Chris M.

I'm running a 79 USA 3.0 CIS motor temporarily in my 82 Euro SC and the air/fuel ratio is really lean at wide open throttle. I have the idle set and the AFR set at idle but at WOT it goes lean (17) as seen on the dyno. Should I be using the CIS from my Euro motor on the 79 motor, or at least the warm-up regulator to get the correct fuel mixture at WOT? Neither the 79 motor nor the 82 motor that was previously in the car were using a lambda system.

Droops83

I would start by checking your fuel pressures. It sounds like you are not getting enough fuel under load. This could be due to a clogged filter or other restriction in the system, or a weak fuel pump. Sometimes this will show up as low system pressure, other times you will have to do a fuel volume test.

This could also be caused by control pressure that is way too high. Check your control pressure against specs, and make sure the correct warmup regulator is installed.

If the fuel pressures/volume are in the ballpark, it could be something more strange like a sticky airflow sensor beam/plate (past backfires through the intake can damage them).

Good luck.

art

I have the same issue. US non lambda engine, fully rebuilt fuel system. I'm Using an Innovate wide band 02 sensor. In order to get it right at full load, I need to have it very rich at lower load. This may be normal, and since I didn't do tons of full load driving, I keep it as is. I would like to figure this out though.

I have never done any CO tests at idle.

I do have an extra fuel filter in the low pressure part of the system that might be adding pressure or flow drop. Maybe I should take out. It was put in because I was reviving a long stored car, it is probably OK to remove by now.