o2 sensors on a redtop

[1991 S13]

quick question, I find myself getting like 200 miles per tank, its horrible especially with the gas prices right now, just wondering if anybody has recently changed out their o2 sensor on a red top and what kind of milage u should expect from it...discuss

[SpeedRacer1]

Good running SR's should get about 25-30 mpg. Its worth a try to replace.

[theimbalance]

are the SR's o2 sensors universal with the KA's? I'm having terrible gas mileage too.

[f150intally]

no, you will need a sensor from the 87 300zx turbo. or if your sensor is the fat type, the 90-96 twin turbo sensor will work.

[1991 S13]

so the 87 300zx turbo model o2 sensor works with the sr redtop? just clearifying.

[bigk]

i got mine from phase2motortrend.i still get only about 180 per tank tho.i m getting a adujustable fpr cuz im dumping so much fuel ant idle.i have a walpro 190lph fuel pump and stock injectors

[180fan]

so the 87 300zx turbo model o2 sensor works with the sr redtop? just clearifying.

yes

[1991 S13]

I have a turbo supra fuel pump and stock injectors, but I also have an safc-2, its not really tuned but I get the worst gas mileage

[theimbalance]

im getting roughly 21 mpg at 9-11psi city driving, only getting on it every now and then. im not sure how big my injectors are, but i do have the 300zx fuel pump. does that sound right? thanks f150intally.

[SpeedRacer1]

I have found that different ECU's will produce different mileages. I have used an auto ECU #63 for two years and got between 26 and 30 MPG's. When I got an SAFC2 the SAFC and the auto ECU started to have problems so I got a manual ECU #62 and immediately my mileage dropped to the low 20's. Somewhere around 20 MPG's. So I put the auto ECU back on and now it works fine with the SAFC and I get about 28 MPG again.

Auto ECU's make the idle air control valve suck in more air throughout the powerband. I have a switch to disable the IACV and have noticed that the boost drops slightly when the iacv is disabled on an auto ECU. When the IACV is turned off on an auto ECU, it acts like a manual ECU but still gets decent 26ish MPG gas mileage.

[nsilviaracer]

with all these low mileage problems do anyone u that have a really big problem with it tend to find your car idling like crap? it misses like crazy at low speeds.. and it will hesiate when its in low rpm's.. i still have a stock fuel pump, but not for long i am getting a 255 walbro this week because the only thing i have not checked on the car is the one thing that was on it before the engine swap. ( this same problem followed from the KA to the SR ) so the only thing i can think of now is the fuel pump..

hope it fix's it

[SpeedRacer1]

Timing may be off.

[TeeJay]

nsilviaracer, are you saying you get bad gas mileage on the stock pump?

hmm.. personally I get good mileage. But then again everything was stock in my setup except for a 3 in downpipe.. Stock IC, cat, boost, exhaust AND fuel pump. I really only do highway miles and I see almost 32 mpg, and that is getting on it every once and a while (to pass trucks and such). When I do a city tank, I never see below 25. And I attribute this to my fuel pump.

I just recently put a test pipe and a 3 inch exhaust on. We'll see how much I lose..

[nsilviaracer]

nsilviaracer, are you saying you get bad gas mileage on the stock pump?

hmm.. personally I get good mileage. But then again everything was stock in my setup except for a 3 in downpipe.. Stock IC, cat, boost, exhaust AND fuel pump. I really only do highway miles and I see almost 32 mpg, and that is getting on it every once and a while (to pass trucks and such). When I do a city tank, I never see below 25. And I attribute this to my fuel pump.

I just recently put a test pipe and a 3 inch exhaust on. We'll see how much I lose..

well i have the new fuel pump and my problem acts like a bad fuel injector when the engine runs rough and the car misses, and i am getting under 150miles per gallon.. its not timing i have checked that already, but it might also be my fuel pressure regulator because the car is running rich has sh..t!any ideas???

[Hijacker]

You could try to check your fuel pressure to see if it's running too high. But my guess would be O2 sensor. My sensor is starting to crap out on me. My economy has gone down (I'm barely getting 300 to a tank right now when I used to pull 330 or so), my exhaust is caked in carbon, and my plugs smell of fuel. I'm going to check my fuel pressure tonight, and if it's not the FPR, the O2 sensor will get changed.

[nsilviaracer]

You could try to check your fuel pressure to see if it's running too high. But my guess would be O2 sensor. My sensor is starting to crap out on me. My economy has gone down (I'm barely getting 300 to a tank right now when I used to pull 330 or so), my exhaust is caked in carbon, and my plugs smell of fuel. I'm going to check my fuel pressure tonight, and if it's not the FPR, the O2 sensor will get changed.

replaced the o2 sensor as well, it has to be fuel pressure