'02 Pathfinder Valve Cover Gasket Replacement

[VStar650CL]

[mppp78]

As far as the IACV relearn goes I've read in the following if not replacing the throttle body, but just disconnected the harness connector (steps 1-3) below, but in my Chilton a whole lot of more steps involving turning on/off, accelerator depressed etc. Which is correct? Steps 1-3 Below from Nissan manual or Chilton with about 10 steps but I will say Chilton states when a new one is installed so I suppose that's the reason for extra steps? Thanks for input all!

1) Make sure accelerator is fully released
2) Turn ignition switch on (btw I assume they mean turn engine on right because chilton says turn on engine?)
3) Turn ignition switch OFF and wait at least 10 seconds

[mdmellott]

I think you're looking at the Throttle Valve Closed Position Learning procedure, regarding those three steps. The IAVL procedure and the preparation steps are much longer. With regards to turning ignition switch On; That is strictly engine not running. My Haynes manual aligns with your Chilton manual and the Nissan manual, yet I have found errors and omissions in all of them. Less so often with the Nissan manual. All of this is on pages EC-73 through EC-75. https://www.nicoclub.com/service-manual ... 4%2Fec.pdf

[mppp78]

You are correct I am referring to throttle closed position 3 steps you highlighted as it says to perform these 3 steps anytime harness is disconnected. So hopefully last question and apologies if I'm not reading in between the lines here. I am not replacing the ECM or electronic control actuator I just disconnected the harness as I removed the throttle body do I first conduct the 3 Throttle body control learning steps then IACV steps as well, correct? (My wife's computer I wish I knew how to snip/steps to show you where I'm looking from your post, annoying!). Thanks again!

[mdmellott]

... do I first conduct the 3 Throttle body control learning steps then IACV steps as well ...

That is essentially correct. The IACV relearn procedure does state that this is necessary when replacing the throttle control but I'm not sure if that would include just disconnecting the harness connector from the throttle control. Those 3 steps may be all you need to do but since the IACV relearn procedure requires no tools and is fairly quick and easy to do, I would go ahead and do that as well, after the throttle valve closed position learning is done. I know VStar650CL would have a definitive answer on whether or not you need to do both.

[VStar650CL]

On the older ones, basically you should do an IAVL anytime you do something which affects the idle position of the butterfly or TPS. If you think about what IAVL does, it's calibrating the MAF reading against a baseline stored in memory and correlating it to a given throttle angle. So anytime you do something which affects the latter, IAVL is called for.

[mppp78]

All put back together and idling smoothly thanks for everyone's help.

[eyedol911]

For spark plug gasket, for aluminum valve cover, it is not that hard to replace it. I replaced my 2001 pathfinder SE valve cover gasket/spark plug seal twice and it is not that hard to replace it. Once remove the valve cover, the seal tab needs to be bent a little to clear out the seal with a plier and use a large flat head screwdriver to remove the spark plug seal by using a block of wood under the screwdriver. Just take time and easy will do fine. Before putting new seals, apply a small amount of engine oil to the seal and using a large enough socket and mullet to tap in.

My biggest problem is the new valve cover gasket is still leaking with new gasket in place, the driver side corner closer to the firewall is still leaking. I am afraid of the valve cover is not as good as before. It has been 24 years and 170+K miles now.

I might try Bar's seal repair and see how it goes.

Other than few engine oil leaks, the Pathy is still running fine.

[Mike W.]

After having had nightmare smoking on start problems with my '03 Q, which turned out to be the valve covers themselves and the hidden, inaccessible baffling, I would just go ahead and replace them if I was at anything besides low mileage. A hundred a pair from the big A, included new gaskets, a new PCV valve and new spark plug seals.

I have stabbed myself with a rusty screwdriver trying to save a couple of dollars too many times. Not that I'm ever to be likely to be in this position on a VQ again, but I would just buy new valve covers in a heartbeat. This gasket, that gasket, working out the SP seals, and on and on. As much as I eternally undervalue mine, time is worth something.

[VStar650CL]

After having had nightmare smoking on start problems with my '03 Q, which turned out to be the valve covers themselves and the hidden, inaccessible baffling, I would just go ahead and replace them if I was at anything besides low mileage. A hundred a pair from the big A, included new gaskets, a new PCV valve and new spark plug seals.

I have stabbed myself with a rusty screwdriver trying to save a couple of dollars too many times. Not that I'm ever to be likely to be in this position on a VQ again, but I would just buy new valve covers in a heartbeat. This gasket, that gasket, working out the SP seals, and on and on. As much as I eternally undervalue mine, time is worth something.

Big +1. The PCV system (hoses too!) is probably the most overlooked troublemaker on Nissans generally, and baffle issues can be -- well -- baffling. @Mike W is right, replace them and don't screw around. Make sure to use RTV at the right-angle corners where the gaskets go from horizontal to vertical, too. That's part of the procedure in the FSM, and neglecting it will almost guarantee an eventual leak.