1mrj911

Hello , I have a 81 911sc euro , I accidentally left the key on all night and completely dead in the morning. I charged the battery back up on a trickle charger, cranks but will not hit at all. just checking to see if anyone new possibly what to look for , checked fuses and found 1 fuse in engine bay melted on plastic but not blown, changed it , still not starting , appears not to be firing . any help would be appreciated.

ahenthus

Hopefully you did not fry your ignition control module. It's an expensive fix, around $2k. Mine was replaced a few months ago but it took a long time to diagnose because my problem was intermittent.

systemsc

Actually, the ignition control module (CDI unit) is less than $500 to repair.

ahenthus

I guess I got screwed. My shop charged me $1,500 plus a new coil with labor for close to $2k. Not in the picture it says "not for your 2023 Porsche" I don't know why the search said 2023, my car is an 87 930 and the part number is a 930 item but I believe is the same as a 911 part. I guess if I had done it myself I could've gotten a DIY price somewhere but the car was in an independent Porsche shop and it exhibited the same problem of 1mrj's car. See link below.
https://cimg5.ibsrv.net/gimg/rennlis...718d3b7e0.jpeg

ahenthus

Another one from a different supplier.

systemsc

That's unfortunate! Here's the same part (Bosch CDI) we've been repairing for the last 25+ yrs for less than 1/3 of what you were charged;

https://www.systemsc.com/products.htm

ahenthus

It is a shame. I wish I had known that but I trusted my shop. I've done a lot of mechanic work over the years but not a lot on Porsches. If I'd have troubleshot the car and found the CDI to be the problem maybe I could've accomplished the repair myself. I guess it was worth it to me to have the car back in good running order so I'll just file it away as a life lesson. Also file away the fact that genuine Porsche parts from legitimate suppliers are way overpriced.

theiceman

my very first thought also, that bad boy squealing all night until the battery died ..

odd thing is though its on all the time while running too... wonder if lack of cooling from not running engine has anything to do with it.. when you turn the ignition on do you hear squealing from the engine bay ? if not, that likely what it is.

theiceman

you roll a 911 turbo into a shop you are going to pay big Porsche tax... pays to always be aware.. trust but verify.

Spyerx

If the CDI is fried get it repaired or use a quality aftermarket unit. I used one from Partsklassik (along with their coil and harness) on my old 914/6 with good results.

Regarding why… could be when voltage drops the unit keeps running and is stressed and causes parts failure.

You should verify no spark on crank before spending money though.