# 1998 Maxima SE what is this part?



## 1998MaxiMa (Aug 12, 2007)

Ok, Ive been getting a 0705,0309 code straight off my Maximas ECU. A OBDII Scanner said it was a Evap Leak and the Control System. Ive been working on my car all night, but I think I found my problem when I would turn the key to the "On" position Id hear this "hiss/click" combo coming from this part, when I would put my hand on it I could feel something rattling around on the inside. When I turn the key to "Off" you can hear it again. Ive been having a hard time starting the maxima the past 3 mornings, I have to slam on the gas while turning the key to get it started.. could this be the problem. Im replacing the fuel filter tomarrow, and doing a coolant flush. 

It has a electrical connector, and two vacumm hoses.. I took the one hose off, and It was almost like a plastic tube.. the otherside looks like the hose is attached to a bolt on the otherside of it. Is this part of the evap control system, where the hell is the canister so I can try cleaning it up a little.

I also tried installing a new PCV valve tonight, but when I pulled on the hose the valve didn't come with, what can I do to get the valve out? I tried pulling on it with pliers, but that didn't work.


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## smj999smj (Jan 1, 2006)

It might make it simpler if you had the "P" code from the OBD II scanner...I believe the part you are referring to may be the EVAP system purge volume control valve, which is bolted to the top of the upper intake plenum not far from the cruise control servo and cyl. #5 coil pack. 

The EVAP canister is at the left side, rear of the car, accessable from the bottom. It cannot be "cleaned out." The evaporative emission control system stores the fuel vapors in the canister (rather than let them vent into the atmosphere) so that they may be re-routed later to the intake manifold via the Purge Volume control valve where those fuel vapors can be burned in the combustion chambers. Attached to the rear of the canister is the vent control valve, which can be opened or closed by the ECM to allow air to be sucked in or closed so that the ECM can do a self-test on the system to test for leaks. It does this through the EVAP system pressure sensor, which is the "eyes" of the system. Apparantly, through the self-test, the ECM has determined that there is a leak in the EVAP system and triggered the code. 

A leak can occur anywhere in the EVAP system. A disconnected or split hose or leaking canister can be the culprit(s). Most common, however, is a bad vent control valve bolted to the canister. Another, less common, issue is when the foam deteriorates in the canister and allows tiny pits of charcoal to be sucked through the EVAP system. When this happens, debris can end up vent valve, purge valve, sensor...everywhere in the EVAP system! There's a TSB that describes the process to clean out the debris, prior to installing a new canister. So, one of the things o do should be to remove the canister assy. and take off the vent control valve and see if any carbon debris falls out of the canister. If not, it's probably fine. You then have to concentrate on the leak. BTW, a loose gas cap can trigger EVAP leak codes. FYI, if the vent control valve is faulty, you need to make sure you get the correct valve for your canister. The canister and vent control valve were later redesigned. Either pair will work, but they must be matched to each other (in other words, not cross-compatable). There's a TSB regarding identification of these parts. 

Normally, to test the system, a scan tool is used to monitor the evap pressure sensor readings and a hand held vacuum pump (ie MityVac) is used with an adapter to allow it to screw into the test port in the engine compartment ( it's identified with a green, plastic schraeder valve cap). Even better is to have access to a smoke machine to attach to the connector to check for leaks. 

I doubt that the purge volume control valve is causing your hard start issues...if that's the part you are talking about. You may want to try cleaning out your throttle body with some throttle body spray and checking your base idle adjusment per the service manual procedure, which is critical for proper IAC/V-AAC/V operation (the part that controls your idle in cold start and load compensation conditions).

As far as the PCV, I usually don't bother with them because they rarely fail. That said, spray some carb cleaner on the hose near the valve and then twist the valve to break it loose from the inside of the hose. Once it has broken loose, it will be able to be pulled out. The carb cleaner softens the rubber hose and makes it a little more flexible for a short time period. This also works when trying to get the hoses off of the fuel filter.


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## 1998MaxiMa (Aug 12, 2007)

Thanks for the reply..

Ok, the OBDII numbers are

*P1448 0309 - Vent Control Valve
*P0440 0705 - EVAP Small Leak

Im going to flush the coolant, and put in a new fuel filter now. Ill try and work that PCV off the manifold with a little WD-40 or Brakleen. Don't have carb clean laying around. If I can't get it off, then Ill just keep the part for another time. 

The base idle in the Haynes manual for this make/engine type is 600-700 RPM normal idle.. That's what Its at, It doesn't idle hard or anything. It smells a little rich though when I have the hood up and Its idling for a bit.


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## smj999smj (Jan 1, 2006)

1) I would concentrate on the vent control valve and/or the possibility of carbon debris from the canister. Remove the canister, unbolt the valve and see if carbon falls out.

2) You need to use carb cleaner...brake cleaner nor WD-40 will soften and expand the rubber like carb cleaner.

3) The IACV-AAC valve is used by the PCM to correct the idle. So, even if your engine normally idles at 650RPM =/-, you still don't know if the BASE idle is correctly set. The BASE idle could be set at 550 RPM and the ECM will try to correct the engine idle to 600-700RPM using the IACV-AAC valve. This is why BASE idle is critical to the valves operation. BASE idle is differant than TARGET idle, which is what the ECM attempts to maintain.

To adjust the base idle (I would recommend cleaning the throttle body if needed and driving the vehicle prior to doing this):

Engine warmed up, wheels straight ahead, loads off. Turn off engine and disconnect the throttle position sensor harness connector. (There are two connectors on the TPS. If you are at the driver's side fender, the one closest to you is for the closed throttle switch and stays connected. The connector farthest from you is for the throttle position sensor and needs to be unplugged.) Start the engine. Rev engine (2000-3000RPM) 2-3 times and then idle. Adjust idle speed screw to achieve an idle of 650 RPM +/- 50 AT models (...575 for MT) in Neutral. Turn off engine and reconnect TPS and erase stored codes. Start engine and rev (2000-3000RPM) 2-3 times no load and let idle. Check idle speed...should be 700 RPM =/- 50RPM AT models (...625 MT).


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## 1998MaxiMa (Aug 12, 2007)

Ok, I will take a look at the canister then. I was looking over vacuum hoses found a few that could use new clamps. I can't do a coolant flush, because I guess the previous asshole owner stripped the piss out of the drain plug, and considering Its plastic.. yeah It aint pretty. My coolant levels are fine though, antifreeze mixture all the way to the top of the radiator line.

I will have to go pick up some carb/throttle body cleaner at Autozone, cleaning the throttle body is easy as taking off the airbox completely, and spraying the cleaner inside of the exposed throttle body.

It did the hard start again this morning.. Ill turn the key and It'll start cranking the motor and then Ill think I have it started and let go of the key and It just stalls itself out.. I held the key in longer this time instead of letting it go, and it hesitated to start but It caught itself and the RPMs jumped up and down a little bit and then settled right under 1000RPM but after letting it idle for about 10 minutes and then turning it off.. I came back to it a hour later and It turned right over without a fuss. Im getting really confused with this car.


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