Set MAF or injector size first??

Alsontime · Post by **Alsontime** » Wed Jan 23, 2008 10:39 am

When I initially open nistune and want to set the ecu for a Q45 maf and 550cc injectors, which do I do first? If I set the injectors for 550 then the maf to Q45, the K-Constant is 50172. If I set the maf to Q45 first then the injectors to 550, the K-Constant is 17404. What am I missing here?

Matt · Post by **Matt** » Wed Jan 23, 2008 4:00 pm

Do the injector change first (Ideally do this with the original MAF so you can confirm the K constant works well with your injectors and your AFRs are all good)

Afterwards with Q45 MAF fitted, do the dropdown to Q45 MAF to change VQ map and K constant

The MAF changeover will send the K constant in the opposite direction to injector upgrades

You can the fine tune this afterwards until the car runs (better)

Alsontime · Post by **Alsontime** » Thu Jan 24, 2008 5:03 am

Thanks, ill give that a try.

Alsontime · Post by **Alsontime** » Fri Jan 25, 2008 10:18 am

I have found when trying to adjust afr while idling and revving the engine in neutral that I almost max the adjustments in each cell just to get close to the afr that I need. Can I adjust the K Constant lower to where the adjustment on the fuel map becomes more reasonable? Right now low load cells have to be in the neighborhood of -60 or so. Thanks.

RB30-POWER · Post by **RB30-POWER** » Sat Jan 26, 2008 5:30 pm

have you disabled closed loop feedback before trying to adjust those cells.

some of the sr20 and other later model nissan ecu use closed loop on idle, so if you try changing the afr, it will just keep returning to 14.7:1 or stoichometric ratio.

if you have big cams or desire a richer or leaner afr (usually richer) you will have to disable closed loop on idle first.

Russ84NA · Post by **Russ84NA** » Sun Jan 27, 2008 4:07 am

What are the steps to do that? Do you turn off all the flags, reset the cells and then turn them on? Or can you use the raw values and change only the cells?
Thanks.

Alsontime · Post by **Alsontime** » Sun Jan 27, 2008 5:59 am

When trying to disable closed loop by pressing "O" with the cells highlighted, some will turn off and others will not. My idle before adjustment in closed loop is staying around 10.5 afr??

Vetal · Post by **Vetal** » Tue Jan 29, 2008 2:51 am

Alsontime wrote:When trying to disable closed loop by pressing "O" with the cells highlighted, some will turn off and others will not.

Values must be positive, so you must have >=192 in the cell to be able to turn off closed loop

Alsontime · Post by **Alsontime** » Tue Jan 29, 2008 8:53 am

Thanks again for the help.