low ignition voltage

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  #1  
Old 02-10-02, 01:24 PM
tammi ann
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low ignition voltage

got a ford f250 6 cyl eec iv ignition, wouldnt light my timing light except for sporadic bursts, now it will not light it at all.

I have 12+ volts to coil, spark output from coil and thru at least the number one wire, I removed each and let them fire onto the block after inserting a small bolt into the plug end.

Spark from both was orange but reached at least a quarter inch.

I feel that spark should be blue and that this orange yellow spark is a sign of a weak spark. Also the guy at advance auto told me that my light would fire sporadically or not at all with a weak spark.

Light works on my car just fine, plug wires are autolight, brand new as are the plugs and distributor rotor and cap, everything has been checked for tightness etc.....

any ideas or comments on this subject, truck will not fire now and I am completly at a loss as to what to try next.

thank you
 
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  #2  
Old 02-10-02, 01:37 PM
trendar
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Is the problem a no-start problem? Or just that the timing light isn't firing consistently?

Did you try reversing the pickup on the spark plug cable? They may have a marking on the inductive pickup indicating the direction towards the plug; usually works better in one direction vs. the other.
 
  #3  
Old 02-10-02, 07:44 PM
tammi ann
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Truck has been running, has not been on the road in a year but I have been running it while working on it. Originally had anintake exaust manifold crack, took a long time for me to secure parts times etc... to repair, have just been working on it as time permits.
Ran fine a while back then all the sudden it seemed to started to act up with the timing light not firing. new plugs, ignition components etc.....

I have tried the light reversed on the wire.

Taking off the plug and setting on the block with a bolt up in the end you can see that it fires pretty regularly but the spark is very weak, producing a dull orange type colored spark. Coil is also brand new and I am 100 percent sure polarity is correct but will be checking that tomorrow morning just to be sure.

After initially having problems getting the truck running this evening it finally smoothed out pretty good but the spark was still weak and missing terribly, went to get a drink and while gone truck died, was unable to even get it to attempt to fire off, will try again in the morning as I am off work.
 
  #4  
Old 02-10-02, 07:59 PM
trendar
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The ignition module on the EEC-IV systems have sometimes shown a tendency to develop problems; did you try swapping it in the process of your diagnostics?

On the ones I've encountered, I would lose spark entirely, and it was intermittent, often losing it when hot and then starting to work again when it was allowed to sit and cool for a while.
 
  #5  
Old 02-11-02, 09:10 AM
Joe_F
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Year of said truck?

As mentioned Ford TFI modules are quite troublesome and if it's the original on there, pitch it anyway. The parts have likely been udpated by Ford a few times since it was made.
 
  #6  
Old 02-13-02, 05:12 PM
tammi ann
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1986 ford f-250 4.9 manual transmission EEC IV ignition

Changed module on distributor, no change...truck will start but it takes a while but will barely idle, exaust is black like it is running extremly rich........

What about the ballast resistor??? there is an oblong shaped rubber or plastic thing about 3 inches long with the symbol of a resistor on it and a slot cut into the center of it. I am ASSuming this is the ballast resistor, looked on a wiring diagram for the truck and it shows a resistor in the wire coming from the EEC module that feeds the coil, this resistor is in that wire near the coil and the wire colors (dark green withg a yellow stripe match up.
Could this resistor be bad??? Neither the wiring diagram I have or the resistor itself on cursory inspection seem to have a value specified... I need to cleanb the resistor off, it is hard to get too and so I could only get a general look at it, may have a value on it after I get something and wipe it off.


BTW on the wiring diagram it says this resistor is only for Manual transmission trucks which mine is.........
 
  #7  
Old 02-13-02, 08:06 PM
Joe_F
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Actually, the distributor mounted TFI style module is the subject of a class action suit/recall.

My cousin just got a notice in the mail on his 93 Taurus which he gave me to review. Basically says that the court feels Ford designed a bad module that can quit under heat or load. Ford says no. I believe the court.

Sounds like carburetor troubles if you have black smoke like that, although you claim that your spark is weak. How many miles on the truck?
 
  #8  
Old 02-13-02, 10:03 PM
trendar
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Might want to check the fuel pressure; could be flooding if the fuel pressure regulator is bad.

There should be a Schraeder valve on the fuel rail to put a gauge on it to get a reading- if it's out of range of about 32 psi or so at idle, it might be a problem.
Or leaky injectors?
 
  #9  
Old 02-14-02, 02:59 AM
tammi ann
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Truck has a carb and is not fuel injected.......

110,000 miles

Yes I have heard about all ther tfi troubles.

The spark I get is orange yellow looking, I checked this the other night too in the dark, doesnt make a loud pop either. I have checked spark on other vehicles I had in the past and this is very weak in my opinion. I will go saturday and get a replacement resistor from advance auto and possibly I will drop the column and see if the ignition switch looks like it has any problems with loose connections arcing etc....

Also, the papers that came with the module say to replace the hall effect unit in the distributor when replacing the module, I did not know this until I was looking at the papers this morning, dont think it has anything to do with the weak spark but I may look into buying this part too.... Might as well hahahahaha

I truly appreciate the help you guys give here, thank you
 
  #10  
Old 02-14-02, 04:31 PM
trendar
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Uh oh, running out of things to replace!

I think the ballast resistor is supposed to be bypassed during cranking, so it should only come into play when you release it from the start position-

Also, the Hall Effect pickup would only be a problem if you're having a no spark or intermittent spark problem; if it triggers the ignition module, it doesn't have any further effect on the strength of the spark, like the coil, ign module, wires, etc.
Strange you're still getting a weak spark if you've already swapped everything- If you have a good 12V and ground to the system, I'd think it should have been okay by now...
 
  #11  
Old 02-14-02, 04:45 PM
trendar
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Originally posted by Joe_F
Actually, the distributor mounted TFI style module is the subject of a class action suit/recall.

My cousin just got a notice in the mail on his 93 Taurus which he gave me to review. Basically says that the court feels Ford designed a bad module that can quit under heat or load. Ford says no. I believe the court.

Hey, I think I just got the same notice, probably for my Mustang! It's a long form from "Ford TFI Module Administration Center"-

Is it worth filling out, I wonder?
 
  #12  
Old 02-14-02, 05:07 PM
Joe_F
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If you replaced your module, dig up the bill and then put the information on there. You might get your money back on the module replacement. That's how I read that notice.
 
  #13  
Old 02-16-02, 12:48 PM
tammi ann
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according to info I have read the tfi does not have a ballast resistor. I show one resistance wire in wiring which checked out and a resistor that checks bad , neither seem to have anything to do with spark intesity.

I read in my instructions that came with my new ignition module that my hall effect switch in the distributor should be replaced. I am wondering if that would have an effect???

Someone else also told me to take the wire from the coil and hook it to a plug out in the open and then check the spark.

also, after pulling my rotor cap off , the inside of the cap seems to have a coating of rust like dust on it, wonder whats up with this

also the hall effect sensor itself, the magnetic part that the windows pass thru is also covered with rust, may just go ahead and replace this part too

I just dont understand what could be wrong, spark output from the coil should only be dependent on recieving 12 volts from battery and having a good ground, I believe the ignition module breaks the ground in order to pulse the coil, but still this would only seem to rely on good electrical connections not anything to do with the computer or any signals it recieves.

truck has me completly stymied, not much else I can do
 

Last edited by tammi ann; 02-16-02 at 02:19 PM.
  #14  
Old 02-16-02, 04:40 PM
mooser1
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here's one more thing you might consider...when you replaced the spark plugs did you buy the high dollar platinum "truck plugs"..if so, replace them with the cheapest Motorcraft or AC's you can buy that fit your engine... don't ask why this works, I can't explain it, I just know the expensive copper & platinum plugs will not fire properly in certain engines.. my brother had an S10 giving him fits, guy he bought it from had installed "truck specials" from Napa, bought 89 cent AC's for it, ran like the day it was made...

just a thought....
 
  #15  
Old 02-16-02, 07:22 PM
Joe_F
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That and Autolite wires tend to be of poor quality.

Swap them for a good set of Motorcrafts or other high quality aftermarket ones.
 
  #16  
Old 02-16-02, 08:16 PM
tammi ann
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I will purchase a cheap set of wires in the morning, cant hurt being as I seem to be driven to parts changing my way out of this thing..... Hate to do that but I am at a complete loss.

Removed dist this evening and completly cleaned the rust out of the body and replaced the hall effect pick up.

I think tomorrow I will replace the wires with the cheapest set autozone carries. I normally buy parts at advance auto but here they carry on autolite and some other brand, the other brand is one that I have been warned away from for the very same reason you guys just mentioned....

Also I may try sending 12 volts to the coil directly from the hot side of the battery, this will eliminate any doubt as to whether I am getting full voltage to the coil. After much reading and searching the internet it seems that the spark is controlled by the electronics on the ground side, but I will study the diagrams on this before doing it. I will also find out where wiring ground points are and check them too.
 
  #17  
Old 02-16-02, 10:14 PM
trendar
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Originally posted by tammi ann
Also I may try sending 12 volts to the coil directly from the hot side of the battery, this will eliminate any doubt as to whether I am getting full voltage to the coil.
If you try this, make sure you hook it up to the right side- like you said, the spark is produced when the current is interrupted by the ignition module, and if you inadvertently hook up to the switched side of the coil, the module will be poofed.

Checking the spark by checking the wire output directly from coil would be a good idea, since then you can rule out the distributor and wires. Still, like Joe said, you may have carb problems- what do the plugs look like? wet with gas maybe?
 
  #18  
Old 02-17-02, 03:20 PM
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I would have to agree as far as the possible carburator problem.
I would definatley Disagree with the statements made about the wires and the stator/pickup coil.If you think the wires are the problem,then take back to Advance and get another set of Autolites.The Autolite wires are made by Allied Signal which also makes the Motorcraft for Ford.Take and compare them to the original and you'll see their basically the same.Do not put Autozone wires on the truck,you'll have problems in the future if you do.
The stator/pickup coil will cause a week spark although a lot of independent shops would tell you different.As a driveability Technician in a dealership i can tell you the stator can do funny things and i always replace the module and it together.
One other thing to check would be your computer ground,which sometimes runs off the negative battery cable end.
 
  #19  
Old 02-17-02, 04:37 PM
Joe_F
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Then the Motorcraft ones must be gum too .

Allied Signal/Autolite makes different grades of wires. The orange ones they make are pretty hokey. My coworker had them on his Camry which someone gave him. I think bell wire for your doorbell would have worked better

Chances are the Motorcraft wires ARE NOT the same as the Allied Signal wires. Also, A/S was bought out by Honeywell and may have been subsequently sold from there.

A lot of Delco aftermarket wires actually use Packard/Delco wire, so they tend to be good.

Newsflash: Motorcraft is just a brand name. They don't make anything. Much the same way that Sears is just a retailer. Delco DOES make some of their stuff.

That being said, I agree with everything else Fordtech said.
 
  #20  
Old 02-17-02, 05:38 PM
trendar
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From an electrical standpoint, the pickup either triggers or it doesn't, and once it does, it really shouldn't have any further effect on the spark, like a digital signal.
It CAN be bad though, and intermittently not trigger, which could cause the missing and same symptoms as the weak spark, so it would be good practice to replace in unison, as advised-
 
  #21  
Old 02-23-02, 01:24 PM
tammi ann
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Its been a while, work etc....

Okay, didnt replace the plug wires as of yet but I did replace the module and the hall effect sensor inside the distributor.

Right now I have no spark, I have checked and rechecked the wiring and no spark.

One odd thing is that I decided to check the eec power relay, after getting in the floorboard and removing the relay from under the dash I noticed several things. 1. the relay does not work, checking around I found that it had no ground, finally traced to to a ground wire hanging off the battery terminal that was not connected, gonna replace the relay as when i used a jumper to power the relay the contacts did not pull in. This wire has not been connected in a while so evidently the eec module itself has not been operating. Cant fiqure out why I went from weak spark to no spark, only replaced the ignition module and distributor guts and did them correctly, rechecked them and all wiring in immediate area.
I have a haynes manual, need a chiltons for this but I only have a haynes, anyhow.... I performed various checks as outlined in their book and have been using it to check all my wiring.

The one test I seem to have failed involves hooking a 12 volt light betwwen tach terminal and ground the light comes on but during cranking it just stays lit, according to the book this indicates trouble in the primary circuit wiring or the module. did some tests that they recommend and it passed all so far, got a couple more to do but I first want to get the eec relay replaced and hook the wire back up for it.

One thing though..... When checking the hot and ground coil terminals on the connector for the relay I get 30 ohms resistance, is this normal ??? I know that any coils or lights between hot and ground will show as a resistance between the two but was just wondering if this would be a short circuit???
I checked the harness and the only connections the ground makes before the relay is to the eec module under the dash and to the bat neg which is not even connected to the wire at the moment.

sorry I post so long hope it is okay, thanks
 
  #22  
Old 02-23-02, 01:54 PM
trendar
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30 ohms might be within range, since it's probably a heavy duty relay, but you applied 12V and ground directly to the coils and it didn't click in? Seeing how you found a disconnected ground wire I would have thought that would have been it-

Do you see a spark output SPOUT jumper plug near the distributor? If you disconnect it, it should bypass the loop to the computer and fire the ignition module directly from the ignition pickup; if it does, then you can check the power and grounds to the ECA. Normally, the pickup sends the PIP signal to the computer, which sends back a SPOUT signal to the module (with the proper timing advance).
Without the plug connected, it should revert to base timing and take the computer out of the loop.
 
  #23  
Old 02-23-02, 08:25 PM
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well if you went from weak spark to no spark at all and all you changed was the pickup and module you probably got a bad part so when you get your eec relay working and you still do not have spark look at the parts you just replaced as being the problem.
i think you are looking into the wrong areas trying to fix your original problem you took a vehicle that was running and now it doesnt although your spark output may of been a little weak the vehicle did run and as you stated the timing light does not work and the vehicle was blowing black smoke which is a fuel problem and not ignition if you pull out a spark plug and it is blackish in color that is why your timing light was not working it is fuel fouled plugs due to the carb problem you have.
when you do get the ignition up and firing again if you replace all your gas fouled plugs, [ ya i know they are new spend the 6 bucks and replace them again.] your timing light will work until those plugs are gas fouled and then it will not work. so you do need to fix your carb problem.
as far as your spark being weak most after market coils are junk right out of the box and although the vehicle will run fair they dont have enough coil reserve and you can see this on an osiliscope really easily and i know that alot of people may disagree on this but alot of name brands do not have the output they should so you should always use oem especially when it comes to coils.
 
  #24  
Old 02-28-02, 08:42 AM
tammi ann
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well, just as my battery died today I heard a spark.
seems that my distributor is not contacting the cam gear and is not turning. Last time I installed it after replacing the module and hall effect sensor I seemed to have trouble getting it to seat right, after jiggling it some I got ti to where it would turn when I rotated the bolt on the front of the engine, today I removed the cap to check again and noticed it not turning, I loosened the hold down bolt and twisted the body a little while pushing down and then it turned, cranked the motor and could here sparking from a plug wire with a plug on it that I have removed, battery is too weak to crank so I just pulled it off and put it on the charger.
Strange that just a little jiggle would engage the distributor, I would think that it would be very well meshed with the cam gear.
Anyhow I will pull the distributor again and recheck everything.
 
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