Aren't the front sensors A/F ratio sensors and don't oscillate like regular O2 sensors? I know some cars have a trick voltage to show in OBD2 mode when dealing with A/F sensors. I think if I remember right in my 06; I had weird issues trying to interpret the A/F voltages in OBD2. If you want to see if they are oscillating correctly; I would assume you'd look at your Bank 1/2 Sensor 2 voltages to see if there is too much air/fuel in the exhaust.

A Nissan tech told me once to unplug my MAF and check the fuel trims. They should run in a default rich state +25%. If it was a weird number then it could be a vacuum leak. It'll probably cause limp mode and set a bunch of codes though.

I'd try a smoke test to make sure there are no leaks you can't see/hear.

 

Thing is sensor 2 is post cat so it's not a good reference for A/F ratio. I initially thought the front (sensor 1) would be a wideband (which it apparently is on the DE engine), but it's a narrow band so it should cycle as cleric stated. I do see cycling it's just at a much higher voltage than it should be. I'm a bit bamboozled by it right now.

As for using a smoke machine I'd think using MAPP gas and/or TB cleaner (or brake cleaner I would think could work) should show a vacuum leak if there is one.

Correction: the post cat O2 sensor can be used for A/F control, not just cat health. Just did some reading on this online. I'm not sure that is the case here, but it's certainly possible.

 

I pulled the TB's and spark plugs. Plugs look worse than I recall them being when I pulled them for the water pump job. I'll include a link to pics when photobucket gets them uploaded. I also pulled the plenum enough to check the gasket to the intake and it is good. The throttle bodies butterfly angles are the same (looked a bit different but checked with feller gauges and they are equal). I don't see any signs of a vacuum leak on any hoses. I've ordered new plugs to pick up locally tomorrow.

Other questions maybe someone could answer if they have a scanner that gives live data.
What timing does it show at idle?
What is the throttle position?
What is the airflow? Grams/second or lbs/min.

http://s1172.photobucket.com/user/tj...brary/Infiniti

 

If I find time I can run different things on my engine with NDS2 to compare

 

I re-read this and I don't see a BIG wire on the passenger side. There are two on the driver's side that connect to the top of the timing cover. All connections check out. I just installed new plugs and on startup idle came down to 1000rpm after the warm-up high idle. I'll take it on a drive later and do the relearn and see where I'm at.

 

I don't think they switched back to front O2 sensors; I'm pretty sure they switched to A/F sensors starting in 03/04. I have an Autel scanner where I can also purchase Nissan/Infiniti software packages and under OBD2 mode. I saw the following and my car does have to compensate for fuel on side, which I've been aware of:

LTFT1 - +10%
LTFT2 - +3%

Both the voltages in OBD2 mode read .4 or .8 (for the compensating) one, but the fuel trim level is not high enough to set the MIL. Reading the same data under Nissan/Infiniti mode showed a voltage of about 1.5v for the sensors. They should remain pretty constant, which is what I was expecting. For a leak I had a few years ago, I had to make a smoke machine. I tried propane, brake cleaner, etc.. but it was in a spot where it wasn't getting sucked into the system.

For my 06 the specs are:

Idle 650 +- 50 without A/C
Maf - 1 - 6 g/ms at idle; 7-20 g/ms at 2500 RPM
Ignition timing - 15 degrees +- 5 BTDC
Throttle sensor I believe two different sensors form a voltage for how open the throttle plate is.

Did you follow the idle relearn verbatim? All loads have to be off, battery voltage good, steering wheel straight, car at operating temp, and ATF as well if it's an automatic. It took me about 50 times to get the idle fixed after cleaning my TB once. I think another step was to turn it off when it got down to the correct RPM and then right back on again.

Did you try reading your fuel trim data with the MAF unplugged?

Are you sure your car is getting into closed loop mode and the ECT is reading right? There should be options in your scan tool to show the fuel status or something. I don't remember what it's called off the top of my head.

 

Coffey,

I appreciate all your input. I was looking through my most recent data log and a previous one and what I missed before is the throttle absolute position is not consistent. I've uploaded the files in Excel 97/XP format and included charts. When increasing throttle opening and RPM the position is kinda all over the place or not changing at all. The airflow increases linearly as it should. I'm thinking TB's at this point. I'll present this data with a shop in the area and see if they agree (although I'm sure they'll push for doing their own diagnosis). I can get the Hitachi TB's for about $250 each, so not too bad, but obviously I don't want to throw money down the drain. I suppose I could get just the left since the O2 sensor is telling me that bank is a problem.

 

I just tried unplugging the MAF's and it won't even run.

 

Hmm, that's weird it should at least still start up and run rough/rich.

Does your car have a push start button? I've been doing some other reading and apparently the reset method is different for dual throttle cars as well. Also, is your idle surging or does it remain high but steady? Are you getting any codes at all; I would expect at least the 507.

Did you clean the throttle bodies or anything like that or unplug the battery when you disconnected them? Have you tried resetting everything in the ECU. You can hold the positive and negative cables together to after you disconnect them from the battery (some people don't agree to do that). You could also leave the negative unplugged over night to make sure everything drains completely.

Then try the re-learn again, but if it doesn't take you might have to take it to the dealer to see if their Consult tool can get the ECU to accept the correct idle.

 

It started, but was very rough and idle was below 300 rpm. It died pretty quickly.

I have done the relearn according to the FSM procedure. I did a light cleaning of the TB's and unplugged them after disconnecting the battery. During cleaning, which was actually a light cleaning, the butterflies snapped back pretty hard and I'm wondering if that caused a voltage surge from the motor to the electronics that caused them to fail. I have tried resetting the ECU to no avail.

Did you have a look at the data files I uploaded? Seeing the airflow track with rpm while the throttle position doesn't seems to point to the TB's to me. Why there's no code associated with them is a mystery.

I just re-tried the no MAF test, but this time I started the car and ran it for a minute, shut it off, then disconnected the MAF's and restarted. Here's what I got:
1. This time it started and stayed running, but fairly smooth. Wouldn't go above 2400 rpm and STFT for both sensors showed -25%. Naturally it threw codes for the MAF's and intake air temp.
2. Throttle position still showed 2 - 2.4% and never really moved above that.
3. One thing that changed is the O2 sensor voltage. With the A/C on (forgot to turn off at first) both were in the .38v range. Turn off the A/C and bank 1 sensor starts moving around from 0 to ~.5v (IIRC, can't get the file downloaded for some reason) and idle started fluctuating. Once I turn A/C on it settles at .38v. This seems odd. Why only one sensor affected? Also, I would expect that just because the MAF's are disconnected it would still rev higher than 2400. I didn't see what the sensor's were showing at that time, but I'm wondering, if it was compensating with 25% richer fuel (which I could smell by the way) and the TB position is unknown if it's merely bogging at 2400 rpm because it can't enrich anymore because it doesn't know how much to give.

 

Did you do the acclerator pedal reset:

Accelerator Pedal Released Position Learning

DESCRIPTION
Accelerator Pedal Released Position Learning is an operation to learn the fully released position of the accelerator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed each time harness connector of accelerator pedal position sensor or ECM is disconnected.

OPERATION PROCEDURE
Make sure that accelerator pedal is fully released.
Turn ignition switch ON and wait at least 2 seconds .
Turn ignition switch OFF and wait at least 10 seconds .
Turn ignition switch ON and wait at least 2 seconds .
Turn ignition switch OFF and wait at least 10 seconds .

And the throttle valve closed reset

DESCRIPTION
Throttle Valve Closed Position Learning is an operation to learn the fully closed position of the throttle valve by monitoring the throttle position sensor output signal. It must be performed each time harness connector of electric throttle control actuator or ECM is disconnected.

OPERATION PROCEDURE
Make sure that accelerator pedal is fully released.
Turn ignition switch ON.
Turn ignition switch OFF and wait at least 10 seconds . Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.

Do you hear them move when you do the above?

If you have the FSM for your car you might want to read about P2135 or P122. I think there are procedures to check the TPS sensor with a multimeter and at the ECU.

It's possible the cleaning messed them up, because I know they're very sensitive. When I clean them; I press the pedal all the way down, so the car opens it up for me. I cleaned my G once by moving the valve and getting the idle back to normal was a PITA.

Does it change at all when you monitor it with your scanner?

 

See my replies in red below.

Did you do the acclerator pedal reset:

Accelerator Pedal Released Position Learning

DESCRIPTION
Accelerator Pedal Released Position Learning is an operation to learn the fully released position of the accelerator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed each time harness connector of accelerator pedal position sensor or ECM is disconnected.

OPERATION PROCEDURE
Make sure that accelerator pedal is fully released.
Turn ignition switch ON and wait at least 2 seconds .
Turn ignition switch OFF and wait at least 10 seconds .
Turn ignition switch ON and wait at least 2 seconds .
Turn ignition switch OFF and wait at least 10 seconds .This I did not do, at least not the way this is written. What I've done is steps 1 & 2.

And the throttle valve closed reset

DESCRIPTION
Throttle Valve Closed Position Learning is an operation to learn the fully closed position of the throttle valve by monitoring the throttle position sensor output signal. It must be performed each time harness connector of electric throttle control actuator or ECM is disconnected.Done. Several times.

OPERATION PROCEDURE
Make sure that accelerator pedal is fully released.
Turn ignition switch ON.
Turn ignition switch OFF and wait at least 10 seconds . Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.

Do you hear them move when you do the above?Yup. Every time.

If you have the FSM for your car you might want to read about P2135 or P122. I think there are procedures to check the TPS sensor with a multimeter and at the ECU. Looking for these. Don't recall which manual they are in though.

It's possible the cleaning messed them up, because I know they're very sensitive. When I clean them; I press the pedal all the way down, so the car opens it up for me. I cleaned my G once by moving the valve and getting the idle back to normal was a PITA.

Does it change at all when you monitor it with your scanner?At this time it pretty much doesn't until shutdown.

Found the code diagnosis pages.

 

tjrob2000, try this to reset your idle speed:
"I can verify that ITB11-060 " INTAKE AIR VOLUME LEARN WILL NOT COMPLETE" TSB worked for me on my 08 G35x Sport.
I cleaned both throttle bodies while during a spark plug change. I did not disconnect the
throttle bodies or the battery and still got the P0507 code and the 800-900 rpm issue.
After 5-6 tries at going through the:
PERFORM ACCELERATOR PEDAL RELEASED POSITION LEARNING
PERFORM THROTTLE VALVE CLOSED POSITION LEARNING
PERFORM IDLE AIR VOLUME LEARNING
procedures with no luck I found out about ITB11-060. I pulled the passenger side MAF connector and got a P0102 code. I cleared the code using my ScanGauge II, went through
the processes again, still didn't work. I noticed on the ScanGauge that my Throttle Position Setting (TPS) was at 2%. I re-did the entire process again, this time pulling the driver side MAF connector. This time I got a P010C code, cleared it, performed the rest of the procedures, and my idle rpm went down to 700. Let the car sit off for an hour, restarted it and my idle speed was 637rpm as measured by the ScanGauge. And the TPS was at 1%.
I think I might have been too fast with the throttle valve closed position procedure the first time I did the MAF reset. But doing the MAF reset before the other procedures worked and my idle speed is within spec now."

 

Just went through the procedure as outlined in ITB11-060 and Red Shogun's post to no avail. Nothing is working at this point, including shorting the battery cables together.

Red, does your scanner show throttle position changing as you rev the engine? Mine is showing in the 2 - 3% range with no load and not much better on a drive.

 

It really helps if you don't get dyslexic with the steps. I just re-read the idle air volume relearn procedure in the FSM and I was apparently mixing up the last two steps. I was releasing the pedal within 3s, but then waiting 20s before starting the engine. Did it right this time and idle is right at 650rpm and timing is at 15 degrees. Lots of headache for no reason. I also made sure to have 5s during the pedal press/release portion.

8. Fully release the accelerator pedal within 3 seconds after the MIL turned ON.
9. Start engine and let it idle.
10. Wait 20 seconds.

Thanks again for all the input!

Tom