924Board.org

Ron B · Joined: 19 May 2014 Posts: 102 Location: Delaware

Curious if you guys have any thoughts before I jump in.

My 924 started running badly all of a sudden, poor acceleration, no power, and rough idle, it got progressively worse. Now it's very hard to start, reset all timing marks no help, pulled plug was black and wet, cap was full of black dust.

Included pics of cap and rotor.

Any thoughts before I start pulling it apart.

Thanks, Ron

https://ibb.co/6Dc9BKJ
https://ibb.co/SJTDF8z

924RACR · Posted: Tue Sep 26, 2023 8:44 pm Post subject:

So, yeah, ignition. Definitely start with new cap and rotor; that dust should be the center button disintegrating.

Also wonder if you might've had some misfiring of the system, like arcing/mis-triggers of the coil, causing arcing internal to the cap... check the low tension leads, distributor pickup etc...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Ron B · Joined: 19 May 2014 Posts: 102 Location: Delaware

Was trying to find a new Bosch coil , Pn on old one is 0221122015, but all my old links show no stock, what are you guys using as replacement.

Here is pic of coil on,

https://ibb.co/JsBky5R

Beartooth · Joined: 05 Apr 2022 Posts: 314 Location: Roberts, MT

I agree with 924RACR: a cap and rotor aren't that expensive, and worth a try. I can't say for sure that the dust is indicative of a problem, but mine didn't look nearly that bad. As for the coil, I'm running an MSD Blaster II. It shouldn't be a problem to use a typical performance aftermarket coil as long as it's not intended for a capacitive-discharge ignition (will typically have a very low primary resistance) or specifies against using on a four-cylinder. The Blaster II calls for a .8 ohm ballast resistor in points or transistorized ignition, and (on my 931 anyway) there's a 1-ohm resistor built in. That said, I'd check the primary and secondary coil resistance before I went any further, and if it's close, definitely do the cap and rotor first. Haynes says 1.0-1.3 ohms primary resistance and 5.5-8.0 ohms secondary resistance.
_________________
1980 931 diamond in the rough

Ron B · Joined: 19 May 2014 Posts: 102 Location: Delaware

Found a NOS replacement Bosch distributor online, so hopefully we'll be in business.