1982 SC CIS Warmup Issue

[mercury26]

So I am trying to track down a CIS issue with my 1982 SC, the problem only occurs during the warmup cycle. The car will start fine (cold sitting for a long time) with the high idle (1100 RPMs) that then settles down to around 900 RPMs. During warmup and until the car hit 180degrees F, the car will have a fairly low idle around 700 RPM or so. Once the car hit 180 degrees, it will settle into an idle of about 950 RPMs. Once it gets very hot up to about 210 degrees, the idle will move up to 1000 to 1050 RPMs. The car is drivable, but would like to figure out what is causing the issue.

A few data points BUT the condition existed before and after the complete rebuild (see below):

* Engine is completely rebuilt (new pistons, cylinders, rings, etc)
* New Airbox with Pop-off Valve
* New CIS seals (intake runners, CIS box, injector seals, etc)
* New Cold Start Valve
* New Frequency Valve
* New Decel Valve
* Rebuilt WUR
* Rebuilt Air Regulator
* New Throttle Switch
* New O2 sensor
* All new temperature sensors
* All vacuum leaks removed

Since the issue is totally temperature related, I am thinking that it could possibly be the ECU. The ECU is the only thing that has not changed between pre-rebuild and post-rebuilt. The only other issue that I need to resolve, is the O2 sensors ceramic connector being broken but the O2 sensor is still sending signal. I would attack this issue BUT that would most likely cause an intermittent issue. The current issue is temp related on the time, changes at 0 degrees, 180 degrees and 210 degrees.

How many bad Jetronic ECUs have folks seen? I am stumped, but figured that I would ask the group.

Thanks,

Chuck

[Scott R]

I doubt very much that it's the ECU. What is the duty cycle reading during the temperatures you listed?

[mercury26]

Originally Posted by Scott R

I doubt very much that it's the ECU. What is the duty cycle reading during the temperatures you listed?

Where do I take the duty cycle measurement?

Thanks,

Chuck