2000 Tahoe 5.7L
Homemade rear mount turbo pushing 7lbs
Snow meth-injection in @ 4lbs
Nelson tune

Gonna give the long story, 3 1/2 months ago Tahoe ran good around 10.5 to 11.5 started missing steady on #7 but i didn't burn it down. found that it was a Popit sticking and not fueling that cylinder. So i did the upgrade CSFI to MFI Conversion that GM offers, a stock replacement. Miss went away and at WOT truck ran richer 10.0 to 1 all the way up to 3800 in first gear then it leans out instantly off the wide band (17+). In any gear anything above 3/4 throttle above 3000rpm it goes way lean. otherwise truck is drivable My first guess is its not the tune, and thought my widband is messed up, truck O2s read the same, loosing fuel pressure?, nope steady at 65psi, 5 more than the popits. No vacuum leaks. I thought that it might be the tune. called up nelsons had them send me a new one. No change. went and bought a new popit to replace the old bad one and put the CSFI back in and went back to the computer that worked before. no change still lean... besides the same sluggish response when i punch it, that the popits had before. Pulled the spring out of the waste gate now it will only build 1 1/2 pounds but still goes lean

Whats next where do i go from here?

 

Are you sure the popits are flowing enough fuel? I know the marine intake is a common upgrade for these engine's as I was gonna do one on my old 5.7l silverado.

 

yea, they worked OK about three months ago. that is why i went back to them when the new tune from nelsons didn't work. i have two tunes and the both act the same way with both stile of injectors.
I was researching the marine intake when i found the MFI conversion that GM offers
BTW does anyone know the rating of the two types?(CSFI~MFI conversion) 19lb/hr 23lb/hr ? i have heard both for both.

 

I cannot see you running out of fuel perhaps if you said 4800 - 5400 range. I would say it is time for an inline pump to help keep psi up. Although I do not have a turbo, mine at 9-10#'s get 75 - 80 psi and runs out of fuel at 5500 or so due to the stock 19#'s.

Are you getting any SES, CEL, or codes? It could sound like a MAF error.

If so, here is something to look into: http://www.blowerworks.net/CODEBUSTER_103_1.html

 

No codes cleaned the MAF w/ brake clean, and it looks clean, with no change. Any voltage/resistance checks i could verify that is good/bad.

 

If it isn't throwing codes, you should be all good.

When does boost kick in for you?

 

Should be but there is something up that i just cant wrap my head around... it worked before and now it doesn't.
Im at 5psi by about 2700, 7psi by 3500 it comes on strong. faster if i Power break it first but thats how i killed my rear end

 

I've ran across this before. Replace the sensor for your wideband.

 

new wideband sensor will not come in till tues next week $120, Is there any way to check it so I'm not just throwing parts at the Tahoe.

 

What kind of wideband?