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Intermittent Misfire at Idle.


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Hello,

 

My R50 Pathfinder (VG33 engine) has an intermittent misfire, mostly at idle. I recently got connected to the ECU and I had a P0325 DTC. Today I installed a new knock senor (relocated), this cleared the P0325 code. However the misfire is still there, coming and going as it feels.

 

My main question here is for anyone who has hooked into the ECU with the Nissan Data Scan software:

I'm noticing a big difference between the LHS and RHS of the engine, O2 sensor and O2_RH sensor and the same with the data in "Injector and Injector RH", is this normal?

 

In the data I've attached the O2 (left) sensor averages 16.0, the RH Sensor averages 86.9. Does this mean that the RHS is burning much less oxygen?

The injector data is LH 4.6 av and RH 3.2 av. The engine was idling (750 RPM).

 

It would be good if someone could send a similar log from their vehicle (preferably  without a misfire) so I can get a baseline of what the data from a happy engine looks like.

 

I am thinking about swapping the O2 sensors over to see if the data follows the sensors. I think the LHS sensor does not affect the engine control, but the RHS does.

Spark plugs & leads have been changed.

 

Any other ideas are welcome.

NDSI20200516_170619.log

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Your data is not what Nissan and most other software gives. 

The sensors are identified as bank 1 or bank 2 sensor 1 to identify which upstream sensor. My scan tool pretty much identifies the right upstream sensor as O2S1B1 with the VG engines. O2S1B1 would be for the left. 

Regardless, the 2 sensors should be giving similar info. 

Injector measurements are in milliseconds and the O2 sensors are usually in millivolt. 

I have no idea what your software is using. 

 

If one bank is off from the other, it is likely a sensor problem, injector problem, a leak on one bank, or possibly a cam off a tooth. 

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I've been working on diagnosing a similar issue with my 3.3L. Sometimes, almost randomly as far as I can tell, after I first start the engine it'll run rough- stumbling like a misfire. Letting it run a bit, or if I just start driving, it'll go away pretty quick and then idle fine. 

 

I haven't yet narrowed it down, but it sounds similar to your issue. I had a knock sensor code, but it went away after I changed out a bad O2 sensor, so the knock code was connected to that thankfully. 

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  • 9 months later...

Same her, I have changed the knock sensor several times, changed injectors, MAF... I woks for a time.. and then.. again... My mechanic said one time, might be the ECU.. i do not know... Still hace knock sensor code...

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