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View Full Version : Rb20det S13 Lean!


S13Gene
01-30-2012, 05:20 PM
1990 240sx, Rb20det, rb25 turbo 11psi wastegate pressure, sard afpr, sidemount, straightpipe, AEM UEGO, safc-2(Only for Rpm),everything else is stock unknown mileage, ive put 2k on the motor since the swap ran fantastic up until about a week ago it started overboost on wastegate pressure to around 18psi but had good afrs but still backed out as soon as i seen it spike well that stopped and now its lean all the time unless its cold when its cold its like 13.5 at idle and as it warms up it leans out to 15+ all the way to 17.9s. now even at WOT 13.5 is as low as it goes and thats not getting full boost at 5psi i let out any advise or pointer would be great im not asking for someone to tell me what the problem is but mere help me get on the right path, it free revs great, pops after a few hard throttles, Ive litteraly had to plug up safc-2 and at 20% at 800-1000 to get it to idle around 13.7.. The AFR do change at WOT but not much cruising is 15.0-16 spiking around as soon as a WOT 14-13.5 and i let out. Im thinking my Fuel pump is going out as it has been in the car for 2 years, its not a walbro its a Circuit sport 255lph


Problem: Lean


Things ive checked:
Plugs (.28)gap (white tips)
Vaccum leaks found 1 didnt help
Fuel pressure 40psi with vacc (my attempt to richen it up)
TPS .45 closed 4.10 WOT
Boost leaks none held 16psi didnt leak down
Maf have not checked voltage but have swap mafs no change
Moving wiring no change in idle or afrs
CTS is 2.0 ohms cold
all Injectors are pulsing via noid light
Cleaned up grounds
Checked Codes 54,34, was all that came up auto signal and knock sensor which only comes on when WOT trans hits firewall just alittle near starter





If you need more info etc please just Lmk

S13Gene
01-31-2012, 08:10 AM
So ive had to add about 20% fuel across my rpm range VIA safc-2 and now I've git it rich enough to get full boost at 11.0 wot still don't see how it changed in a few weeks.

S13Gene
02-01-2012, 10:22 AM
I guess no one here has advice or can lead me in the right direction?