gtfhercules

Hello,

It looked like the original Bosch unit.

The loaner came in the post today, and sure enough the car started! It was a very smoke filled venture which was fantastic...for about 20 minutes, and then it died again and refuses to start back up. The tank reads a bit less than 1/4 full so I thought it ran out of fuel. I got three gallons and put it in - no effect.

I didn't attach the loaner to the car for testing purposes; I thought that was the problem, so I screwed it into the car using the top bolt to hold it down. Still nothing. For fun, I cleaned the fuel pump fuse contacts and made sure it had power. It does.

I confirmed that once again there is no spark coming from the coil using a timing light.

I have confirmed that there is power coming from the green wire and that pins 31/1 and A (the furthest to the right of the connector when facing it in the car which connect to the stupid green wire) are not broken. I have also confirmed that the plug itself is getting +12v when the ignition is on.

Could the battery itself just be too weak? During the successful starting attempt, I had to jump the car with a jump pack - and as much as I'd like to try again, the damned jump pack decided it was out of juice so it's on the charger now.

I connected the main battery to a charger and it's charging now...I'm running out of ideas here.

Perhaps the coil?

Lorenfb

You need to call the CDI rebuilder;

1. To determine whether your CDI was tested and the test results. And if it failed, what component failed.
This could help determine the main cause of the CDI failure, e.g. wiring, bad coil, reverse battery connection.
2. For help in troubleshooting why the "rebuilt" CDI you received doesn't produce a spark.

theiceman

is it a silver bosch coil ? ( paperweight )

gtfhercules

I didn't even mail in the old one yet - I was going to send it off today, but...I'll have to figure out what to do now. I really dread calling Mr. Ashlock and saying that the loaner is kaput.

Tell me - having the box not attached to the chassis wouldn't fry it, right? I totally didn't just fry an expensive box because I was a dummy - right?

It's a Bosch coil that's silver - doesn't look recent though. I can get a photo in a few

theiceman

the bosch silver coil is absolute garbage ( made in Brasil right ? ) , it has been long recognized as crap. That would have been the very first thing i would have changed. regardless of whether it is the problem now or not, sooner or later it will leave you at the side of the road. Mine lasted exactly 10 minutes.

google this : bosch silver ignition coil is crap

gtfhercules

I swapped in this coil from the 77 S - it was working there, and the original coil on this car is now in that one and working. I was thinking of swapping the known good coil back and seeing if that's the problem since that costs nothing but a bit of time...

Tell me, what coil should I get instead (new?) Also, can a bad coil fry the CDI box?

I really just do not want to hear that I killed a loaner expensive box

Lorenfb

So now you have two non-functioning CDIs (loaner & original 78SC), but still one good CDI on the 77S, right? You have two working coils, the 77S one and the silver from the 78SC, right?

gtfhercules

Morning,

Correct - I sent both non working units back to Ashlock (spoke on the phone, he was pretty cool about it and reassured me that I most likely didn't break it). They will arrive in his place tomorrow and he'll update me on the units so I can at least figure out wtf is wrong.

I put the known good coil back in the 77 for now and I'll continue to work on that car and make her more perfect - well, as best as I can reasonably do (and not thinking about the seatbelt or parking brake lights since those seem to be a PITA to get to).

In the meantime, I'll go fret if I installed the donut bushing correctly in the S - does the bracket for that bushing go below the floor or above it? I put it above as the ball cup kept popping out when I put it below, but that could be because I was using a spacer that I found with the car for the two smaller bolts that was put in by the PO (the old shift rod is...I'll have to get a photo of it. It seems longer than the SSK rod and I'm sure it was not factory.) Because of the spacer, the ball cup kept popping out.

If it's supposed to go below the floor, is it worth taking the whole thing apart again to correct? Surely it's a few mm of difference.

Lorenfb

No, as long as the pin 31/1 has a good chassis ground.

theiceman

My original one was actually okay and i bought the silver one as a spare as my car is over 40 years old with he original on, i put the silver one in to make sure it was okay and sure enough 10 minutes later i was at the side of the road. I then picked up a msd blaster coil and it worked great , ran with it for a year ( didnt like the look of it however ) put it back in my parts bin as a known good spare and went back to my original, still running strong 43 years later

gtfhercules

Good morning,

I confirmed that the coil is the original 1970s one with the CDI rebuilder via the part number. I'll consider picking up the MSD at some point just to have a spare.

Ah okay, good - I confirmed with the rebuilder that I didn't fry the box so I'm happy with that.

The bad news, though, is that both the loaner and the original boxes were confirmed functioning. What the f***!

What the hell else could it possibly be? I've confirmed good signals to the CDI plug and there doesn't appear to be any wiring faults to that plug.

A mechanic I talked to yesterday suggested that I clean all the fuses just in case so I'll do that, but...ugh.

On the bright side the S drives pretty good - now, to fix the broken audio...

I'm waiting for another loaner box while I go ahead and get mine rebuilt.

Lorenfb

That's good.

Why are you wasting money when your CDI unit tested OK?
I've been repairing Bosch CDI units for over 30 years, and for the most part, they are very reliable.
Furthermore, why switch to a MSD unit when they have a higher failure rate than the Bosch units;
http://forums.pelicanparts.com/porsc...n-exposed.html

systemsc

Any update for the forum?

gtfhercules

Hi all,

Apologies for the lack of updates. A lot has happened since I last updated:

The S drives pretty good - took her on a nice drive through the canyons and got a speeding ticket doing 60 in a 55 the cop also tried to bull**** me about not being allowed to use my dealer plate on the weekend but of course since that has no binding he didn't write me up for that. That alone has ruined my mood altogether on working on the SC since I do not want to drive any of these cars without a proper good radar detector, like say the Uniden R7 (which I'm saving to buy.) The car also needs expensive tyres as well, and it's just becoming harder and harder to justify throwing money at it.

I got the newly refurbished unit back - he upgraded the discharge capacitor and made the unit pretty again. I've not installed it in the car or given it a try. When I do, I'll let you know what happens - could the fuel pump be gummed up? Is it worth replacing it just in case?

Because of the uncertainty of getting the SC running I didn't get a spot in Werks, and after seeing hotel prices I was going to not go altogether...but I found a better deal so I'll be taking my E38 down for a few days. Pic related, twelve cylinders of Bavarian goodness:

gtfhercules

Hello Rennlist,

Quick update: I put the new old CDI box back and cleaned every single fuse and its seating and predictably, the car did not start. I'm wondering if the battery has just gone flat as the car didn't sound particularly strong.

Here is an I smell fuel and I can hear the pump working; when the car is on (but not cranking) I'm noticing that the coil is not getting 12v - I take it that this is normal?

Otherwise, I'll go down the checklist once more to rule out no spark, but I'm getting a bit worried lads.