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I was wondering if anyone here could shed some light on this issue I have been having. I have a 2001.5 s4 b5 rebuilt bel block rebuilt 2.7 heads with 2.8 cams stock intake manifold with 1000cc Bosch ev 14 injectors. The car has been boost test and smoke test for leaks. Idles great no misfires drives great. Its running rich I have replaced both primary 02 sensors new hitachi map sensor. my long-term fuel trims are pegged rich and there’s a nasty split between both bank 1 and bank 2.About 8 percent split.my fuel pressure is on the higher side 59 psi with vacuum. The idle trim sits at 0.8 to 1.0.
Yes -25 on long term.i have a walbro 450 fuel pump with a 4 bar Bosch fuel pressure regulator.034 diver valves hold vacuum and cleaned. I did notice the fuel pressure is higher 60psi with a vacuum hose connected.
Sounds like not enough intake air aka intake air leak or the fuel system is overpowering aka injectors too big etc.
What tune are you running?
Do you have VCDS or equivalent to do some logging? Log the MAF and requested vs actual boost on a couple 2nd gear pulls, etc.
What is the actual LTFT number for each bank? You mentioned 8% difference.
Are you convinced there is no intake leak? You mentioned smoke test. How about a pressure test to no more than 10PSI?
I am running a base tune from ETspec tuning rs6 hybrid turbos 1000cc Bosch EV 14 injectors,Torque Factory intake setup.The car idles great drives fine no misfiresBoost tested up to 15psi smoke tested just rich LTFT.
Bank1 is out of spec for pulling long term fuel but Bank2 is within the acceptable range.
Consider remove Bank1 spark plugs and see if they are all burning the same or not. Maybe one injector is leaking or stuck open.
The injectors were brand new but I took them had them clean and serviced with a data sheet showing that they were not bad so I could rule that out.I even swapped injectors from bank 1 to bank 2 same issue.
BxS1’s are the front O2’s where x represents either of the two banks.
Sounds like everything is new and you already swapped all critical parts between bank1 and bank2 and you are still getting the same LTFT readings. Is this correct?
11-27-2023, 05:34 AM
B4 S4 Long term fuel trims
