While mocking up measurements for my new intake tubes that I am making, something prompted me to check my spark plug wires again. I did look them over previously as being the potential culprit in my starting/running/idling issue on my 87 S4, but missed it...I pulled off every boot going to each distributor and found my problem. Number one, upon close inspection, had a crack in the top of the boot that went all the way through. When I pulled the boot off the distributor cap, it separated from the wire loom with almost no effort at all. The wire was completely oxidized like a car battery terminal with powdered dust to the touch.

This was a great find and a big motivator for me to bring this beauty back to life that much sooner. Once I replace all my fuel lines and do some rewiring due to last weeks small, near fuse panel fire, she should (hopefully) purr like a kitten. It will be ironic if this is the problem as the previous owner spent nearly $4000 replacing sensors, the intake and the MAF twice thinking that was the problem and nobody was able to figure it out. This is why I own the car today. The poor guy got so frustrated and washed his hands with the car and I got it.

 

Omg! Nice find. Wow....don't see that everyday....

 

Good pick up.
I'd change the spark plugs, not take a look at them. If for the problems you described had only the big, complex, ticket items looked at, the little things may have been paid no mind.

 

I changed them twice. First time I put in NGK R plugs and was later recommended to put Bosch back in as the motor came with them from the factory and would perform better. All done within a week apart...

 

Well, as we say up here 'you're all set'. This should probably wash out you idle issue if all that other stuff was previously done. Till our next gremlins, happy motoring.

 

Your right on that one for sure. I have been going over the grounds and vacuum lines and so far found two vacuum hoses cracked, two unplugged at the tree behind the intake as well as poor grounds in the trunk and engine bay.

 

Anyone have an extra wire? I don't want to have to go for an entire $300 set of 8 when I just need number 1.

 

bite the bullet. buy the set!

 

Have you dealt with the two grounds atop the bell house deep under the airbox and rear fuel apparatus ? These are the ground points for your major engine controllers. After you get your faulty ignition wire replaced hopefully you'll be good. If not I would service the two ground points - they could be mission critical for you. They are a major PITA to access. In the Search Forum there is a good thread with pics. IIRC the one on the Right was nearly impossible for me to reach.

 

Anyone have a source for the crimp-on screw terminal wire ends?

 

So far I did one in the spare tire area which had three wires attached, rear ground for lights (I believe), Main ground for battery, both coil grounds and cleaned up the positive connections on front passenger side fender. I honestly have not even been under the car yet except for assessing my fire damage and tank sucking itself in due to evap malfunction. Just picked it up on Mother's Day.

 

One of your speedometer connection harnesses is in the spare tire recess should you ever need to know.
There is a main engine block ground under the car, but the two I'm talking about are up top deep under the airbox. There are also ground points in both footwell areas. One above the central electrical panel and two on the driver's side if IIRC. One on the wall (definitely) and one above the shelf at base of steering wheel (?) - maybe not here but prove me wrong.

Best Wishes with your 928.
I'm partial to 87 S4's.

 

Thank you. This car is all new to me and I will be absorbing all info given. I am learning very fast as I am relentless when I am interested. In this car's case, I am obsessed...

 

I also cleaned the connectors on the one relay in the back by the lights. While doing so, I found a plug pulled out which I believe is the actuator for the power trunk? I remember that not working on either drivers/passengers side when I bought the car a few weeks ago. That was a good find. I plugged it back in and will see if they now work once the car is all sorted out. Great progress I feel so far.

 

Yep, know the feeling.

Do you know where the Central Electrical Panel is ? Access it under the carpet, behind the wood panels of the passenger footrest. On the Forum it is commonly referred to as the 'CE'. With the exception of the rear relay you mentioned, all relays and fuses are here. With the exception of checking a fuse, don't work here unless you DISCONNECT the battery from the large wing nut in the rear hatch by the wiper motor. When releasing the flat cable don't make contact with the wiper motor.
As a beginning, check all your fuses to see where you may have electrical issues.