Aftermarket SR O2 housing: which O2 sensor?

[SHIFT_*grind*]

To clarify: I have searched the forums for this, found a lot of good info, there's just one thing that confuses me that I wanted to see if anyone could clear up.

Installed an exhaust, test pipe, and knockoff divided turbo elbow yesterday. The elbow I bought used from a guy locally, and it didn't include the fat-to-skinny reducer fitting; it DID include some random fat-type O2 sensor already screwed into it. I install the elbow, find out my SR uses the skinny type, try to use the fat type, drive the car home sputtering and spewing black smoke, etc. etc. So obviously I need to find an adapter to put the skinny sensor in the fat hole of the new turbo elbow.

I found good info here on how to tap an 18mm cap bolt for the skinny sensor. Here's where I'm confused: This thread states that only S13 redtop SRs come stock with the skinny sensor, and all others come stock with the fat type. The sensor I pulled out was a skinny type, but my SR is a 97-98 S13 blacktop. It's a stock swap. So my question is...why would I have a skinny O2 sensor from the factory? Would I stand to gain anything from running a fat type instead? (The car runs fine with the skinny type, I probably get around ~25mpg) Is it possible the car's running a redtop ECU? I only bought the car ~2 weeks ago, so I'm still learning it.

Thanks.

[SHIFT_*grind*]

Just found the following here:

"also in the update model 180sx's (type X 1996-98) there was a different ECU and some different sensors (water temp sensor)."

Maybe the type X blacktop used the skinny type O2 sensor stock (as well as the water temp sensor) and my car isn't some strange anomaly or hack job?

[s13silvia123]

you can call any shop and buy it. call megan racing. they have them. or swap your O2 sensor to the fat one.

[nissanguy13]

Did you run that motor with the stock elbow and o2 first? The sputtering and black smoke doesn't sound like an o2 problem. I ran the fat o2 sensor on my redtop for a year. It got shitty mpg and the idle would bounce a little every once in a while but never any black smoke or sputtering and spewing.

[SHIFT_*grind*]

I've driven the car the last 2 weeks on the stock elbow and skinny O2, ran perfect. Drove it to the garage, installed a 3" exhaust, 3" test pipe, already had a 3" downpipe, and a divided turbo elbow. The fat O2 sensor in the elbow was some random thing; the guy I bought it from said he thought it was from an 86 300ZX and would probably make my car run like shit, but I had to drive it home with that sensor because the skinny wouldn't fit

I mean, it has to be the O2 sensor that's causing it; more exhaust flow wouldn't make the car do what it was doing.

It actually ran fine for a while, up until I got to a stretch of road and punched it. It boosted up, got up to ~60MPH, and then fell flat on its face; sputtered and wouldn't go over 3000RPM the rest of the way home.

[SHIFT_*grind*]

So, now that I think about it some more...the guy who sold me the car said that, when he bought it, it had a blown SR20 in it (probably a redtop?). He swapped in a new kouki S13 blacktop motor, fixed it up, and sold it to me. I think I'm looking at two possible scenarios:

1.) When he swapped the engine in, it didn't come with the blacktop elbow and sensor, so he used the one already in the car (redtop elbow & skinny sensor). It runs fine, so I could drill/tap a bolt to fit the skinny sensor, or buy the adapter from megan racing.

2.) I could just buy a brand new sensor from some company. www.oxygensensors.com ... legit? Has the 95 300ZX TT sensor for $49.90, although they show that it's the same part number as for the non-turbo version, which sounds a little fishy.

[SHIFT_*grind*]

Originally Posted by nissanguy13

Did you run that motor with the stock elbow and o2 first? The sputtering and black smoke doesn't sound like an o2 problem.

This made me start thinking; I had a friend helping me work on the car yesterday and he switched out my air filter while I was working on the exhaust stuff. I just went out to check, and......the metal retaining piece on the MAF plug is gone and the plug is hanging loose Guess that explains why it ran fine for a while, and then fell on its face after I punched it (must have shaken the plug loose).

[nissanguy13]

So the problem is solved?

Since you have a S13 SR20DET BLACKTOP: You should use the 95 300ZX TT O2 sensor

[SHIFT_*grind*]

The problem should be solved, although I'm at work so I haven't had time to put another retaining piece on the MAF plug and drive the car around. And it would probably run a lot better with a new O2 sensor than the random one that's hooked up right now.

Does it matter whether I buy the left pre-cat O2 sensor or the right one? Probably not, but I thought I'd ask...

[SHIFT_*grind*]

So not only was the MAF unplugged, I had blown off an intercooler hose. Previous owner hadn't even really tightened the hose clamp Fastened the MAF, reattached (and TIGHTENED) the IC hose and it finally runs.

It backfires and hiccups some though, and kinda bucked a little bit when I accelerated in 2nd. Does that sound like a faulty/incorrect O2 sensor? I think so, but I'm not ruling out anything...

Anyone?

[statik]

Anything other than light cruising/idle, the ecu is operating in open loop mode, which means its ignoring the o2 sensor and calculating fuel requirements based on input to the ecu from things like tps, maf etc. The O2 sensor is ONLY used for cruising and idle (closed loop) to give you an approx 14.7 AFR for better gas mileage.

Check to make sure have no boost leaks, check your spark plug gap and see how the plugs look.

[xplicit240]

try the greddy turbo elbow. what turbo do you have? if its the t25 stock turbo the fit is a lil off you might have to just enlarge one of the holes for the studs a tiny bit. if its a t28 its a direct fit. it has the adaptor fit into it already. part number is 11920100. its a great fit. find it at www.240sxmotoring.com

[SHIFT_*grind*]

It's the stock T25.

I replaced the O2 sensor and I'm getting a hesitation right around 3000RPM, maybe a little earlier. Still feels like it needs some help =(

It has an FMIC setup with aluminum hard piping on the cold side, but stock rubber hoses/couplings on the hot side...might that cause a problem? Pressure drop? I dunno

I'm going to try the following:

-Check gapping/replace spark plugs
-Check all intercooler piping for leaks
-Pressure test the IC?

[slideways2004]

Originally Posted by RB200SX

It's the stock T25.

I replaced the O2 sensor and I'm getting a hesitation right around 3000RPM, maybe a little earlier. Still feels like it needs some help =(

It has an FMIC setup with aluminum hard piping on the cold side, but stock rubber hoses/couplings on the hot side...might that cause a problem? Pressure drop? I dunno

I'm going to try the following:

-Check gapping/replace spark plugs
-Check all intercooler piping for leaks
-Pressure test the IC?

check gaps
check for boost leaks- take your time
check the timing- make sure you unplug the tps and do it right the way with the spark plug method

[SHIFT_*grind*]

In addition to the stuff already mentioned, I'll add this since it's probably relevant:

I can smell fuel pretty frequently while driving. I'm not sure if the car has a Walbro or other upgraded fuel pump, but if I can smell fuel (and it seems like the car's running rich), then it's probably safe to say that it does.

Maybe the pump is overrunning the stock FPR and flowing too much, and causing a rich mixture? I read about this possible problem when I did my RB20 swap several years ago, and made sure to install an adjustable FPR along with my Walbro 255; this car doesn't have one.

I'll check the other things for sure, just wondering if that's something I should consider as well.

[statik]

I dunno if you hooked up an O2 yet, but I'm pretty sure if there is no O2 reading in closed loop mode the ECU will add more fuel so you don't wind up running lean, which would explain why you smell fuel, it can't calculate the proper amount of fuel to run stoich.

[SHIFT_*grind*]

I installed a new Z32 300ZX O2 sensor the other day.

[nissanguy13]

Originally Posted by RB200SX

I installed a new Z32 300ZX O2 sensor the other day.

and........did it help, anything change.

[SHIFT_*grind*]

A little. It stopped missing at idle, but under acceleration it still bogs, usually in the midrange around 3K or so. I can hear it spool but it won't pull very hard, it feels like something's holding the car back, and then I shift and it backfires.

[SHIFT_*grind*]

Any input on the fuel pump/FPR?

[fliprayzin240sx]

Borrow a MAF from somebody and swap it with yours. Sounds like a MAF issue if you already changed the o2 sensor. If the MAFs are good, then double check the o2 wiring. Another things is ECU water temp sensor, check and see if thats good.

[SHIFT_*grind*]

Discovered two things:

-There is no fuel pump o-ring Guess this could be why I'm smelling gas. I'll be replacing that shortly. Could this also cause the car to hesitate/bog? Since the fuel tank probably isn't pressurizing properly?
-There's aluminum hard piping on the cold side of the IC, and stock shitty rubber hose/coupling on the hot side. I already knew this, but the "elbow" coming off of the compressor is bent slightly greater than 90 degrees and it's a little kinked. Could that be a source of my problems as well?

[UNISA JECS]

Look at the last post then look at your ECU.

http://www.zilvia.net/f/showthread.p...hlight=titania

[SHIFT_*grind*]

I haven't checked the part # on the ECU, but when I looked at it last week I noticed it's a #62 ECU, which according to some links I just checked out makes it part #23710-50F00. So my 97-98 blacktop X motor is running a 91-94 redtop ECU.

Which means the fatty O2 sensor I just bought and installed isn't the right one I guess I can stick it back in the box and try to take it back...

Also, the comment about the water temp sensor...I read last week that one of the *only* things that distinguishes the 97-98 S13 blacktop from other blacktops (and redtops) is a different water temp sensor. And I'm guessing that while my car's running a redtop ECU, it's probably still running the different blacktop temp sensor which could be throwing things off...?

So I guess I need to do the following:

-Drill/tap a 12mm cap bolt so I can run the skinny O2 sensor
-Find/install a redtop water temp sensor
-Buy a new fuel pump o-ring and put that in
-Gap/install new spark plugs (just got some NGK BKR7EIX iridiums today)
-Check my timing
-Find an aluminum hardpipe so I won't have kinked up shit? And triple-check for boost leaks.

And THEN maybe my car will run right =D

EDIT: I pulled ECU codes the other day and got a 55 all clear, would I be throwing a Water Temp Sensor code if I were running the incorrect sensor for my ECU?

[fliprayzin240sx]

97-98 type Xs has some slight repin difference on the harness. If its running fine before, my guess is your running the type x engine with a redtop wiring harness mated to a redtop ECU. As long as the harness and ECU is the same, it should work. As far as the o2 sensor, it doesnt matter what o2 you run, what ever fits the elbow you have is good. So if you have an elbow for a fattie, run a fattie o2.

Not too sure about the water temp thing...
Spark plug, gap it to .030

[UNISA JECS]

ok here are some of the main difference between an ecu that uses a skinny o2 sesnor and a fatty o2 sesnor is:

Skinny o2 sensor black (ground) wire is grounded to the body
*bonus info: the skinny o2 sensor works off an entirely different refference then the fatty o2 sensor (the ecu checks resistance from the skinny type o2 sensor whereas the fatty is based on a 0-1v oscillating voltage refference.

Fatty o2 sensor is grounded inline between the engine ground and the shielded wire of the o2 signal wire and the refference of the fatty is based on a 0-1volt scale unlike the skinny type o2 sensor.

[fliprayzin240sx]

Eh, Ive used both fattie and skinny o2 on my car. That was mixed and match to hell. Started off with a blacktop, then got a redtop engine, but kept the blacktop wiring and ecu.

[UNISA JECS]

Basically the ECU of the skinny o2 sensor supplies it 1 volt and the ECU compares the resistance of titania against a comparative resistance built into the ECU.

Basically the fatty o2 sensor creates its own voltage.

[SHIFT_*grind*]

Well. Anyone want to buy a fatty O2 sensor? Since they won't let me return it? Fuck.

[SHIFT_*grind*]

Edited because I figured out which temp sensor to buy.

So I'm going to try to sell the fatty O2 sensor and buy the megan 18mm cap bolt (or try to find one locally) and tap it for the skinny sensor that I already have.