f2racer

iTrader: (1)

I swapped out the aging O2 sensor in 2002 with a Bosch universal one wire unit. Within the last month or so, my Autometer A/F meter no longer reads in the green part under any acceleration much less WOT, yet the exhaust stinks like mucho unburnt gas. Should an O2 sensor go bad this quick?

Thanks!

f2racer

iTrader: (1)

I replaced the O2 sensor for another Bosch universal, and it reads exactly the same. Am I running lean or are these sensors just crappy? Just a couple of months ago, the A/F meter would go to the middle of the green (rich) under WOT, now it's only getting to the middle of the yellow. Car still smells like it's running a little rich out of the exhaust... Should I just track down an OEM NTK sensor?

Thanks!

Hyperite

1- What makes you think it's a sensor problem and not a fuel delivery problem?
2- Are the EGT values different now than when you installed it? Remember, the narrowband sensor is only reliable at certain temperatures and for a very limited amount of data (=14.7 A/F,+,-)
3- Are there any problems? Are you using the stock ECU? List your mods, my friend.

f2racer

iTrader: (1)

The reason that I don't think that it's the fuel delivery is because on the old O2 sensor the car really smelled quite rich just about everywhere. With the new O2 sensor, it still smells kinda rich when I get on the throttle.

I also replaced the cat with an almost new one, and still failed emissions due to high CO (which mean incomplete burn of the fuel I believe), HC and NOx passed.

Haven't checked the EGT can I take the temp of the downpipe as any indication?

The only other "issue" that I'm having with the car is a high rpm boost leak. My boost pattern is a 10-8-10-7-8 in third which I believe is coming from the IC to intake elbow pipe.

I've still got the stock ECU and the only performance mods I have on the car is a downpipe and a Racing Beat intake duct.

I plan on wiring up my voltameter up to the splice I did for the A/F meter just to make sure the gauge hasn't gone bad. Anybody know how many volts mean lean to rich?

Thanks!

f2racer

iTrader: (1)

If my car is in fact running lean, how do I fix it?

Thanks!

Hyperite

But...the old O2 sensor was bad, hence the replacement, right?

Airpump connected and functioning? Stock cat? or Aftermarket? High-Flow?

Like, putting your hand on it? No, I guess I was hoping you had an EGT Gauge and a good memory.

What the hell boost pattern is that? I can't begin to deciper it, and can only suggest doing a search for all possible boost leak scenarios.

That's fine. Did you do any of the mods *since* the O2 replacement? I've found the stock ECU to run fairly rich, even with full exhaust, intercooler, and intake. (dont' do this, though)

I *doubt* the gauge went bad, it's a very very simple circuit, but like I said, it's not going to be very accurate to begin with. To be honest, fix that boost leak and call it a day.

OK, you seem bent on "correcting" the Autometer feedback. So, here's what you can do, in order or ease/cost:
Replace O2 sensor (you know you want to)
Replace Fuel Filter (how long's it been?)
Send the injectors for a cleaning and balancing (running some cleaner through *can* help)
Check charcoal canister and all related fuel lines


Hope that helped a bit.

f2racer

iTrader: (1)

I'm guessing the O2 sensor was bad, it started reading lean from partial to WOT, but the car smelled badly of unburnt gas all the time, additionally I failed emissions due to high HC and CO

Air pump is connected, but may be on its way out. Would that have an impact on what the O2 sensor reads? I thought the air pump pumps air into the main cat which is after the O2 sensor. I do have a downpipe and just replaced the main cat with a near new (only 6k miles on it) one. Stock catback if that matters at all.

Rather not, I like my skin! I don't have an EGT gauge, but do have an oven thermometer (I think it goes up to 600F).

I'm guessing that my boost pattern (10psi on the primary, 8-9psi at transition, 11psi when the secondary comes on, the 7-8psi at 5.5k rising to 8-9psi by redline) is due to one or more of the ancient vacuum tubes or check valves under the UIM. I plan on replacing them this weekend.

The only "mod" I did was replace the original cat for the newer one as I mentioned above. The newer cat seems to be working somewhat as it cut the HC to 1/2 of what was read on my first emissions test. I'm failing on only CO now (that would say that I'm running rich right)?

Yeah, I know that an A/F meter hooked up to the narrowband O2 sensor ain't gonna be all that accurate or useful, but It'd give me peace of mind to see it read in the rich area when running WOT. Scares me that it's not.

I plan on replacing the Bosch O2 sensor for an NTK one as soon as I can track one down. The fuel filter has maybe 6k miles on it (I replace it about every 15k miles) and should be OK. Probably will send the injectors out for cleaning when I do the vacuum tubes. Anybody know a quality shop that won't charge an arm and a leg?

I'm also considering sticking a fuel pressure gauge after the fuel pressure regulator. Anybody have a pic of which fuel line I need to tap into?

Thanks a bunch for all the feedback!

f2racer

iTrader: (1)

Just a quick update. The problem ended up not being the Bosch O2 sensor at all (although I did end up getting yet another one, free since they come with a 2 year warranty), but rather a short in the wiring in the stock wiring harness. Must have shorted to the shield somehow (the stock wire is shielded and the shielding is ground according to the wiring diagram in the workshop manual). So I ended running shielded wire directly from the O2 Sensor to the ECU connector. Didn't bother grounding the shield (is that a problem?). I also replaced my Autometer digital A/F meter with a Westach analog A/F meter.



Although I know that the A/F meter (hooked up the "stock" narrowband O2 sensor) is near useless from a tuning perspective, it's nice to know that the signal that it's sending isn't all screwed up (I hooked up a multimeter to diagnose the problem and with the shorted stock wiring, it was reading negative volts most of the time!)...

Hyperite

Bro, that gauge only goes down to 12 A/F. Most of us (hopefully you included) run low 11's on boost (the only time you really need to care anyway). Return it and get the Defi D-link Analog gauge.

f2racer

iTrader: (1)

Hyperite, I'm mostly stock with the exception of a DP and Racing Beat intake duct as the only "performance" mods to the car (although I've got a host of reliability mods like an aluminum AST, aluminum radiator, silicone vacuum hose job, and recently serviced FIs). From what I can tell, the stock narrow-band O2 sensor doesn't have nearly enough range/accuracy to "tune" by. The Westach A/F meter is pretty well "calibrated" from what I've heard. It reads 12 at extacly 1V (I've tested it), which is from what I understand is all a stock (NTK, Bosch or any other replacement narrow-band) O2 sensor will put out. Since this is the case, what exactly would the Defi gauge by me? BTW, the gauge is in my car, more to validate that the O2 sensor/wire ain't bad (like it was before) and for looks than to warn me if something is wrong.

I had an Autometer digital A/F meter on the car prior. When it started reading wacky (way lean WOT in spite of the fact that the exhaust smelled terribly rich) it told me something was wrong with either the O2 sensor or the wiring to the ECU.

That being said, I really prefer the Westach gauge to the Autometer. The readings are damped to a certain degree which means that it doesn't flicker too and fro like the Autometer. And at WOT, the needle goes all the way to the right