Pathfinder w/ intermittent power

[corygrant85]

I am new to the forum. I have been reading about all of the regular causes of my problem for some time now and none fit. I have a good friend who is a Nissan tech and he is upset because he cannot figure out the problem.

The problem is as follows; last winter (february 2013) my truck would start fine but have very little power (barely able to do 115km/h). At this point in time it was VERY cold (-35 C) and the truck would stay like this all day. When it warmed up a little bit (-20 C) The truck would have full power by about 30km into a highway drive. I drove it like this all winter.

Come summer, one day the truck just stopped "warming up" and now has no power at any point, except for the odd time that has no rhyme or reason. I have put on maybe 2000km like this (I drive for work, can't help it) and about 100km of those it has had "normal" levels of power.

Now the fun part, some of you are going to say "MAF", or "Clogged Pre Cats" . None of the above. The truck has been gone over by a Nissan technician who is not trying to screw me, and the fuel system, exhaust (all 4 cats), electrical and sensors all are checking out and running normally.

I did replace a passenger side cam angle solenoid at his advice because it was not running in sync with the drivers side bank. The truck had a new MAF 2 years ago and I have picked up a spare and neither makes a difference. The truck throws NO codes. Nissan Tech line told my friend its "tired" but thats not the case. Especially with perfect oil pressure, no burned oil (10W30 synth) and only 199000km on the clock.

I have not had the upper intake plenum off yet, but the power valves seem to open and close (by hand) just fine. I've even pinned them wide open and tried but no difference. Judging by the fact that it doesnt burn oil it likely hasnt thrown screws out of the power valves. It has a light ticking only on startup (within spec according to nissan), and does have a pre-ignition sound once hot.

Help!

[Towncivilian]

R50 Pathfinders don't have four cats (even in California), nor do they have pre-cats.

The power valves closing and opening by hand would not indicate if any power valve screws have been ingested. Excessive oil consumption is not the only symptom of power valve screw ingestion, either.

Have you tried changing the fuel filter? Cleaned the throttle body? Were spark plugs replaced around 186k KM?

So the engine does not warm up in a reasonable amount of time? Inspect the radiator cap according to this TSB. Has the coolant ever been serviced?

In very cold weather, 5W-30 or 0W-30 oils will have much better flow over 10W-30 with its mediocre viscosity index due to relative lack of viscosity index improvers.

What is the manufacturing date of your Pathfinder? This can be found on the driver door jamb sticker.

Welcome to NICO.

[corygrant85]

Thanks for the response and welcome,

This is a 3.5L and yes it has 2 Pre-cats and 2 regular cats, as equipped from the factory- not sure if it makes a difference but it is a Canadian truck. Fuel filter has been changed and I don't think the spark plugs have been. Maybe I will take a peak at (the easiest to access) one of those. The engine warms up just fine, what I meant by that was it had no power when cold, and it seemed once it got hot it would work fine. It now just runs like crap all of the time. Temperature is steady at about 89 degrees C to maybe 91 C in traffic.

Still gets about the same fuel economy too as it should

I will correct myself and note that in the winter the truck does run 5W-20 I believe (or 30...not sure my friend did the winter oil changes...whatever is recommended) and I switched to 10W-30 in the summer because I drive it pretty hard, and I now recall that it DOES burn a small amount of oil when running 5W. Its been awhile I had forgotten this. I'm talking like 0.5 litres over 6000km or so.

[corygrant85]

Build date of the truck is December 2000, built in Japan.

Spark plugs look very good.

[Towncivilian]

5W-20 is not specified or suitable for our engine. You can use 5W-30 or 0W-30 year round, there is no reason to use 10W-30. It's something of an obsolete grade. It will be thicker at startup but within the same viscosity range at operating temperature. That amount of oil consumption is inconsequential.

Spark plugs are specified for a 186k KM replacement interval. Did you check all of them? Perhaps it would be worth a shot to replace them regardless.

Does the "service engine soon" light illuminate when you turn the ignition to "ON"? The bulb might be dead (mine burnt out once).

You have a 2001.5 Pathfinder with the revised coil packs. Coil pack issues should be less prevalent; I've not had any with my 10/00 build date Pathfinder with 144k miles so far.

Could you provide your VIN? I was not aware that *any* Pathfinder model had more than two cats (which are easily found more or less under the front seats on the underside of the vehicle, and look different than the rest of the exhaust with their woven looking mesh around them). I will be able to look up exactly how many cats your car has with your VIN.

Pulling the upper intake plenum to take a look at the power valve screws is not a particularly difficult job, it's just fairly time consuming and you have a moderate amount of bolts to keep track of. There is a fairly detailed pictorial guide on the forum here.

If you decide to take a look at them, I would suggest applying red threadlocker to all of them; red threadlocker (permanent, high-heat) is preferable since there is no reason to remove the power valve screws for any service. It may be easier to pull the lower intake manifold as well, so you have more room to work with the upper intake manifold and its power valve assembly off the vehicle (otherwise it's pretty cramped - I had to crouch on the radiator core support to reach all of them, and that was not comfortable even as a small guy).

With the lower intake manifold removed, you will also have access to the PCV valve (and its grommet) as well as much easier access to the spark plugs with the throttle body removed (in order to pull the two manifolds). While it does not necessarily have a stated replacement interval, the valve can still malfunction over time and the rubber grommet surrounding it will become hard and brittle. It is a good idea to replace it, especially while you've got everything apart already anyways for the power valve screws.

If you would like the necessary OEM part numbers for the various gaskets required and the PCV valve and its grommet, let me know and I'll look them up for your with your VIN.

[Buzzman]

A few random comments from an '02 owner (Canadian to boot) with 275,000 kms.: There are only 2 cats. No where have I ever seen an R50 with 4 cats, Canadian or otherwise.
I have been running Mobil 1 full synthetic 5W-20 oil for almost 10 years. No problems whatsoever. No leaks, no burning. I run that stuff year round.
I just don't see what the controversy is with that grade of oil.
I checked my power valves (finally) about a month ago. I only removed the upper plenum. There was no need to remove the lower one.
(They were all fine BTW. all of them were present and accounted for, and all the screws were tight.) The whole thing took no more than an hour.

Now, when you say the truck stopped "warming up", do you mean the temp gauge stayed low, as in the engine actually stays cold,
or does the temp gauge go to normal all the time?
If it's not warming up, then it may be nothing more than a bad thermostat.
You also stated that the MAF is not the problem. How did you determine that? Your problems actually sound like they are MAF related.
Has it been replaced?
Keep us posted.

[Towncivilian]

There is no reason for controversy with xW-20 engine oils when specified by the manufacturer (or back-specified as is the case with many Toyota engines). A 30-grade oil will have a higher HTHS (high temperature high shear) specification than a 20-grade oil.

The HTHS test is a simulation of the shearing effects that would occur within an engine. In fact, it's actually designed to simulate motor oil viscosity in operating crankshaft bearings. Under high stress conditions where shearing can occur, the viscosity index improvers (polymers) break down. As they do, the viscosity of the oil decreases. This is what the HTHS test checks for.

Since a 20-grade oil has a lower HTHS value than a 30-grade oil, I would tend to avoid running one where not specified by the manufacturer. While I doubt you'll cause any engine damage running a 5W-20 or a 0W-20 oil in our VQ35DE engine, personally I would get a couple used oil analyses done to check the condition of the oil at the end of a typical OCI with both 5W-20 and 5W-30 oils; if there is a significant increase in wear with the 20-grade oil over the 30-grade there's no question as to which I'd pick.

I digress at this point, anyway. If you want to discuss the "finer points" of oils further, feel free to start a new thread.

[corygrant85]

haha I will avoid the oil debate as well, I understand all the science and have made my oil choices (5W-30 winter 10W-30 summer- both Mobil 1) based on alot of oil changes. I'm a nerd but what can you say! If the manual says 10W can be used in hot weather I will!

In reference to the MAF query I picked up a used one at a local scrap yard (not reliable) and it performs the same as the almost new one in it. I then was over at Nissan and my friend gave me a known-working MAF to test against those two- again no difference. That same (third) MAF had been used the same day to diagnose a seperate R50 for a bad MAF. So theres a very good chance MAF is not the culprit.

And for comments about the Pre-cat (I believe no platinum?) Can someone tell me how to upload a picture? Basically the Pre-cat hangs off the back of the exhaust manifold and is round (not flat shaped like regular cat) . It is there for cold start emissions I think as I believe it lights off very quickly. They are known (especially on the QR25DE Vspec Sentra) to clog and cause some issues (toast engines). If your Pathfinder has LEV status it likely has one of these. Not sure if they are on the 3.3L. Here is what they look like http://w ww.ebay.com/itm/01-03-QX4-00-01-Pathfinder-D-S-Pre-Catalytic-Converter-/190281274004. If you look under your hood, passenger side down at where the front O2 sensor is, you can usually see the tip of the heat shield for it.

Anyhow, I have had both rear cats checked and both front pre-cats checked. This will not become a discussion as to whether they exist or not, because there is no question that they do.

lol moving on!

I will be taking my truck off the road here soon (got a sweet little 98 Accord V6 for a beater) and will dive into the world of power valves and swirl valves.

Can a bad PCV valve cause any severe driveability issues such as mine? And then the ominous question.... if my power valves are all where they should be, my oil pressure and compression is great, what else could it be...? My tech friend claims that all sensors are working correctly and in unison. As mentioned before I have replaced the cam angle solenoid because it was out of phase for some reason. All is good now with that.

[Towncivilian]

You can upload pictures at http://www.imgur.com, after uploading it will give you options for posting on forums.

A bad PCV valve can cause oil consumption and a rough idle, but I'm pretty sure it wouldn't cause any driveability issues.

I still believe you're mistaking the "pre-cats" for the actual cats, and the rear resonators for additional cats. Courtesy Parts' exploded parts view diagram shows 20900+A(LH) as the part you linked on eBay.


But I'll shut up about catalytic converters now, anyway. It's a moot point if your cats have been verified as functioning properly.

There have been no reported cases of malfunctions with the swirl valves, just power valve screws being ingested. If they are all present, you're in luck - if not, then there is your answer. Still, an ingested power valve screw would likely cause oil consumption, show up on a compression test, and probably damage the cats as the screw(s) passed through them.

Do you think you can snap a decent photo looking through the oil fill hole to check for sludge? I doubt there is any given your use of high quality oil and presumably sane oil change intervals, unless there are other mechanical issues that can hasten sludge formation.

We have been focusing so much on the engine side of things. Have you maintained the drivetrain? Transmission fluid drain & fills or complete fluid exchanges, differential(s) drain and fills, transfer case drain and fill (if applicable), etc? Any noticeable issues with shifting? Engine coolant maintained?

[corygrant85]

No idea on last coolant change. What can this cause? Transmission fluid has likely been changed once in the trucks like, but I'm not sure. I am going to have my friend print me the trucks entire history (It has been serviced at Nissan since new, we are the original owners).

Diffs and transfer case (Its the fancy torque splitting transfer case, whatever thats called I can't remember) were actually just changed this spring. Transmission shifts well except at full throttle out of first gear it bangs a little hard into second. It rarely does this however because flooring it in first gear is an all day affair it has so little power.

I'm prepared to be wrong on the cat thing except my buddy told me he checked the cats and the pre-cats... so the mystery there goes on! More research required on my end! But as you said moot point.

Lets also move back to the original symptoms. It would have no power when cold, and once it was right up to operating temperature it would work. Depending on how cold it was outside it would take varying lengths of time to start driving normally. And then one day it just stopped running properly all together. What can this possible indicate? It does not sound power valve related to me (I am still going to be checking that out, however).

[corygrant85]

Because you've all got me curious about catalytic converters I did some digging;

http://www.nissanpartswarehouse.com/par ... &maxRow=10

Items #4 and #5 front and rear converters. Maybe some areas didn't have them, but the only resonator in my truck is as this diagram depicts; behind the rear axle. The interesting part is the rear O2 sensor is actually BEFORE the rear converter...maybe this is why you think it is a resonator?

[Towncivilian]

Hard transmission shift between 1 -> 2 and sometimes the slow/lazy shift from 2 -> 3 is normal and characteristic of our transmissions, nothing to worry about.

You have the automatic transfer case. It has its own fluid filter, but this should not require replacement and it is a stupidly expensive OEM part with no aftermarket options. If you're so inclined, it can be removed and cleaned with brake cleaner, but you'd have to replace its two O-rings.

I wonder if the engine is not in open loop mode for some reason during warm-up. It would help if you could read live data - do you have an Android smartphone or tablet? If so, you can purchase a cheapo $15-ish ELM327 OBD-II Bluetooth adapter that will plug into the car's OBD-II port and interface with Torque (a $5 Android application, or you can opt for the free "Torque Lite" app) and read many of the vehicle's sensors, including fuel system status.

Engine coolant temperature sensor may also be malfunctioning - you can test its resistance against reference values which are shown on page EC-169 of the factory service manual.

I will have to examine my own vehicle further to check for the cats. I wish the exploded parts views were better labeled, especially in cases where not all vehicles have the same emissions equipment.

[corygrant85]

I have a Scan Gauage (II) and will check on the open loop at warmup. It works as it should otherwise- switching to open loop when you floor it and remaining in closed loop under most other circumstances. I've never paid attention to warm up.

The scan gauge also "claims" the water temperature is getting into the proper range but I'm not sure if this is the ultimate truth or not I don't know enough about it.

Its frustrating because everything on the truck works so well, and since its always been rust proofed its very clean for our climate. I have a scrap yard up here that has (literally) 250 R50's (infiniti and older 3.3L's) all written off by Nissan for rust. My own personal parts source! If I end up needing a motor, I know where to go!

[Towncivilian]

Wow, that is a lot of junked R50s. I didn't know they ended up in the junkyard when bought back from the strut housing corrosion recall, nobody ever posted a certain answer as to their fate.

Does the ScanGauge tell you what the coolant temperature is? The needle reaches "normal" middle at about 154F. Thermostat is fully open at 170F, and the water control valve (secondary thermostat at rear of engine) opens fully at 203F. I don't recall when the needle starts climbing.
I would still check the resistance of the ECTS if possible.

[Buzzman]

There is no reason for controversy with xW-20 engine oils when specified by the manufacturer
I digress at this point, anyway. If you want to discuss the "finer points" of oils further, feel free to start a new thread.

Hey Town, I didn't intend to start a discussion on oil grades. My apologies.
This subject has been discussed many times on here in past years, so I had no intention of opening up old wounds again.
I checked my owners manual, and it specifies 5W-30, or 10W-30 in warmer weather. Oh well. I'll still continue to run the Mobil 1 5w-20, as I've done for the past 10 years.

This is a 3.5L and yes it has 2 Pre-cats and 2 regular cats, as equipped from the factory- not sure if it makes a difference but it is a Canadian truck.

I also decided out of curiosity to check out this 4 cats thing. I thought all along that our trucks only had the two.
I looked at the diagrams from your link, as well as the parts diagrams from Courtesyparts.com.
I also looked under the hood of my truck, and sure enough, the pre-cats are there, along with the two regular catalytic converters. Surprise surprise.
Learn something every day.
I'm going to call my tech next week and ask him about those pre-cats.
BTW, I had a 2003 Sentra SE/R that I bought new. It had the 2.5 engine that liked to eat pre-cats.
I got rid of it before anything bad happened.
I also have a 2006 Altima with the same engine. Nothing bad has happened yet, but I'm thinking of trading it soon as well.
There are a lot of nice mid size cars out there now. The Altima has some serious competition.
Cheers.

[Towncivilian]

No worries Buzzman, I did not mean to show any annoyance at the topic - I just don't want the thread to get too off-topic. I enjoy discussing engine oil, filters, and other automotive lubricants.

It seems that corygrant85 is right about there being four catalytic converters on our VQ35DE-equipped Pathfinders. I'm sorry we doubted you so much. It's just that previously many members would mistake the resonators (I believe there were two on VG33E-equipped R50s, which further perpetuated the misconception) for additional cats. Thank you for opening our eyes!

I think that the pre-cat issues of the QR25DE on early to mid 2000s Altima / Sentra / Maxima (?) models was ironically also caused by butterfly valve (aka power valve) screws being ingested and causing the pre-cat to disintegrate or become damaged and, if I recall correctly, getting sucked back in through the intake somehow and causing further damage and oil consumption. It's still a shame that Nissan acknowledged this problem and issued a recall on those vehicles but not on our Pathfinders which can and have suffered from similar (if not the same) issue with the power valve screws working themselves loose and getting ingested with similar consequences.

[corygrant85]

*sigh* I use a blackberry. I was actually looking around this morning for software that would use my scangauge 2 cord...its an RJ45 but all software you can find is either serial or usb. crap. Maybe it is time to get an andriod (hate my blackberry anyways).

I'm going to check now for open loop while cold. I wonder if my tech friend was wrong about all sensors being ok. In the past I have replaced an O2 sensor for similar symptoms...and since they are heated it might explain the "drives like s*** when cold, ok when warm" symptom if they were getting carboned up. I believe I've had a single "no O2 response" check engine light that I erased and never came back quite awhile ago. Its frustrating that so many things can cause similar symptoms. FYI I am right at oil change interval (+/- 5000km) and it has not burned any oil, so I don't think it is likely a screw has been sucked in. Although anything is possible at this point.

[corygrant85]

quick update, started the truck and it stays in open-loop for about 25 seconds before going to closed. This is on a coolish summer day (about 70 F outside). Is this about normal?

[corygrant85]

PROBLEM SOLVED: Apparentely a few people out there in the forum universe have had this problem too. Basically if you're VQ35 is pinging at low RPM, and has no power above 3000rpm it is very likely your swirl valves are stuck closed. The linkage is directly beneath the linkage for the power valves. Basically I sprayed a bunch of deep creep on the linkage and worked it back and forth a bunch, and then put 3/4 of a bottle of deep creep in the engine and let it sit for a few hours. Damn truck runs like new.

[Towncivilian]

I'm surprised that didn't throw a code! Congratulations on getting it fixed, I'm glad it was such a simple fix.

[Pwnin O'Brien]

Side note: Excessive consumption of oil can also cause this issue. When the oil level drops to low levels (if you see the oil light turn on when you come to a stop, you need to add/change oil), the intake manifold butterfly valves fail to function and you lose all torque. This happens all too often to me as my valve cover gaskets are leaking epic amounts of oil. Nothing like trying to climb a small hill at 4000 RPMs.