pyrophilus

Hi,

My 2001 Pathfinder (VQ35DE) has been idling rough once about a minute and sometimes stalls during idle. Drives perfectly fine.

Anyway, brought car into dealer and I was just told "no codes", but the "MIL" light is on!?!?!?

Dealer mechanic says that I should get TB cleaning and fuel injector cleaning. I did have codes read about 2 weeks ago and I was told that the engine was running rich.
Car also makes wisp of black smoke during morning starts.

Considering that the dealer is saying it is a "simple" throttle body carbon build-up, or dirty injectors, I am wondering how dirty injectors can lead to rich running engine (wouldn't it be running lean then?). Also, I was pretty sure that most repair manuals says to not clean the TB, because (at least for the pathfinder) it has a special coating to keep it from getting build-ups...

Anyway, the dealer wants $189 plus tax for these two, "for starters" and wants to see how that "deals" with the problem (they sound like local exxon gas station mechanics). Sadly, all three local nissan service is like this (other one charged me $225 to reset MIL light).

I wanted to know if someone thinks dirty throttle body can be cause of rough idle/stalling during idle?

thank you for any help,

b67

How many miles? Every couple thousand miles my 99 will start to idle unevenly - the rpm guage will bob around - I figured out I could solve this by adding a bottle of fuel injector cleaner to a quarter of a tank of gas. Supposedly if you take long highway ride (being aggressive with the throttle) it helps the cleaning.

After doing this my rpms will be steady at idle for at least 7-10k miles. The cleaner I use is cheveron brand - not sure if brand is relevant

pyrophilus

I reluctantly agreed to the TB and Injector cleaning (at least they weren't dumping injector "cleaner" into the gas tank and charging me $189, the other dealer did). The guy calls back and tells me that after the cleaning the car was even worse and then they "realized" that the Air Flow meter is clogged?!?! He then told me that perhaps it was partly clogged and cleaning the TB caused more carbon deposit to get stuck in the MAF really tripping it (his exact words!).

I initially thoguht it might be MAF, and courtesy Nissan quoted over $400 for the MAF, so I brought the car in hoping that they'd check the MAF (since I have warranty). I guess dealer wanted to make extra $200 through TB cleaning...

I then asked if he means the Mass Air Flow sensor when he tells me Air flow meter. He said yes. I have a question. Isn't the MAF before the throttle body? I never really looked for one (thank God it's okay in my Max), but I thought it was between the air filter housing and the throttle body? If I am correct, how did cleaning the TB cuase carbon deposit to flow against airflow into the MAF???

Anyway, thank God that I still have my extended warranty. As for today, I more than evened out with the initial extended warranty price through the MAF service. I used to think they were crap, but now I realize that maybe it's not so bad after all.

Thank you everyone who tried to help

pyrophilus

B67, I think your Pathfinder will really benefit from a throttle body cleaning. I had a '97 SE (same VG33E engine), and it was notorious for carbon deposits (would gum up the throttle and make the pedal stick too).

I think it's pretty easy.
http://www.motorvate.ca/mvp.php/517

Follow these instructions (very similar), but DO NOT USE CARBURATOR CLEANER! The Nissan throttle body has a coating that resists carbon build-up. If you use carburator cleaner, it will strip this coating and will make it worse. They sell "THROTTLE BODY CLEANER". This is what you need. I used to use fuel injector cleaner in the gas and had to do this every other oil change, but once I cleaned the TB, I had perfect idle (couldn't hear the engine) until I sold it 2 years later.