[Andy Catts]

Bought my first Titan (2006 LE, 155k miles) about a month ago. Everything seemed great at first...and then.

The first sign something was wrong was the CEL/SES light came on. Checked it with my code scanner, and I had a code: P1148 (closed loop bank 1). Cleared it, 2 days later, got P0171, system too lean, bank 1. Starting to think I needed a new oxygen sensor/AFR. I cleared it again, and then got those two codes again. OK. Probably should get a new oxygen sensor/AFR. Then, I started having white smoke puff out of the exhaust on startup. :eek_surprise: Found a thread here that spoke of replacing the PCV valves. Ordered a pair on Amazon, and the problem continued to get worse while I waited for them to arrive. 2 days later, when they arrived, the truck was running terribly. Had codes for misfires in cylinder 8, and a "general misfire" code. ::crying:: That evening, I drained the oil (no milkyness, just dark, and about 2qt. low), put in new 5W-30 full synthetic, a new oil filter, new PCV valves, and 8 new spark plugs. I also took off the PCV hoses, sprayed them out with carb cleaner and then ran a bunch of patches through them until they were clean. Coolant reservoir has been full this whole time. No white gunk/sludge on the inside of oil filler cap.

The next morning, it started and ran like a champ. Cleared codes, they haven't come back in 2 days of driving. However, it still puffs white/blue smoke (though not as much) on startup, and under hard acceleration. Help!! When reading about the PCV valves, a lot of people said to replace the valve covers - did they mean replace the entire valve cover, or just take it off, clean it and replace the gasket?? I don't know if this is just residual effects of having clogged PCV valves, or if something worse is going on...

Help! What should my next steps be? I'm about ready to just trade it in and walk away, but I don't want to lose a ton of money on this thing. I'm fairly handy with a wrench, and willing to tackle just about anything. Thanks in advance!

 

[Pale Rider]

sounds like you read well and did the common issues/repairs first.
yes, some replace the entire valve cover as they are not that expensive bc they are all gooked up.
as far as the white smoke/blue smoke, could be valve stem seals, residual crap under the valve covers, rings, and a coolant leak issue in the head or gasket area.
not so easy test is to do a leak down test and compression test to check on the health of the cylinders/rings and valve sealing.

if you are going to throw money at it, replace the upstream and down stream O2`s as they may be contaminated now...

another issue is if your exhaust manifolds are cracked and leaking, the primary cats will deteriorate and pieces get sucked back into the engine upon exhaust reversion, literally killing the cylinder walls...

theres just no easy way around it other than keep looking at possible issues and reslutions, or take the loss and dump the truck for another. Seems it is hit or miss with how these USED Titans are maintained then resold to the next owner.
.

 

[Andy Catts]

Thanks for the information Pale Rider.

How would I check/test the exhaust manifolds for cracks/leaking? Where would you suggest buying new valve covers (I've only ever bought the gaskets before.)

Will a leakdown & compression test diagnose most of the potential issues besides the exhaust manifolds? I understand what it does, I've just never gotten this technical in diagnosing my own vehicle.

Anything that involves tearing the engine apart sounds like I should just light it on fire based on what I just read about replacing the valve stem seals.

 

[Pale Rider]

https://www.courtesyparts.com/
https://www.tascaparts.com/


a cracked manifold will tick like crazy,

leak down test is a test when you need/want to know if you have a leak or cylinder damage, guides, seals, valves, cylinder scoring, weak rings, when everything you`ve tried proved right/good. true the VK56 is not an easy engine to move around on.

and the weird thing about Titans and nissan in particular is Bad engine grounds, bad chassis ground, and bad body grounds cause all kinds of BS issues and codes that may not even relate to a real issue.

you just might have to take the truck to Nissan to have them hook it up and runs some diagnostics... not cheap either...

 

[Andy Catts]

Thanks again. The "tick like crazy" sound, is that all the time? Or just under certain conditions?

The engine sounds normal, though I'm not exactly sure what this "tick" sounds like.