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Rich76_911s Rich76_911s is offline
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Join Date: Jun 2004
Location: Ardmore, PA
Posts: 2,955
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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?

New:


Old:


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.
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Old 06-09-2017, 10:17 AM
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