Swap coil pack from cylinder 2 to another cylinder to see if the CEL code change.
Also you say they changed gasket for manifold leak, you sure it's not a cracked manifold?

 

As stated in my OP, coils already rotated and tested. They are fine. ... And yes. Exhaust manifold is fine. It was just the gasket that needed to be replaced.

 

Ever had a new fuel pump?

 

Never had a new fuel pump, but mechanic said he checked and it was ok. But if it was fuel pump, wouldn't that affect all cylinders? Misfire is only on #2.

 

Nah. Recently had a mustang v8 with a miss on number 5. It was the fuel pump.

 

sounded to be intermittent problem at first. still swap that coil with another one and drive it till the CEL comes back and check it again to see if the misfire has changed to another cylinder.

they may have checked vacuum but still see if the intake gasket at the cylinder is bad. you can take a can of brake clean and spray around the intake gasket and seals. check if the injector seal is sealing.

last thing right now i can think of ONLY if its a problem in 1 cylinder is the injector. swap injector with another cylinder and see if any change. do only 1 thing at a time though..

oh and beware if you use brake clean.... we do it all the time at my work but be careful and keep it away from hot stuff like exhaust manifolds... i dont want to see you light your truck on fire! just dont douse it just spray little bits in small sections

when you swap a coil or injector swap it with one on the opposite bank... the technology these days have gotten very accurate at detecting the exact cylinder that has problems but to get a more accurate diagnoses swapping to the opposite bank will help

 

Thank you for the input guys. I don't have time, space, energy or know-how to do any of this stuff. I just take it to a mechanic and once they admit being baffle, I share with them what I've found on the net. (i wait until they admit they can't figure it out, then share stuff, so not to be insulting) ... I will give this info to my new mechanic ....he has welcomed the input....

If anyone has any more suggestions let me know.

I also forgot to mention that it runs super rich when misfiring. Smells like gas is practically pouring out. Another weird thing happened yesterday. It was back to misfiring. When I got in the truck yesterday and started it, fuel light was on, and gauge read almost empty. Drive it around for a while at those higher RPMs, and fuel light turned off and gauge got back up to about a quarter tank (which is correct). Once again, misfire disappeared after driving around at higher RPM.

 

Spark plugs are loading up. Take a look at the fuel pressure regulator.

 

there was a recall sent out by nissan for the fuel gauge reading inaccurately, have you had the recall done?

 

FUEL SYSTEM, OTHER:STORAGE:FUEL GAUGE SYSTEM
Recall for 2005 Nissan Titan

Recall Announced
MARCH 03 2010
NHTSA Reference
#10V074000
Number Affected
340,000
Summary: Nissan is recalling certain model year 2005-2009 Titan, armada, and infiniti QX56 vehicles. The instrument panel fuel gauge may inaccurately display that the vehicle still has some fuel, typically about one quarter tank, when the fuel tank is empty.

Consequence: This could cause the vehicle to run out of gas and stall on the highway, which could cause a crash.

Fix: Dealers will replace the fuel sender unit inside the fuel tank with a new improved sender card. This service will be performed free of charge. The safety recall began on March 22, 2010. Owners may contact Nissan at 1-800-647-7261.

For detailed information & supporting documents, see the official NHTSA page concerning recall #10V074000 »

 

Never had the fuel gauge replaced as far as I know. This was first time it happened and sounds like I had the opposite problem. Mine showed empty when plenty of gas in it. Obviously need to check that out now too.

Thanks for the info on fuel pump. I'll have new guy double check.

 

Thanks walrus. I will def pass that on and get that done.

 

Try swapping injectors on that cylinder and see if problem is a fouled injector.

 

any updates about this problem? has it been solved?

 

Low compression in cylinder 2. Put in a can of engine restorer and it's running great. Only took 14 months and thousands of dollars at the Nissan dealership. . . DO NOT GO TO PACIFIC NISSAN IF YOU LIVE IN SAN DIEGO.

 

Which engine restorer did you use? Having similar problem with cylinder #3.