Fuel Injection Air Flow Meter Adjustment?

Can someone explain this measurement procedure as per the Ferrari Bosch KE3 Fuel Injection System manual? What does the 2 divided by 2.2 spec mean? Does this mean a range of 2mm to 2.2mm? My spec is way greater than this, more like 2cm, that is how much the air plate goes down when I push down on the mixture screw. I am obviously measuring the wrong thing. The reference to position C by touch is confusing.

How would one adjust this, would this be the mixture screw? Or does one go right to the plunger and adjust this for the proper initial spec? Is this the way to set the initial mixture, as opposed to the alternative method of removing a fuel hose from a port with the fuel pump on and adjusting the mixture just so a bit of gas flows in the port as is stated in other threads (eg. the Larry CIS rebuilder)?




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Thank you, makes sense, but what is the point of pushing on the CO screw down with a tool, can you not just push the plate itself by hand and feel the plunger being contacted? And if the measurement is off, what does one do to adjust?

 

Yes, I see that is quite the lever system, would not take much to bend and the small measurements translate to large movements.

Still curious how one actually adjusts for this if the measurement is off.

 

Thank you for the various responses. To be clear, I have the car running well enough after my fuel distributor rebuild. But there is an anomaly that is bothering me.

If I adjust the mixture with the O2 sensor blocked, and tune to the CO spec pre cat, the idle is fine but the engine will stall on pushing the throttle. If I connect the O2 sensor the engine immediately stalls. If I richen the mixture by more than a half turn, the idle is rough presumably too rich based on my Gunson CO readings but the car runs well off idle with O2 blocked. Under this outcome, with O2 connected the car will idle properly, but CO is much higher than with the O2 blocked. This mixture setting seems to cause hot start issues, and sometimes cold start as well. I have found a setting where the car runs well with the O2 sensor connected, and starts ok hot or cold and runs with some cold stumble, but CO reads too high at idle. But emission readings aside it runs well, and does start albeit with more cranks than it used to, but I could just leave it at that.

But since it I would expect the car to run at idle more or less the same with or without the O2 sensor at the same mixture setting, and especially when cold starting with the O2 effectively disabled till warm up, I am getting different off idle responsiveness depending upon the O2 blocked or unblocked. It appears I can set the mixture optimally for idle and off idle but not both optimally. It got me thinking that perhaps my initial mixture plunger setting is off, maybe I do have too much fuel coming in all the time at the air meter neutral position. Hence I am revisiting whether I have the correct initial plunger setting in spec. I have also played with the TPS to make sure it clicks just off idle, and swapped with a spare to make sure that is not the issue.

By the way, if the initial plunger setting does not allow fuel flow at the neutral air meter plate setting, how does the car get any fuel to hold an idle?

I am tempted to get a proper gas analyzer on this, as my Gunson may not be accurate enough, but since I have the car running well enough, I suspect if I tune for proper CO with more sophisticated equipment I will just end up with the anomaly as I noted with the Gunson. So I want to understand the initial set up specs and make sure my starting points were done properly in the first instance. I may have the initial mixture screw way off, it has been turned so much I have lost the trail of where it was, and my initial plunger measurement may have not been precise when I did the distributor rebuild, my theory is I may have found the compromised setting at a wrong starting point that works but is not optimal. I have checked for vacuum leaks but there is nothing obviously a problem.

Hence I am reviewing the Bosch Ferrari manual carefully for adjustment specs.

Thoughts? I suppose the key question is why would my car need a richer base line mixture to allow the car to start and idle with the O2 sensor connected, than without it connected?

 

New O2 sensor, new water temp sensor, new factory shrink wrapped fuel ecu. Was very careful in doing the distributor rebuild to not touch or alter the flow ports, did not need to clean the unit as it was very clean already so unless it was off calibration before it should not have changed. But it is possible my rebuild was not as thorough and port tested as a pro rebuild would do and therefore not optimal. I did not test the fuel flow for each port, rather I hoped by leaving things largely be that the unit calibration would be maintained.

All my adjustments were done when fully warmed up, blocking and unblocking the O2 sensor. Cold starts the next day to see how things behaved cold.

I suspect I am fine and just need to tweak the mixture 1/16 a turn at a time, it is running very well, the interplay between the mixture screw and the air bypass makes for a lot of fine tuning potential. My Gunson meter is pretty basic and it is not a perfect connection to the pre cat port so getting air dilution is likely when I measure CO. I am making an adapter to direct fit to the port. Getting the car running with rock stable idle at 1,000 Rpm, no hesitation off idle has been achieved with the O2 Sensor conndcted, there is a very minor hunting at about 2,000rpm which I understand is normal as the O2 sensor does its thing, I still need to do a few more cold and hard starts after finer adjustments to see if that is ok.

Needless to say, I understand the set up quite well, it is quite brilliant with all the interactions going on. Will probably do new injectors and seals this winter, they are on special order, and I will do the Dixie cup tests then and confirm if my distributor rebuild calibration is off.