Hey guys--

So I got my replacement ECM and BCMs today, put them in, and changed nothing :rant2: Oh well, at least I'll have a replacement, or can resell them.

On another, better note, I think I may have discovered my issue: I was flipping through my 85 FSM today and noticed a special added section to the FSM that was put in for this "Final Edition" book--I guess so many mechanics were having trouble diagnosing problems properly that Cadillac actually updated their FSM part way through 1985.

In any case, here's a symptom listed under "Rough, Unstable, or Incorrect Idle, Stalling:"

"Check distributor gear for wear or loose gear to shaft fit. Idle surge complaint due to worn distributor gear may also be accompanied by hard or intermittant code E30. Replace distributor gear or shaft as necessary, see Section 6D. If the gear is worn check cam gear, distributor bore in engine block for metal shavings, for excessive oil pump drive effort (the distributor gear drives the oil pump)."

This is my problem exactly (the hard code E30 and the surging idle). As I've said before, the car has had a full tuneup, new ISC, and ECM/BCMs. What do you guys think of this diagnosis? Seems like this could be causing my lack of power issue too if it's effecting the distributor--remember my fuel pressure is great. I've heard these distributors wear out quickly too...

I've never removed a distributor before, but how hard is it to do? Looks relatively simple, but I don't want to screw it up.

What do you guys think of this diagnosis from the FSM? Seems like the only thing left if my fuel pressure is good and the engine is mechanically sound.

By the way--how can I check the distributor gear for the wear or loose play as it talks about? Do these wear out after only 31k miles?

You have to remove the distributor from the engine to check the gear for wear. Generally, the only time a distributor gear wear problem surfaces is when the engine has an internal coolant leak and the depleted/contaminated oil has caused the gear to wear. Not generally a problem but could happen at 31K if coolant intrusion was an issue.

Getting the bolt out of the distributor hold down is usually the hardest part. Take the cap off and mark the location of the distributor base and the orientation of the rotor for reinstallation. When it goes back in you MUST have the rotor and base in the same position for the timing to be close and then you have to reset the timing before tightening down the holddown bolt for the last time.

Mark the cap, base location and rotor location with the cap off. Remove the hold down bolt. Pull the distributor out of the engine. There is a seal so it may be hard to pull out. Steady, firm pressure will remove it.

Look at the gear. There should a shiny, even contact pattern on the gear from the mating cam gear. The contact should just polish the surface of the gear and should be even on the center of each tooth. As you spin the gear there shouldn't be any runout in the pattern on the teeth. If there is any visible scoring of the gear (material removal or scuffing that you can hang your fingernail on) then the gear is starting to wear. If the gear looks worn like an apple core it is ready to fail completely.

The gear can be purchased separately if needed and is replaced by removing the rolled pin and putting the new gear on. If a new gear is installed be SURE and liberally coat the new gear with a heavy coat of heavy moly grease for breakin protection. Use the moly grease, add a pint of EOS to the engine oil fill and keep the RPM low for the first hour or so to break in the new gear. Keep the RPM to idle or just off idle to give the new gear a chance to mate to the (worn) cam gear.


If the gear on the distributor is worn it will cause uneven distributor rotation and uneven distributor reference signals to the PCM causing the idle problems. Doubtful that this is your problem but it is worth checking and could be the issue.

So, could this be an alternative way? --put the PCM in timing mode and check the timing. If the timing moves (not steady), you may conclude that it is due to worn distributor gear. If it turns out to be the case, it would be worth taking the distributor out and check gear...

Am I correct?