ok. I have a b18b with a t3/t4 turbo, bigger fuel pump and fmu. the only work i did was to replace a crappy nissan turbo, with this t3/t4. After the upgrade the car starts and immediatly runs extreemely rich all though i have 45lbs fuel pressure. I am running check valves inline with the map senser that were there before. Before this mod, the car ran rcich. Anyone know what might have happened?

 

well, if all you did was change the turbo and turbo only...that would have nothing to do with it

the bigger turbo may add a little backpressure which would run a touch leaner but not crazy richer as you are describing

maybe you have a vacuum leak...forgot to hook up a vacuum tube to the proper location?

also....get rid of the FMU (my $.02), chip your ECU

 

really simple man bigger turbo = increased air intake... = more fuel needed to match air intake so basically the bigger the turbo the more air /gas mixture ur car needs ur o2 sensor might be compensating for the lack of gas i would check that for starters. when i had my car turboed i found that if u put a 300 ohms resistor inline on the signal wire of the o2 sensor actually in ur cat it will decrease the over compensation... dunno just a thought. good luck

 

chip your ECU, uberdata :bigok:

http://www.ecimulti.org/uberdata/forum/

 

Did the old turbo hold boost to redline?
I only ask this because the same thing happend to me.
I used to run a garrett t3 on my b16a (.42 /.48) it would hit 7psi at about 2,500rpm then drop off from there (down to about 2-3psi by redline). I swapped turbo's to a garrett t3t4OE (.57trim .63 a/r) and it ran rich as a pig. That was using a 8:1 fmu and 310cc injectors. On the dyno with a 4:1 fmu and the 310's it was still rich (because of my gs-r ecu). I had to purchase a sfc to lean it out a bit. I was able to get my afr between 11.9:1 and 12.3:1 across the board. It's just an idea...otherwise i'd drop your fuel pressure down to about 36psi and try that.

 

i had that same problem with my turbo. i had the greddy 18g kit on my car and had 310 cc injectors with 10:1 fmu the car ran so rihc it would stall. i removed the fmu and go the apexi stand alone comp and got the car dyno tuned ran like a champ till i blew it =( twice.....