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Frontier Nissan Frontier/HB/Truck Discussion Forum

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Old 01-09-2018, 11:46 AM
Mr.L Mr.L is offline
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Default Fuel control feedback question

Greetings,


Mine is a 2006 Frontier, 4L, I've owned about 18 months. Both CATs were changed when I bought the truck. According to my wonderful BlueDriver Christmas present there are no codes, pending or otherwise. The truck runs very well and aside from an annoying deep vibration (about 60 Hz) that sets in when the idle drops below about 600 rpm, which it does on occasion, I've no complaints.


My concern probably stems from having too much information from the BlueDriver. When I use the Live option and monitor Fuel System Status, I get the result: System A: closed loop, using all oxygen sensors... and System B: open loop - has yet to satisfy conditions to go to closed loop (Bank 1, or both).


Questions: 1) just what is System A, and System B? I can't find the answer to this despite some considerable effort. 2) If part of the fuel system is not going to the desired closed loop condition, then shouldn't there be a code and shouldn't the BlueDriver say the will truck fail smog, which it does not say. In fact, it says the truck is ready for smog check.


I did check the O2 sensor #1 for each bank and for bank 1 the O2 sensor has a very different (lazy) pattern than that on bank 2. I have no records that the sensors have ever been changed so I'm considering just changing them anyway...at least the upstream sensors. Sensor #2 on each bank seem fine.


Thanks for any insight anyone can offer on this. And if anyone is in the market for a really good OBD reader, the BlueDriver is a pleasure to use.


Leon
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  #2  
Old 01-09-2018, 08:22 PM
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smj999smj smj999smj is offline
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Default

I can't answer your question about "System A or B," but maybe the tech support of your particular scan tool can. I've never seen that reference on a Nissan CONSULT scan tool that I can remember.
Vibration at idle is common for the VQ40DE engine. There were some issues with bad motor mounts in the early years of this engine and addressed in a TSB. Most of the time it's just the idle going too low that caused it. A capable scan tool or tuner (like Superchips Flashpaq) can tweak the base idle and allow one to raise it a little, which helps some.
The sensor in the front are "technically" not oxygen sensors (like in the rear), but are air/fuel ratio sensors. They work a little differently than oxygen sensors and operate in a much narrower range. If there is no code triggering for them and the engine is running okay, they are probably just fine. They are also not cheap, either! If you do decide to change them, stick with NTK or Denso brand.
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Old 01-12-2018, 11:20 AM
Mr.L Mr.L is offline
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Thanks for your response! I think you are right regarding use of the term “system” in that I’ll have to contact BlueDriver to figure out what “System A” and “System B” refer to and frankly I wouldn’t have given it a second thought had System B not failed to reach Closed Loop status. My first thought was that A and B referred to bank A and B but then I should have had a code. I’ll contact BlueDriver when I get home and to reliable internet. (In a Starbucks in Puerto Vallarta now.)

Your comment regarding the idle-vibration connection is right on. As I monitor rpm with the BlueDriver, the vibration sets in when idle drops below about 600 rpm. In an effort to address this I removed and cleaned the tps, which was quite carboned up downstream. My efforts had no effect other than to teach me to use a stop watch when going through the interesting sequence of pedal pushing and key turning required to reset it. I will look into the Superchips suggestion, or just live with it. Frankly, I miss the days when I could just give the idle stop screw a quarter turn to achieve the same result.

Finally, regarding the “02” sensors. My concern w bank 1 sensor stems from the live plot of it vs that of the bank 2 sensor. At idle, for example, bank 2’s live plot shows a very symmetric high frequency sin(ish) wave, and when I rap the throttle it responds immediately high amplitude positive pulse. Bank 1’s plot, at idle, produces very small seemingly random square-(ish) waves, and when I rap throttle it responds in roughly the same way bank 2 did, but at much smaller amplitude. What I will do when I get home is switch the sensors and check the live outputs. If I change one I will stick with NTK or DENSO. I’ll avoid Bosch with which I’ve had issues in the past, even though it is half the cost.
Thanks again for your comments! I will post here my findings as well.
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Old 01-31-2018, 06:29 PM
Mr.L Mr.L is offline
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Default followup and final outcome

First of all, while I still really like the Blue Driver code reader, the "available any time" for questions, by email or chat, is hype. So I still don't know what the System A, System B reference means.


Regarding the O2 (a/f ratio) sensors, as I mentioned, the bank 1 sensor was "lazy", meaning that when watching the live waveform and periodically rapping the throttle (about +-/500 rpm, about 1/second), bank one sensor would respond with about 1/3 the amplitude, and quite rounded waveforms, compared with bank 2 which had sharp immediate peaks clearly synchronized with the rpm. I removed and switched them, installing 1 in 2 and 2 in 1. When I viewed the waveform again, both responded identically and like 2 did originally! Conclusion: dirty contacts for the bank 1 connector. I then cleaned both connectors and put everything back together. The truck runs noticeably smoother and, surprisingly, the rough idle issue is noticeably better.
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