Running lean??

[DSMChase]

so I just finished my build, basically all stock except adj cam gears, e316g, fp mani, injen intake, greddy 24" fmic, 255 fuel pump w/rewire, aeromotive fpr. I have a narrow-band air/fuel gauge (please dont tell me I need a wide-band, I KNOW), when I first start and drive my car the gauge seems to read accurately, but after about 5-10 minutes of normal driving the gauge gets leaner and leaner, until it is pretty much stuck at the first led in the lean zone. The car doesn't seem to run any differently, my fuel pressure is right on, could this be a bad gauge? bad O2 sensor? (O2 sensor was sitting in rain for a while), also there is CEL, not sure why, all smog stuff is hooked up correctly. I did start my car on accident without the MAF hooked up, could this have anything to do with it? Recommendations?

Update: I unplugged the battery and reset the computer, drove 30 miles, the CEL stayed off, but the air/fuel gauge did the same thing again. Somebody please help! I dont think its really running that lean, it would run differently, but I am afraid that it will detonate and crack my new pistons! Anybody??

 

[Chaosweaver]

Don't even worry about that, those gauges aren't accurate at all. It may say its running lean but its more than likely fine, do yourself a favor and just rip it out.

 

[93_fwd_tsi]

dont worry about it. like what Chaosweaver said, those gause are not accurate at all.

starting your car with the maf unhook wont do anything. did you check what code you were throwing before you reset the computer?

 

[DSMChase]

didnt check the code, but it came on when I started it with the MAF unhooked, figured that what it was. Its just weird because I had the gauge on it before I tore it apart (all stock except fmic, injen, 3" exhaust) and it acted like a normal piece of junk narrow band, jumping from lean to rich and vibrating in stoich, no matter how long I drove it, now, like I said, it acts the way it used to but only for 10 or so minutes, then it stops bouncing and begins to solidly go down one led at a time without bouncing, then when I let off the gas or idle it used to bounce around now it just sits in lean. It just makes me think the O2 sensor is bad, or my car is actually running leaner and leaner, i have a lot of money invested in this thing, just dont want something bad to happen does the computer use O2 sensor readings at all for AFR? or only MAF? if MAF, could there be something wrong with that? I appreciate the help

 

[Imback]

The ecu uses the o2 to try to keep a stoich reading of 14.7. Also if your o2 is dieing your car will not go into closed loop. Since you already know you need a wideband no need to remind but with so much money what is 200 to keep a eye on your AFR. If your NB was working before then you very well could have a dieing o2.

 

[AWD Devious]

I have the same problem. when i bought my 97 gsx about a month ago it came with a autometer a\f ratio meter. The car is stock except for a FMIC w/ greddy type-s bov recirculated and a hks catback exhaust. it was jumping from lean to rich, but after i replace my exhaust manifold gasket, o2 housing gaskets and down pipe gasket and my battery was disconnected at the time, so the computer reset itself the meter started to read lean all the time and when im in gear and when i drop it to neutral it shoots up to stoitch and when i drive it stays in lean. i got a check engine light and it gave me a code P0171. It's either my maf sensor or o2 sensor that is bad. i just bought a maf sensor waiting to install it to see if that is the problem. im going to buy a o2 sensor while im at it. i don't trust the meter at all. going to take it off.

 

[DSMChase]

I'm going to get WB next week, could leaving the O2 sensor out in the rain for a while, like 2 months, screw it up? Also when my original motor died before, due to a failed turbo bearing, I was burning a s**t load of oil. Is it ok to drive it how it is?? like I said I cant notice any difference in the way it drives/spools/idles

Did you use copper spray? I wonder if that has something to do with it because I used it on all my exhaust gaskets

 

[Imback]

You will be fine running with a bad o2. But if you have a fresh motor build as well i would get a new o2 since running rich on a new engine is not good.

 

[DSMChase]

ok, one more question, I have my fuel pressure set at 45# off, its usually around 36-38 at idle, does this sound good? stock injectors, only running 12 psi right now