Ignition Trouble...Help!

The latest in my (never-ending) maintenance saga with my beloved SC! Brief and to the point, it doesn't want to run. I have narrowed it down to something electrical (surprise!) dealing with the ignition. Here's the issues...

Monday night-ran great. I've been having a "miss" under acceleration and tried a couple little things to no avial.

Tuesday morning--won't start. It just turns over and over. The upshift light does come on, which leads me to think that it is the crank sensor. Except that I replaced it only 2 1/2 weeks ago. It ran great (except for a pesky miss) up until this time. I did get it to start, but it will only run for about 10 seconds then goes to Hell in a handbasket. I remember reading somewhere that if the EEC does not receive a signal from a sensor (I'm thinking it was the MAF) then the EEC will "guess" what the reading is supposed to be for about 10 seconds or so. Can anyone verify this?

Tuesday night--Ruled out the DIS module and MAF as the problems. I have a crank sensor to put in tonight to rule that out as well. I can still get the car to start, but it does not want to run for more than 10 seconds or so.

I found that there was a broken ground wire (on the harness that has the DIS module, cam and crank sensors) and re-soldered it, but did not fix the problem. Here is what I have fixed (ignition related) on the car to date. Every thing is a year old or less.

Spark Plugs (OEM)
Wires (OEM)
DIS Module
Cam Sensor
Crank Sensor

Any and all help will be greatly appreciated. I'm going to rule out the crank sensor tonight and go from there. I just need more places to start if that fails. The only other guess that I have is that the wiring harness have become too old and brittle and failed at some point. Although, driving just fine one night and then less than 12 hours later, not at all. I'm getting plenty of fuel, just no spark to keep it running. I'm keeping my fingers crossed that it isn't the EEC... Thanks for your help

Before you put another crank sensor on check the balancer, they go bad and wobble causing the crank sensor to get wiped out. Kinda sounds like thats what happened.
Pull the codes and see what say.

There are no stored codes and the engine won't run long enough to get any codes for the EO test. The balancer is still in good shape, with no wobble. The center bolt is still firmly attached. A visual inspection of the crank sensor shows no sign of damage that would be caused by the balancer making contact with it.

OK run the KOEO test, that will at least test the wireing and sensors and maybe rule out the electical system which will point to a mechanical problem. See what you can do.

There are not any stored codes. KOEO = stored codes in the computer. 99% of those are emmission related. A bad cam sensor, crank sensor, DIS module will not register codes. There may be some codes that can be pulled from them, but nothing that says, "Hey this sensor is bad." At least I don't have that type of diagnostic equipment. And I don't know anyone who does, besides a couple mechanics that charge $65/hour to test it. I prefer to spend that $$ to actually fix the car...

Yes they will, if electricaly they are bad.
In KOEO the computer checks the entire system for electrical condition of the system, if the system pass's you do KOER and that tests the system for mechanical condition of all sensors. The computer will also do a third test called "cylinder ballance test" to test each individual injector and will tell you which cylinder has the problem and if its too rich or lean.
If the car pass's all 3 test's you have a mechanical problem not electrical.

According to your thought pattern, if a sensor were say disconnected from the rest of the electrical system, there should be a code. I would definately think that a "missing" sensor would create a 'fault' in the electrical test because it is simply not there. Well, unfortunately, it doesn't work that way. I took the liberty of unplugging my cam sensor to validate your claim. I was prepared to eat my words. But my KOEO test still passed. And to the very best of my knowledge, the KOEO test simply tells you the codes that are actually stored in the memory (AKA continuous codes). And as I have stated twice before, my car will not run long enough to register the number of cylinders, let alone any codes that can be received from the KOER test. And yes, I'm aware of the cylinder balance test and just FYI there is another test that I can perform that is called the "wiggle" test. I can wiggle the electrical connection of the sensors to determine if there is a poor connection.

Dude I'm sorry, I'm not jerkin your chain.
I can only tell you what I've been doing since 1999 when working on these cars and I have never had a problem with the ECU system like you just described. The "Ford Fuel Injection & Electronic Engine Control" manual says the system works that way and I do it that way. Works for me, always has!
I was'nt trying to talk down to you!
I'm sorry I bothered you and I wont interfere again.
Really I'm sorry.

There was no offense taken, truely. I'm sure that there is diagnostic equipment that can check the validity of each sensor. I just don't have it. I've got the cheap $40 CarQuest version. I've been spending too much actually fixing my car instead of getting the good diagnostic equip. I've got a sneaking suspicion it is the crank sensor, but wasn't able to get to it tonight. My thought is that whenever my ground wire broke for that wiring harness, it overloaded one or more of the sensors. I'm simply guessing at the crank sensor because all other components of the ignition system will allow the car to run, just really crappy. I was just hoping I'd get some info to validate this or point me in another direction (preferably). I'm really not too keen on changing a crank sensor I just replaced 2 weeks ago. Know what I mean!

At any rate, I receive the all clear from my KOEO test, but have no way of testing further.

OK.... I must have just taken it the wrong way, I'm sorry.
I think your confused. I take it from your last post that you think that you need some kind code scanner or something to do this, but you dont. The ECU has those diagnostic capability's built right in it. All you have to do is trigger the system just like you have been doing to run KOEO test then follow the procedures and go through the steps. The cars own computer does it all. You just sit in the seat and count flash's of the CEL.
You dont need anyother equipment.


Edit: Woah... The car will not run long enough to do the other tests. Damn Alzhiemers! If you got a code 11 on KOEO then the comp IS saying everythings good electricaly, But I just reread your first post and you talk about finding broken wires in the ignition harness.
You will now have to manualy check each sensor yourself because those broken wires may have shorted out and messed up the computer causing it to give false info. Do you have a voltmeter? If so I can walk you through testing each component and the wiring.

sounds like fuel to me if it runs about 10 sec then quits maybe fuel cutout switch in trunk or fuel pump

rlong,

Fuel issues are OK. There's no trouble there (yet).

Mike 38sc
No, I don't have a voltmeter yet, but getting ahold of one is not hard. And the wire that was broken was the ground wire for that harness itself. It is the ground wire that is connected right next to the DIS module. I have resoldered it, but I think that the damage has been done. And I'm guessing it's the crank sensor. Everything else, the car will run, just really sh!tty. And last night I did read somewhere in my shop manual that the EEC will go with a "known" reading if it is not receiving a signal (forget if it specified a sensor or not) for about 10 seconds. After which, the EEC then 'guesses' the appropriate reading based upon other sensor readings. It also stated that it may take a few times of starting it to get the correct 'formula' worked out. But I think mine is beyond that... So much for the track tomorrow night... If you could email me a brief step by step on checking the sensors, I think that would be easier than replacing each sensor until I find it! Then I can get to it at my leasure (don't have much of that kind of time!). I appreciate your help.

* and there is some diagnostic equip that can determine each sensor reading that the EEC "sees" but it is way too costly for a weekend mechanic with only one SC that I work on. Hell, the $65/hour to have my mechanic do that is too much for my blood!

OK I understand a little better now whats going on. I also know all about the sensor your talking about the comp geussing with, because thats the very first problem I ever fixed on an SC and it was the very thing that pushed me kicking and screaming into learning everything I could about these cars. No one was of any help, not dealerships not other mechanic friends and not any of the commonly found manuals out there that should be of help.
Thats when I found this site. I'm not saying you will find every single answer to your problems here, but you can get more than enough info to at least know where to go to get some answers and what qeustions you need to be asking.
It is frustrating at times, beleive me I know.

The sensor your talking about it the cam(CID) sensor, if the comp doesnt get a signal from it the comp will geuss, its the only sensor on the engine that has that much leeway to allow the comp to do that. The reading from that sensor is not that critical and thats why the comp can get away with geussing. Trust me I'm not trying to toot my own horn here, but I spent over 2 weeks chasing that problem and I do know what I'm talking about here. The big reason it threw me so bad was that I know of no other comp system on any car that would allow that and I refused to beleive it was so. That is until I got the manual I mentioned to you in my previous post.
The manual lists each and every sensor ford used on these cars as well as others and the values needed to check everything with a voltmeter in case you end up in a situation where the comp cannot be used or trusted. Sooo..... we CAN figure it out, but it will take more time. I know you dont know me, but trust me we can check every aspect of the engine control system without any special readers or high cost tools. All we need is a voltmeter, this manual and our time. You said you can get a voltmeter and I have the manual now all we need is the time. None of this is going to cost you one penny.
When were done you WILL know for sure if its electrical or not.
Doesnt that sound better than just throwing parts and your hard earned money at the problem where at the end of it all you've spent a fortune and the problem was never fixed or found leaving you very angry?

When I was trying to fix my cam sensor problem I first suspected the ignition, so I run out and bought a new module and of course it didnt fix it. The module cost me $117. That was the moment I realized that I could take that route till I was in the poorhouse, so I decided to get educated and stop pissing in the wind, life is too short for that.

I've been around this site for a long time and I dont know everything. I dont claim to. I come here to try to help people with things I've learned about through the years. Mainly because I understand there frustration, but also to give back to the community that has given me alot and helped me with my very first SC problem. We are basicaly all we have, nobody else knows or cares about our cars.

We can take it to Email if you want, but why not do it right here so others can see and learn, it just might help some other person that ends up having a problem. I beleive until I'm told otherwise by the owner of the club that this is part of the intent of this site, but we will do it anyway you want. Just let me know which way to do it and we will get started.

We can certainly do it online. I was just thinking that we could also have a "printer friendly" text version. I can do that though.

I do have a spare crank sensor that I can get put in sometime. My first shot at it took about 2 hours. But much of that was spent holding my hand because I was doing it on a warm engine! I'll only try that though if you think it is what it may be, just guessing, of course. I need to head home now, I'll check back in later.

No dont change anything yet, after you get the VOM we will test things and then we will change what tests bad. You wont fix it by just snatching parts off and throwing others on it will just confuse things and make it harder to diagnose. Get a VOM and we will get started. This isnt going to be hard.

I'll try to track one down today. If not, it may not be for about a week as I've got to head out of town.

Here is a link to a document I made up based on the Ford Pinpoint tests for a no-start condition on an 89 T-bird SC with DIS. It recommended not using a meter to do the tests, instead to create or purchase an LED sensor due to the possible issues with the meter throwing off any values.



http://mnharms.com/tutorials/disnostart/

Murphy's Law?

So how is it again that Murphy's Law works??? I went out and just for sh!ts and giggles tried to start the SC just a minute ago. And, you guessed it, she fired right up and ran great. Let her run for a couple minutes and shut her off and tried again...just to see. Again, she ran fine. You just have to love these cars! She just must have wanted a week vacation! Thanks for the input guys. Mike8675309 I saved your article for future reference if I need it. I'll also keep this post at the top of my list incase I need to "re-open" it at a later date.

Check Your Coil

007 SC........sounds like a problem I had about a month ago. Pull your coil out and see if there is a buldge in the bottom. I had a medium to high speed miss and then it just quit. Finally got it started and drove it home. I had no power. I had just enough to get home. I pulled the coil out and sure enough there was a real pretty buldge (white stuff running out) in the coil closest to the SC. Replaced the coil and everything is wonderful in SC land. I noticed that was something that had not been suggested.

Ed Springer

90 Black XR7 5-speed: 70mm TB, Fresh Air Intake, Upgraded '94 Supercharger, 5% SC Pulley, Raised SC Top, I/C Fan, Underdrive Pulleys, Headers, Magnaflow Muffler (no cats) with stock resoantors, 3:27 Gears, Ripper Shifter, Rear Air Bags, 73 CL MAF, Magnacore Wires.

94 Red SC Auto: 70mm TB, Fresh Air Intake, Stock 90 SC Pulley, Raised SC Top, I/C Fan, Underdrive Pulleys, Headers, Raven Muffler (no cats) with stock resoantors, 3:73 Gears, 73 CL MAF, Magnacore Wires, TRANSGO Shift Kit, Haydon Auxiliary Transmission Cooler.

I can check that, but unlike your situation, I've got plenty of power. In fact, drove it a short distance tonight, (enough to get it to warm up) and I didn't even have the miss that I've been plagued with the past few weeks. Thanks for the thought though.