Dan87951

Tried that already then I tore everything a part again and started with the basics. If I cant get the coil to fire nothing else is going to fire either. Could the ignition switch be a root problem? How do I change that out?

Kevin Baker

Now does the DME tie the "ground switch" into the injector pulses? If so, and the injectors are not "pulsing" would this cause the DME not to pulse the coil to ground?

In other words, would cranking the engine with the injectors unplugged be the cause of the no spark at the coil?

Kevin Baker

Sorry, I hadn't read throught the whole thread.

Perry 951

Sure... the ignition switch does provide a path to the coil, however, if you get nothing with the key off, and 12v with the key on, it is operating. (making it much more simple than it is)

Short of tracing wires and looking at the schematics, I could not tell you how the signal is distributed.

If you are getting 12V on the ground terminal, you have a problem. As stated before, the green wire (pin1 of DME) is a switched ground that fires the coil. The black should be a constant 12v. Check pin 1 on the DME harness and make sure the pin itself did not push up into the connector.

I'll bust out my wire diagrams this weekend, but that does not help you right now.

Danno

"Danno the car is pumping fuel I have the fuel hose running into a empty 6 gallon gas tank just to check that exact thing. So fuel is being pumped when I crank so I must assume the referense sensors are correct right? "

Ok, with the fuel-pump going, we know the alarm isn't disabling the DME-relay. We're still not sure about the speed & reference sensors. Did you do the light test on the injector plugs to make sure they're firing?

As for spark:

"If you are getting 12V on the ground terminal, you have a problem. As stated before, the green wire (pin1 of DME) is a switched ground that fires the coil. The black should be a constant 12v."

You should see +12v on both terminals of the coil. That's because there's no current flow, thus no voltage drop across the internal resistance. It's only when the DME grounds pin#1 at the green wire, does current flow and you'll see zero-volt on the green wire at that time. But you'll need an oscilloscope to catch it. Do these two tests on the coil circuits.

1. Hook everything up like it should be. Then disconnect the center wire from the distributor and stick a spark plug in there. Lay the side of the plug onto the metal cam-gear cover. Crank the car over, do you see spark?

2. To test the coil, fire it manually. Leave the plug in the wire coming from the coil. Disconnect the green wire to remove the DME control. Hook up a wire to that terminal that you can ground it yourself manually at the battery. Turn on the ign. key to supply +12 to the black-wire on the coil. Then quickly tap on and off the ground wire to the battery's ground. You should be able to make the splark-plug fire this way, and your tapping like morse-code should generate a corresponding spark. If this works, we know the coil is good.

Dan87951

Perry when we force the coil to ground state the I do get spark from the coil. In other words when I take the green wire off from the coil and hook up my own wire from that coil terminal where the green wire goes to the engine block the coil will fire. I was also told that with the ignition on I should get 12 volts from the green wire, I should only get a low state from the green wire when the car is cranking or when the car is running as it switches back and forth from a low to high state. Already checked pin 1 from the DME harness. I even ran my own PIN1 from the DME harness to the coil and STILL nothing!!

Right now I'm thinking its a ground problem somewhere. Exactly what terminals are the grounds for the DME?? I know PIN28 is suppose to be a ground but does PIN28 provide the ground for the whole computer? For example does PIN28 provide the ground for PIN1 on the DME harness? Looks like this car will be sitting for another year...

Dan

I'm going to bed and giving that car my final universal signal for the day. Thanks for the help guys keep it coming.

Perry 951

The way I read your earlier post about the green ground wire was thay you had it off the coil and was testing from the terminal to ground. My bad reading that wrong.

It sounds like the DME is not sending the switched ground to the coil. There are 3 grounds that enter the DME.. all are brown wires. You coud do a continuity check to the battery ground. If they all check out, things are good there, and I would start looking at the speed and refrence sensors. That is the only triggers for the DME.

Do you have a new flywheel on the car? Were the allen head triggers on it?

89magic98

Dan,

Well, Danno got to my reply to Brian Perry before I did. I agree with Danno 100% on seeing 12v on both sides of the coil when the car is not cranking/running.

Some more questions for you:

What did you do with the two grounds that you posted on sometime in the last week? Please post a picture if you can. These were the brown wires on the back of the firewall, that go through the firewall into the passenger compartment. If these grounds are not connected properly... no start. I think the DME gets its ground from there.

So, your negative battery cable has three connections:

1. negative battey post
2. chassis ground (should be a 10mm bolt within 1 foot of the battery, inside of the battery compartment)
3. engine block/bellhousing, under the timing/reference mark sensors.

Now, the 2 brown ground wires that you held up in that picture:

1. The bigger one goes through the same bolt that holds the battery cable ground in #3 above. On my car you have to remove the coolant hose (a small section, about 3") in order to see the bolt hole.

2. The other goes in another bolt hole (this one, on the bellhousing, I think). This bolt is slightly smaller than the other one.

When assembled, Both bolts are less than 4 inches apart from each other.

Also, could you try taking a set of jumper cables, and connecting the negative post of the batter to the engine block (with everything assembled) and try starting the car? (In this case, you are using one of the two jumper cables as a big ground wire. Do not use the positive jumper cable at all in this test.) This helped me to find a grounding problem before.

-Kevin

Dan87951

I dunno what kind of flywheel is on this engine. John says he put a lighten flywheel on it. Flywheel looks factory to me. John installed the clutch and put on the bell housing for me when I received the engine so I did not do that.

QUOTE
"1. Hook everything up like it should be. Then disconnect the center wire from the distributor and stick a spark plug in there. Lay the side of the plug onto the metal cam-gear cover. Crank the car over, do you see spark?"
/QUOTE

Thats how I have been testing for spark the whole time.

Also both of my speed and reference sensors are brand new from paragon. I also have not done the fuel injector pulse test with the bulb. I do have some LED's that I picked up at radio shack will those works?

Dan87951

That’s exactly where my ground wires are at. I will post a picture after my batteries charge.

Perry 951

If John had the flywheel lightened, I would assume the allen head triggers were taken out. I'd hope they were put back in when he put it all together.

If the triggers are not gapped right.. the DME will have no idea where the motor is sitting. All it will see is the 132 teeth on the flywheel from the speed sensor. (and because of the way the bracket works, you gapped that one correctly)

I'd start looking that direction. You may have to pull the refrence sensor and roll the motor over by hand to check if they are there, then check the height on them.

Dan87951

Well if anybody wants to come to adrian michigan (half hour north of Toledo Ohio) they are more than welcomed to come and have a place to stay for the night and eat. Would spot a $20 to help with gas. I just can't figure it out, and John Anderson will not answer his phone or return my messages I left him. great..

89magic98

I remember the bellhousing now, because in the pictures, it looked pretty dirty in comparison to the motor.

If the triggers were missing, I assume that would be a good reason to scream, right? I imagine they can't be installed without pulling the motor again.

Dan has an oscilliscope. He could probe the signals coming to the DME from the speed/reference sensors, see if they are in spec with respect to peak-to-peak voltage (which is a function of the mounting position of the sensors) and period (which should be a function of the engine revolutions). The only problem would be how to tap into those signals without cutting up the harness.

-Kevin

Danno

" The only problem would be how to tap into those signals without cutting up the harness."

Just unplug the connectors at the back of the manifold. Use pins#1 & #2 to hook up to 'scope. Or you can unplug the DME from the connector and just crank the engine while testing pins #8 &27 (speed) and #25 & 26 (reference). This will ensure at least that the signal makes it through all the wiring. I think the book says minimum 2.0v peak to peak.

Aligning the speed & reference-sensors to themselves then to the flywheel-triggers can be a pain. Easy way is to make an 0.8mm steel shim that will stick to the end of the sensors. Then adjust the bracket so that the shim is fully touching the triggers, but doesn't push the sensors out of the bracket. Tighten racket down, pull out sensors, remove shims and re-install.

89magic98

OK, I wasn't sure if you could do a measurement with the sensors unplugged at the connectors at the back of the firewall. For some reason, the rubber boot on my reference sensor looks like it was cut (not by me) to make this measurement. I was thinking it might be handy to make some kind of a signal "splitter" so that this could be checked out on a running car.

Just make sure that the shim will not come off inside the bell housing while doing this. The factory manual suggests taking an old sensor (which Dan has, because he said he has two brand-new ones in the car) and crazy-gluing a .8mm shim to it, and making it a permanent measurement tool.

-Kevin