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Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 20386
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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Altima: '03 Altima w/ QR25 160,000 miles. Problem w/ Excessive

Customer Question

'03 Altima w/ QR25 160,000 miles. Problem w/ Excessive oil consumption & smoking. Installed re- man long block, new pre- cat & cat,new valve cover & PCV valve. Same problem. Found Nissan NTB03-070c which refers to excessive oil consumption, cats replacement, & ECM reprogramming. Will ECM reprogramming spelled out in this bulletin address my oil consumption problem & if so, how? HELP !!! I'm running out of money!
Submitted: 2 years ago.
Category: Nissan
Expert:  Jake replied 2 years ago.
Hi there, thanks for your question.
Did you replace the catalyst because your failed?
Customer: replied 2 years ago.
Expert:  Jake replied 2 years ago.
Then your likely going to need a new engine.
In 05 Nissan revised the catalyst design because the 03-04 models are known to scavenge parts of the catalyst back into the engine when the catalyst fails. When this happens the engine grinds the metal pieces into a fine paste like lapping compound that slowly eats away at internal components and the oil rings are usually the first obvious indication of it.
Customer: replied 2 years ago.
In my original question I stated "installed re-man long block". To me that means "new engine".
Expert:  Jake replied 2 years ago.
How many miles on the new long block? The ECM programming is not going to correct oil consumption.
Customer: replied 2 years ago.
557 miles on new engine. Followed recommended break-in procedure as spelled out in Nissan service manual and basically the same procedure I have followed for the past 43 years.
Expert:  Jake replied 2 years ago.
Well as you know it's normal to burn some oil the first few thousand miles but NOT an excessive amount.
The only things we see cause oil consumption issues on these cars are what I already mentioned and what you have replaced already. I mean other than rings, valve seals, valve cover baffle, and PCV. There is not much else that will cause oil consumption and all that has been addressed according to your original post.
I don't think I would over analyze this here, but instead go back to the basics and do a leak down test to see if there is an issue with the newly purchased long block.
Customer: replied 2 years ago.
Leak-down tests indicate less than 10% leakage & vacuum gauge diagnostics reveal no abnormalities.
Expert:  Jake replied 2 years ago.
Yea, I understand your frustration then. I am about of ideas on this one if it's not losing oil, but actually consuming it. I will open it back up and maybe someone else has seen this particular issue.
Customer: replied 2 years ago.
No external oil leaks. I even installed an air/oil separator in the PCV line. The canister has a 24 ounce capacity. It will collect 8 ounces of oil in 40 miles of normal driving!
Expert:  Jay replied 2 years ago.
Hi, My name is***** happy to help you. During our conversation, I may be presenting you with different things to try, and ask you some Questions to get a better understand of the issue so I can answer your question properly. So stick with me to the end, and I am sure we should be able to get this issue resolved for you!
When you replaced the long block, did you re-use your original Valve Cover?