Hey I hear you guys know your nissans and thought maybe someone could give me a good idea of whats going on. So anyways I am running a complete stock s14 sr20det with a t28 turbo, stock boost. Car seems to run normal at idle / cruising but as soon as im wide open throttle the car leans off the charts, im talking as much as 18:1 a/f mixture? Any idea’s?
what kind of fuel pump are you running?
Just a stock 180sx fuel pump, starts up fine, idles nice, doesn’t seem to lose any power or have hesitation just running lean as heck at wot :S. I will check fuel pressure today and see what I get.
i would upgrade it to a 255, might fix your problem
I just got over a problem sort of like this. I originally thought it was fuel related as well but it ended up being electrical.
My problem was my car would pull hard until 5500rpm then it would lean out and I would have to get off the gas right away.
It ended up being low voltage to the ECU. My MAF voltage was maxing at 5Volts around 5500.
The ECU relay was not fully closing so I was only get 11 to 12Volts at my ECU. The ECU was actually running off the backup power source. After fixing this I now have 14 volts at the ECU and it runs perfect again.
Check your maf voltage and wiring. Check your ECU voltage. Change your fuel filter. This is all assuming you know your fuel pump is still good and your car has ran fine with that pump and set up. Upgrading to a 255 will help but if you didn’t have this problem before with the 180sx pump you have I guarantee it won’t fix it.
good luck
Yes very interesting I will defiantly have a look. I didn’t get a chance to check fuel pressure today but I will first thing tomorrow. So looks like I got some homework to do, I will keep this problem updated! Thanks for the help everyone I really appreciate it. 
Alright so I checked fuel pressure at idle was about 34. Then checked the voltage and was getting 12.6V with car off and 11.8 on. So I guess that could be a problem lol… So I wonder whats wrong with my charging system? Altinator was checked last week and was good. All connections are good, fuse good.
I had this exact same problem before and had to connect the wire that usually goes to my dash battery light to a 100ohm 10w 5% resistor then to my battery so it would tell my altinator to charge, it fixed my problem. Now its not charging again, I tried putting on a new resistor, still no charge, so I dono wtf is wrong now. I will try a spare altinator in the morning but something is fishy… If anyone has any ideas please let me know, I will keep working on it.
connect white / red strip wire from altinator plug to dash battery light.
this is exactly what happened to me. Check your ECU relay. My ECU was running off the back up power. Take a look the pin out and follow the main ECU power you wire. Check for continuity. I had a massive voltage drop over this relay. I ended up messing around with it for about 2 weeks with no luck as to why the voltage was dropping. I got pissed and replaced the relay with a switch inside my car. I’ve been running it this way for over a month now and have been to two track days since with no problems at all the car is running better than ever
Hooked the white and red stripe from the altinator to the dash battery light and I got charge again !
Fuel pressure went up to about 38 at idle and about 42 at 2000rpm. So now to hook it up to the wideband and see what I get for air fuel ratio on a good
3rd-4th gear pull.
I am guessing with no charge from altinator I wasnt getting enough voltage to power my fuel system causing it to lean out crazy at wot.
I hope all goes well with the next test, ill keep this problem updated, thanks for the help everyone.