O2 Sensor Fix Gone Bad...
#11
AudiWorld Super User
#12
Had MAF malfunction only when hot
Well, I cleaned the MAF sensor and it ran great up and down the mountain. No misfiring at all. In fact, it damn near drove like new. After about 20 minutes of driving, I came back home, with it still driving perfect and let it idle for like 5 minutes in the garage to cool down a bit. Of course, near the end of those five minutes it started running rough and the check engine light started flashing. Back to the old P0300 random misfire with no additional info. The only other code is for the Bank 2 Side 2 O2 heater. It's tough when their are no other codes or specific cylinders...
Anyone know if I may just need a new MAF since cleaning it alone seemed to alleviate the misfire under throttle?
Edit: More specifically, the engine cleared up the misfire on it's own after about 10 seconds and started running smoothly again. Revving the engine slightly also cleared it up causing it to run smoothly again...
Anyone know if I may just need a new MAF since cleaning it alone seemed to alleviate the misfire under throttle?
Edit: More specifically, the engine cleared up the misfire on it's own after about 10 seconds and started running smoothly again. Revving the engine slightly also cleared it up causing it to run smoothly again...
#13
Side note: I re-checked the codes today upon arriving at work. I really hoped I would get at least either bank info on the misfires or individual cylinders but still don't. The only new code is for Bank 1 Side 1 O2 circuit malfunction.
Since it's a random misfire code with no specified cylinders, it seems more MAF related though, right?
#14
Looking up options for the MAF Sensor replacement... It looks like both Bosch and Hitachi are similarly priced. Will I see a difference in either of the two if I were to replace it? Also, Pierburg (apparently the OEM Audi MAF that is made by Hitachi) can be found for around $140 as well. Anyone have a recommendation before I pull the trigger?
Also, if I were to unplug the MAF when experiencing misfiring at idle, would it prove that I needed a new one or would it be inconclusive?
Also, if I were to unplug the MAF when experiencing misfiring at idle, would it prove that I needed a new one or would it be inconclusive?
#15
Update... I ordered the Hitachi maf on Amazon for $118... It should be here tomorrow evening and I'll install it to see if that was the problem. In other news, my b1s1 o2 sensor code came back on today and included a bank 1 lean code.... Any chance the pre cat o2 could have been causing this whole mess?
#16
Fixed!
Thank you to sloop and the other posters. I got my car back on the road with a little bit of effort. Turns out the whole problem was due to the faulty pre cat o2 on the passenger side. I ended up ordering an NGK o2 with factory connector and put it in in like 30 minutes. I thought it was going to be significantly harder due to the angle but it wasn't bad at all to route the wiring and remove the old one. Old maf ended up being fine and I am returning the Hitachi to Amazon. It turns out a faulty pre cat sensor can screw the ecu big time causing lots of random misfires.
#17
Can you tell me a few details about removing the pre cat O2? What kind of wrench? Lots of heat or just engine warm(after a long drive, etc.). I know I have the same problem. I tried to loosen that same O2 and it wouldn't budge. I used some PB Blaster, and the car was cold. The wrench I used was a 'claw' wrench like this one
#18
Can you tell me a few details about removing the pre cat O2? What kind of wrench? Lots of heat or just engine warm(after a long drive, etc.). I know I have the same problem. I tried to loosen that same O2 and it wouldn't budge. I used some PB Blaster, and the car was cold. The wrench I used was a 'claw' wrench like this one
#19
Update :
I went back to try and remove the passenger front O2 sensor. I put the 'claw wrench' on the O2 by hand and tried to spin it to get it into a good position for the 1/4" extensions. But the wrench kept spinning by hand. I had a scare thinking I stripped the nut on the O2. It turned out the O2 sensor was loose. I must've loosen it last time I worked on it, and the wrench stopped in the screw on the down pipe. It's tight and dark down there so I didn't notice that screw the last time. Yet it seemed there should be about an inch of clearance before the wrench hit the block. So for anyone trying to remove the passenger front O2 sensor, look out for the down pipe screw that might be getting in the way of loosening the sensor.
Anyway, after I changed that O2 sensor, my car has been CEL free and the fumes odor is gone...I have yet to check if the mileage improved after the next fuel up, hopefully it did
I went back to try and remove the passenger front O2 sensor. I put the 'claw wrench' on the O2 by hand and tried to spin it to get it into a good position for the 1/4" extensions. But the wrench kept spinning by hand. I had a scare thinking I stripped the nut on the O2. It turned out the O2 sensor was loose. I must've loosen it last time I worked on it, and the wrench stopped in the screw on the down pipe. It's tight and dark down there so I didn't notice that screw the last time. Yet it seemed there should be about an inch of clearance before the wrench hit the block. So for anyone trying to remove the passenger front O2 sensor, look out for the down pipe screw that might be getting in the way of loosening the sensor.
Anyway, after I changed that O2 sensor, my car has been CEL free and the fumes odor is gone...I have yet to check if the mileage improved after the next fuel up, hopefully it did
#20
Awesome man, glad to hear it. Yeah, there are several things down there that can be bumped into when trying to spin the o2 wrench. For me, it was the exhaust shield. Like you said, I had about a little under an inch to spin before needing to reset it again.
Anyway, hopefully your car stays CEL free!
Anyway, hopefully your car stays CEL free!
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