O2 Sensor bad already?
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! |
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! |
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. |
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! |
If my car is in fact running lean, how do I fix it?
Thanks! |
Originally Posted by f2racer
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? If my car is in fact running lean, how do I fix it? 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. |
Originally Posted by 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 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! |
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.
http://www.westach.com/images/showca...Fuel_Ratio.jpg 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!)... |
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.
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Originally Posted by 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.
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 ;) |
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