Just installed a wideband on my S4 TII with stock boost, injectors and ECU with all emissions removed and it is leaning out as soon as boost hits. In 5th gear doing 55mph I see a 13.9 to 14.1 AFR. Anything higher then 2500rpm brings it into the 15+ range.

So upon checking my fuel pressure regulator, I can't adjust it up past 28 PSI which made me believe that the fuel pump isn't getting enough voltage or the fuel pump is leaking inside the tank. Currently have a Walbro 255 installed in the tank.

I did the rewire but this didn't change my AFR or allow me to turn up the PSI on my FPR. I just want to make sure the way I did this (I am terrible with wiring) deleted the 2-step relay. I would have checked voltage under boost, but I was by myself.

I used this kit

STM FUEL PUMP REWIRE KIT | 1G DSM | 2G DSM | EVO

And I followed this diagram, mostly. Only thing I did different was I went straight from pin 87 on the relay to the cut on the fuel pump blue wire. I did not connect anything from new relay to old resister/relay



Also, I did not cut any of the engine bay harness or stock fuel pump relay/resister. Please let me know if I got it right, and to try changing fuel pumps next. Or any other possible suggestions.

 

Apparently I must have done something wrong, I pulled the fuse for the new power wire and the car just keeps running.

 

1). The fuse you used is placed between the battery and pin 30 of the relay?

2). Are you still jumpering the fuel check connector?

 

Yeah The fuse between battery and the pen 30 of relay, and if the fuel check connector are 85 and 86 then yes

 

When you pull the fuse and the engine continues to run, I gather you still have the key in the on position? If that's the case, then you need to make sure the relay you installed is wired as in the diagram aside from the fact that you are running the wire from pin 87 directly to the Blue wire of the fuel pump. If you wired things correctly to pin 85 and 86 then there should not be voltage feeding the fuel pump. Are you sure the Blue wire to the pump was cut and connected to pin 87 or did you just splice into this wire from pin 87? And this is important, if you did indeed cut the wire you need to make sure you chose the proper side of the cut wire that you connected to pin 87. When the Blue wire which powers the pump is cut you have one side of the cut wire which runs directly to the pump and the other side of the cut wire runs to the Circuit Opening Relay. In your case you do not want pin 87 connected to the wire which runs back to the Circuit Opening Relay. A continuity test would tell you if you chose the right end of the Blue wire.

 

Got it! The pump is getting a continuous 14vs, and the fuel pressure regulator is adjusting just fine. Unfortunately, it hasn't fixed my lean issue. I am just going to assume it is from the ECU not compensating for street port etc.

 

It is definitely because you have a streetport on the stock ecu. You have to have bigger injectors and a proper ecu to tune it, whether it be just an rtek or full standalone. I'm going 720 secondaries and rtek 2.1 on my fresh streetport motor.

 

Im not so sure that the streetport is the issue. Double check timing and ohm out your injectors. Inspect the injector o-rings while your at it.

I am running (well was as of two weeks ago) a very large streetport on a stock ecu with just a FCD. My AFR are normal both with the stock S4 Tii Pump and an FD pump. Only difference being when I'm around 8-10psi my AFR are closer to 11.3:1 with the FD may have touched 10 a few times.

Besides that I would suspect fueling. The only issue I have with my streetport on a stock ECU is it will only Idle happy at 1100. I'm sure once I wire the Haltech and injectors, blahblah all will be fine

 

I haven't ran a streetport on a stock ecu, but it should be fine. Try a stock fuel pump or something other than that walbro. Seen too many problems with those.

 

you might also want to put a boost gauge in the FPR vacuum line, not all of the stock nipples see boost AND vacuum. its a really common n00b move to put the FPR vacuum line in the wrong place.

when you get it wrong, the FPR will see vacuum, so the car will run ok, but not boost. a stock T2 will just hesitate and fall on its face

 

Ok so you suspect that the line I used to connect to the FPR is coming from the wrong spot on my motor?

 

The line to the FPR is def the one I used from this picture, hopefully the picture was accurate?