MFI idle miture ( for the ,, time ;-) )

[Cauf61]

Hello I'm adjusting a reconditioned pump after installing on an 2,4 engine. Pump setting point is ok.Idle air screws are 2 turns out. My idle is way too high (1500 rpm) and my mixture is way too lean (0,8%) . The fuel pressure is ok, ignition is ok and there is no false air suction to be found. Now I've screwed in the lower set screw many (5?) revolutions CW but the mixture doesn't react to it. Remains far too lean. The top screw does give a reaction to richer. Should I keep turning the bottom screw in CW until it stops or do something else? Grts Patrick

[RSTarga]

STOP!
Do you have a copy of CMA?

[RSTarga]

Check, Measure, Adjust manual for MFI

[Cauf61]

Originally Posted by RSTarga

STOP!
Do you have a copy of CMA?

Yep and I have the settings/data.
Like said I did not rebuild the MFI. Only trying to adjust the mixture.

So my questions remains: has the bottom (spring) screw a CW stop or is it "endless" ?

[tobluforu]

No, it will stop in either direction, but I can't remember how many clicks, main/load rack is 12. Now, that screw barely does anything, it's more of a fine-tuning adjustment after you get the main enrichment correctly adjusted.
From edmayo: The usual procedure is to get the load (rack) adjustment done first since that affects the entire range. After that is done the final step is to adjust the idle adjustment since that ONLY affects idle. The idle circuit carries up through ABOUT 2500-3,000 RPM at which point the load circuit will start having a greater influence.

[RSTarga]

Start with the linkage to make sure there is no preload and that all of the throttle bodies are closed.
Check length of main throttle rod.
Is your timing set correctly, does the distributor move freely?
If your pump was rebuilt properly it should not take much to get proper idle mixture.
Do you have a gas analyser?

[Cauf61]

Check length of main throttle rod. Is done : ok
Is your timing set correctly, does the distributor move freely? Yes; ok
If your pump was rebuilt properly it should not take much to get proper idle mixture.
Do you have a gas analyser? Yes.

[Bobboloo]

FYI turning the idle mixture screw will do nothing to the mixture above 1000 rpm. It only makes adjustments below 1000 rpm. i.e. it's inactive at 1500 rpms
Have you checked correlation or flow matched the throttle bodies?
In my experience if you haven't gone through the throttle bodies to confirm their operation you will be chasing your tail. These magnesium throttle bodies suffer from years of operation. The get out of adjustment and warp from heat cycles. I always put the cylinder side on a flat stone or glass and resurface them on wet sandpaper. The minute you start to surface them you will see how warped they get. At least you have the later style because the 2.0/2.2 versions are particularly bad.
The next step is to flow match the throttles on a bench. This can be done using a small shop vac and a synchrometer if need be.
After flow matching you need to reset ALL the linkage, except the main link if it's set to factory spec, so that there is no preload on any throttles.

[Cauf61]

"Have you checked correlation or flow matched the throttle bodies?"

Everything new and calibrated.