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Discussion Starter · #1 ·
Hi, I have a 87 F-150, and while it isnt a hot rod, you guys seem pretty smart, and maybe you could help me. I have a 302 with stock electronic ignition. I started having problems when the truck wouldn't crank, and I think I narrowed it down to an electrical problem. I wasnt getting good spark at the plugs, and wanted to see if it was the cap and rotor, or the coil, so I took off the coil to dist. wire, and held it close to the dist. center post. Funny thing happend, it cranked. But when i put the wire back on the dist. it dies. So I ended up replacing the cap, rotor, plugs and plug wires, coil, TFI module, and a friend gave me a dist. out of a running truck. Now it will crank sometimes, but runs really rough, with NO power. It won't even move the truck. But if i pull the wire off the dist. and hold it so that it arcs to the center post, the idle smooths out and runs good. Ive timed it, and the timing is with in spec. but I dont know what else to check. Anyone have ANY ideas, please. Thank you
 

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Doc here, :pimp:

Check all your Body and ENGINE grounds, Run a jumper cable from the battery to the block, see if it runs better.

Be SURE you have the RIGHT distributer for the Dura Spark module..

If the grounds are not the fault, I'd suspect a defective DS Module.

Doc :pimp:
 

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Discussion Starter · #4 ·
Yeah, i scanned for codes, nothing there, but ive done some work on it, so ill run a full scan today, and post the results. It has a brand new module on it, that was one of the first things I replaced. Ill check the engine ground after work to.
 

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I'm having a hard time connecting the crank problem with the ign/no power/runs rough issue. I would start by looking at them as two separate problems. Check the battery cables, remove and clean the terminals at the battery, block, and solenoid. Check the black wires at the B- terminal near the battery (if applicable) for corrosion (common problem on Ford). It should be a black 2 wire connector. That wire is connected to pins 40 and 60 of the PCM. It is a very important ground for the EEC system. Check the engine ground strap. Check the 02 sensor ground. It is on the back of the engine and is an orange wire. It is also a very important ground that will cause all kinds of driveability problems if not a properly cleaned and connected. Do not do a visual check on these connections. They need to be disconnected and cleaned before you can go on with the diagnosis of this issue.

Are you using genuine Ford parts? I have seen a night mares diagnosing problems with aftermarket parts.
 

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Discussion Starter · #6 ·
Ok, i thoughly checked all grounds, and had to fix a couple, but there is still no change. The engine cranks, but has no power, misses, and smokes. But still if i let the coil arc to the dist. buy removing the wire, it runs great, idles, and has power. The optimum arc is between 3/8 and 1/2 inch. Any less or more, it runs rough, or dies. I tried the jumper cable to engine to help the ground, and even tried hooking it directly to the coil case. A system scan shows 11 on key on engine off, and 31 and 43 on memory. I tried disconnecting the neg. batt. cable for more than 5 min. to clear the Keep Alive Memory (according to Haynes). The engine time is at 34 deg. btc when the coil is arcing. :confused:
 

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To properly check timing you would need to disconnect the spout wire (yellow with a black connector) near the distributor. Set the timing to 10 deg with the spout disconnected, then plug it back in.

Seems to me it still has some kind of secondary problem. When you pull the coil wire away it runs better. The coil only works as hard as is has to, so when you increase the distance it works harder and you get a hotter spark. What color is the spark when it is real close and running rough compared to when you pull it away. If you have a yellow spark, its weak. Blue to white is what you should see. Do you have full battery voltage at the red wire on the E-coil? On one problem I had situation where there was a problem in the IDM circuit (pin 4 at the PCM). I disconnected the PCM and removed the green wire (pin 4) and the problem went away. I never knew what caused it but the problem must have been in the PCM.

You said it smokes. Black when running rough or blue at any speed or condition?

31 code is an EGR problem, 43 is a AIR system malfunction if I remember correctly. Should not affect the situation you're having.
 

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Doc here, :pimp:

I am NOT a Ford guy at all...and am not up on the Ford systems...

BUT Electrically, IF the only way you can generate a spark is by holding the trigger (power) at a distance off the coil..you have a Ground or a Defective coil problem, (the spark being generated by having to "jump" between the wire and terminals..) or a discharging capacitive element that is generated when the "gap" is added to the coil power.

Try testing the coil..using a DVOM , set you RX1 scale, measure the primary of the coil, it should read less than an ohm, but more than 000, if not get a new one..(new ones have a High OBF rate)

Set the Scale to RX10k or higher and measure the secondary of the coil, it should read between 10,000 and 11,000 ohms, out of that range replace it..

Measure with all wires disconnected from the coil.



BE sure the Coil Foot has a properly bonded ground (use star washers , and burnish the paint) AS well as any foot on the DS module...



Which Could be seeking a ground for a discharging Capacitor from it, through the gap at the coil resistance..

Doc :pimp:
 

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Discussion Starter · #9 · (Edited)
Ok, spent another whole day working on it. 2-many it is getting a purpleish to orange spark. I did a whole bunch of stuff to it, let me see if i can remember everything.Docvette, I tested the new coil, and the old coil. They were both out of range, so i got another new one, this one an expensive Borg-Werner. It tested in range, so i put it on, cleaned the mounting bracket to the block, and the coil body to bracket, down to bare metal so i could get a better ground. No change. I even put a jumper cable from the neg. batt. to the body of the coil. I am getting about 1 volt drop at the + side of the coil, so i ran a heavy gauge wire straight from the + battery term. to that terminal. Which I am pretty sure that would bypass the ign. switch. I am wondering what the voltage on the other side of the coil should be. Is it supposed to be a ground or what? Im pretty sure it goes into the EEC, from the TFI dist. ignition module. It is 6.2 to 6.6 volts. That term. has 2 green w/ yellow stripped wires, and if I disconnect them and wire the - coil term. to ground, it doesnt run.

I timed the engine, disconnected the SPOUT, set it at 10 deg. btc. with spout disconnected, it seemed to run a little better, but still not great. with the coil connected to the dist. #1 misses so bad i cant hardly time it. With it arcing to the dist. it hits every time.

I am thinking it may be a EEC problem. How can i find and disconnect terminal 4?
BTW 2-many, it has always had some bluish smoke when the engine is under load, but this is thick, black smoke. I think that was about it, I metered and tested everything I could think of, with nothing really odd, except what I mentioned about coil neg. voltage. If that is even odd, Im not sure.

one more thing, what does the condenser, on the side of the coil, do? Im going to replace it when i go to town tomorrow. And Doc, could you explain what you mean by a "discharging capacitive element"? I have eliminated the bad coil, bad ground. Thanks for all your help. :)
 

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Spark color and intensity sounds OK. It should jump up to 1/2"gap.

Running B+ to the hot side of the coil and Batt- to the coil mount and block eliminates a voltage drop or bad ground issue. (BTW the coil will work without even being grounded to the engine. It only needs red and green wires installed at the 2 pin coil connection).

The 2 green/yellow wires at the coil is the ign minus side. One wire goes to the module and the other goes to the PCM IDM (ign diagnostic monitor) circuit. If the PCM sees a problem with the ign primary side you will get a code 14 and/or 18. Since you are not getting 14/18 I would assume there is not a ign. primary problem.

Your basic engine timing is now correct. All Fords with EEC are set this way.

Disconnection pin 4 at the PCM is a long shot. You need to disconnect the 10mm bolt at the 60 pin harness connector, and pull the connector away from the PCM. You can then remove the red plastic retainer in the connector by pushing in on the red clip on each end of the connector and using a small screwdriver or sharp pointed tool, pull the red retainer out of the connector. Then find pin 4 G/Y wire and pull it out of the connector from the harness side. This wont affect the engine running because it is only a monitor, not a control system.

Now about the black smoke. This is a sign of a full rich condition. Does this truck have a MAP sensor or MAF (mass air flow) sensor on it?
Even though there is no rich code it could have a bad sensor. A MAP sensor is usually mounted on the firewall and has a 3 wire connector and a vac hose on it. Remove the vac hose and look inside the hose for a jelly like substance in it. If it is clogged with the jelly you need to replace the MAP. If you have the MAF system you would need to disconnect the MAF electrical connector and see if it runs better disconnected. MAF have a tendency to go bad and cause the driveability problem you are describing. The only things in that EEC system that wont "tell on themselves" (give a code) is a bad MAF or a PCM. Then its a "try known good part" diagnosis. A vac leak can give a false reading to the MAP sensor and cause a black smoke problem. Check vac hoses by pinching them off as close to the engine source as possible. Pinch off the hose to the brake booster too. Have you or anyone else had the intake manifold off. Again check for an orange wire with a large eyelet and see if its disconnect from the back of the intake manifold. It WILL contribute to this problem. It is a single wire usually wrapped in a convoluted black plastic tube.

It is a possibility that by giving the spark a larger gap to jump you are helping to burn an overly rich mixture. Another long shot, but this is an unusual problem (or multiple problems) you are having with this vehicle. I kinda think there are several issues at work here.
 
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