adjustable fuel pressure regulator - The Unofficial BMW M5 Messageboard (m5board.com)

stilov · 11th September 2007, 05:25

Has anyone had any experience with them on your M5?

I have heard a general consensus that the M5's run rich... that coupled with the fact that I am almost a mile high elevation...I thought maybe I could do what I have done with other cars and lean it out a hair with one...on the dyno of course as to not get too lean.

Any thoughts?

PS Preferably thoughts from people with tuning experience.

jclyman · 11th September 2007, 08:49

My answer (I don't have recent tuning experience, but a lot of tuning experience with carburated cars):

My understanding is that the ECU compensates for altitude.

I would rather have a tad more fuel at all speeds than too little ... burns pistons to have too lean a mixture.

M5s have spark plugs that can go 100,000 miles (or so they say). Mine have gone 62,000 without a misfire. If the car were too rich, that wouldn't be the case. The sophisticated electronics control engine parameters so closely, I wouldn't even consider fussing with fuel pressure ... and, screwing up a good thing.

Finally, if they were so great, Dinan would recommend them ... and, I don't think they do ... but, am not sure about that ... ask 'em to find out.

stilov · 12th September 2007, 04:46

good perspective!!! Thanks!