the last thing is truth , just block the air passages . i would leave the catalyst alone if good , they dont really affect the gas mileage .the fuel mixture is adjustable , so , you can lean it out . fuel is getting cheap .
Hello agillot Happy Holidays .
My Good luck you replied thanks
The SEL Sedan is a 1975 with equal Compression 145 / 155 EFI fuel delivery
Idle a bit Lumpy but car runs excellent all ranges
(1) When you say the Fuel Mixture is adjustable do you mean at the MPS ?
I would have to install a AFR ( Air Fuel Ratio ) gauge to adjust the MPS and instal a Wideband Oxygen sensor
(1a) Unless you Know another way to adjust the MPS I would think the Altitude would make the adjustment Vary some .
(2) do you know a Better way to adjust the MPS without buying and installing a Air Fuel Ratio guage and a wideband Oxygen sensor .
For the Idle Mixture :
I have adjusted the Idle Mixture at the ECU with the Dial Adjuster Wheel mostly to the left counter clockwise .
The car sat for some years inside but I had to replace the Cold Start Valve ( was dumping gas in and the Cats got red hot , black smoke out the back ) The ECU Unit In replaced with a good used one ( smelled Burned very bad and had a burn trail on the mother board between two polls )
Dismantled and Cleaned out the AAV Valve ( plunger was stuck at the bottom ) works great now
Cleaned out the Distributor and set all the 5 points top and Trigger bottom , shaft is tight without wobble in the bearings , was tricky for me but I expect they well stay set a long long time .
I got these MPS Settings from another poster for the MPS and they are as I understand it from Bosch . I Think they are correct .