Someone please school me on O2's.
08-11-2008, 06:04 AM
#1
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Someone please school me on O2's.
The last 2 weeks I have been getting a precat O2 code. resistance too high I think it is. I get one mostly sometime the other one triggers too.
I noticed this weekend my car is starting to misfire on WOT.
I am changing the O2 sometime this week or next but I am trying to figure out if I need to budget myself for more sensors or something.
When I get the misfiring no codes come up except the O2 code.
My questions are.
Do the O2's affect the car at WOT?
Has anyone had a pre cat O2 go bad and cause misfires?
The part thats getting me is I thought during WOT the O2 don't do much so why the misfires?
I have pretty new EGT's in there so I don't think its that.
And no misfire code is weird too. Maybe its something else that feels like a misfire but isn't.
Can I log a block with my VAG to get a better idea?
Thanks again guy!
I noticed this weekend my car is starting to misfire on WOT.
I am changing the O2 sometime this week or next but I am trying to figure out if I need to budget myself for more sensors or something.
When I get the misfiring no codes come up except the O2 code.
My questions are.
Do the O2's affect the car at WOT?
Has anyone had a pre cat O2 go bad and cause misfires?
The part thats getting me is I thought during WOT the O2 don't do much so why the misfires?
I have pretty new EGT's in there so I don't think its that.
And no misfire code is weird too. Maybe its something else that feels like a misfire but isn't.
Can I log a block with my VAG to get a better idea?
Thanks again guy!
08-11-2008, 06:30 AM
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Bad 02 sensors should not affect WOT because they are only an output at that point.
02 sensors are used for closed loop fueling at idle and part throttle, though. If they were bad, that is when you'd probably notice it.
08-11-2008, 06:42 AM
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If you're talking about WOT misfires, I don't see how that could be related to 02 sensors.
Could be a coilpack. Log 02 voltages and WOT and see if one bank has "dips" when you feel the misfires. I've seen this on a few cars where the voltage drops out on a particular bank when a cylinder misfires. It's commonly a coilpack issue.
08-11-2008, 06:50 AM
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Yea I had a pack go bad on me and it felt the same but that threw codes.
I'll log that block and try to get a misfire code to trigger.
I still have 5 spare (used) coil packs from the first time. I hope thats the problem.
Thanks for the 411.
I still have 5 spare (used) coil packs from the first time. I hope thats the problem.
Thanks for the 411.
08-11-2008, 11:01 AM
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had similar issue this weekend...CEL came up, I got 2 codes for O2 sensors and misfires on idle...
I cleared them and they haven't com back again...I noticed a small popping sound shortly before the CEL came up but the sound has gone away since clearing as well. Is it possible that I temporarily messed something up (did a hard pull shortly before all this happened) and it's back to normal or should I replace the O2 sensors ASAP?
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08-11-2008, 11:32 AM
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Thats where I am going to start. They only have about 1000 miles on them.
I am going to go from plugs to coil packs. I hope I can get it to throw a misfire code first though. it would help!
08-11-2008, 01:20 PM
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If your O2 is going, you will probably notice....
that the primary O2 readings are noticeably different from each other (2 banks) when you take a log. Also, good chance that your fuel trims will be different between banks and that you will idle roughly (possibly with misfires). Fuel economy will suffer too. At least, that's what happened for me.
08-12-2008, 04:42 AM
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update: I didn't have time to log yesterday b/c It was poker night. I did scan it there and back.
When I got home from work no codes. I leave I have both precat O2 codes. I clear and drive off.
I get there and I was driving all sorts of ways to try to get a code. I got random misfires and also in #5 and #6. I also noticed a little bit of a rough idle. With these track density motor mounts I can feel everything.
So I think my O2's are done and I am going to buy new ones once I sell my LWFW.
I am also going to check #5 and 6 today and change the plugs and coil packs and see what happens.
I get there and I was driving all sorts of ways to try to get a code. I got random misfires and also in #5 and #6. I also noticed a little bit of a rough idle. With these track density motor mounts I can feel everything.
So I think my O2's are done and I am going to buy new ones once I sell my LWFW.
I am also going to check #5 and 6 today and change the plugs and coil packs and see what happens.
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