2002 Pathfinder surging in Park

[frog111]

At 196k I replaced the worn out spark plugs with new Bosch platinum plugs, new fuel filter and cleaned the throttle body and cleaned mass air flow sensor(that's it).

Results: Surging +50 rpms and a high idle while in park, smooth but high rpms in drive and stumbles when decelerating to a stop. Codes all point to the idle air control valve even though I did not touch the dang thing?

Spark plugs gapped wrong? Coils? TPS? IAC? Like I said all I've done is a spark plug/fuel filter replacement, throttle body and mass sensor cleaning. Pulled neg off battery overnight, same surging problem. Codes pointing to IAC but I pulled it and checked the voltage and its fine.??

I'm stumped because the truck ran fine I messed with it.

[Buzzman]

Gut feeling tells me that the MAF has gone bad after cleaning it.
It is very sensitive, and if cleaned incorrectly, or if the wrong cleaning fluid was used, you can f**k it up.
Personally, I've never touched the MAF in my truck (2002, 275,000 kms on it). If it ain't broke, I don't fix it.
Check your MAF, and maybe try cleaning it again. Cross your fingers.

[frog111]

thanks I'll check the mass out, but no codes have pointed to it and when I disconnect it while the engine is running it still surges?

[Pathfound49]

If you unplug the maf with the engine running the idle should jump and surge. If there is no change, then that makes buzzman's post even more valid. Your codes will only show high idle as well.

[frog111]

I'll see what I can do with the maf and will repost with results. Thanks!

[frog111]

after installing a new MAF the engine still surges without much noticeable difference. Spark plug gap wrong on platinums? Coils?

[Buzzman]

If it's just surging, then I would think it's firing on all cylinders.
If it idles roughly, or the engine shakes, then there's probably a misfire.
The only other thing that comes to mind right now is a vacuum leak somewhere.
Are all the hoses and vacuum lines secured and tight?

[frog111]

Could this be as simple as a stuck PC valve or EGR valve? I squirted cleaner down the PC valve more than onceDrives fine unless you let off the gas then surges when coasting to a stop. But when you come to a stop (while its in drive) purrs fine with no stumbling on acceleration. The moment you put it in park it surges +/- 500 rpms. Seems to be idling fast @1400 when in drive. When I did the IAC reset for a 2002 it doesn't seem to take? IAC has been cleaned when doing the throttle body and tested ok with voltmeter.
As far as a vacuum leak: I spent many a beer looking all the vac lines over when I decided to replace them one by one being careful not to cross any. The only ones I did not replace were located under the manifold, so I left them alone. Also I decide to pull all electrical connectors, cleaned with electronic cleaner, and reinstalled using electrolyte gel just to make sure a connector wasn't the issue. No blown fuses, but I did not test relays.

If you stomp on the gas it gets up and going 90+, its when you decelerate it lopes like the brakes are on, in park it surges. I think that I need a diagram of the components that hook up to from the air cleaner to the throttle body since there is a noticeable sound of an air suck coming from the driverside area?

Could this be as simple as a stuck PC valve or EGR valve? I squirted cleaner down the PC valve more than once. Is there a vacuum hose diagram to follow anywhere?

[Buzzman]

I think that I need a diagram of the components that hook up to from the air cleaner to the throttle body since there is a noticeable sound of an air suck coming from the driver side area?

Sounds like that's where you should be looking next. Find that air leak and you've probably solved your problem (that's my $.02 worth anyway).
Good luck.

[Chuck Tribolet]

I'll vote for vacuum leak too. I've been there twice on the 'vette.

There's a diagram in the FSM.

But if you take a piece of about 1/2" tubing, put one end in your ear, an earplug in the other ear, and move the free end around where you think the leak is, you can probably find the leak by how loud the hissing in the tubing is.

[jorghern]

Frog111 - were you ever able to isolate the issue?

[frog111]

My surging was fixed with a new IAC, no vacuum leak. Truck ran weird after cleaning the throttle body. I replaced the IAC after 200k. The ECM and and IAC would not relearn. Had a mechanic use his computer to relearn and he said it accepted but yet the ECM would not take the relearn since the truck still idled bad. Mechanic said I possibly needed a new ECM. I took out the ECM, opened it and looked for possible burning or any electric smell of death. Nope it looked as good as new so I put the whole ECM back in and it cranked up like a new truck idling at 750 rpm. So far so good. I think the Nissans are super sensitive to the fresh air after throttle body cleaning, leave the emphezyma in place(this isn't a Chevy NOVA). New MAF, IAC, Spark Plugs, Fuel filter, Vacuum lines, Air Filter.