How to test the MAFs yourself and How MAFs work - Page 25

mubarak · 23rd October 2006, 15:33

Quote:

Originally Posted by DavidS

Mubarak,

Are you looking at the instrument cluster display, please? (The orange line of text just below the speedometer)?

You use the instrument cluster display, not the Nav screen, for these tests.

Print the first post in this thread, and the post linked from it, and follow those instructions step by step, and it will work.

It seems you are looking at the correct display, but you haven´t switched to
the hidden diagnostic mode yet. You need to do that first. It is described in complete detail in the posts mentioned. Print those, and give it a try. If it still does not work, let me know, and I´ll figure something out.

Cheers,

David

i got 137 in second gear first run..second run i got 139 is that good or my maf is bad...the temp here around 33 c..
thank you

Silverstreak · 23rd October 2006, 15:55

David:

In South Floirda, where the temperature is 85 -90 degrees and the humidity is 85+, what adjustment would there be to my readings?

DavidS · 24th October 2006, 00:07

Quote:

Originally Posted by EWade15

Mark,

My raw numbers displayed were 106-107 with old MAFs. After replacing them, I saw 108 - 112.5 and figured that the variation was the DME adjusting. I might just drive over the hill Monday to Sacramento (25 ft elev.) and check my numbers. It sounds like our numbers were indeed similar before I replaced the MAFs. Have you replaced yours recently?

Eric

Eric & Mark,

We don´t have very much data from high altitude, so yours is especially appreciated. If you have some environmental data too (temp, barometric pressure, altitude, humidity) it makes the data even more useful.

BTW, I can imagine the dialogue going on:

Husband to Spouse:

Darling, I need to drive an errand. Just to check if the car gets stronger with
lower altitude, so I´ll drive to the Pacific and back, just to check if the fuel flow numbers gett any better. I´ll be collecting Data, all for Science, you know. See you in a couple of days, hon!

Spouse:

Have fun! I´ll spend those days power-shopping!

David

DavidS · 24th October 2006, 00:09

Quote:

Originally Posted by mubarak

i got 137 in second gear first run..second run i got 139 is that good or my maf is bad...the temp here around 33 c..
thank you

Those are probably excellent numbers, but I need the barometric pressure and elevation too, in order to tell for sure.

David

DavidS · 24th October 2006, 00:55

Quote:

Originally Posted by Silverstreak

David:

In South Floirda, where the temperature is 85 -90 degrees and the humidity is 85+, what adjustment would there be to my readings?

I assume elevation is about zero, but I need the barometric pressure too to calculate it for you.

(Or download the excel file attached to the first post in this thread)

David

DavidS · 24th October 2006, 01:08

I have updated the Excel-file used for correcting the peak fuel flow numbers, so that you now just need to enter the numbers and the calculation is automatic.

The updated file is attached to the first post in this thread.

(The results calculated are the exact same as those produced by the old version, this version is just a lot easier to use.)

David

DavidS · 24th October 2006, 01:10

Quote:

Originally Posted by EWade15

... I don't think it would hurt anything to replace the fuel filter, and then check fuel pressure - I'll do a search and figure out how to do that.

There is some info about how to test the fuel pressure properly in the first post in this thread.

David

mubarak · 24th October 2006, 09:58

Quote:

Originally Posted by DavidS

Those are probably excellent numbers, but I need the barometric pressure and elevation too, in order to tell for sure.

David

thanks..... i will

mubarak · 24th October 2006, 13:59

Quote:

Originally Posted by DavidS

Those are probably excellent numbers, but I need the barometric pressure and elevation too, in order to tell for sure.

David

altitue is 0m ...barometic is 1011 hpa...temp 35c... humitiy is 52%...what do think.... i get 138 to 139..not seen 140 or 142 or 145 as some members mentioned ...all in 2nd gear till hit limiters.

cheera...mubarak

red_wings05 · 24th October 2006, 21:48

Tested my car last night.

Temp 16C
988mbar
20m above seelevel

Did three runs in second gear and got 122, 123 and 126. This seems a bit low if it should be around 140.

By the way David I think you missed a bit when you did the new version of the spredsheet. The eqasions are not linked to the blue fields, they are still linked to the old values (D17-D19).