Lexmart

My 2013 ES350 has had this slight vibration since I bought it about a year ago. I have 168,000 miles and over the last several months have been using my time to learn more about maintenance and see what I could find. Youtube and googling lead me to many videos and discussions of long term fuel trims. So, I fired up my bluedriver OBDII tool and starting scanning. I learned that my ES350 had a slightly higher than normal long term fuel trim on both bank 1 and, in the range of 9-10 % for bank 1 and 12-13% for bank 2. Not high enough to trip any codes, verified by my scan. I learned that this means a lean condition is being measured by the fuel-air ratio sensor (upstream sensor is not the simpler oxygen sensor) and the ECU adjusts fuel injector pulse to spray more fuel to reach stoichiometric ratios (too much youtube, sorry). Watching Schroedinger's box and Scanner Danner has been eye opening, but also just raised more questions. I learned that if you rev the engine, and the long term fuel trim drops, it usually points to a vacuum leak. And, that anything below 5% trim (plus or minus) is not unusual and normal for engines (maybe even up to +/- 10%). Also, it could be signs of a worn engine. I do have 168,000 miles after all even on the normally reliable 2GR-FE.

So, I'm planning to go back and study some more, but I'm looking to bounce ideas off members here who may also be more mechanically inclined or perhaps experienced with lean conditions.

What I've done to date.

1. Checked for obvious cracks in vaccum lines, like snorkel between the air filter box and the throttle body. No holes.
2. Checked my MAF sensor, cleaning it and measuring the resistance of sensor. It meets alldatadiy specs. Also, airflow rate is in spec for engine off (per alldatadiy procedure). No real change, maybe a little lower long term but not a lot.
3. Checked brake booster for vaccum leaks (again following alldatadiy procedures). No indication of booster vaccum leak. I even clamped off the booster vac line while watching RPM and long term fuel trim and listening. No change.
4. Did a propane leakage test around the vacuum lines, valve covers, intake manifold, fuel injector seals, PVC. It's hard to reach the back bank injectors, valve cover, rear intake manifold, but I did my best to flood those areas with propane. No changes.
5. Water leak testing (Scanner Danner) not changes.
6. Induced rich condition and watched air-fuel ratio sensors respond as well as reduced long term and short term fuel trims by using propane into the air filter box.
7. Induced large vaccum leak by pulling various vaccum lines and watch air-fuel sensor and LTFT and STFT respond appropriately.
8. Increased RPMs in park and watched bank 1 and bank 2 LTFT. There might be something interesting there. More details below.
9. Measured resistance of bank 2 (front of car) air-fuel ratio sensor. Good.

What I haven't gotten around to is a smoke test (gathering pieces to build a DIY tester ala youtube), measured the rear air-fuel ratio sensor (pain to find and access, or either of the two downstream bank 1 and bank 2 oxygen sensors (haven't crawled under the car for that yet).

Back to the interesting RPM results. I logged a drive I took from COSTCO to home and before I parked at home, ran the RPMs in park up and down and recorded the LTFT for both banks. WHat I found was that as I increased the RPM from idle, bank 1 LTFT started to drop at each increasing RPM level, and bank 2 increased. They were opposite eachother. This is different than I normally observe if I record these after a cold start, where increased RPMs tend to drop those LTFT in both banks a few percent.

So, I'm wondering if anyone is willing to lend ideas and advice. Hopefully I haven't bored you to death. Thanks.

MikeFig82

iTrader: (13)

I am resurrecting this thread since it's similar to what I'm working on recently. I picked up a 2013 GS350 Fsport RWD with 110k.

I've done all as stated above checked vac leaks evap purge valve, brake booster check valve, hoses... etc.

I'm familiar with fuel trims somewhat not a pro.

At this point I'm leaning towards a clogged fuel filter. Fuel trims stay lean shorts, longs come down while cruising, but it feels like I have the brakes applied somewhat.

OP did you ever figure out your lean condition?

2013FSport

iTrader: (2)

Mike, his last post was nearly 2 years ago.
If the LPFP were strained for volume your AFR would be off under load. I'd suggest monitoring each bank while pulling a good hill where it can reach and hold a steady RPM >4500 RPM for a while.

Have you disconnected the battery and let it relearn? And do you have access to Techstream? It has an option for power train relearn. When I had the 2GR-FSE ECM flashed it started up and held like 2000 RPM for several minutes and hammered on the DI and PI doing some rhythmic exercise. In the times since 2017 when I bought it, it's never done this from any battery disconnect and I'm wondering what about the flash induced this action.

Has your 250 ever done this before? You've had it for a while...