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  #1  
Old 04-01-2012, 09:17 PM
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Bob's Garage Bob's Garage is offline
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Default Nissan Evap Issue 1997 Pathfinder


I am calling out to my bretheren out there. I am getting involved a lot more than I thought I would be on this Pathfinder.

P0450 FTP Pressure problem & P0446 Vent problems fixed, now P01447 returns intermittent.

Parts Replaced:

According to Tech, FTP sensor (known as Boost Sensor) near tank was stuck at 5 volts. Voltage did change with new sensor 3.3 volts static. Found charcoal in purge system.


My questions? Why does this code P1447 keep returning? Also, what scanner has bi-directional control for the Vent solenoid and bypass valves? My Snap-on and Autel scanners do not have any bi-directional for any solenoids in the rear (vent & bypass). The Snap-on scanners do have 3 bi-directional (functional) tests for the Evap system, two of which seem to be the same test for the purge Volume control which seem to work and one test for the Purge, which doesn't seem to actuate anything in my testing, cannot hear any solenoids click in front or rear.

Diagnostic Steps Performed:

What I found was this: Charcoal in the purge system, canister has lost it's abilty to keep charcoal in it. Blew out vacuum hoses from front to rear. Took canister off vehicle and dumped as much charcoal out as possible and put back on vehicle. For now, added clear fuel filters between canister and purge hose system. No charcoal has shown in these filters yet. I will not change the canister till I know the whole story asthis is the kind of job that gets expensive, you know the kind of job that customer leaves at your shop after they realize they shouldn't have authorized the work...


Testing under hood:

Purge volume control solenoid is bleeding vacuum at 0% command, possibly charcoal stuck in valve. Purge volume control valve seems to respond to bi-directional control from Solus Ultra and Verus.
Purge cutoff solenoid functions when grounded, passes vacuum to purge cutoff vacuum valve, and allows purge vacuum to flow when solenoid is grounded. This valve seals front of system under hood so no purge leaks to tank, confirmed no vacuum increase in tank with Vent solenoid hose pinched off when valve does not receive vacuum from solenoid. No Bi-direction control to the Purge cutoff solenoid. Have not confirmed if PCM is capable of actuating this solenoid yet.


Testing in rear:

Vent solenoid has power and closes when grounded, and seals, confirmed by blowing into vent, when closes will not pass air. No bi-directional control for Vent solenoid. Bypass valve, has power and will allow flow when grounded. cannot confirm if white plastic "cut valve" works or not. I need a test procedure for that piece. I remember back when I did a lot more Nissan Evap, there was procedure for testing that valve, don't recall how to do it now.

33003001.BMP

Fuel tank pressure remains at 3.38 volts and voltage will rise to near 5 volts when vent solenoid is pinched off due to pressure build up in tank and will drop to 0 volts when purge is allowed to flow. Also when high vacuum is pulled into tank, pinching off purge hose in front keeps vacuum in the tank indefinitly, so at least that part of tank is tight. When driving, I don't think I see much change from 3.38 volts

Not sure what to do next except attach scope leads to all control lines on all solenoids. and monitor fuel temp and fuel tank pressure.

Also, I did not energize the bypass solenoid while there was vacuum held in tank, to see if fuel tank pressure changes. Will do that tomorrow.

So, who is a Nissan Evap Guru out there? Are you familiar with all these solenoids and vacuum valves?

Thanks in advance, Bob

Last edited by Bob's Garage : 04-01-2012 at 10:02 PM.
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Old 04-02-2012, 03:24 AM
Crusty Crusty is offline
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Default

Hi Bob
The Nissan's are kinda 'round about in their valving. LOL
I have a very good customer with a 2002 Pathfinder.
What I have concluded is the "cut valve" and its' associated valves/solenoids can isolate the fill tubes from testing under some conditions.

There is a TSB/Recall regarding the 97 to 2001 ??? for rusting of the fill tube lower brackets where the support plate is welded onto the tubes.
It didn't help the 2002 I was working on but the plastic tube guard holds tons of sand and can hold moisture in contact with the fill tubes.

Leave the ignition OFF and the scanner disconnected. Pinch off the water separator hose at the back. Hook onto the test port under the hood. The purge solenoid should stay closed on its' own. You should have a "sealed" system at this point without any valves isolating any sections.
That's what worked for the Pathfinder I had with intermittent "very small leak" and "small leak" codes.

HTH
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Old 04-02-2012, 04:58 AM
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Default Nissan Evap

Quote:
Originally Posted by Crusty View Post
Hi Bob
What I have concluded is the "cut valve" and its' associated valves/solenoids can isolate the fill tubes from testing under some conditions.

Leave the ignition OFF and the scanner disconnected. Pinch off the water separator hose at the back. Hook onto the test port under the hood. The purge solenoid should stay closed on its' own. You should have a "sealed" system at this point without any valves isolating any sections.
That's what worked for the Pathfinder I had with intermittent "very small leak" and "small leak" codes.

HTH


Hi Jay,

Thanks for your kind offer of help, I had a feeling you would reply.

I was able tull pull a very high vacuum in the tank (.5v) and hold it by pinching off the vent solenoid fresh air tube. It held for a long time. Also, the tank held pressure for a long time, with the same method of pinching mthe vent hose with the engine running. (i had mentioned that in my post).

I never activated the green cut valve solenoid (in back above rear differential) with vacuum pulled in the tank. I only activated the solenoid to see if it worked and it did. I also didn't see if those 4 ports on the white plastic "cut valve" did what they are supposed to. That is one of my questions. What does each port do?

I think what I will do this morning is pull the vacuum in the tank and activate the cut valve solenoid and monitor the FTP sensor (boost valve?).

Don't you just love Nissan terminology? I am sure that they totally ignored OBD 2 regulations and figured they would get away with murder. They did. Running readiness monitors on theis era of Nissan is harder than hell and this one is no exception. I even got my required 3 out 5 monitors on this one but the code sets. It takes at least an hour to get 3 monitors ready. The EPA should have made them replace every PCM in every 1996 - 1997 Nissan for that issue. Instead they came up with a 2 hour procedure. Who pays for that? Not Nissan...


A few minutes on the phone with my local Nissan parts department and I clearly see that my parts guy was confused. They just send a FAX and let you tell them the part #. They don't trust the terminology either!!!

At any rate, do you (or anyone else) know if the Consult 2 has bi-directional control for the Vent, Bypass or underhood purge (cutoff?) valve? Snap-on does the Purge volume control valve in 2 different functional tests(same test? just named different?) .

Also there is a test named "Purge solenoid", but appears to do nothing.

My strategy today is to use my "test drive" scope leads and fill all 4 labscope channels with Evap control and scan at the same time using the Verus. I will need a seperate scanner because Snap-on only allows scoping and scanning at the same time with CTM, a 2 channel only function.

Anyone else have any good suggestions?


Thanks again, Bob
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Old 04-02-2012, 05:37 AM
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I think the code sets while the vent is open. Since the PCM is looking for a slight vacuum build-up during purge (FTP voltage goes down), there has to be a restrictor in the system. That should be the canister, which you already confirmed to be bad. Pinch off the vent and then perform the purge system check per SI (P1447.pdf). I bet the FTP voltage will drop. I would just go ahead and replace it, along with the leaking volume control valve and the purge control valve.

Quote:
According to Tech, FTP sensor (known as Boost Sensor) near tank

I would think the MAP/BARO sensor is called the BOOST sensor at times...
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Old 04-02-2012, 08:55 PM
greasybob greasybob is offline
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Here is what it says in shop key "Vacuum cut valve prevents manifold vacuum from reaching the fuel tank. Vacuum cut bypass valve opens only during on board diagnostic leak and flow checks" Does the scanner indicate when the on board diagnostic test is active ? Does it indicate when purge is being commanded ? Any change in tank pressure during purge ?
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Old 04-02-2012, 09:48 PM
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Default All this charcoal and no barbeque!

Quote:
Originally Posted by Orevin View Post
I think the code sets while the vent is open. Since the PCM is looking for a slight vacuum build-up during purge (FTP voltage goes down), there has to be a restrictor in the system. That should be the canister, which you already confirmed to be bad. Pinch off the vent and then perform the purge system check per SI (Attachment 9874).

I bet the FTP voltage will drop.

It does. Purge volume control is bad.


I would just go ahead and replace it, along with the leaking
volume control valve and the purge control valve.

I would love to see how the customer reacts to a $1200 estimate. Yeah, not just parts, I want some labor time too!!


I would think the MAP/BARO sensor is called the BOOST sensor at times...

It is called a "boost sensor". "Boost sensor" is actually molded into the part. I meant to get a photo. I called my local Nissan dealer today and he confirmed that is the given name in the parts catalog. He also gave me a parts breakdown, which I will post later with pics.

Funny thing, a similar sensor under the hood which should be called a "boost sensor" is called a "Pressure sensor". Figure that out.

Well Kai,

I have some new developments today. More charcoal! Yes, that is part of the problem, anyhow. It seems that it hides in every corner
.

I was able to get more charcoal out of the system by removing a connecting hose in the purge line and blowing it out from there, both ways:

DSC01956 low res.JPG



The Purge Volume control was loaded back up:

DSC01950 low res.JPG



I took it apart, and cleaned it as well as possible:

DSC01949 low res.JPG



Don't laugh, I had to do this to continue my testing!! These filters have stopped any more migration of charcoal, for now. :

DSC01946 low res.JPG



I was able to pull a lot of vacuum in the tank in the shop:

20120402-1211-1.jpg

But on the road... not so much:

20120402-1506-2.jpg

And, the new codes:

20120402-1609-1.jpg


It looks as if the Volume control valve has given up. After I first cleaned it, it did not leak vacuum. Sometime during my test drive, it started leaking vacuum again. I took it apart one last time, but it was still clean. Every time I drive this POS, I get new codes. The P0443 is electrical in nature, I believe, so this is the end of it's life, Too much charcoal, I suspect.

This is why I did not replace the canister yet. These Evap parts are only available from Nissan and carry a hefty price tag.

A price like that is hard to justify on a 1997 Pathfinder. So, now, I have to get another estimate together. These are the kinds of jobs that just never seem to end. You put a part on and it pops another code. It looks like Evap isn't the only problem I'll be fighting.

I can just hear the customer. "I just want to pay my one hour of diagnostic".... We'll see today

The other problem is that The monitors are so hard to run on this year Nissan, that one code or another always comes up before I get the required 3 out of 5 non continous monitors... Sigh...
Thanks, Bob


Last edited by Bob's Garage : 04-21-2012 at 07:23 PM.
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Old 04-02-2012, 10:17 PM
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Hi greasybob!

Quote:
Originally Posted by greasybob View Post
Here is what it says in shop key "Vacuum cut valve prevents manifold vacuum from reaching the fuel tank. Vacuum cut bypass valve opens only during on board diagnostic leak and flow checks" Does the scanner indicate when the on board diagnostic test is active ?

No, It won't run the leak check now because it sets a P0443. My testing with ground the bypass valve show it can switch and chane from tank to canister. Note the minute changes in FTP. I was graphing Vent and Bypass to see if the test would run. No chance:

20120402-1506-2.jpg



Does it indicate when purge is being commanded ? Any change in tank pressure during purge ?

It takes a long time to get the Purge volume control to go up to a hundred, 1% at a time. This is poor planning on Nissan's part. 10% at a time would be nicer... :
20120402-1622-1.jpg


I can always get the full range of the FTP, but I have to pinch off the Vent valve hose. There is no commanded purge at this time. The damn Volume control is leaking so bad, within seconds I have 0 volts at the FTP:


20120402-1239-1.jpg
Thanks, Bob

Last edited by Bob's Garage : 04-03-2012 at 04:46 AM.
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Old 04-03-2012, 05:18 AM
greasybob greasybob is offline
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$1300 ? Cheap !!! Don't forget the consultant fees.... heheee just kidding
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Old 04-03-2012, 08:48 AM
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I know this is not the most ethical approach Bob, but I would explain to your customer that the canister exploding charcoal bits has contaminated the whole system, and thus requires complete system replacement. It is not your fault Nissan used a shoddy canister. I have personally seen this with a dozen Xteras and Pathfinders, but in those cases, just the canister and purge valve were all that need to be replaced. Oh yeah, a small bit of photo advise, if I may, when shooting close ups, set your camera to "macro", this will allow the lens to change its focal point to a much closer depth of field. HTH.


Good luck,
Stacey
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Old 04-03-2012, 02:57 PM
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Hi Bob
From what I understand, the Vacuum Cut Valve stops any vacuum from applying to the tank (behind the cannister) under all conditions, except when it does its self test, when it opens the Vacuum Cut Valve Bypass Valve so it can see if there is a leak behind the cannister.
As for the Pressure sensor, which you've already replaced, it, and anything else ahead of the cannister appears to be contaminated with the charcoal.
A look at the schematic in the P1447 chart kindly provided by Kai, indicates that anything in the flow path of the purge is likely fouled.

...Found a couple of bulletins today in ALLDATA....LOL

----------
Recall 07V435000: Fuel Filler Tube Replacement
MAKE/MODELS: MODEL/BUILD YEARS:
Infinity/QX4 1997-2001
Nissan/Pathfinder 1997-2001
MANUFACTURER: Nissan North America, Inc.
NHTSA CAMPAIGN ID NUMBER: 07V435000 MFR'S REPORT DATE: September 12, 2007
Component: Fuel System, Gasoline: Storage: Tank Assembly: Filler Pipe and Cap

---------------
EVAP Canister - Charcoal Leakage
Classification:
EC00-022
Reference:
NTB00-085
Date:
October 17, 2000
EVAPORATIVE (EVAP) EMISSION CONTROL SYSTEM CLEANING PROCEDURE FOR EVAP CANISTER CHARCOAL LEAKAGE
INCIDENTS
APPLIED VEHICLES:
All vehicles with OBD-II EVAP monitoring
SERVICE INFORMATION
If the EVAP canister leaks (or has leaked) charcoal, it must be replaced. In addition to replacing the canister, the entire EVAP emission control system
must be cleaned to remove charcoal particles released by the leaking canister. To clean the EVAP emission control system, use the service procedure listed below.
-------------------

Apparently there are two kinds of Purge Volume Control Valves possibly used and each has it's own test sequences.... One is a "duty cycle type" and the other is a "stepper motor type",

As for the Vacuum Cut Valve, and the Vacuum Cut valve BYPASS valve, I couldn't find any description in 1997, 98 or 99 but the 2000 showed the following......

COMPONENT DESCRIPTION
The vacuum cut valve and vacuum cut valve bypass valve are installed in parallel on the EVAP purge line between the fuel tank and the EVAP canister.
The vacuum cut valve prevents the intake manifold vacuum from being applied to the fuel tank.
The vacuum cut valve bypass valve is a solenoid type valve and generally remains closed. It opens only for on board diagnosis. The vacuum cut valve
bypass valve responds to signals from the ECM. When the ECM sends an ON (ground) signal, the valve is opened. The vacuum cut valve is then
bypassed to apply intake manifold vacuum to the fuel tank.

--------------------
This vehicle sounds like it needs a new canister and the components that the charcoal has contaminated.
Hopefully the customer doesn't blame the messenger......at least you can show him the recall for the filler tubes....

HTH
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