Ignition problem

[Mountain Main]

TPS looks good.

I jumped all three wires. I put the DMM negative lead on the black wire and DMM positive lead on the red wire. The first part of range throttle plate starts out at .8 of a volt and opens all the way to 4.95 of a volt at wot. I did this test while KOEO. The tps seems to go smooth through out the range.

What to do now? Where to start? Try to pull more codes. I think I am going to try to run a KOER test. What do you think?

[tmoss]

I still don't know what it won't do. You say it won't crank - which means it won't engage the starter motor - but what I think you mean is it won't run unless you pull the coil wire. How does it run then? - just fire a couple of times and die or does it run and idle ok?

You've got a new distributor, coil, TFI, checked sensors, etc. Time to get into the wiring - especially the engine and main harness grounds. Ypou need to find them all, pull them loose, clean them up and reconnect them. Include the main ground from the battery to the block and the EEC ground on the driver fender near the coil location. I am going to post two pics of the Engine harness and the Main harness - study then closely and do the grounds.

Engine harness........

[tmoss]

Main harness.............

[Mountain Main]

I just bought some electric cleaner I will work on it tommorrow. The car turns over. I made a mistake with terms. The engine does not run unless I pull the center wire off of the distributor and let it arc. I have new TFI, Coil, ECM, spark plug wire, spark plugs, Map, ECT, EGR ,O2 and IAB. I turned the car from an AOD to a T-5. T-5 wiring harness going to the cruise control box. I had a shop do the wiring from the clutch peddal. I put a new fuel pump assembly in the car.

The only modifications that I have done is put the battery in the trunk of the car. Adjustible fuel pressure regulator. I get my new fuel pressure gauge tommorrow. Mack Header, Max off road x-pipe, Mack mufflers and tail pipes. I also have by passed the smog pump.

I am worried about seperating the Main engine harness and the injector harness. I hear this is a good place to clean the connections.

Thankx,

Mountain Main

[FritzDaKat]

Hmmm. The more I read this, the stranger it sound's.

Try using a different Coil wire, if it's a carbon core wire, perhaps the fillament is cracked and not passing a strong enough current down to the plug's?

[drtbiker]

yeah so let me get this straight aswell. The car only runs when u have the coil wire arc'd on the distributor? That makes no sence have u tried a different dist cap??? Or a new wire dist wire. So the car does not run at all then. Except what i stated above. It sounds like u have a bad ground some where did it ever run properly since the swap? Is there a good spark on the coil?


Like fritz said the more i read this the stranger it gets.

later hopefully we can get u back on the road

you got chris fired up and he has never let me down...

[Mountain Main]

So yesterday and today I worked on cleaning all the harness connections. Same problem and I went through the whole main harness and injector harness.

I got the car running perfect when the distributor cap wasn' totally on. I realized the distributor rotor has a huge burn mark on it. I believe it was accell from summit.

I just ordered a new distributor cap and rotor from summit. A ford motor sport racing cap and rotor.

The other distrubutor cap was only had 6 months of use on it. Crazy! I will post when I receive the new parts.

Has any body seen that.

Thanks

Mountain Main

[Nixon1]

Stranger things have happened. It's believable. Hope that cap works.... Wonder what made it burn in the first place. Was there any cracks in the cap or rotor assembly? Do you have any sort of aftermarket ignition device, like an MSD box?

[tmoss]

About a year ago, I was doing a tuneup on my friends boat and we put a new cap and rotor on. After the new parts it would not start - just crank. I pulled the coil wire from the cap and had spark. Pulled a plug wire - no spark. We found that the new rotor ahd a manufacturing void which broke down and passed the spark right to the distbributor rotor. Put the old rotor back on and it fired right up.

[FritzDaKat]

Yep, that big black burnt soot mark is more than likely the coil's chosen carbon pathway to ground.

if you dont feel like waiting for the replacement, simply get a small wire brush, scrub the heck out of it and wipe it clean with some rubbing alcohol... then after it dries, snap it on and fire it up.

it's also a good "first check" to make if you ever start suffering from a rough idle / backfiring out of the blue.

[PKRWUD]

I suspect that the burn marks were caused by the arcing that happened when you pulled the coil wire. My instincts tell me that you have a weak ground between the distributor body and the battery, but I can't explain it. I am having trouble understanding why it would run with the coil wire arcing, but not with the coil wire in place. The arcing will quickly dirty the contact points in the cap and rotor, but what caused this problem in the first place, except for a bad cap, which I thought had been replaced.


Hmmmm. Try a new cap and rotor, and see if that does it. If it doesn't, try improving the ground to the block.

Take care,
~Chris

[drtbiker]

How is the spark on the coil?? Is it a weak spark? Did u check the plug on the coil to see if it is loose. It is a weird situation i have never heard of a car only running when you have the cap arcing.

[88fivepointoh]

ok, I have had this same exact problem for the longest time and figured it out and finally am clear of it. Its a Grounding problem to the motor and distributor. The distributor is not grounding to the motor and causeing failures to the TFI and the Stator in the distributor. what you need to do is get a new distributor and TFI ( warranty them out if you can ) and where the distributor hold down bolt is wrap a heavy gauge wire to it and bolt it down and them ground it to the negative side of the battery. Make sure you ground it right to the battery. I will 99% gauranttee you problem will be gone. once you did it this way then you can go ahead and replace all the engine grounds and negative battery cable. once the engine dies its 100% that both the stator and TFI are cooked no matter what the parts store says. they fail almost instantly. save yourself the time, gte new parts right off the bat and ground it out at the distributor.. you'll see the difference. then goi ahead and fix the grounds correctly. The may look in good shape but acually are corroded out from the inside out. the can't handle the amp load. good luck!

[Mountain Main]

I am still waiting on a Ford Racing Cap and Rotor from Summit. I will plan on running a ground from the distibutor bolt. I don't have money for a new MSD Distibutor. When I first started having problems I bought a used distributor from Colorado Mustang Specialist. I installed a brand new TFI module from Napa when I received my new used distributor. I thought my stator was going bad. When I installed the new used distributor I put my cap and rotor back that were only 6 months old. I didn't think they would be the problem

When doing the extra ground to distributor adjustment bolt would it be ok to ground it to the body of the car. My battery is in the truck of the car and I really don't want run a new wire back there.

I will be real currious if this new rotor and cap will fix the problem. My current rotor has a huge burt crater in it.

[Nixon1]

With the current rotor being damaged like that, the new cap and rotor should definitely make a difference. The question is, what made the rotor roast like that.

[tmoss]

Originally posted by Nixon1
With the current rotor being damaged like that, the new cap and rotor should definitely make a difference. The question is, what made the rotor roast like that.

The proper term for that is "carbon tracking" and it happens in high voltage electrical equipment insulation also. One thing that will start the process is if you have a cool night with high humidity air in the distributor cap. You start the car and the engine starts to heat. Well, at some point that high humidity in the cap and condense in the cap or on the rotor or both. This encourages the high voltage to start carbonizing the insulation in a search for a shorter path to ground (through the rotor to the distributor steel shaft). It can also cause cross-fire from one cylinder on the cap to the other across the insulation. Any kind of air void or crack in the plastic rotor or cap created in the molding process will REALLY encourage this to happen too.

[88fivepointoh]

as long as you ground it to a good lean chassis ground u should be ok. thats if your cAble negitive is in good shape and grounded well itself.

[Mountain Main]

I received a Ford Racing distibutor and rotor for a efi 5.0. It works great. I think some body gave me the wrong distributor before.

I cleared the codes in the car and took it for a spin. The check engine light came on so I pulled KOEO code I received code 63 and code 67.

(63) TP circuit below minimum voltage.

(67) Clutch switch circuit failure

I believe 67 is a problem because I wasn't able to install a wiring connection correctly. I wasn't able to get to the switch that is on top of the transmission. So a mechanic and I installed a manual switch inside the car. I push the switch up to start the car and push the switch down when I am driving. I believed the switch tells the computer to read load. I think what is happening is when I do a KOEO test the ECM is not able to test the switch because it is not hooked up

But I don't know what is going on with the TP circuit. I tested the TP sensor and we thought is was good. May be their is some kind of problem in the return line.

What do you guys think the car likes to back fire. This code 63 has been a reoccuring code for a while.

[PKRWUD]

You could try cleaning the conector with some electric contact cleaner. Other than that, you may have to replace the TPS.

[Mountain Main]

I cleaned the connector like when Jimberg sent me the message to clean all the injector wiring harness and main engine wiring harness.

I have not installed the extra ground wire to the distibutor. I am going to put the extra ground wire this after noon.

Can I test OHMS of resistance of the wires going to the tps. What would those numbers be. I don't want to replace the tps if the wiring is bad. If this is not the right way to go after this approach. Please speak up.

Thankx

Mountain Main