Fuel Pressure and Trims

[311GSX]

Hi, I recently installed my MAFT and I am having Problems setting my fuel trims. I got the base set where it runs great at WOT but my mid and high trims are both at 81. If I lean out the base I get crazy knock at WOT. When I checked my FP guage It said 40 and with the hose off it went to 43? Isnt it supposed to be 36?I've got a 190 Walbro pump and 660's, could my FP cause rich trims?

thanks

 

[kpt4321]

How are you adjusting the mix, simply with the knobs on the MAFT?

I'm not 100% sure about the ranges of the knobs on the MAFT, but I do know one thing: WOT and idle/cruise use different knobs. You should adjust the idle and cruise stuff first, in order to get the fuel trims as close as possible, then you should adjust the WOT settings with the OTHER knob.

IIRC, the MAFT has 3 or 4 knobs. I am not sure how far the hi fuel trim will progress into the midrange.

Yes, your fuel pressure is a bit high. You should still be able to get the fuel trims closer with the knobs though.

.....Kyle T.

 

[Tallen]

99% of the time the MID is too lean.

 

[311GSX]

Right now the settings are the idle and mid knobs are at one click leaner and the wot knob is at zero.my low trim is at 139,mid 81, high 81,with the stock mas the low was always at 139 but the others were at high 120's.maybe I will try the base one click leaner and adjust the wot knob to richer and see if it knocks.my o2 would still read .92 even when I got Knock.

 

[kpt4321]

Lean out the idle knob, and richen up the mid knob.

Don't worry about what the O2 is, just worry about knock. If you are knocking, then you are too lean.

...Kyle T.

 

[311GSX]

OK, I moved my base setting one click leaner and the mid one click richer. My trims are much better now,but I am having to seriously richen the wot to get rid of the knock,too the point that it feels like it fuel cuts. I think I will change the base and lean out the idle and mid as you suggested. I would rather have the trims rich and not much knock at wot,then good trims and knock.

 

[kpt4321]

The trims and the knock at WOT should function independently.


...Kyle T.

 

[311GSX]

Yea your right, I think I need to log more runs and tune the wot knob. I plan on going to the track friday if it doesn't rain. I will let you know how it works out.

 

[311GSX]

Went to the track and ran 12.56@110. I was running race gas and 21lbs of boost. I leaned out the wot knob and it worked out good