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Discussion Starter #21
hm.... thats interesting yes check the wiring harness for the throttle body and the pedal postion switches very well, you might have something wrong with the bcm or ecm
I cleaned the throttle body, changed the PCV valve, both cam sensors, and crank sensor. The aforementioned codes did not come back up and I only have the generic P0300 code since. As far as the rough noise, it probably wouldn't come out on video/audio that well. It vibrates more than it is loud but it does both at a level above normal. I suppose one could compare it to how it would run with a misfire. I haven't ruled out the coil packs being defective since I paid $52 for all six. What I want to do is look at the live data stream for the O2 sensors, STFT, LTFT, as well as check the coil packs and injectors (for sporadic firing). The problem now is that my CE light will start flashing within 60-90 seconds of startup. I was able to get to a CL (closed loop) and saw I was -17 for STFT1 and 22 for STFT2. That makes me think I'm running rich on bank 1 (where I found #3 plug with black soot/grime after only 2k miles) and lean on bank 2. The frustrating part is my hands are sort of tied because I don't want to run the engine when the CE light is flashing so I can't do some of these other checks I would like to do.

Oh yeah, could be coincidental but I did lose power to my stereo the other day. Also, I have had an issue where the car won't start/turn over every once in a while on the first attempt (nothing happens) but starts fine on the second attempt. I've never given it a second thought simply because the plastic part on both my keys is cracked and glued back together so I figured maybe the chip was out of alignment? Anyway, my year (2007) isn't affected by the IPDM recall but perhaps the ECM could be tied in? My readings for STFT are from this morning but points at multiple issues so not really sure where to go from here.

What I would like to do:
1 Check coil pack resistance & unplug each to ensure they're functioning
2 Check resistance and voltage of fuel injectors and listen for rhythmic clicking (vs. sporadic)
3 Run smoke through the system to detect leaks
4 Verify via live data stream if cats are functioning or disconnect cat(s) and/or exhaust for possible clogs

I don't want to run the engine while the CE light is flashing so I wouldn't be able to test since it happens within 90 seconds of startup. Would you all agree that because I am already in a fault code, I shouldn't run the engine once it begins flashing?

Oh yeah, I've now got all my parts for the timing chain guide fix. This latest diagnostic reading makes me think that it can't be a timing issue if one bank is rich and the other bank is lean.
 

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I cleaned the throttle body, changed the PCV valve, both cam sensors, and crank sensor. The aforementioned codes did not come back up and I only have the generic P0300 code since. As far as the rough noise, it probably wouldn't come out on video/audio that well. It vibrates more than it is loud but it does both at a level above normal. I suppose one could compare it to how it would run with a misfire. I haven't ruled out the coil packs being defective since I paid $52 for all six. What I want to do is look at the live data stream for the O2 sensors, STFT, LTFT, as well as check the coil packs and injectors (for sporadic firing). The problem now is that my CE light will start flashing within 60-90 seconds of startup. I was able to get to a CL (closed loop) and saw I was -17 for STFT1 and 22 for STFT2. That makes me think I'm running rich on bank 1 (where I found #3 plug with black soot/grime after only 2k miles) and lean on bank 2. The frustrating part is my hands are sort of tied because I don't want to run the engine when the CE light is flashing so I can't do some of these other checks I would like to do.

Oh yeah, could be coincidental but I did lose power to my stereo the other day. Also, I have had an issue where the car won't start/turn over every once in a while on the first attempt (nothing happens) but starts fine on the second attempt. I've never given it a second thought simply because the plastic part on both my keys is cracked and glued back together so I figured maybe the chip was out of alignment? Anyway, my year (2007) isn't affected by the IPDM recall but perhaps the ECM could be tied in? My readings for STFT are from this morning but points at multiple issues so not really sure where to go from here.

What I would like to do:
1 Check coil pack resistance & unplug each to ensure they're functioning
2 Check resistance and voltage of fuel injectors and listen for rhythmic clicking (vs. sporadic)
3 Run smoke through the system to detect leaks
4 Verify via live data stream if cats are functioning or disconnect cat(s) and/or exhaust for possible clogs

I don't want to run the engine while the CE light is flashing so I wouldn't be able to test since it happens within 90 seconds of startup. Would you all agree that because I am already in a fault code, I shouldn't run the engine once it begins flashing?

Oh yeah, I've now got all my parts for the timing chain guide fix. This latest diagnostic reading makes me think that it can't be a timing issue if one bank is rich and the other bank is lean.
i'd swing er by a dealer and have the bcm tested, its a module that controls a ton of the electrical stuff it really is starting to sound more and more like you have either some rubbed bare wires crossing or a bcm failing slowly on you.
 

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Discussion Starter #25
I cleaned the throttle body, changed the PCV valve, both cam sensors, and crank sensor. The aforementioned codes did not come back up and I only have the generic P0300 code since. As far as the rough noise, it probably wouldn't come out on video/audio that well. It vibrates more than it is loud but it does both at a level above normal. I suppose one could compare it to how it would run with a misfire. I haven't ruled out the coil packs being defective since I paid $52 for all six. What I want to do is look at the live data stream for the O2 sensors, STFT, LTFT, as well as check the coil packs and injectors (for sporadic firing). The problem now is that my CE light will start flashing within 60-90 seconds of startup. I was able to get to a CL (closed loop) and saw I was -17 for STFT1 and 22 for STFT2. That makes me think I'm running rich on bank 1 (where I found #3 plug with black soot/grime after only 2k miles) and lean on bank 2. The frustrating part is my hands are sort of tied because I don't want to run the engine when the CE light is flashing so I can't do some of these other checks I would like to do.

Oh yeah, could be coincidental but I did lose power to my stereo the other day. Also, I have had an issue where the car won't start/turn over every once in a while on the first attempt (nothing happens) but starts fine on the second attempt. I've never given it a second thought simply because the plastic part on both my keys is cracked and glued back together so I figured maybe the chip was out of alignment? Anyway, my year (2007) isn't affected by the IPDM recall but perhaps the ECM could be tied in? My readings for STFT are from this morning but points at multiple issues so not really sure where to go from here.

What I would like to do:
1 Check coil pack resistance & unplug each to ensure they're functioning
2 Check resistance and voltage of fuel injectors and listen for rhythmic clicking (vs. sporadic)
3 Run smoke through the system to detect leaks
4 Verify via live data stream if cats are functioning or disconnect cat(s) and/or exhaust for possible clogs

I don't want to run the engine while the CE light is flashing so I wouldn't be able to test since it happens within 90 seconds of startup. Would you all agree that because I am already in a fault code, I shouldn't run the engine once it begins flashing?

Oh yeah, I've now got all my parts for the timing chain guide fix. This latest diagnostic reading makes me think that it can't be a timing issue if one bank is rich and the other bank is lean.
i'd swing er by a dealer and have the bcm tested, its a module that controls a ton of the electrical stuff it really is starting to sound more and more like you have either some rubbed bare wires crossing or a bcm failing slowly on you.
Thanks again for the suggestions. Yeah, I did a thorough inspection of the wires again today. I did find the tab that locks the crank sensor connector had broken and the connector easily slides off. That did seem to affect the rich condition of bank 1 and it is now within specs but bank 2 is still running lean 22%, CE light still flashing, and white smoke is now steady out of the exhaust with strong fumes. Did find a pinhole at the back, bottom edge of the muffler where water is dripping out but no other leaks could be seen.

The horn hasn’t worked since I’ve owned the vehicle. The remote alarm chirps used to work but that also stopped working a few months ago. The steering wheel controls (stereo, cruise control) don’t work but that’s because it wasn’t rewired after replacement of factory stereo. (I did replace the clock spring because there were other issues — airbag light, but it didn’t help.) Outside of the ignition key not starting sometimes,I don’t see how the BCM could cause my engine issues? My understanding is it controls most of the interior motor control functions only (locks, lights, wipers, etc.). That being said, I am not ruling out the ECM or a short somewhere in the system. Once the engine cools down? I am going to try and deal with the crank sensor connector and will disconnect and reconnect the connectors I can reach, while inspecting the wiring further.

This is honestly one of the most frustrating experiences. The CE light still flashes within 90 seconds of initial startup and sooner on subsequent starts. How do I troubleshoot when I can’t even run the engine for longer than a minute or two?
 

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Discussion Starter #26
Okay, replaced the downstream O2 sensor bank 2 (already had it so figured why not). It did start up and run normally for a few seconds. I almost got excited but it started idling rough again and the light started flashing immediately. Did notice a broken ground strap from the heat shield to the exhaust just downstream from the O2 sensor. Also, correction on the bank 1 running rich being fixed. That apparently was just the one time and I had to shut off the engine due to the flashing light. It is back to running -17%.

I flexed the wire bundles going to the BCM and a couple of other wires under the steering column. My stereo is now working again. Of course, my main issue is still unresolved.
 

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Okay, replaced the downstream O2 sensor bank 2 (already had it so figured why not). It did start up and run normally for a few seconds. I almost got excited but it started idling rough again and the light started flashing immediately. Did notice a broken ground strap from the heat shield to the exhaust just downstream from the O2 sensor. Also, correction on the bank 1 running rich being fixed. That apparently was just the one time and I had to shut off the engine due to the flashing light. It is back to running -17%.

I flexed the wire bundles going to the BCM and a couple of other wires under the steering column. My stereo is now working again. Of course, my main issue is still unresolved.
man, i can see why this is getting frustrating if you were anywhere near fort worth, texas i'd say swing er by and lets take a look or i could come by after work, but doubt you are. this really is sounding like it will need some major shop time to find the source, looks like we have many small things snowballing into huge issues guessing you bought the truck 2nd or 3rd ahnd and arent the orginial owner and likely have no full repair records right?
 

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Discussion Starter #28
man, i can see why this is getting frustrating if you were anywhere near fort worth, texas i'd say swing er by and lets take a look or i could come by after work, but doubt you are. this really is sounding like it will need some major shop time to find the source, looks like we have many small things snowballing into huge issues guessing you bought the truck 2nd or 3rd ahnd and arent the orginial owner and likely have no full repair records right?
Yeah, I bought it from the original owner and he did take great care of it. Until this issue, all the fluids were in great shape, it's undercoated, skid plated, etc. Even the plugs had ideal wear on them when I changed them 2k miles ago.

I appreciated the thought but yeah, I'm in Hawaii. Do you know about the throttle body? The plate on mine doesn't shut all the way and sits on a slight angle. As far as I am aware, it should shut completely? I read in the FSM that in failsafe mode, it will stay open at 5 degrees. (Mine is more than 5 degrees but it isn't shut and that's what puzzles me.)
74997
74998
 

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Discussion Starter #29
I ended up swapping the coil packs between banks 1 & 2 and the ports for bank 1 show carbon fouling. Interesting thing is all 6 plugs also showed (dry) carbon fouling and some smelled of fuel. (I thought bank 2 wouldn't since it was running lean.) This has all happened with zero miles since I last checked the plugs due to this issue. So a dozen or so startups and idling. Oh yeah, the CE light will now flash with KOEO. It will flash five times then go solid.
 

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Okay, replaced the downstream O2 sensor bank 2 (already had it so figured why not). It did start up and run normally for a few seconds. I almost got excited but it started idling rough again and the light started flashing immediately. Did notice a broken ground strap from the heat shield to the exhaust just downstream from the O2 sensor. .....
My intuition: Folks often switch out A/F ratio sensors and O2 sensors when the real culprit is a poor or broken ground connection. I believe one or two clubXTERRA.org members made this point years ago.

There are two ground straps that connect to the exhaust pipes. Reconnect both. Use small alligator clips if bolts are seized.

Given the miles driven and the difficulties experienced, I would check the ground connections in the engine bay under the battery on the passenger side and under the air filter box on the driver side. Make sure they are clean, well seated, and if you remove, perhaps add a small dab of dialectic grease before reinstalling. If nothing else the grease will help keep out moisture and dust.

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Looks can be deceiving but your air throttle body intake valve still looks dirty.

If you have it still out, perhaps using some brake cleaner and a soft tooth brush might be an idea. If back in, continue cleaning with designated air throttle body cleaner but let it sit a while before reassembling so the cleaner can fully dissipate.

In passing, I have never bothered to clean the MAF sensor on the old pathfinder WD-21 or our 2nd gen Xterra. But I have often cleaned the air throttle body and butterfly valve. Especially on the old pathie because, in hindsight, I probably did not clean and maintain the emissions system (e.g., PCV valve) as I could have or should have.
 
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Kind of insane the amount of trouble you’ve been having with this. I’ll tell you it sounds to me more like skipped timing. Throttle body will not cause P0300. Rear o2 will not cause it either. Front A/F sensors can cause mixture imbalance and cause misfire. Cam and crank sensors are very unlikely too. Damaged tone wheel on flywheel could be but more than likely is just fine. You could perform a compression test and verify even numbers but if you install new chains and guides and it still runs the same I’d say you need to take it to the dealer. I’d bring any and all of your old coils and other parts with you.
 

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Discussion Starter #32
My intuition: Folks often switch out A/F ratio sensors and O2 sensors when the real culprit is a poor or broken ground connection. I believe one or two clubXTERRA.org members made this point years ago.

There are two ground straps that connect to the exhaust pipes. Reconnect both. Use small alligator clips if bolts are seized.

Given the miles driven and the difficulties experienced, I would check the ground connections in the engine bay under the battery on the passenger side and under the air filter box on the driver side. Make sure they are clean, well seated, and if you remove, perhaps add a small dab of dialectic grease before reinstalling. If nothing else the grease will help keep out moisture and dust.

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Looks can be deceiving but your air throttle body intake valve still looks dirty.

If you have it still out, perhaps using some brake cleaner and a soft tooth brush might be an idea. If back in, continue cleaning with designated air throttle body cleaner but let it sit a while before reassembling so the cleaner can fully dissipate.

In passing, I have never bothered to clean the MAF sensor on the old pathfinder WD-21 or our 2nd gen Xterra. But I have often cleaned the air throttle body and butterfly valve. Especially on the old pathie because, in hindsight, I probably did not clean and maintain the emissions system (e.g., PCV valve) as I could have or should have.
I was planning to replace the broken ground strap. I’ll look for the other one and verify it is good. I was just reading about the three ground straps under battery and air filter box and will check those as well.

Yes, the throttle body is still dirty. I am planning to clean it up as I still have it out. The STFT1 was -17 and STFT2 was 22. This is the part that is making me second guess. Logic dictates that fuel pump, regulator, MAF, throttle body couldn’t cause opposing conditions so there must be two separate issues or an issue with the IPDM possibly? Anyway, I’ll start with the things that don’t require me to run the engine.
 

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Discussion Starter #33
Kind of insane the amount of trouble you’ve been having with this. I’ll tell you it sounds to me more like skipped timing. Throttle body will not cause P0300. Rear o2 will not cause it either. Front A/F sensors can cause mixture imbalance and cause misfire. Cam and crank sensors are very unlikely too. Damaged tone wheel on flywheel could be but more than likely is just fine. You could perform a compression test and verify even numbers but if you install new chains and guides and it still runs the same I’d say you need to take it to the dealer. I’d bring any and all of your old coils and other parts with you.
I changed the sensors and VVT due to my initial code P0021 & P0300. (P0021 went away after I filled, then changed the oil but replaced parts anyway.)

I did a compression test and the readings were between 155-168, so within the 14psi tolerance. I pretty much have all the parts for the timing chain guide fix but it’s been a tough call because I don’t want to go through that if there’s an issue with the engine but seeing how this could be an issue kind of necessitates me doing so.

I’ve also thought about the IPDM. The horn and cruise control don’t work (and I’ve already replaced the clock spring). I’ve lost power to the stereo a couple times and currently, the CE light will flash with KOEO. I’m just tired of replacing parts that aren’t known to be bad.

I’ve been weary of the dealer because I’m dreading the dealer parts (and prices) of replacing things that may not fix this issue. Having said that, I’m just about there.
 

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The engine light will flash with the engine off if the codes have been cleared and the SRT tests haven’t run yet. The dealer knows things like this. Don’t buy an IPDM, it won’t help. At the dealer, we don’t use OBD values of STFT or LTFT. We use A/F alpha which is a live reading of exactly how much fuel the engine needs compared to a calibrated value. Despite the compression looking good, the first thing I would check would be the intake timing values for both banks. Those tell us how synced the computer sees the cams and crank. Many OBD values don’t even show up on our scanner and many things that do show up, I’ve never seen on an OBD scanner. Just to say, the prices may seem unfair but you’d probably be less invested if you went to the dealer in the first place and it’s not a level playing field between what we do and what others can.
 

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If timing were ok, I’d check A/F sensor values while running. These can fail and skew A/F alpha one direction.

I’ve also seen many aftermarket coils not work properly out of the box. You could be causing more problems by installing substandard parts.
 

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Discussion Starter #36
If timing were ok, I’d check A/F sensor values while running. These can fail and skew A/F alpha one direction.

I’ve also seen many aftermarket coils not work properly out of the box. You could be causing more problems by installing substandard parts.
I considered the coils as being bad as well. In fact, I’ve been second guessing almost everything.
Below is the reading with a little throttle (CE started flashing so I didn’t want to rev too much.)
75001
75002
75003
 

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Discussion Starter #38
The engine light will flash with the engine off if the codes have been cleared and the SRT tests haven’t run yet. The dealer knows things like this. Don’t buy an IPDM, it won’t help. At the dealer, we don’t use OBD values of STFT or LTFT. We use A/F alpha which is a live reading of exactly how much fuel the engine needs compared to a calibrated value. Despite the compression looking good, the first thing I would check would be the intake timing values for both banks. Those tell us how synced the computer sees the cams and crank. Many OBD values don’t even show up on our scanner and many things that do show up, I’ve never seen on an OBD scanner. Just to say, the prices may seem unfair but you’d probably be less invested if you went to the dealer in the first place and it’s not a level playing field between what we do and what others can.
I hear ya. I’m not trying to slam the dealers. Some of the posts on these forums talk about how the dealers replaced various parts and the issue isn’t resolved. I realize these may be outliers but once I started down the path of trying something easy, it snowballed.

We only have two Nissan dealers on our island and they’re owned by the same family. Their service department (at least, near me) doesn’t have the best reputation if you’re not a loyal buyer/owner that regularly gets their vehicle serviced there. There have even been claims that their surcharge on parts is higher than at other Nissan dealers. Anyway, not that you’re interested or any of this matters, but that is part of the reason why I’ve stayed away from them so far.
I’m at a loss now so I think that’s what I’ll need to do.
 

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Well part of the reason I don’t trust generic scanners, is sometimes they use “computed values”. When OBD was written, o2 sensors read from 0-1 volt. Your car is equipped with air fuel sensors that should run at 2.2v when running properly. If your O2B1S1 and O2B2S1 values were correct, it probably wouldn’t even run. I really wish we could see what the intake timing values are when running. Some better scanners may be able to provide this value. Nissan calls it INT/V TIM(B1) or B2. Your handheld probably doesn’t read that value.
 

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Discussion Starter #40
Well part of the reason I don’t trust generic scanners, is sometimes they use “computed values”. When OBD was written, o2 sensors read from 0-1 volt. Your car is equipped with air fuel sensors that should run at 2.2v when running properly. If your O2B1S1 and O2B2S1 values were correct, it probably wouldn’t even run. I really wish we could see what the intake timing values are when running. Some better scanners may be able to provide this value. Nissan calls it INT/V TIM(B1) or B2. Your handheld probably doesn’t read that value.
No, it doesn’t show that value.
 
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