Intake Valve Error Code And Lazy O2 Narrow Band

[30ONA]

So i had a post cat sensor on bank 2 giving very slow readings compared to bank 1. Had both replaced and no changes. Except now i have a bank 2 intake error code P0021 as well. Are they linked? Why has the new sensor not worked? Help please. Next step is to check the intake solenoid resistance and cleanliness. But what if the narrow band sensor?

[sonicii]

Was the O2 sensors triggering a CEL? If not, there probably wasn't anything wrong, all they do is confirm the cat is working. Only the pre-cat WB sensors are used for fuel mix management. Also, each bank is managed separately, so there is no reason to assume the output of each bank's O2 sensors will be in sync, you are better off comparing each bank's WB sensors with the O2 sensor from the same side.

I can't see how the P0021 error could be related to an O2 sensor, but perhaps something was disturbed or not re-connected when the O2 sensors were replaced.

[30ONA]

No CEL before or after. I know how they are supposed to work and I understand they are independent. What I meant was that they vary like the pre-cat ones but should still vary from 0-1V continuously, not stay in one spot as bank 2 is doing. If you look at this graph you can see bank 2 is not working properly. After the new sensors I'm still getting the same reading. So perhaps something else is wrong back towards the engine, or a problem with the connection between the sensor and ECU?

[sonicii]

you didn't attach any graph.. If they are just responding slow, then chances are it isn't a bad connection between the sensor and the ECU. If you can attach the graph you spoke of, perhaps it will make it clearer to understand what you are describing.

[30ONA]

Blue Bank 1

Orange Bank 2

Edited December 30, 2015 by 30ONA

[sonicii]

how does Bank 2 WB vs Bank 2 NB look?

[30ONA]

I'll do it tomorrow. Data wasn't recording WB at the time.

Edited December 30, 2015 by 30ONA

[30ONA]

This morning it thre both P0011 and P0021. So I checked the solenoids according tot he workshop manual and could not produce the DTC's. The colenoids look clean and are at correct resistance. I did check for loose bolts whilst under the hood and the intake clamps on B2 were quite loose at the TB. I've set up the data scan for a more suitable set of co-ords then I'll go for a run. No codes when revving stationary at running temps. Must only happen under load.

[30ONA]

I've attached the graph you requested and a few more. Haven't got the error since tightening the TB pipe and cleaning the air filters. Coincidence? Bank 2 post cat still looks strange to me. For some reason when converting the graphs to JPG they cut the edges off.

Exhaust sensors bank 2 only

Dark blue WB B2

Light blue NB B2

All exhaust sensors

Yellow NB B1

Light blue NB B2

Green WB B1

Dark blue WB B2

Post cat sensors bank 1 vs 2

Yellow NB B1

Blue NB B2

Edited December 31, 2015 by 30ONA

[sonicii]

It is a bit hard to say for sure, but it looks like the B2 WB is also reading higher than the B1 WB? which may mean B2 is running lean, thus the consistently high voltage from the B2 NB sensor.

Could possibly be a airleak in B2 intake, or a bad MAF? if you don't have any luck finding any intake leaks, perhaps try swapping MAFs over and see if the fault appears on B1. Might be worth doing a long term fuel trim reset if you do that too.

[30ONA]

It is a bit hard to say for sure, but it looks like the B2 WB is also reading higher than the B1 WB? which may mean B2 is running lean, thus the consistently high voltage from the B2 NB sensor.

Could possibly be a airleak in B2 intake, or a bad MAF? if you don't have any luck finding any intake leaks, perhaps try swapping MAFs over and see if the fault appears on B1. Might be worth doing a long term fuel trim reset if you do that too.

Yes B2 WB is higher. If I pressurise the intake to look for leaks wat is a safe pressure? 10psi?

I read somewhere once that disconnecting the MAF resulted in a trip to Nissan to fix/reset. I can't remember why.

[sonicii]

I can't see why, unless you try to start the car with the MAF disconnected, but even that should just store a code in the ECU and trigger the CEL, which you should be able to clear without needing a trip to a nissan dealer. But I don't have a VQ35HR powered car, so I can't speak from experience.

I also can't see 10psi causing issues with the intake, but maybe start with less than that and see if you can find anything.

[30ONA]

Here is the two MAF sensors compared. B2 reading slightly lower all of the time. Does lower voltage equates to more or less air/fuel? I've going to swap the MAF sensors and see if all the readings swap over to B1. These online conversion programs do weird things to the pdf file.

Edited January 2, 2016 by 30ONA

[sonicii]

I'm not sure what the output of the MAF sensor represents, maybe just experiment while watching the live output of the MAF while you get on and off the throttle.

[30ONA]

I'm not sure what the output of the MAF sensor represents, maybe just experiment while watching the live output of the MAF while you get on and off the throttle.

Just realised I can't swap them as the B1 sensor has the intake temperature sensor and the ECU won't know what temps to use if the harness only reads from the B1 side.

I really don't know where to go now but I still don't have any codes since cleaning the air filters and tightening the intake pipes. I might leave it alone now.

[30ONA]

P0021 is back.

Bank two tps air flow and wb sensor all higher than bank 1. What is the closed tps voltage supposed to be? I'm summising b2 tps is high.

[sonicii]

Sorry, I am not sure there is too much more I can add. I would expect that each bank would be drawing the same amount of air if all things are equal, but in the real world, one bank could have a clogged filter, or a dirty throttle body which will show up as a difference in airflow. It is a bit hard to say if this is the cause of the problem.

[30ONA]

Sorry, I am not sure there is too much more I can add. I would expect that each bank would be drawing the same amount of air if all things are equal, but in the real world, one bank could have a clogged filter, or a dirty throttle body which will show up as a difference in airflow. It is a bit hard to say if this is the cause of the problem.

I've cleaned the air filters and TB's before taking these readings.

[30ONA]

Intake error codes P0021 & P0022 fixed. Turned out to be a failed oil gallery gasket in the front of the motor. Apparently quite common between 80k-120k miles. Mine was at the upper end of the expected failure time. Gasket $12, Labour and parts for timing kit, $5000.

Basically when the gallery fails the oil pressure plays up blowing oil past the gasket into the timing chain cover. This impacts on the intake and exhaust valve solenoid that are triggered with oil pressure. They chatter because the oil pressure can't be maintained properly.

 

I hope this helps someone in the future with diagnostic as this one had a few people stumped. I found the answer on g35 driver.