rich jetting question is back

[Trxster]

Ok, replaced old manifold with updated header and had the sled up today at 6000ft and 62' temp. Had 50/50 av gas-premium 92. Needles in middle slot, fuel screws 2 turns out, 125 jets, glass pack muffler. I replaced the T's with the MPI Billet T's and the carb caps with the Billet caps. Also replaced all of the vacuum hose with 3/16 fuel and the vacuum gauge shows a good stead reading. Also ran the fuel regulator to back of carbs and reduced pressure to about 3.5. The good news is that I don't have a rich bog at all (except at lower rpms when I let off the gas quickly it seems to load a bit) and my rpm's are now spot on 10,500 +- at about 10-12 psi and it is rippin. The new header definitely helped the exhaust flow better and turbo spools up very fast now. Love it.

HOWEVER, my a/f meter is still reading about 14 at idle and gets as low as 10.5 at WOT. I am not sure if I should just leave it and ride it or jet it down again to 122.5 or 120's??? If it is running good....and it is on the safe side rather than the lean side, why not leave it? Will I gain much more power or are we talking about 4 hp??? Are there any guys out there running 120's?

Rt

PS I also installed the shockwave adjustable helix and it is AWESOME for fine tuning the rpms and getting better hook up.

 

[BlgsRX-1mtn]

O2 sensor placement could be your problem also. I have mine in the front of my Whiteknuckle can. Mac at MPI said this is too close to the tips and will cause a leane reading at low speeds due to the weaker exhaust pulses.

If you have the O2 far enough away from the outlet, try going up one more size on the pilots or try going to 2 1/2 turns out to see what you see for a A/F drop down low and leave the mains. If your seeing 10.5 at WFO in 62 deg weather the reading should lean out during colder temps.

Just an FYI my SC is close to what you see. My idle readings are mid/upper 13s, mid range is upper 12s and WFO is upper 10s to low/mid 11s. I have 850 miles of smiles .

Jim

 

[Trxster]

Thanks for the reply....and thanks for everyone that replied to my old posts as well. I talked to Dustin @ Outlaw Motorsports and he suggested that with the stock air intake being so close to the turbo that I am sucking a lot of hot air (no pun intended) when the hood is closed. He suggested running the filter outside of the hood. So, I fired it up in the driveway and let it warm up, then checked the 02 levels at idle with the hood closed and open and sure enough, when closed it was quite a bit lower. So I decided I am goint to run the air intake forward to the bulkead below the front vents. Seems like a good spot that doesn't get warmed up and has good air access. I got some flexible exhaust hose and it works really well and looks pretty good too. Might even be able to polish it. I wanted to keep it stealth looking rather than getting the air filter outside of the hood. We'll see if that does it....hopefully I will know this week. Thanks again.


Rt

 

[BlgsRX-1mtn]

Hmmm, your "hot" air intake should cause a richer reading than with the hood open getting cooler air though. I find it wierd that the readings would go from leaner to richer by letting more cold air in. It would help the WFO readings getting colder air but your idle should have actually went up rather than down.