The problem is that (and I am no expert by any means or even close, just speaking from my own experience) it causes such a huge headache. In my case, the distributor rotors a bunch of other things ended up going bad on it too because of this. So I would think you're not in the wrong for going ahead and changing them out since it seems that is the root to a lot of other problems when they do happen.

 

I would for sure change out the rotors as maintenance. For the coils you could replace them in advance but it may be just as good to keep a spare one in the trunk or something like that, pretty easy to plug it in even on the side of the road.

 

Hey everyone, I have a 92 sc400 that has the symptoms of a bad coil (Fuel smell, felt like half the engine was running, no CEL etc) so I went ahead and extracted/ tested both.

Looks like the drivers side was already replaced because it wasn't OEM (passenger side was however), also the drivers side coil was covered in oil.

I ordered some spectra coils and the thing that stuck me as strange was that the OEM and the replaced coil had readings of 0.5 and 0.6, 12k & 13k respectively so it looks like both were almost in spec.

The stranger part is that both new coils had a reading of .7 ohms which I fear is out of spec.

Anyway, I'm going to install today and post back to see if she cranks up.

Thanks all,

 

if its not the coils it can be the rotor inside the distributors going bad. if it was covered in oil its probably that one, could be shorting out even.
generally you can just disconnect the connector and see if the engine changes how its running. if no change then that is the bad coil.

 

Cool thanks for the tip and i'll definitely post back the results.

I am in the midst of the timing belt job as well and since I have half the car apart.. I'm changing the Distys, rotors, spark wires and sparks (Bosch, Bosch, NGK, NGK) + also fixed ECU with correct new caps about 2 years ago...have around 400 miles to the tank so everything was ship shape for a while.

Thanks!

 

a friend mentioned someone came up with a better driver side coil bracket, is this on the forum somewhere.

 

I wouldn't be surprised if heat and/or oil drips contribute to failures of that location.

 

It was the drivers side Coil! womp womp...

I think it was a combo of the heat from the cat and the oil.

I ended up changing the coils, spark plugs/spark wires dist/rotors.

Rotors were cracked, still had the original spark plug cables! and, the resistance values were all significantly under spec.

Same story with the coils, the passenger side was the original coil from the factory and the drivers side was aftermarket and both were technically within spec for the resistance values.

Moral of the story, I wish I had known you could simply unplug the coil to see if the engine behaves differently...that way I could have verified without taking everything apart, on the other hand...my car got a nice tuneup.

I'm also gonna keep the OEM coil as a backup! part of me suspects I'll see this problem again down the line so I'll also look into creating a heat shield.

Good luck everyone and thanks for the help

EDIT: Coil failure was at 136k on a 1992 SC400