1984 Ignition coil question?

ballysdad · 05-06-2009, 05:22 PM

The resistance reading across the pos (black) and neg(green) fluctuates and settles on .2 ohms the spec is .4 ohms to .6 ohms. Would flucuating readings cause a faulty coil? The secondary readings were 5500k and the spec is 5k to 7200k so that seemed alright. I get 12v to pos and 12v neg to ground. I am getting an intermitant no start condition hot or cold. Anyone with thoughts?
Reference sensors tested good and the tach bounces past 200 rpms..

thekidd · 05-07-2009, 11:26 AM

Hey Trever. I got you PM, just let me know if your around, and I will give you a call. I forget what I got when I tested my coil back in February, but I wanna say that I got .2 also, but not quite sure. Intermitent huh, what does it sound like when you try to start it and it doesnt go? The same as when it does start up? I will gladely help you out, but not too knowledgeable, I'm a persone that learns while doing things, just to let you know.

Razorback1980 · Razorback1980's Garage

Probably not...coils are rarely a problem on this car. Intermittent problems are really tough but here is what I would do.... Try to get it to fail and then perform these tests....

Check for power at the coil and at the injectors with the key on.

No power at the coil it's the ignition switch or related wiring. Make sure you have clean battery cables and all wires going to the battery are good.

No power at the injectors it's the DME relay. Sometimes the wiring harness breaks and you won't have power to all injectors so test all of them.

Power at the coil and injectors points to a bad reference sensor. The connector may be corroded and/or not plugged in all the way or cracked and may have broken the wires inside.

Check if the sensor is working by pulling a plug wire, inserting a spare plug, grounding the plug to the intake and cranking the engine. If there is spark then the reference sensor is working.

Could be the second set of contacts in the DME relay. These are for the fuel pump. The fuel pump should run for a half second after you stop cranking. Have someone listen for it behind the passengerside wheel well. Check the fuse for the pump too.

On the early 944's you can use an alligator clip jumper between Aux fuse #2 and #3 to run the fuel pump directly. Count from the drivers door. Don't leave the clip on.