weird no boost issue

[rustest86]

ok...... i have just gone through and done a bunch of "upgrades" and repairs on my SR 2 weeks ago, ie metal head gasket, arp head studs, ka transmission, the right oil pump, i was using a fwd one and decided to do it right, rebuilt the turbo, and new wastegate.

now that yall know that.... for the past 2 weeks ive been running 3psi because i didnt ajust the wastegate properly and for rebreakin of the turbo. saturday i finnaly got of my lazy A$$ and ajusted it, to 10psi. it ran perfect. later that night it ran perfect also, but the next morning no boost, only vacume. i thought well i got a BIG leak somewhere. but my wideband wasnt reading rich like a leak but so lean it doesnt even dispaly a number. also theres no sound of the turbo spooling or even the bov.

today i checked for leaks and i dont have any, the turbo spins freely and wastegate flaper is still there, not like they disapear though. so i dont have a single clue. im gonna redo a few vacume lines but i dont thing itll do anything to help it

[rustest86]

ok new development... when i was leaving work today it started bucking like crazy, kinda like when the MAF or TPS is disconnected, when i pulled over a checked the 02 wires were burn't. not the harness side but the sensor side of the connector is burnt. i know this is why it was bucking like crazy, but would a bad sensor cause the very lean condition and no boost? why would the wires burn like that? there not touching anything. also could the ecu be damaged because of this? i have an extra 02 but i dont wanna put it on if its just gonna burn it too.

[fast_s13]

something has t be wrong with your turbo for it not to build boost. if you had a leak big enough that your car wouldnt build boost it wouldnt even idle..i would pull the turbo and check the compressor wheel

[Hijacker]

The only thing that could make the wires burn up are swapped terminals (unlikely since the car ran right before), extreme voltage running through the heated element, or touching the turbo/manifold. Usually it's the latter that burns up the sensor wires. However, the computer usually ditches the O2 sender when anything hinky goes wrong with it, which would put you in closed loop rich. But when I start thinking about the situation you're looking at, I start thinking it could be a simple fact that the exhaust gasses are too hot from your lean condition and that burned up the O2 sensor.

I have a feeling your bucking issue might be MAF related since you said it was bucking like the MAF was unplugged. It could also explain why you were having lean issues.

Now, what fuel management are you running? I see you have an 18g turbo, so I assume you upgraded the fuel system while you were at it. It could be related in your tune, or the MAF itself could be dirty/fouled/damaged. Also, you could have a bad injector or bad injector controller causing not enough fuel to get to the cylinder. It could be a broken FPR that's allowed a low pressure situation in the rail to exist, which would effectively lower output of the injectors and cause you to lean out. Also check for any possible leaks on the rail or around the injectors themselves.

Did you check the turbine wheel for any damage? Running really lean could have damaged the wastegate flapper or the turbine itself.

[rustest86]

well i just checked the ecu for visable damage and it looked good, and i still have 12volts to the connector for the o2. but the o2 itself has some funny readings which makes me think it was my whole problem. i ohm'ed out all the leads on the o2 and got this

red and black wires- 71.058 ohm's "heater circuit"red and white wires- 1.365 ohms's "?"black and white wires- 1.624 ohms's "?"white to case- 0.43ohms's and dosn't change as its heated " ecu signal"

so im assuming right now that the o2 went out and it started running lean which burned the heater circuit causing it to short out burning the wires.

no i havent fully checked it, but hopefully the turbo isnt hurt in anyway. im hoping that its just that it was running so lean it couldnt spool it as its not making any funny noises and does spin when the engine is running.i dont have any fuel leaks, walbro pump, still using the stocks 370's "bigger injectors are in the works after i get this fixed", emanage blue that shows the q45 MAF to be reading and working right. i havent checked the FPR yet and i heard they dont last long with the walbro's. the bucking though i think was those wires shorting out the ecu. right now itll start and run, lean of couse, but will run fine till it warms up then start missing real bad. and also i noticed free reving it, it will start missing at 4k untill it gets to 4.5k then rev past it.

[Hijacker]

Where's your wideband placed at? Cause from the sounds of it, you're only running the factory heated O2 sensor

[rustest86]

my wideband is futher downstream in front of the test pipe, im running an aem uego with the gage.

[Hijacker]

Since it's the sensor harness that got burned up, disconnect the plug and drive the car around and see if you can replicate the issue. Disconnecting the O2 sensor should just stick the ECU into closed loop and enrichen your mixture out. If it doesn't, then you have some other issue causing your lean problem.

[rustest86]

dumb question, is there a way to check the FPR with out a gage or is that the only way?

[Hijacker]

You need a gauge to be accurate. I can tell if pressure's built up in a line by squeezing it, I just couldn't tell you if it's 20 psi or 60 psi.

[rustest86]

well 2 things that fix my problems o2 was bad. runs super rich with the o2 unpluged and now even spools the turbo, but i now have a boost leak consisting of a broken t-bolt clamp that looks like i over tightned it. it broke while i was free reving it so no drive yet, but it does get about 2 lbs now reving it. so ill fix those tonight and see how it goes.

[Hijacker]

Perfect!

[rustest86]

new o2 fixed all the problems,boost 10lbs again thanks for the help Hijacker

[rustest86]

ok problem came back again last night right when i got home . i think its a wiring issue now but i dont know why it been running good for a year then this, but the extra used o2 that i had a different pinout in the connector then the one i was using, same colors though so i hooked up the new one the same as the old one and i think thats my problem.

old connector black wire white wire red wire

new connectorwhite wire black wire red wire

which one is the right order? my engine harness is done just like frsport says to, and like i said been running for a year with no problems. unless i just had an extra bad o2. i dont think it burnt the wires this time but it was dark so ill look when i get home.

[Hijacker]

I only have a circuit diagram from the japanese S13 manual, so no color coding yet. However according to the circuit diagram, that plug's pinout should be this _1 2 3

1 12v heated element power source2 Sensor Signal wire to ECU3 Heated Element ground

The little _ in my plug pinout is for the clip on top of the plug. Due to the forum's formatting, the _ should be over 2, but it's being displayed over the 1.

The heated element is powered off the ignition switch's circuit, so without an actual color coded diagram from the JDM manual, I couldn't tell you the exact power routing. And KA manuals are useless for this since they're all single wire, no heated element sensors.

[rustest86]

ok then, this is my diagram base off of yours. red i know is +12volts, but ive heard that the black and white wires can be grounds or signals. i know both wires go to ground but as far as which one is ecu ground i dont know either.

old connector-r,w,bl

new connector-r,bl,w

all the pics i found on the net make me think that the new connector was right and my old connector was wrong, but there just pics, they could be from anything and look similar. and im the only one running an SR around here so i just cant go look at someone elses to find out. this is getting fustrating.

[Hijacker]

Continuity test will be your friend in this matter. The ECU Pin that the signal wire comes out on is 19. And given Nissan's propensity for using white as signal carrying wires, I'm going to say that your old plug is correct. Black is always a ground in a Nissan.

[rustest86]

well i just tried it both ways. it runs better wired the way it was-bl,w,r

runs like absolute crap with -w,bl,r

heres the wierd thing though both the black wire and white wire ossolate on my digital meter!?another thing it runs like crap now with the o2 unpluged unlike last night when it ran fine with it unpluged. i think it was just a fluke and ran right long enough for me to get it home. and there is another problem deeper in thats causing this. and then i just might have 2 bad o2 sensors.also now im not building boost again,its also running lean again tooim gonna try and see if i get any codes in a few min.

[rustest86]

well ijust tried pulling codes and well all i get is a single flash when i first turn on the key then nothing after turning the switch. i did manage to get it light up but it stayed on, and i have no idea what the means.

but in the mean time my buddy just got his front clip in so im gonna go steal his ecu and try it......its a MINES tune for basicly my same setup so we shall see.............

[rustest86]

ok well i have all the parts to try now, we started my friends clip before he pulls it and it runs great. so i grabbed the o2, ecu, CAS, and my old MAF. the o2 reads the same as mine and does nothing to improve the running. the CAS also does nothing for it. the ecu makes it run alittle bit better, but not enough to say thats the problem. the MAF also dosent help in anyway, i think it runs worse. it still wont boost past 2psi, its running about the right AFR, but starts getting lean up top still. also it started to not idle steady, kit keeps surging from 1500rpm to 300rpm and has a afr of 15.9-17.0 which is WAY TOO lean.i still cant pull any codes at all from my ecu, on the other ecu the light just stays on but i think its because its chiped by MINES.i will be pulling the turbo this weekend to check it and checking the fuel pressure. after that i give up . i guess ill have to do my buddies harness and test it on mine, if nothing else works. maybe i have somemore shorted wires somewhere else that i cant find..... i dunno..... im lost

[rustest86]

well i havent had a chance to pull the turbo and wont be able to untill monday. but i have tried new spark plugs, which didnt help, and a new walbro pump. i tried that because it sounded like it was running out of gas. BOOM it idles 800rpm but its a very rough idle. not like a miss but it isnt right. but it is running the correct afr now. it still wont boost though. it runs like there isnt enough timing, but its set to 15*. im still at a loss but i am slowly getting it back right. i need this thing running right........ im tired of driving my yota. 22r carbed automatic............. yea you know what im talking about, im going nuts.

[rustest86]

well the problem is so far resolved. i did another boost leak test just for kicks and giggles. i turned the pressure up from 10psi to 15 and found a leak right at the coupler on the front of the turbo. i replaced another broken clamp and everything runs perfect now. boosting 10psi again