NR350z

Just wanted to ask a few quick questions that I couldn't quite find the answers to when searching. I've read mixed reviews on the gas cap theory. Some say that you MUST USE OEM and some say it doesn't matter. I've recently had my SES come on with P0455, and maybe two weeks or so ago I replaced my gas cap with a generic Auto Zone one.

After scanning and erasing the code, popped the door, removed and then reinstalled to ensure it was tight. Is there a specific given time it would take to allow me to know if that fixed it? I've heard to start cycles, and I've heard 200mi. Since Monday I've driven 70mi, would you say I'm in the clear or not yet?

Thanks.

zakmartin

Clear the code and see if it comes back. If it does, my guess is it's your Evap Purge Solenoid. It's simple enough to check for a leak if you do a smoke test or use compressed air set REALLY low and listen for air leaks at the solenoid, which would indicate it's in the stuck open position. Don't jump the lead on the solenoid; use a bi-directional tool to activate it. Otherwise, you could easily fry the computer.

As for using aftermarket parts for things like gas caps: I'd recommend you stick with OEM because it eliminates a known variable and you won't sit there asking yourself if the problem's still around because you bought a cheap, POS part.

tampa_joey

much wisdom in this
many folks should heed such advice

NR350z

Thanks, I did clear the code, it has yet to come back after ~110mi of driving, just not sure how long it takes to fully reset and when I'm "in the clear" or not...

I've done a boost leak test before, just never have done a smoke test, if I do the compressed air test where do I put it? When I would do boost leak tests in the past I would hook it up to the intake, same thing apply?

Thanks for the help

NR350z

Just didn't think there was a big huge deal using an aftermarket gas cap... you guys are making it seem like I bought eBay coilovers ... and still couldn't give a difinitive yes or no ....

zakmartin

Refer back to the FSM and follow the plumbing that goes to the Evap Purge Solenoid. Since you didn't mention the year of your Z, just start from here and find your car.

http://www.nicoclub.com/manuals/350Z/

It's in the Engine Control chapter of the FSM. You can look at the procedure on a 2005 on page 354 here:

http://www.nicoclub.com/manuals/350Z/coupe/2005/ec.pdf

They recommend you don't use compressed air on the 350Z (I generally use a gauged control valve turned down to almost nothing). I recommend you follow the guidelines laid out in the FSM exactly as written. If you're not using a bi-directional tool to activate the solenoid, then disconnect the harness. DO NOT back-probe into a connected harness to open the vent control valve. You can destroy your ECM pulling a stunt like that.

To be honest, if the problem took 110 miles to throw a new code, I'd start by getting an OEM fuel cap first. That being said, YES, Evap Purge Solenoids are prone to failure on our cars. If you get a new one of those, stay away from the $40 Dorman garbage and just spend the few extra beans (I think they're a little over $100) to get a factory unit.

I never recommend replacing anything on a car until it's been tested and is known to be defective. Between a new fuel cap and the Evap Purge Solenoid, you'd have most of your P0455 thrown code covered. However, it could be any number of other issues, including leaks in the evap lines, bad electrical connectors, etc.. That's why I recommend you test the parts first. That's also why I recommend you stick with OEM, particularly for things like emission systems, which can give you so much heartburn.

NR350z

Thanks for all the help, but since erasing the code it hasn't come back, and I've driven ~185 mi. Do you think I'm in the clear since tightening the gas cap? Not sure how long it would take for the code to pop back up since erasing the code ?

zakmartin

Yeah, if you're 185 miles in and the code hasn't come back, then smile and enjoy the car. Everything I wrote above was based on the assumption that your issue was still active. If the problem comes back, then at least you have a diagnostic starting point now.

NR350z

Yeah I figures and downloaded all necessary diagnostic info in my search. Appreciate the help and hopefully it doesn't come back. I didn't know if there was a certain mileage it took for ecu relearn the EVAP system.

isy_nismo

iTrader: (1)

Coming back to the EVAP system...I have a modified upper plenum without the EVAP purge valve port, Do you know what that vacuum port does to the EVAP puge valve? Is it a vacuum? I'm thinking in to blank that line and see if this affect to the system.. Any recomendation, anyone have a similar upper plenum or has deleted the whole system?

Many Thanks!!