I finally have the car running really well. If I had to do it again I would do it a little differently.

My rich idle was the result of the fuel distributor’s plunger extending too far down onto the roller on the flapper. Adjusting the position of the roller with the 3 mm CO screw did not work for me. I could get the idle mixture correct but then something else went wrong: bad throttle response, hard restarts, surging idle, high RPM idle, etc. The rich idle could have been the result of the flapper spring fatiguing over time as well. Who knows? Bottom line, adjusting the plunger (moving it up into the distributor) about half a turn allowed the other parts of the fuel system to work as designed.

If I had to do it again on a running car I would:

-Make notes of fuel economy, idle mixture and fuel pressures at the top and bottom of the distributor (there are removable plugs on the top and bottom where you can attach your FP gauge) before I took anything apart. I would also remove the air filter and make a note of the position of the flapper when it just contacts the fuel distributor’s (FD's) plunger with the motor just turned off (residual fuel pressure in the distributor). This is a feel thing and a magnet helps to lift the flapper so you can let it drop just until you feel the point of greater resistance. Now mark that point on the aluminum housing around the flapper. Start the car and see if the flapper has moved down past the mark. If so, measure the drop. The ratio of flapper movement to plunger movement is 7 to 1. If I read the specs correctly, there should be from 0.1 to 2 mm of free play at the flapper at idle. That means 0.014 to 0.29 mm at the roller/plunger which you really can’t measure, but you can “feel”. Point is that the flapper should NOT push the roller into the plunger at idle. I do not know the thread pitch of the screw on the plunger but I assume it is a 1.0 mm pitch. If the flapper moves down 7 mm at idle from the resistance point you felt with the car off then you need to turn the plunger screw IN just over one turn. More likely you will need less. While you have it all taken apart, check the injectors for flow with plunger all the way out (idle) and all the way in and then adjust flow of up to five of the six injectors until all are matched. The min spec is 4-6 cc/min but suggested is 6.0 – 6.6 cc/min. A cc of water is a gram. Fuel is about 75% less massive, so 4.5 – 5 grams of fuel per minute is your target if you use a scale and plastic water bottles as I did. I flowed mine for three minutes at idle and was over the spec. Also check flow rates with the plunger pressed all the way in. There are two specs here: 100 – 109 cc/min (75 – 82 grams/min) and 140 cc/min. The 140 is a max. I just got the idle numbers in spec and then used the high flow to more precisely match the injectors. Since I removed the fuel distributor from the flapper assembly while flow matching I had no way to know how far the flapper was depressing the plunger so I could not check the “full” numbers. I saw mid 80 grams per minute with the plunger completely pressed into the distributor, so I concluded the fuel distributor was okay.

-Check the resistances of the air temp and water temp sensors at the computer’s connector. If out of spec (or more likely completely open or closed circuits), fix. Check the O2 sensor on the bench with a volt meter and torch.

-Put it all back together and go back to your notes. The differential pressure should be 3 – 4.5 Bar (difference between pressures at the top and bottom of the fuel distributor). If you are out of spec, remove the EHA and adjust the small Allen behind the cap screw. Be careful here. The lower pressure changes as the car warms up, so make notes of the ranges you see. If you can’t start the car after the EHA adjustment, you will need to adjust the idle/CO screw. If you turned the EHA CW a ¼ turn you will need to turn the idle/CO screw about ½ turn CCW, or the other way and twice as much (roughly). Careful again. If you had to go CCW on the EHA and CW on the idle/CO too much you will/might have allowed the flapper roller to contact the FD’s plunger at idle….meaning another adjustment to the plunger screw, sorry it all comes apart again.

-Once you get here you should be able to give the idle/CO screw small adjustments to get the car to start and run well. If you are not a hot-rodder, you can adjust it all on the lean side and improve your fuel mileage.

HTH!!!