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Discussion Starter · #1 · (Edited)
100,000 Tune-Up Needed - Power/MPG Loss

Hi everyone!

I have a 05 Frontier SE with the V6 / manual and it is just now at 100,000 miles. I am having some power loss and MPG loss and want to do some tune-up work to try and correct it. There is no check engine light on, or any codes that an OBD II picks up.

1. The main issues is a loss of power while accelerating that almost instantly kicks back in around 3,750-4,000 RPM. You can hear it and feel it. I believe this is affecting gas mileage as well, as I used to get over 21 MPG on trips, and now get 18. This is present all the time.

2. In the past, while pulling long hills especially, I have heard a very strange noise that sounds like it is coming from somewhere in the top of the engine compartment. It almost sounds like electricity arcing or a piece of plastic flapping in a strong wind. I believe it was at a lower RPM compared to the power loss. I have not heard this sound in a while. I found a TSB (NTB05015 maybe) that might be related. I believe it was a VIAS valve. Will this cause performance problems? Should I bother fixing it?


I bought this truck used in 2009 with 50,000 miles on it. It has suffered from this power loss before, and although I thought it was fixed, it may still be suffering from when it initially started a few years ago. I don't drive that much so I have not tried to track it down till now.


Maintenance done since I have owned the truck.

New spark plugs a few years ago (trying to fix the power loss, and I thought it did temporarily)

New coil packs last year **From Amazon, not OEM** (trying to fix the power loss, don't think it helped)

A bunch of other non related stuff like (belts, tensioner, idler, fan clutch) new radiator & antifreze, fuel sending unit, etc.


What would you suggest to look at for the above experienced issues, and what else do I need to think about replacing now that it has 100,000 miles and is going on 12 years old?


Thank you all for your help.
 

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Discussion Starter · #2 ·
Initial Investigation (With Pics)

So I am starting at the beginning of the food chain and working my way back.


1. Air filter was cleaned and oiled about 500 miles ago. I have a cold air intake.

2. Mass Air Flow sensor is out, and I am going to buy cleaner tomorrow to clean that.

3. I found the 3" rubber coupler (OEM) that joins the throttle body to the cold air intake tube was cracked a slight bit. Since this is after the MAF sensor, this could be a problem, but i really had to press on it to see the crack so I am not sure how much air would have leaked. Will replace when I put it back together.

4. Throttle body has a little buildup. Does this look abnormal for 100k?





5. I took the intake off so I could get to the spark plugs easier, and look around more. Is a little oil in the intake normal?







6. One of the valves. They all looked fairly similar.





7. Pulled all the spark plugs and they all look the same. These are the NGK Iridium (OEM are Platinum I believe) with ~30k on them.

Cylinder 5 had a little oil laying down where the spark plug seats and I think it came from the top of the spark plug tube.







8. I have two exhaust leaks. I believe one is on the Y tube after the 2nd CAT's and the other is in the muffler. I will check that out when I get a chance.

Deciding what all I should replace on the exhaust system. Without any lights or codes, would it be safe to say the CAT's and O2 sensors are still OK with 100K and 12 years of PA salt on them?
 

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What symptoms would an over-oiled air filter cause?
 

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Discussion Starter · #4 ·
What symptoms would an over-oiled air filter cause?
An over-oiled filter would cause a restriction in airflow across the entire RPM range limiting power and MPG. Its affects would not end abruptly at 3,750 RPM as I am experiencing though (at least I would not expect it to). It would also cause a buildup of air filter oil in the cold air intake and on the MAF sensor, which I did not see when I removed it.

And as for the oil in the intake, it is motor oil, not air filter oil, and is most abundant closest to the engine. It is not present upstream of the throttle body.
 

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classic dirty Mass Air Flow sensor symptoms
 

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I had a "crackling" sound coming through the dashboard. I pulled the code (sorry, do not remember what it was) and it indicated problem with two of the solenoids that have to do with the lifters. Since my truck had over 85,000 miles and I hadn't had an oil change for more than 7,500 miles, I chose to reset the code. It came back some hours later. When engine load is reduced the crackling sound continues for about 30 seconds. On several internet searches I discovered an alternate reason for the problem is due to viscosity of the engine oil. So, I played dumb and had my oil changed. The problem resolved itself within 10 miles of driving and has not returned in almost 2 years.
 

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Discussion Starter · #7 · (Edited)
Mass Air Flow Sensor

classic dirty Mass Air Flow sensor symptoms
Which symptoms of the ones I listed? The power loss that recovers at higher RPM? Any others? I am guessing not the oil in the intake lol. Would this be dirty enough to cause all my problems? The only dirt I can see on it at all is circled in yellow in the second picture. All the elements look clean to me. I will be buying a can of MAF sensor cleaner to spray it down. Also, I plan on needing a new PCV valve once I investigate it. I am guessing that is where the oil is coming from.



 

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The bulletin on the VIAS was for a rattle issue, not a performance issue, if I remember correctly. While the bulletin offers a repair methods, it is for dealers which are purchasing the repair materials in bulk to do a lot of them. For the consumer doing the job himself, it is actually more cost efficient to purchase a new, replacement VIAS than to repair the old one.
The plugs you removed appear to be Nissan Iridium IX plugs. These will work, but they are only a 60,000 mile, economy iridium spark plug. The original plugs, the laser platinums, are actually a better plug as they are a 105,000 mile, double-platinum spark plug. If you want to upgrade from the factory platinums, then you'll want the NGK OE Laser Iridiums, part #93759), which is the original equipment plug in 2008 and later VQ40DE engines and the 5.6L V8. They are rated for 105,000 miles, as well, but will really last to 120,000 miles without issues. To be honest, you are really not going to notice any performance increase or better gas mileage using the iridium plugs as opposed to the laser platinums. I replace the spark plugs without removing the upper plenum. It can be done in about 40 minutes if you have a good assortment of universals and extensions and reducers. You do have to disassemble the #1 coil pack to slip it between the hole in the plenum, but it can be done with a little patience.
That amount of oil in the intake is normal. The build-up on the throttle body is normal. Keep in mind if you clean the throttle body, you may have to relearn the idle air volume.
An over-oiled air filter will cause the hotwire of the MAS to get contaminated, attract dust and cause a false reading, affecting engine management. This is one of the reasons I went with a dry filter when I installed my aFe CAI system. Make sure your intake is actually a cold air intake and not a ram air intake without a heat shield, as this will drastically affect performance by sucking in hot air from the engine compartment.
If you haven't triggered any codes, it is likely your converters and oxygen sensors are fine. The rear sensors are only for monitoring the catalyst efficiency and have no affect on performance, anyway. If you really want to be sure, you can have an exhaust back-pressure test performed.
The front sensors are actually air/fuel ratio sensors, although they look like "regular" oxygen sensors. While they will typically trigger codes when they are not working properly, they can get "lazy" and not trigger a code and can be difficult to assess their performance even with a scan tool. That said, they tend to be expensive and it is best to stick with the OE sensor: NTK.
 

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Discussion Starter · #9 ·
Thanks smj999smj for that information!!

For now, I think I will put the original VIAS valve back in as I have not heard the noise associated with it in a while, and it should not be a performance concern.

Yes, when I put these NGK Iridium IX plugs in a few years ago, I did it without taking the intake off, but wanted to take it off this time to help me investigate for any issues I might not be able to see with it installed. I am just going to clean them up a tiny bit, and run them for another 30K or so.

I am going to clean up the intake & throttle body and install a new PCV valve while I have easy access to it. Thank you for the heads up on the need to relearn the idle air volume. I should only need to do that if it falls outside the idle RPM range correct?


As for the cold-air intake, yes, mine draws air from in front of the radiator core support and inside the fender cavity, not the engine bay.
 

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Discussion Starter · #10 ·
Phase 1 Complete

I put everything back together, and now I just need some drive time to see if anything helped.

Actions taken;

Cleaned MAF sensor
Replaced 3" rubber coupler at throttle body
Cleaned throttle body and intake of oil (relearn idle was needed)
Replaced PCV valve
Lightly cleaned spark plugs and re-installed with anti-seize and dielectric grease


I think I read somewhere that changes to Air/Fuel ratio may take a little while to recalculate as the computer adjusts the long term fuel trim? Is this true, and if so, how long would this take?
 

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The ECM is self-learning, so it is constantly "recalculating" based on driving habits, conditions, etc., so there really is no definitive time answer to your question. FYI, when you do install new spark plugs eventually, NGK actually recommends NOT using anything on the threads (like anti-seize).
 

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Discussion Starter · #12 ·
The ECM is self-learning, so it is constantly "recalculating" based on driving habits, conditions, etc., so there really is no definitive time answer to your question. FYI, when you do install new spark plugs eventually, NGK actually recommends NOT using anything on the threads (like anti-seize).
I did not know that about NGK, thank you for that info.

I found a really good website about air/fuel ratios, how the short term and long term trims work, and what to look for if you have high trim values. It is very in depth, and well written.

Fuel trim: How it works and how to make it work for you

After reading that article, I decided to break down and finally buy an OBD II scanner.

BAFX Products 34t5 Bluetooth OBDII Scan Tool for Android Devices


Anyone ever use this scanner on a Frontier with the Torque app for Android? It should be here next week, and I will continue my investigation if things are still not completely fixed.
 

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I have that scanner and app. I have used it on my Frontier, I run it almost daily on my 98 cavalier beater car (200k mile car, I use it to keep close tabs on vitals) and ran it a few times on my wife's 08 Ford Fusion. It is a great combo. Though, it doesn't read all codes the Frontier may have stored (mine didn't show stored codes for steering angle sensor and rear diff lock) but works great for the average Joe needing to read/clear a code here and there.
 

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Discussion Starter · #14 ·
First day with the OBD II scanner

Here are some screenshots from the Torque app after a quick drive to the gas station today. My initial reaction to the app and scanner are mixed, but I may just need to learn how to use it. I did not see Long-Term Fuel Trim as an option in the app (SAD). I also only had Short-Term Fuel Trim for bank 1, although it was exactly the same as Fuel Trim O2 Sensor 1 Bank 1, and I did have one of those for each bank.

Remember, these are from the first real drive after the fixes I have completed, so I think it is still learning the new "normal".

1. Sitting at a stop sign engine warm. Notice O2 1x1 is reading 0.3 and O2 2x1 is reading 0.6? This has been like that since I first plugged the scanner in before starting the engine. They do change, but that is the normal resting point.




2. This is while driving, just after a shift. Notice the rear O2 1x2 abrupt change while shifting gears.




3. Immediately after I pulled into my garage and left it idle. I was seeing negative fuel trims on my entire trip (except while accelerating), but this was the only time they were at -25%.




4. Revving the engine while parked in my garage. Both wide-band O2 sensors are reacting (although not in sync with each other). Notice the reactions in the after CAT O2 sensors as well.




5. Idling in the garage trying to get everything to level out to steady state. STFT leveled out at -25% again, and the front O2 sensors are still reading different from each other by about the same amount. Notice the one rear after CAT O2 sensor randomly changing from 0.7 to 0.1 without changes to the rest of the system.




Do any of these values or reactions look bad? I hope the LTFT (which I can not see) is +% based on the dirty MAF sensor and the possible leak in front of the throttle body. This would push STFT negative now that those are fixed until the LTFT comes down a bit. Sound reasonable?

I will do some more driving this week and will get additional screenshots after 50 miles or so.
 

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Discussion Starter · #15 ·
Short Drive Update - Cross Country Drive Pending

I may have a 2400 mile cross country drive coming up, pulling my Seadoo, 4-wheeler in the bed, loaded cab and all, and I want to make sure things are OK.

I have only taken my truck on one long drive since my last update. The good news was, all the short-term fuel trim numbers were much better +/- 10 was the range I was most commonly seeing.

The front O2 sensors are still reading 0.3 and 0.6 volts. Should I replace these before such a long journey?

The rear O2 sensors are still jumping all over the place, like 0-1 volt and covering the entire graph in Torque. I do have 1 or 2 exhaust leaks, and one might be close enough to the rear O2 sensors to cause it to read incorrectly.


Question: If you had a 05 Frontier with 100,000 miles on, a slight exhaust leak, and the O2 readings I am seeing, would you replace some stuff before the journey, or just drive it? I know I need a new exhaust system soon (cat back at minimum). I am trying to decide if I need to replace more, like O2's and Cat's as well.

I am going to schedule differential, transfer case, and transmission fluid changes before the trip for sure.

Thanks.
 

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Discussion Starter · #16 ·
O2 Sensor Questions

I have that scanner and app. I have used it on my Frontier, I run it almost daily on my 98 cavalier beater car (200k mile car, I use it to keep close tabs on vitals) and ran it a few times on my wife's 08 Ford Fusion. It is a great combo. Though, it doesn't read all codes the Frontier may have stored (mine didn't show stored codes for steering angle sensor and rear diff lock) but works great for the average Joe needing to read/clear a code here and there.
shizzy, have you ever used the Torque App to look at the O2 sensors on the Frontier? I know the first ones are wide-band O2 sensors that don't just read simple 0.1-0.9 V readings. I am guessing that in 2005 they were just converting them to look like a normal reading for display with OBD II readers.

Since these are in front of the CATs, there should be nothing causing them to read different (0.3 vs 0.6) right? I can get new Bosch wide-band O2 sensors for around $60 but don't want to replace them if I am not 100% sure those readings are suspect.

As for the secondary O2 readings, with them bouncing around, that is telling me the CATs are possibly not working properly. Is it worth the money to replace those O2 sensors and possibly 2 or even all 4 CATs?


Thanks
 

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Discussion Starter · #19 ·
Replace the b2s1 and when you do the cat back change the b1s2
Thank you for the reply. Are you suggesting to change B2S1 because it is reading 0.6 when B1S1 is reading 0.3?

I found a very good post just this morning What are Your OBDII O2 Sensor Voltage Readings? that seems to suggest everyone with older Nissans and OBD II scanners see 0.3 and 0.6 as the normal. This is confusing lol.

As for replacing B1S2 and not B2S2, any additional info?

Thanks!
 

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The random jumps to me are a sign of a failing sensor. Unless you have a decent leak pre cat i would not worry about it. yes the second sensor on either side is just a check to ensure the cat is functioning
 
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