Sr20det blacktop S13 running lean.

[BB4rank]

Hi guys im using this as a last resort to see what others have to say about my issue im having with my 240sx. Ive been trying to fix it for months now and still cant. To register an out of state car I need to pass emissions first and I keep either failing on CO% or they cant pick up any exhaust and keep telling me its a leak which it isnt because ive replaced every gasket from the turbo elbow back. I have a vibrant high flow cat installed and innovative wideband lc-1. Now Ill post up a video so you guys can take a look but basically it runs good afrs when the engines cold, vacuum is 20inhg, and idle is good. But as it starts warming up the afrs start leaning out like crazy and ive double checked with another wideband(lc-1) as well showing the same results. It goes up to like 17-19ish and so thats why I think the emissions place thinks I have a leak and cant pick up the right exhaust to oxygen level. I opened up the whole wire harness about 2 months ago and fixed all the wires that seemed sketchy and tested every wire. Maf is showing good voltage, injector impedence is all perfect as well as coil packs. So obviously Im thinking the O2 is just no beuno as the problem occurs when the ECU goes into open loop right? Well just replaced the O2 the other day with a brand new OEM redtop one to go along with my #62 ecu and still nothing. Now when im cruising its around 14.5-16ish and when under load it drops down to 12.5 about. TPS was showing .564V closed and 4.6V open. Timing was adjusted to about 16 degrees as well. Everything seems to run perfect except for this thing that has me stumped, so short of buying another #62. Any ideas guys? I would really like to register the car after buying it back in November and driving around since, super sketched. Btw compression is slightly low about 125-135 all cylinders and leakdown is about 20-45% coming from the rings. Sparks arent black and are BKR7-IX. Havent gapped them which im thinking of doing next before getting another ECU. No idea if the ECU has been flashed or not and supporting mods are listed below. I really doubt a stock ecu would run so lean with just basic mods.

Mods:
Cone air filter
3" exhaust and turbo elbow
255 fuel pump
newish looking fuel filter with adjustable fpr and b&m fp gauge showing 40psi on idle
Greddy intercooler and piping
Greddy Profec Spec B controller that doesnt seem to be working so boost is at 6-7psi.

[BB4rank]

Heres a video of it warming up in the morning.

Sr20det running lean after warmup - YouTube (http://www.youtube.com/watch?v=zc9wq_hzoNI&feature=youtu.be)

and cruising

Sr20det cruising - YouTube (http://www.youtube.com/watch?v=AY8VfTwzO9g&feature=youtu.be)

[ShadowMan]

I just replaced my ecu coolant temp sensor and that solved a majority of my lean/rich issues. Maybe it's that.

[BB4rank]

Hmm that's been in the back of my head. I've read about it affecting others but I don't understand how it does unless it shorts or jumps some sensor wire

[BB4rank]

Just bought a new coolant temp sensor anyway.

[Kingtal0n]

1. Try unplugging the o2 sensor and see if it still does that

I think the wideband could be wrong. 18:1 air fuel ratio and its pulling 19" of vacuum and purring like that? Although an OEM engine might be able to pull it off. Perhaps the cat is clogged and that is messing with the A/F ratio.. but then the idle vacuum might be lower. 18" is pretty much on spot for healthy idle.

If you unplug the O2 sensor, then the computer will no longer correct fuel values. So the table of the maf fuel input will be unaffected by learned multipliers inside the ECU. Instead, it will run from the basemap, and inject the correct quantity of fuel (should read around 14:1) provided your MAF and ECU and wiring and injectors and fuel pressure is all good.

[nismolvr]

Check your fuel pressure

[BB4rank]

Ok guys looks like ive found the culprit after so many months. Looks like my B&M fuel pressure gauge was either not properly installed or is just faulty. It was showing 40 with vacuum and about 43 without so I assumed it was working. Then i looked at the vaccum line and it had a couple small tears so I chopped off the end and it seemed to fix the problem and the car was idling about 14-15:1 but after a few minutes it went back up to 18ish. So I decided why not turn up the fuel pressure and WALLA WALLA! The afr started to richen up while turning up the pressure. So I turned it up to supposedly 60psi so the gauge showed and the car was idling around 14.5-15.5 but cruising its like 13-14ish but gas mileage doesnt concern me a whole lot right now. Under boost it goes anywhere from 11-12.5 and holds a steady 12.5 on 7lbs higher in the powerband. Now I can hear my fuel pump or something whining which I remember my Nissan Pickup I used to have did. So I was told theres a walboro 255lph fuel pump but I dont know for sure so either its a stock fuel pump, faulty fuel pressure gauge(which is going to be checked against a fuel pressure test kit I have) or chipped ecu and/or bigger injectors.

[nismolvr]

Good stuff , glad to hear .

[BB4rank]

Thanks for the tip too I wouldn't have looked into it if it wasn't for your tip. It looked all good since the gauge was showing 40psi but when I pinched the vacuum line the pressure rose and the afr richened. Gunna go take emissions tomorrow. Moment of truth haha.

[AsleepAltima]

you shouldnt have to turn your fuel pressure up that high. check the voltage to the fuel pump while the engine is at idle and see if youre getting 12+ volts. if youre not, you probably need to redo the wiring or add a relay so that it IS getting 12 volts. i fought this problem for about 2 months until i realized my voltage at the pump sucked ass.

[BB4rank]

Pass emissions today with flying colors on the eighth try! I'm going to check the voltage on the pump and gap the plugs

[AsleepAltima]

did you check that voltage?

[BB4rank]

About to in a few hours. Celebrating a birthday today

[nismolvr]

you shouldnt have to turn your fuel pressure up that high. check the voltage to the fuel pump while the engine is at idle and see if youre getting 12+ volts. if youre not, you probably need to redo the wiring or add a relay so that it IS getting 12 volts. i fought this problem for about 2 months until i realized my voltage at the pump sucked ass.

Yes, I had to wire a relay to my wallbro ,now it gets 12 plus V. I also learned the hard way.

[BB4rank]

sorry for the delayed update but i checked the voltage on the white/purple and yellow wire and one had 14V and the other about 10.6V on startup. Am I ok on voltage? Should I replace my fuel filter maybe its clogged?

[AsleepAltima]

the white wire with purple stripe HAS to get 12+ volts. if it doesnt, you are going to have problems.

[BB4rank]

do you check it while its running or with the key in the on position?

[AsleepAltima]

check it running.

[AsleepAltima]

did you check it?

[KiLLeR2001]

Whining fuel pump is not good. If you're not seeing 12V, that's also not good.

[BB4rank]

Ok just rechecked it yellow/blue has 13.8 and white/purple has 10.4V on fully warm idle. Weird thing is it was running very lean maybe because its a really hot day? Idk it seems to run rich/normal at night but in the day lean on idle. Still need to change the coolant temp sensor maybe it has something to do with this since a lot of people have weird problems because of it.

[AsleepAltima]

you need to have 12+ volts on that white/purple wire. run a hot wire to it while its running and that pump will light right up.

[BB4rank]

hmm any ideas as to why it has a weaker signal?

[AsleepAltima]

im not sure what year car yours is, but mine, being a 91 is 21 years old... thats 21 year old wiring and im sure the relay hasnt been changed for a while either... it just doesnt hold the current you need it to anymore. you can add a relay like i did and give it a full 12 volts every time you start your car.

[KiLLeR2001]

Pull the pump out and check the crimps. My ground was loose and I had low fuel pressure and extremely whiny pump.

[BB4rank]

Its not that whiny i cant even hear it anymore but its getting low voltage on the white/purple wire so im going to try and trace the problem. Running new wires would be a last resort.

[AsleepAltima]

forget tracing it for now and just run a hot wire to it - if it jumps in sound, you found your problem.

[BB4rank]

ok ill try that first. but its not really whiny anymore but the white/purple still gets a weak voltage.

[AsleepAltima]

the second i connected a hot wire to it, you could hear the pump come to life and my wideband stabilized instantly as well.

[BB4rank]

Fixed the issue finally! I was just looking at the motor while it was running the other day and was checking for leaks and where a recent chain noise has come up around the cams and I was checking my blow off valve which is a Greddy Type S which has 2 vacuum nipples on it and realized the previous owner put the vacuum line on the wrong nipple so the bov was never opening up! Anyways my AFRs evened out and are at 14.5 at cruising and about 15-16 at idle.

[steve shadows]

Leaky/crappy knock off Blow Off valve's can also create issues like this...

[BB4rank]

Ya well it was hooked up to the nipple that you hook up a boost source before tb on high boost application (20 psi) To help the valve open.

[[email protected]]

curious to know if you fixed the low voltage and if that made a difference to your a/f at all?

[BB4rank]

No havent done anything to the wiring just fixed the vacuum routing on the bov and now its around 14:1-14.5:1 while cruising ~16-16.5 during idle. I looked into the white/purple wire and it seems as if its the signal wire from the ecu so thats why i think if fluctuates.