97 SE -- First pinging, now high idle?!

ecsnyder · Jun 21st, 2007, 11:39 AM

So I've had a pinging problem for a while in my 97 Pathy SE (153,000 mi). I've put high octane gas in it, and that's fixed the problem but I'd rather find out why it used to run fine on 87 and why I can't do that anymore.

So in an attempt to fix that, I cleaned the MAF with some throttle body cleaner and cleaned the throttle body, too. Now, in addition to pinging, it has a high idle when it's cold!! After it warms up the idle is fine, but it will sit at 1,500 when I start it up in the morning.

I cleaned the MAF again to no avail, and checked all the grounds for the electical system.

Now this morning I think I was getting some knocking, but I'm not sure (maybe I'm just paranoid), but something felt like knocking when I was at driving but I couldn't replicate it without a load on the engine.

The CEL isn't lit, so that's not giving me any clues.

Help please? I really don't want to shell out the $$ for a new MAF because I'm trying to sell the thing...

dvdswanson · Jun 21st, 2007, 04:30 PM

could be cause its summer time and most 87 has ethanol in it.

ecsnyder · Jun 21st, 2007, 04:35 PM

Possibly, but it didn't do this last summer.

dvdswanson · Jun 21st, 2007, 04:47 PM

could also be the knock sensor/wiring is going bad, I can't remember but that may be one of the sensors that only sends failed signal to the ECM whens totally bad.

ecsnyder · Jul 30th, 2007, 11:36 AM

Okay, so this problem is still going on and now I have something new to add: The CEL lit up and I pulled two codes:

P0440 - EVAP system leak
P0446 - EVAP canister vent control valve circuit fault

Any ideas on if this is causing the problem and what I can do to fix it?

smj999smj · Jul 31st, 2007, 01:50 PM

It is supposed to have a high idle when you first start it up. You may have actually fixed a problem with the fast idle by cleaning out the throttle body.

Nissan, as well as some other manufacturers, had some problems with their evaporative emission systems when the government mandated some changes in the system for environmental concerns. Basically the idea was to have the ECM the power to self test the system and make sure that it is working properly and not tampered with.

Your problem will probably be found at the evap canister itself, located at the left side, rear, underneath of the vehicle. The vent control valve controls a vent port on the canister. It's possible that the vent control valve failed....but there are a number of other possibilities as well. The evap pressure sensor is the "eyes" of the system and is sensing that there is a leak in the system, which is why the codes have set.

I would take the canister and vent assy. and remove it from the vehicle. Unbolt the vent control valve and with the port facing the ground, give the canister a shake and see if there are any tiny pieces of carbon that fall out...or anything for that matter. The carbon in the canister is held in a foam casing, which sometimes deteriorates and allows the carbon to be sucked through the evap system, which is a real pain to clean out! If no debris falls out, there is a pretty good chance that the vent control valve failed. FYI, the canister and vent control valve was redesigned and parts do not interchange. The updated canister most be used with the updated valve, the old style canister must be used with the old style valve. Your Nissan parts dept. can help you wih this and there was also a TSB on the subject.

If debris falls out of the canister, you will need to replace the canister and valve and completly clean out the evap system from the canister connections to the purge volume control valve at the engine intake manifold. This is a pain! There is a TSB on the proper cleaning procedure.