Ignition coil question

PorscheFanatic · 09-28-2010, 03:19 PM

I pulled a spark plug and saw no visible spark. I then pulled the coil wire off and saw no visible spark. I put my tester inside the coil wire and there seemed to be a hint of something. My question is, with a new coil, should there be lots of visible spark from the coil wire in order to gauge that the coil is still good?

Also, where does the green wire connect to the distributor?

Thanks again for everyone's help.

Mrmerlin · 09-28-2010, 05:50 PM

OK please give the year of the car your working on and list all of the things you have fixed

PorscheFanatic · 09-28-2010, 06:40 PM

The car is a 1980 928S Euro - it has a new fuel pump and relay. I checked the coil wire and it doesn't seem like much spark. The problem is I'm not sure just how much one should see of spark from a fully functioning ignition coil.

Mrmerlin · 09-28-2010, 06:57 PM

are there 2 white looking things bolted to the the fenderwell with wires on them?? if so one of the these resistors may be failing

JhwShark · JhwShark's Garage

Quote:

Originally Posted by PorscheFanatic

I pulled a spark plug and saw no visible spark. I then pulled the coil wire off and saw no visible spark. I put my tester inside the coil wire and there seemed to be a hint of something. My question is, with a new coil, should there be lots of visible spark from the coil wire in order to gauge that the coil is still good?

Also, where does the green wire connect to the distributor?

Thanks again for everyone's help.

The green wire goes across the engine front top to the right inner fender wall connecting to a two pin connector. It connects to the Transistor Ignition Unit.

Jon

Maleficio · Maleficio's Garage

Check your input to the coil for voltage with a multimeter. Not sure what reading you should get, WSM will tell you. If volts are good, replace your coil.

PorscheFanatic · 09-29-2010, 07:16 PM

I still cannot find the green wire in my engine compartment. Would anyone have a picture of that location?

Also, who is WSM?

Thanks everyone for your help

stepson · 09-29-2010, 08:14 PM

With a 30 yo car, it may not be green anymore. It may look more white with a yellowish/cream colored tint. You will probably need to find the end at the distributor and work back from there.

tmpusfugit · 09-30-2010, 04:26 AM

WSM is "work shop manual"........

JhwShark · JhwShark's Garage

Quote:

Originally Posted by stepson

With a 30 yo car, it may not be green anymore. It may look more white with a yellowish/cream colored tint. You will probably need to find the end at the distributor and work back from there.

There is a wire on the side of the distributor facing the driver with a plug that is held in-place by a metal strap/piece with two screws (not the vacum, on the other side). It was green now could be discolored as mentioned. This wire should travel as I described earlier. You may have to twist the dist a bit to see it or just pull it out like I did when I replaced it.

The Ballast resistors (two of them) can be in white ceramic rectangular casings as Merlin mentions (like a few of my previous BMW's)...but on my rig they are cylinderical Black mounted in front of the coil on the fender wall. One for the Start circuit and one (with different resistance value) for the Run circuit; each has a wire to it and a wire from it. If no start and weak voltage the Start resistor may be bad.

PorscheFanatic · 10-02-2010, 06:44 PM

Thanks everyone for your help. This gave me great ideas to proceed. Thanks again.

John

Mrmerlin · 02-28-2018, 04:54 PM

did you ever get the engine running?

JK McDonald · JK McDonald's Garage

Like many threads - this one was simply left open ended with no reported results ?

It is always a pleasure to try and help a 928 owner breath life back into their car. As a rookie buyer about 10 years ago the Pelican Parts crew (and others) really came to my rescue many times as I worked out all the kinks in "Lady in Red (85) and then "Miss Purdy" (84).

For me the best part of the experience was that it builds your knowledge and confidence enough to tackle and assist other owners with their problems. It would be nice though - to hear back after someone asks for assistance in diagnosing a problem so we'd know what solved the issue. This would build a common troubleshooting reference base that could be passed along to everyone.

Michael