Knick in Primary O2 sensor wiring causing erratic AFRs at light acceleration?

andrew_ms3

andrew_ms3

Greenie N00B Member
Hey guys I've been trying to figure out why my AFRs dip to 13.5 and raise to 15.5 during light throttle inputs in 1st-3rd gear. The moments these dips and raises occur are very brief and the AFRs quickly return to 14.7. Part throttle LTFTs are always under +5 and idle LTFTs always under +9 (changes with AC on or off). They don't fluctuate like this while at a constant RPM at higher cruising speeds. I've loosened and retightened boost tubes, CS short ram, and the stock TIP to ensure I have no boost leaks. I have cleaned the MAF sensor numerous times as well as the throttle body. I did notice that there is a knick on one of the O2 sensor wires and was wondering if this was causing my issues? Only other guess I have is that I do not have an air straightener which could be causing the fluctuations. Before I start spending money on replacement parts I would like you guys input. Only mods are CS short ram, HPFP internals, and a Hypertech tune.
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andrew_ms3 said:
Hey guys I've been trying to figure out why my AFRs dip to 13.5 and raise to 15.5 during light throttle inputs in 1st-3rd gear. The moments these dips and raises occur are very brief and the AFRs quickly return to 14.7. Part throttle LTFTs are always under +5 and idle LTFTs always under +9 (changes with AC on or off). They don't fluctuate like this while at a constant RPM at higher cruising speeds. I've loosened and retightened boost tubes, CS short ram, and the stock TIP to ensure I have no boost leaks. I have cleaned the MAF sensor numerous times as well as the throttle body. I did notice that there is a knick on one of the O2 sensor wires and was wondering if this was causing my issues? Only other guess I have is that I do not have an air straightener which could be causing the fluctuations. Before I start spending money on replacement parts I would like you guys input. Only mods are CS short ram, HPFP internals, and a Hypertech tune.
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7ec75c8a5ddbb05485b5430b43739a7b.jpg
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It's probably fine and the fluctuations are related to the ECU making changes to timings/fueling based on the pedal. If your primary o2 doesn't change then you have a problem. I would plan on replacing it at some point and put some electrical tape over it to prevent anything from grounding it.

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monkey.bones.007 said:
It's probably fine and the fluctuations are related to the ECU making changes to timings/fueling based on the pedal. If your primary o2 doesn't change then you have a problem. I would plan on replacing it at some point and put some electrical tape over it to prevent anything from grounding it.

crapatalk it sucks for free
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Thanks for that, I'll wrap it up tomorrow with some electrical tape.

Funny enough I ended up throwing a P0113 (IAT sensor high voltage) immediately after starting my car up after retightening everything. I cleared the code and it hasn't popped up again. This completely unrelated?
 
andrew_ms3 said:
Thanks for that, I'll wrap it up tomorrow with some electrical tape.

Funny enough I ended up throwing a P0113 (IAT sensor high voltage) immediately after starting my car up after retightening everything. I cleared the code and it hasn't popped up again. This completely unrelated?
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That's your intake sensor, so not related.

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First rule with oxygen sensors is to replace them if any of the wires going into the sensor are damaged. This is because most oxygen sensors use the wires to supply oxygen to the middle of the sensor which allows the sensor the operate correctly. It is kind of hard to believe, but oxygen does make its way down the wires, underneath the insulation, into the sensor.
 
I also started noticing that the engine is really jerky and not smooth while lightly accelerating and coasting in gear till about 2k RPMs. Could this be related to the O2 sensor?
 
andrew_ms3 said:
I also started noticing that the engine is really jerky and not smooth while lightly accelerating and coasting in gear till about 2k RPMs. Could this be related to the O2 sensor?
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It's likely. The sensor is almost assuredly reading incorrectly, so there's no telling what your actual AFR really is.

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Update: replaced the primary o2 sensor and I'm still having the problem. The car is also now oscillating AFRs at idle from 15.5 - 13.3. I noticed that I don't have an air straightener for my CS intake so could that be it?
 
What's your vacuum at idle look like?

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I doubt it's the air straightener. How long have you been driving it since replacing the O2 sensor? And did you reset the ECU?

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btstarcher said:
I doubt it's the air straightener. How long have you been driving it since replacing the O2 sensor? And did you reset the ECU?

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I've put about 500 miles on the new sensor. No I actually haven't reset it. You do that by unplugging the battery for 20 minutes right?
 
andrew_ms3 said:
I've put about 500 miles on the new sensor. No I actually haven't reset it. You do that by unplugging the battery for 20 minutes right?
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Yes, try it just in case. I'd have thought if that was the only problem the fuel trims would have settled by now.

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andrew_ms3 said:
I've put about 500 miles on the new sensor. No I actually haven't reset it. You do that by unplugging the battery for 20 minutes right?
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Not sure if you are still active here but were you able to solve your issue? I have a similar AFR fluctuation between 13.xx and 15.xx and not sure what's going on. If you found a solution to your issue, I'd appreciate you sharing.
 
bajgainp said:
Not sure if you are still active here but were you able to solve your issue? I have a similar AFR fluctuation between 13.xx and 15.xx and not sure what's going on. If you found a solution to your issue, I'd appreciate you sharing.
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A bit late to the club but running into this exact same issue as you guys. Did anyone here end up finding a solid solution or possible problem that could be causing this. I had just replaced downpipe and full exhaust. Ran pretty good no afr issues till like 50 miles later. Then switched bov cause bov locked up helped a little but still running into 13.xx-15.xx afr after a short pull or occasionaly at idle but evens out after a couple seconds. O2 sensor has no visual damage but will be replacing soon.
 
Start a new thread with the troubleshooting info this one is too old to help
 
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