Adjusting MFi with engine running?

[nigel911]

Asking purely out of interest... aware the various MFi articles state adjust with engine off - but years ago when I relocated to CO from FL I took my car to Eisenbud's in Denver, and John Eisenbud adjusted my car while it was running (main only, obviously not idle!)

My car recently passed the Spanish ITV / importation road test - but my emissions were flagged as they were a little high - basically need to lean it out and be retested just for the emissions part of the test.

Struggling to find a garage with a gas analyzer mainly because independent shops cannot process road tests, they are government operated - as such most garages won't spend the money on kit they very rarely use. However, the test centers do allow adjustment at their facilities... hence the question.

No biggie either way, but was interested as to why they state adjustments should be made 'with engine off'.

[47silver]

If your oil line is attached to the motor, when you remove the socket head bolt oil will come out.

[Correyyt]

The reason most of the MFI manuals say to adjust the main rack with the engine off is mostly about safety and repeatability, not because the engine has to be off for the adjustment to work.

[Magyar Kiwi]

Hi
Bosch MFI main rack adjustment must be made with the engine off.
The adjuster is turning when the engine is running, (Wrong, main rack adjuster is not turning.)
See more below.
Cheers:
https://www.pelicanparts.com/techarticles/911_mfi/Adjusting_MFI_Lee_Rice.pdf?srsltid=AfmBOooPNjWmGTR fpqiq6qglK8C51VoukwVEpFak-YESLej8f6tXhU77
https://pbase.com/slidevalve911rsr/image/126794570

[rowingone]

Recently had John Eisenbud (retired but still the best) adjust my MFI and yes he did it with engine running . . did get a few drops of oil on the engine during the adjustment but no big deal. I would not let some tech at the Spanish ITV mess with the adjustment .. . surely there is a Porsche shop or club that has someone familiar with MFI . . some people lean it out a few clicks and then put it back to where it was after passing emissions.

[stownsen914]

Was going to ask - is the rack turning? Guess I've always done my adjustments with the engine off so never thought about it.

If you take a look at the diagram here => https://forums.pelicanparts.com/porsche-911-technical-forum/379815-mfi-diagram-routing-hoses.html


I think the main rack may not turn, but the low-speed / idle circuit does appear to be on the rotating portion of the internal assembly.

[stownsen914]

Main rack adjustment is below the rubber stopper that's between #14 and #15 (the numbers, not what they point to) in the diagram

[nigel911]

Trust me, I'll be doing the adjustment - lean her out, pass the test, set back to where it was.

[47silver]

On ourvl 72T if you have the long flat blade tool, it slides under a notch in the.coil bracket which helps to guide it to the spot in the adjustment bolt. If interested i can do a you tube on how I do it

[r lane]

Originally Posted by stownsen914

Was going to ask - is the rack turning? Guess I've always done my adjustments with the engine off so never thought about it.

If you take a look at the diagram here => https://forums.pelicanparts.com/porsche-911-technical-forum/379815-mfi-diagram-routing-hoses.html


I think the main rack may not turn, but the low-speed / idle circuit does appear to be on the rotating portion of the internal assembly.

I have always made adjustments with the engine off, but main rack does not spin, lower adjustment which is part of the governor does spin and is adjusted with engine off. Bob

[nigel911]

Passed the emissions test - all good.