sirdizzle

Hi guys, I have an 2009 IS350 with 62,000 miles. I took my car into the dealership for new spark plugs and brake fluid. Didn't need to do the official 60k tune up as everything else was up to date, and they charge $1,065 for the tune up which is mostly to "inspect."

Anyways, I leave the dealership and about 30 minutes later I get a check engine light, and the traction control light turns on as well. I have an OBDII bluetooth adapter, so I pulled 2 error codes: P0174 & P1170. Car definitely felt more sluggish, and my gas mileage became horrible.

Upon some research online, I found that the engine was running lean. My Air/Fuel Adjustment % was 20% and 21%, where before that it was at 0% and 2% warmed up, at idle. I came back to the dealership guns blazing, and they took a look and said that some dirt got underneath the manifold (probably when they were changing the spark plugs). They cleaned it up, took it on a test drive, and said that the air/fuel ratio was now at 5% and 3%. I plugged in my OBDII sensor, and confirmed that I was seeing the same exact numbers. They told me that it was now within specifications, and shouldn't throw any more error codes. After about 45 minutes of driving, I checked the Air/Fuel Adjustment % and was getting a 9% and 7%. Car definitely feels MUCH better than it did, but I'm wondering if I should go back to the dealership for them to do more "cleaning" to hopefully get the adjustment back to what it was before this whole ordeal.

Dealership also offered to do my next service free, so I'm wondering what I should tell them to do.

Can anyone with an IS350 tell me what their fuel trim is at? Is 9% and 7% acceptable? Shouldn't it be at 0% (or at least closer to 0%) when warmed up and idling??

Any help would truly be appreciated.

Noeh

iTrader: (3)

If it happened right after the spark plug device, then maybe they didn't put everything together properly and there's a vacuum leak somewhere. Go back and complain, they should look into it for free.

DKIS350

If they pulled the manifold and the gasket wasnt sitting right or like they said dirt got under the manifold upon reassembly, a lean condition would be likely since the car is pulling in un-metered air. Id drive the car a little more if the lights are off and its driving normally I wouldnt worry. If they didnt fix you will get a light back on pretty quickly.

I was able to do my plugs without taking the manifold off so i cant say i have ever seen this issue on my own car.

accelerate

You don't pull the manifold when changing the sparkplugs on a 350.

sirdizzle

well, it much better now. Fuel Trims are coming back to normal, and mileage is better (still not what it was though)

Gville350

iTrader: (10)

Exactly what I was about to say!

If the CEL comes back, do a full systems reboot by disconnecting the battery for 20 minutes.

sirdizzle

That is definitely worrisome, as that's what they said they did to fix the problem...