Help! No spark!

[catuck]

I just completed my 3.2 conversion. Hooked up the DME, wiring, etc. crank it over, but no spark. The engine ran fine in the donor car. I'm pretty sure I have everything hooked up correctly. I am using a CraneCams performance coil that worked fine on my old engine. I couldn't find any ground wires I may have forgotten.

Any ideas?

[marcesq]

Check what you did against my wiring diagram.

Make sure you have the proper wires going to the coil.

Make sure the sensors are connected properly and fully.

If everything is hooked up right and still no spark then it is either the coil, DME relay or less likely the DME.

[marcesq]

Don't forget the 6 pin injector connector that is behind the blower fan

[catuck]

Marc,
Actually I used your web site to do the conversion. I have double checked the connections and can't see any problems. The black coil wire is getting 12 volts and the green wire checks at about 0 ohlms to ground. I have tried two different coils with no difference. It seems as though the coil isn't getting the signal to fire. I'll try a new DME relay as soon as I can pick one up.

As for sensors, the two on the flywheel are connected and worked before I bought the engine. I only have two though, and it looks like you have an additional sensor??? Am I missing one somehow?

Could anything else cause this problem?

[marcesq]

Chris:

You have the head temp sensor (white plug on top of tree) that must be connected for the car to run.

When you say you are not getting any spark . . . I assume that you tested the coil wire to ground.

Post a picture of the tree that holds the 3 connectors for the sensors. The harness from the engine should have 1 white and 2 black (I think, but they are the same color). The white connector from the harness goes to the white connector on the tree (usually on top).

The other 2 go to the other sensors that you mentioned. You might try switching the 2 black ones as they might have gotten switched.

Did you gap the sensors on the flywheel.

You checked the ground straps - particularly the tranny to chassis one.

Is the coil getting 12 volts when the engine is cranking. Some fuses don't get power when the switch hits the crank position.

[catuck]

Ok,

I tried swapping the two black connectors on the tree - no change. The white connector is connected to the white receptacle on top.

I did test the coil wire to ground - no spark

I did gap the sensors on the flywheel. My Hanes manual specs 0.8mm which is where they were when I checked.

Ground strap is connected to tranny and chassis. I will try cleaning all ground straps and batt. leads tonight.

I get 10.6 volts at the coil when cranking. 12+ volts with the key on.

I ordered a new DME Relay - should be here tomorrow. (I have my fingers crossed that that's the problem!)

[marcesq]

Sounds like you have it covered.

Let us know when the sparks fly.

Good luck.

[Superman]

You say the green wire has 0 ohms resistance. I believe the trigger in the distributor is supposed to show some resistance. That is, resistance through the windings of that trigger are supposed to have a tad bit of resistance. Don't recall how much, perhaps less than an ohm, but when mine died, it showed no resistance. And it was not telling the CD box to fire.

[catuck]

Originally posted by Superman
You say the green wire has 0 ohms resistance. I believe the trigger in the distributor is supposed to show some resistance. That is, resistance through the windings of that trigger are supposed to have a tad bit of resistance. Don't recall how much, perhaps less than an ohm, but when mine died, it showed no resistance. And it was not telling the CD box to fire.

I have disgarded my cis/cd box for a 3.2 with motronic/DME. Should there be any resistance on the green wire with this system?

If the DME Relay is not the problem, is there a way to check the DME?

[marcesq]

Chris:

See if you can swap with someone that has a working system.

I would be surprized if the DME was bad given that it was working before . . . but it could happen.

Steve W's thread on the DME relay is timely.

Hope the relay is the problem.

[catuck]

Thanks Marc,

Actually, the engine ran but the seller gave me a DME he had on his shelf, not the one from his car He seemed like an honest guy...
I'll let you know tomorrow.

[marcesq]

Originally posted by catuck
Thanks Marc,

Actually, the engine ran but the seller gave me a DME he had on his shelf, not the one from his car

Hmmmmmmmmmmm. Keeping fingers crossed.

Remember that the boxes are not the same for all 3.2s. The earlier motors had 207 hp, and the later 217 hp. I don't think that the pin designations for the DME changed, but I haven't studied that question thoughly.

[Superman]

I'm no expert and Carreras have several components that can cause this kind of problem, but I suspect your green wire and distributor windings may be the same as mine. If you see no resistance at all (open circuit) through those windings, then that's probably your problem. There are several folks here who know much more about this than I, so it's just a matter of time before one chimes in here.

[rick-l]

Looking at Mr Wilks schematics http://frwilk.com/944dme/

Looking into the DME from the coil you should measure 1.8k in series with the parrellel combination of 5.62k and 8.26k or 5.14k ohms between the coil wire and ground. This is with the ignition off.

Also looking at the schematic (I haven't tried this) with the ignition on and the engine not running the DME should be sinking about .5 (.47) amps through the wire to primary of the coil. I think that is what those transistors that form a diff amp do.

[ChrisBennet]

Some data points:
3.2's don't have a "green wire" on the distributor.
A CIS "coil" is not the same as a Motronic one. The CIS "coil" isn't even a coil, it's an "ignition transformer".
The big connector that is mounted on the firewall of a 3.2 with only 4 pins in it, runs the injectors.
-Chris

[catuck]

Ok, now I'm very confused. The green and black wires on the 3.2 harness go to the coil right? The CIS coil isn't a coil??? That might be the problem then. Can I use a generic coil for the 3.2?

The p/n on my DME is 911.618.111.09 and the motor is from an '87 Carrera. Anyone know if this is the correct one???

[marcesq]

Chris B: With all due respect the 3.2 harness has a green wire and black wire that go to the coil. They are in a separate harness that branch off of the main harness that goes to the engine compartment.

Chris T: Use the right coil for the motor. They are not expensive. The CIS coil is more than the other coils because they were designed to tolorate the CDI ingnitions.

[catuck]

Thanks Marc, I'll order a Carrera coil today. I was trying to get the car running tonight and PepBoys has coils, but if a generic coil won't work or is bad for the computer etc. I'll wait for the correct one.

And I thought a coil was a coil!!

[marcesq]

Originally posted by catuck
The p/n on my DME is 911.618.111.09 and the motor is from an '87 Carrera. Anyone know if this is the correct one???

Appears to be from '84 ROW motor. Don't know the compatablility, but I would go back to the seller and ask for the one that was in the car.

[ChrisBennet]

Originally posted by marcesq
Chris B: Will all due respect the 3.2 harness has a green wire and black wire that go to the coil. They are in a separate harness that branch off of the main harness that goes to the engine compartment.

Chris T: Use the right coil for the motor. They are not expensive. The CIS coil is more than the other coils because they were designed to tolorate the CDI ingnitions.

Wrong wire. Sorry, I thought Superman was referring to the green distributor wire. As in "3.2's don't have a "green wire" on the distributor. "
-Chris