my stang is possessed.

hey maurice, do you have a pin diagram/layout list for the eec 4 with mass air? they guys at the shop asked for one. i'm trying to google myself up one, but you do have the best links in the world. :bigthumbsup thanks bud
 

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Discussion Starter · #14 ·
i found a good link for a pin diagram, so i'm good on that.
ford eec iv
this is a good one, so wanted to share it.
 

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Awesome. I got another but for the life of me can't find it. Maurice
 

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Discussion Starter · #16 ·
i am so sorry for not posting in a long time, but my computer died. after 11 years the motherboard fried about a month ago. the new tower showed up about 3 hours ago. i will post a full update in the next couple days. :)
 
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