P0446 causing erratic idle?

[amym600]

I just bought a 1996 Maxima. I love the darn car! Unfortunately it did not pass emissions. I have been working on that for the last few weeks, the MIL light was on with P0446 and P0440, replaced the valve and the canister so far, checked everything else. However in the last few weeks I have a terrible erratic idle. It is mostly in drive at a stop, worse with a load on the engine. Only after the car warms up. The only codes I get are the P0446 and P0440. Although after the canister replace that has not shown up again for the last 2 days. Has anyone had an idle problem with these codes or an idle problem with no codes? So far I cleaned the MAF, IAC, EGR and throttle body. NO difference. Thanks!!!

[MinisterofDOOM]

Welcome to NICO.

Was the idle problem present before the car failed emissions?

[amym600]

Yes, but it was hardly even noticeable at that point. I should also mention I used Bosch platinum plugs when I replaced the old ones. Now I realize I should not have used those. What type of NGK should I be using?

[MinisterofDOOM]

I'm not sure of the exact plug number is for your car, but you should be fine just asking for a set of NGK double platinums for a '96 Maxima.

[maxhopper]

The Bosch plugs are more than likely the cause of the bad idle. It is recommended that you use the NGK Platinums (good for 60k miles). http://www.sparkplugs.com has them for a good price - part # PFR5G-11.

[amym600]

Thanks All! I am going to replace the plugs today and see if it clears the problem. I swear it was doing it before I replaced the plugs but it may have been the plugs before, they were pretty bad.

[amym600]

Yes, the Bosch plugs appear to have been a huge problem. I have a small stutter at idle every once in a great while but not missing like it was and I am so happy. I think my only last problem is I have a pending code of P1445 which is purge control valve. Any ideas where that is? I got my evap and evap control valve replaced, no idea where the purge valve is.

[maxhopper]

The Purge Control Valve is located between the motor and the firewall, not too far from the throttle body. If you follow the hose from the Evap Canister, you should find it. Here is a picture of what it looks like and a picture of the location (best I could find).