View Single Post
Rich76_911s Rich76_911s is offline
Work in Progress
Rich76_911s's Avatar
Join Date: Jun 2004
Location: Ardmore, PA
Posts: 3,047
Help Troubleshooting

As we all know I recently rebuilt this engine. It was running fine, then started missing and it got progressively worse.

I checked my fuel pressure settings. AFR's were in a decent range while I was driving.
I checked my fuel pressures today at 18 degrees C I had:
Cold Pressure: 1.4 Bar
Warm Pressure: 3.4 Bar
*this is an '87 engine that has had the frequency valve deleted by Brain at Rarlyl8. So I've leaned towards setting the fuel closer to a 930/66 engine.

The cold setting is a bit high on the range for 18C, but is still within the gray area on the chart.

I also took a look at the ignition system. I have a distributor and permatune ignition system.
1. I checked my spark plug wires and they have between 4 and 4.15K of resistance on each.

2. My green wire had between 6-18K of resistance depending on where I put the probe into the socket. Jiggling the green wire did not impact resistance at all. The ground wire sheeting had no resistance at all. I think when it's fully contacted the 6K of resistance is probably about right.

3. I put new NGK BPR8ES spark plugs in it. I previously had non-resistor plugs in it. I also have a set of the bosch w3dpo's on the way.

4. Put a new Rotor and Cap in, as in I had new ones when I rebuilt the engine, then I put another new set in. The newest rotor was slightly different than the older one. Had a much wider contact point. Anyone know which is correct?



What else can I check? Are the spark plug wires an issue with 4-4.15K of resistance?

Want to be driving this like 2 months ago, so any help would be appreciated.
"The reason most people give up is because they look at how far they have to go, not how far they have come." -Bruce Anderson via FB
-Marine Blue '87 930
Old 06-09-2017, 10:17 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)