Need help with the ignition!!!

94fordmustanggt · Dec 30, 2009

Ok- I have a 1994 Mustang GT 5.0 5pd. I finally found a noise I've been trying to track down and it was the distributor. I put a new distributor in today (of course was off a tooth so I put it in where it was supposed to go), and went ahead and put a new cap and rotor on. I moved the distributor around a little so the timing may not be perfect but it drove fine- no pinging, detonation, etc. I took it home and let it sit till it was cool so I could put new plugs in it and it wouldn't start. Not even try to fire- just turn over. I checked the ohms on the coil and it's good, checked where the harness connects on the distributor and it has 12 volts. I checked the SPOUT connector to see if it has voltage and can't get the test light to light up. I unplugged the spout connector and it fires right up and runs good. So as long as the SPOUT is unplugged it's fine. If I plug it in while it's running it's fine. If I have the SPOUT connector in and try to start it it will not start. What is the problem? What do I need to replace? Thanks!

Chythar · Dec 30, 2009

Hmmm. First, on our cars there's technically no way to really be "off by a tooth" - we had a long discussion on that. You turn the distributor to set the timing, so if the dizzy gear is "off a tooth" from where it was before, you rotate the dizzy until you get to 10* BTDC.

Speaking of which, your post implies that you did not check the timing after replacing the dizzy. Removing the SPOUT connector disables computer timing advancement, locking it at whatever the dizzy has set. If you try to change the timing with the SPOUT in, the timing jumps all over. My first guess would be that your timing is so far off that the computer advances the timing to a point that it can't figure out when to start the spark plugs.

Of course, I think I'm talking out my @$$ on that last part - I'm not sure exactly how the computer uses the dizzy to determine when to initiate spark. I know there's SOMETHING in there, but not sure exactly what.

Irregardless, you should check your timing and make sure you are at 10* BTDC.

94fordmustanggt · Dec 30, 2009

Yeah I need to invest in a timing light. Will do that tomorrow. Something I forgot to mention- when the SPOUT is connected the engine will just crank and not even attempt to fire I am not getting any spark. When I disconnect the SPOUT it starts and runs fine. If it starts and runs fine with the SPOUT disconnected then the timing couldn't be too far off could it?

liljoe07 · Dec 30, 2009

Its called the PIP sensor and vane rotor. As the vanes pass by the PIP sensor, it gives the signal to fire.

You can be a tooth off, but it doesnt effect spark, what it does effect, it the injector timing. If you look at the vane rotor inside the distributor, you will see one vane is smaller than all the rest. That vane sends a smaller square wave pulse than the rest, and lets the ECM know to fire the number one injector. If this is off, it called a "waste injection".

liljoe07 · Dec 30, 2009

94fordmustanggt said:
Yeah I need to invest in a timing light. Will do that tomorrow. Something I forgot to mention- when the SPOUT is connected the engine will just crank and not even attempt to fire I am not getting any spark. When I disconnect the SPOUT it starts and runs fine. If it starts and runs fine with the SPOUT disconnected then the timing couldn't be too far off could it?

Timing retards to base timing during cranking. Definately get a timing light and verify where you are at.

94fordmustanggt · Dec 30, 2009

Any ideas why I don't get spark with the spout connector hooked up?

99FiveOh · Dec 30, 2009

liljoe07 said:
Its called the PIP sensor and vane rotor. As the vanes pass by the PIP sensor, it gives the signal to fire.

You can be a tooth off, but it doesnt effect spark, what it does effect, it the injector timing. If you look at the vane rotor inside the distributor, you will see one vane is smaller than all the rest. That vane sends a smaller square wave pulse than the rest, and lets the ECM know to fire the number one injector. If this is off, it called a "waste injection".

Nice try, but incorrect. You see, there is a reluctor wheel (vane) and a PIP sensor. I don't care what else happens. When the car is timed, the relationship between the reluctor wheel and PIP sensor is ALL THAT MATTERS. So you really can't be a tooth off. Remember, the rotor only goes on one way and is directly installed on top of the reluctor wheel. So IF the car DOES start and runs in time, then the smaller vane on the reluctor wheel is right where it supposed to be.

Ford put the notch at the bottom of the distributor to show us the "ideal" place to line everything up so things like plug wires will reach and the dizzy housing won't interfere with anything. On Foxes this was a big deal because the bulky TFI module, not so much on our cars though. But it makes no difference to the computer or the motor if you don't install the dizzy with the notches lined up.

So, because the shaft/reluctor wheel/rotor is all a fixed unit spinning in unison with one another, there's no way one can be out of sync with the others, therefore no chance to be a tooth off IF the car is timed and running.

Oh, and I wanted to add that since everything that spins inside the dizzy is combined into a unit, if the correct cylinders are firing where they should, it ALSO means that the correct vane on the reluctor wheel IS where it's supposed to be.

Chythar · Dec 30, 2009

Ah, here we go again. liljoe07, thanks for the reminder about the smaller vane, I had forgotten that detail. However, The_Mustang is correct. The 5.0 distributor is held down by a single bolt and plate clamping it down. Loosening that bolt just enough allows us to to rotate the dizzy thus adjusting the alignment of the smaller vane with the PIP sensor. So, it doesn't matter how you align the teeth in the dizzy gear to the camshaft. If you have enough plug wire length to rotate the dizzy to 10* BTDC, you're set. If you don't have enough plug length, pull the dizzy and re-stab it to get it closer in range.

The only consideration then is then having the dizzy 180* out (camshaft rotates once per every 2 crank rotations). So timing would appear to be right but the car runs like crap. So you pull the dizzy and rotate the rotor halfway around, re-stab the dizzy and re-time it.

94fordmustanggt, the timing may not actually be the problem. But you do need to make sure your timing is set properly before you continue troubleshooting. Wrong timing can mess up later diagnostics and make troubleshooting more difficult.

99FiveOh · Dec 30, 2009

I'm betting on timing myself. If the dizzy is what he messed with and he hasn't reset his timing with the aid of a timing light, then he's chasing his tail at this point. Confirm proper timing: step #1 then go from there.

Chythar · Dec 31, 2009

My thought exactly.

liljoe07 · Dec 31, 2009

The_Mustang said:
Nice try, but incorrect. You see, there is a reluctor wheel (vane) and a PIP sensor. I don't care what else happens. When the car is timed, the relationship between the reluctor wheel and PIP sensor is ALL THAT MATTERS. So you really can't be a tooth off. Remember, the rotor only goes on one way and is directly installed on top of the reluctor wheel. So IF the car DOES start and runs in time, then the smaller vane on the reluctor wheel is right where it supposed to be.

Ford put the notch at the bottom of the distributor to show us the "ideal" place to line everything up so things like plug wires will reach and the dizzy housing won't interfere with anything. On Foxes this was a big deal because the bulky TFI module, not so much on our cars though. But it makes no difference to the computer or the motor if you don't install the dizzy with the notches lined up.

So, because the shaft/reluctor wheel/rotor is all a fixed unit spinning in unison with one another, there's no way one can be out of sync with the others, therefore no chance to be a tooth off IF the car is timed and running.

Oh, and I wanted to add that since everything that spins inside the dizzy is combined into a unit, if the correct cylinders are firing where they should, it ALSO means that the correct vane on the reluctor wheel IS where it's supposed to be.

I had left a part out of my previous post. What I was getting at is if your were a tooth off(theoretically), and had rotated the number one plug location on the cap, to get the rotor and number plug wire to line up. It will still fire and time right, since the plugs only fire when the vane passed by the PIP, doenst matter what vane it is, but if a vane passes by the PIP at the same time as the Rotor crosses the terminal on the plug cap, it will fire on number one cylinder. But the injection can be off. On a stock ford cap with the number one plug location designated, its hard to do. But on a cap like the MSD, it can be done. Since its not labled. But its normaly by the D in MSD.

But you are correct, if you keep the orginal position of the number one plug wire, it doesnt matter if the rotor is off one way or the other, you would just have to turn it to get it in sync.

94fordmustanggt · Dec 31, 2009

Got another distributor today and that solved the problem with the no spark. I also got a timing light and here's where more problems begin. I warmed it up; shut off, unplugged SPOUT, started it up and set it to 10* BTDC. It was running quite rough. Shut it off and plugged in the SPOUT and started it back up and it would barely run then surge up to 1000rpm, back down to a few hundred, then shut off. So if there's no way it's off a tooth I guess I should just set it by ear? Supposedly the car had a cam in it when I bought it- maybe it's off? I had the balancer replaced a few years ago and had the guy set the timing to 12* at that time and he didn't seem to have any problems. I can get the car to idle smooth and run good but it is no where near the indicated 10* BTDC. Ideas?

desertcox05 · Dec 31, 2009

has the harmonic balancer ever been replaced?
The rubber in them can slip and that can give you the wrong readings for timing.
Did you advance the timing any to see how it would run.

99FiveOh · Dec 31, 2009

Apparently he said he can time it by ear and get the car to idle smooth. Something is off somewhere!

94fordmustanggt · Dec 31, 2009

That's what's messing me up. If I advance the timing quite a bit it runs properly. The balancer has been replaced and was set by a mechanic- he didn't mention anything about it being off. So if it was correct (allegedly) before and it doesn't matter if it's off a tooth what would throw it off?

Chythar · Dec 31, 2009

I have three guesses:

1. Your distributor is out 180*. Try pulling the dizzy, rotating toe rotor 180*, then re-stab it and re-time it.
2. Your harmonic balancer has slipped. Feel behind it and see if you can feel any rubber sticking out.
3. Do you have an aftermarket adjustable timing pointer? The stock one is simply stamped metal; aftermarket ones are chrome or various colors. I had an adjustable one and set it incorrectly - when I thought I had 10* BTDC, I was really around 0* or so.

Oh, BTDC is on the right side of 0:

ATDC 10...5...0...5...10...15...20 BTDC

ATDC only goes to 10, BTDC usually goes to 20 or 25. I also sadly made this mistake once, set my timing to 10* ATDC. I wondered why the car ran like crap...

99FiveOh · Dec 31, 2009

when I had my last problem with ignition, I tried it 180* out and it wouldn't even start, much less idle at all..all I got was a super loud bang when the car backfired!

94fordmustanggt · Dec 31, 2009

How could the distributor be out 180? I haven't cranked the engine at all with the dizzy out. The balancer looks good- it was replaced a few years ago. I have a stock timing pointer- with the little O . So from what ya'll have said even if I put the dizzy in 1 tooth off from where it was the timing should not be affected at all? It almost seems like it's just a little off from where it's reading. O and the balancer has the ATC then BTC marked on it

Chythar · Dec 31, 2009

If you put the dizzy in 1 tooth off, the timing will be affected - but you just re-time it by rotating the dizzy and using your timing light. Did you perhaps switch a spark plug wire around on the distributor cap? Here's a handy firing order chart that you can use.

I'm running out of ideas, honestly. Gotta be something we're missing.

94fordmustanggt · Dec 31, 2009

Thanks for the help. I checked the wires and they're all in the right places. Just for S&G's tomorrow if it's slow at work I might pull the dizzy out and move it a tooth just to see if it does anything. I couldn't really read the marks that it's set at right now but looking through that little circle they call a timing marker it looks to be around 10* ATC. It runs great, starts easily, doesn't ping, spark knock, diesel, etc. so at least I can drive it to work tomorrow I'll keep looking around and see if I can come up with anything.

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