More D-Jet, High Idle Lean Mixture Options

[ggress]

Just getting a '74 2.0 running that I purchased few years back. Replaced all fuel lines, vacuum lines, and FI Harness. It runs better than I expected but not good enough.

It idles too fast (1300 / 1400 RPM) considering throttle valve bypass screw is all the way in. Also, it runs lean (using WB A/F meter). I have set the mixture adjustment on the ECU full CW to get mixture around 13.7:1. I think I have covered all the common vacuum leak issues described in other threads. Any suggestions appreciated. I have two specific questions below.


1) Is my ECU P/N correct? The base P/N is correct but not sure what the 090 suffix means.

2) With the throttle valve bypass screw turned in full CW there is still vacuum getting past the screw. Does anybody know if that is normal ? I can put my finger over the port and feel vacuum. Maybe by design it is not meant to provide positive shut off but I don't have enough experience to say one way or the other.

Thx

[ggress]

Thanks for the input !!!

I am familiar with the B Anders site. Also, the J Bowlsby site and products. We are lucky to have some of these guys who have contributed so much.

Dwell, timing, and TPS are adjusted (checked multiple times). Verified that mixture selector on ECU changes A/F mixture with throttle valve closed. Verified vacuum lines are in proper locations using diagram from trusted site.

I have spent hours trying to locate a vacuum leak but have not discovered a significant culprit. MPS holds vacuum. For diagnostic purposes I plugged AAV connection at manifold /plenum and plugged decal valve connections.

Since the last post I did discover that the vacuum retard unit on distributor has a very small leak that can be detected with a vacuum pump. Also, valves are noisy for sure.

I will resolve vacuum retard leak and adjust valves next.

Thx