2007 Lexus ES350 long terms running lean, no codes (at the moment). Lost (LONG)

Hello all. Thanks for taking the time to read, as I'm pretty lost. I have a 2007 ES350 with 134k miles. WARNING. THIS WILL BE LONG. Please follow along carefully. I'm going to list all issues I've had in case there's any connections between anything. I'm in NYC so it's generally city driving and speeds. I try to take it on the highway when I can. The MPG has kind of annoyed me since I bought it (have had LS's of the same year from other owners telling me they get better MPG than me) and maybe this is related.

CAR: 2007 Lexus ES350 - 2GR-FE 3.5L V6

I'm in between jobs right now so I started using my car to deliver food. I don't use this car much, I bought it 11 months ago at 132k miles. I didn't let it sit, I do drive it.

So it started when I noticed after the engine was warmed up, and I shut the car off, run for a few minutes to pick up food or deliver it, come back, and start the car, the engine may struggle for a second. The RPM needle will drop low, but the engine won't stall, then it turns on. Other times, the RPM needle may shoot up very high. This only happens when the engine is warmed up. This video I have is the worst example of it. (This car is my first experience with a start stop button, so I always thought you had to hold the button. The engine didn't turn over until I let go of the button. I then read I just have to press the button once, so this issued never occurred at this length of 10 seconds again, but still occurs briefly sometimes)

I plugged in a OBD2 scanner I borrowed 2 days after that video. It said there was a P0300 on the day that video was taken. I did not see any check engine light, nor any was present. The bulb does work because I see it when I'm in accessory mode. Anyways, I looked at the fuel trims and the long terms were in double digits, 21-22% on bank 2 was the worst.

This is where I went down the rabbit hole. I was trying to get help on other forums. I was told to clear it, and see if it comes back. Well it didn't. Someone then asked for my downstream O2 sensor readings. They both sit around .7-.8V. They said oh they're dead, they're supposed to oscillate like a sine wave, replace them. I find out it's normal on Toyotas. The A/F upstream's oscillate. So that was for no reason, but I have new ones on, they both still sit around .7-.8V.

Then I was asked to report long terms at idle, 2500 RPM or 3000 RPM, etc. Usually, the long terms would drop when revving, which seems to be a vacuum leak. So I made a DIY smoke tester, and the smoke being from incense. Though I found out incense suck and need to constantly be relit, so I didn't get far. But I found a torn hose on the fuel vapor line. I patched it. Fuel trims dropped to 5-8% on both banks. That only lasted that day, they returned to 16-17%. But my gasoline smell at least has seemed to disappear.

Went to autozone when I was having starting problems. They tested the car. Said the battery and starter fine, the voltage regulator on the alternator is failing on a load (lights, wipers, radio, etc). 13.1V. Now the thing is, they told me the alternator was failing 7 months ago in October and it would die in 30 days. That never happened.

So then I decided to go to a mechanic last week so they can smoke test it and I explained everything I'm writing here. They take the car. After the whole day, I call them and they said they did not have any bad fuel trims, and if there was no code, to not worry about it. They had fuel trims 5-8% they said, so they did NOT do a smoke test as he thought it was unnecessary. They also could not replicate the starting problem. No charge.

Take the car home, and everyday since then the car has continually double digits fuel trim nearing 20%. They told me I can bring it by if it did the starting issue, which it did 3 times in an hour when I was delivering. Of course when I got there, the car didn't do it. He said sorry, can't help me, has to be consistent, and I had to leave. He didn't seem interested in wasting any more time, but I also understand he can't do anything if the car is acting fine.

I dumped techron into the tank yesterday cause my friend is insisting it's the fuel injectors. After 8 hours of delivering, still double digits, and in fact, they reached 22% on bank 2!.

This is what I've done with the car since I bought it.

• New Spark Plugs at 132.5k miles, 8 months ago. (The old ones, some, especially 1, had black oil on the threads, wet.
• Autozone battery from last owner less than a year old died in January. Replaced with Interstate Battery
• Replaced downstream O2 sensors last week (both of them)
• Replaced return power steering line (but obviously not related)
• Repaired torn fuel vapor line

Another two things but they're unrelated I guess. The subwoofer has static, especially when I turn on the rear defogger. Some of the lines are broken.

The other thing is the fuel rail facing towards the front of the car, they have wet looking spots on the engine bay, as if they leak a bit? But I was told the way it looked it's normal and when I touch the spots, it's dry. Although I guess the heat could evaporate whatever is there.

After doing some research again, I read the problems plus some material on the threads of the old spark plugs may mean a bad EGR valve. So I bought one from Lexus. Installed it today. It's currently setting with the locktite on the threads. I also put a new gasket on the oil fill cap in case there was a vacuum leak there. Haven't checked the long terms yet. Although I don't think the old valve was stuck open, I heard it rattle.

So if anyone can point on where I should start over and investigate again, that would be great. Thanks. I can post any data you need.

Update: After doing some more reading last night, I read to unplug the MAF sensor and see how the car runs on default values.

Well, the car instantly dies, RPM completely drops to 0! Tried it 3 times. Any clues?

Hello all. Thanks for taking the time to read, as I'm pretty lost. I have a 2007 ES350 with 134k miles.

One day back in Feb. I decided to plug in my scan tool because I had a very slow start. I looked at the fuel trims and the long terms were in double digits, 21-22% on bank 2 was the worst. They're lean on BOTH banks.

I was trying to get help on other forums. Someone then asked for my downstream O2 sensor readings. They both sit around .7-.8V. They said oh they're dead, they're supposed to oscillate like a sine wave, replace them. I find out it's normal on Toyotas. The A/F upstream's oscillate. So that was for no reason, but I have new ones on, they both still sit around .7-.8V.

Then I was asked to report long terms at idle, 2500 RPM or 3000 RPM, etc. If the long terms for example were around 20%, they drop to around 12-14% if I rev the engine for 20-30 seconds.

So then I decided to go to a mechanic 3 weeks ago so they can smoke test it and I explained everything I'm writing here. They take the car. After the whole day, I call them and they said they did not have any bad fuel trims, and if there was no code, to not worry about it. They had fuel trims 5-8% they said, so they did NOT do a smoke test as he thought it was unnecessary. They also could not replicate the starting problem. No charge.

Take the car home, and everyday since then the car has continually double digits fuel trim nearing 20%. The highest they've been is 22%. I smoke tested the manifold myself with a diy smoker. Nothing. In fact, if I remove the pump, the system forcefully pushes the smoke out through the jar. I reconnected the airbox etc, and then tested for leaks there. Nothing. I also tried spraying water, didn't see any changes. The only place I can't spray water is 3 injectors that are hidden under the mainfold. I have pinched the PCV hose to the manifold, barely a change to the short terms.

I found the factory service manual. According to the manual, two things fail.

For the brake booster, the brakes push back up against me once I depress and shut off the engine. It immediately does so. But the other tests, it doesn't fail. Also, when I press the brakes, the short term fuel trims can rise up to 10% and stay there. I have pinched off the hose for the brake booster, and the short terms at a max moved to -5% but on avg were -2 to -3%. I tested the valve on the booster, it works fine.

For the MAF, at 75C: at idle: Expected: 3.1-4.7g/s: Actual: 2.75g. At 2500 RPM, Expected 13.1g/s-18.9g/s: Actual 10.6g/s. It says replace the MAF. I got one from a junkyard ($20 buck gamble). Yes the part number is right. From an 08 Toyota. It reads around the same as this one. So either that one is bad, but now I'm reading a vacuum leak can cause the mafs to underreport? Yes, BOTH sensors were cleaned with maf cleaner.

I feel like I'm going in circles and about to lose my mind. 2 months trying to figure this out.


This is what I've done with the car since I bought it.

• New Spark Plugs at 132.5k miles, 8 months ago. (The old ones, some, especially 1, had black oil on the threads, wet.
• Autozone battery from last owner less than a year old died in January. Replaced with Interstate Battery
• Replaced downstream O2 sensors last week (both of them)
• Replaced return power steering line (but obviously not related)
• Repaired torn fuel vapor line
• New EGR Valve
• New oil fill cap gasket

I merged your topics for you so that all of the relevant information is in one place.
If your post gets pushed back a page, you can just reply "bump", and it will get bumped back up to the top of the list where everyone will see it again.

So if I understand correctly, stepping on the brake pedal causes a positive increase in fuel trim?
And that condition is corrected by blocking the vacuum line to the booster?
Sounds like you found a leaking booster.

Hi Noah. Thanks for the response. I actually purposely didn't bump the thread, because I thought maybe people thought it was too much to read, so I tried to shorten it to the best of my abilities.

If I step on the brake pedal, the short term can go to the max of around 10%. I was told to pinch the brake booster hose, and if the short term goes wildly into the negatives I found my leak.At idle with the brake not pressed, when I pinch the hose, it does not go wildly into the negatives, it just goes around -2 to -3% on average. So I am confused whether the short terms going positive when pressing the brake is normal behavior.

Would a vacuum leak cause the maf to underreport? Or should I try a new OEM maf?

I have a video here of a sound I hear from the brake pedal. Not sure if it's the sound of a leak, because I heard there should be a sound from normal behavior. streamable.com/bktt62

A slight update. I was trying to demonstrate this to a friend. I drove a bit today. Long terms both banks were at 20%. Holding the brake pedal down, I was able to.push the short terms from 0 to.double digits, all the way to 20 as the highest. Then it dropped down after a min to the lowest around 7%. The long terms got pushed to 25%!!

On his Chevy Tahoe 06, his car did not emit this behavior. Also his gas pedal does not immediately press back on him if he presses down and shuts the engine off, where mine does.

Can I smoke test the booster? Would smoke come into the pedal area if there was a leak?

I think the trims tell the whole story.
I don't know about the pedal pushing back after turning off the engine, but the trims tell you the booster is leaking vacuum.
I guess you could smoke it? I don't like DIY "smoke machines" that rely on combustibles. You're, quite literally, playing with fire. Not to mention the residue that gets left behind from burning incense or paper or whatever. But that's just me.

+1 on the ."smoke machine" comment.

If the op was prepared to step "harder" on the brake he just could block the vacuum hose running from the booster to the intake and watch the fuel trims on a test drive. He should do apply diligence and necessarily precautions while driving/braking without vacuum support.

Thanks for the replies. The reason I'd want to smoke test is because I've thrown some stuff at this already and being told oh it's X, and it ends up not being it. It seems to be a very expensive part...

The Toyota documentation I have says the following:
"Depress the brake pedal while the engine is
running, and stop the engine with the pedal
depressed.
HINT:
If there is no change in the pedal reserve
distance while holding the pedal for 30
seconds, the booster is airtight."

The reserve distance does not hold, it immediately presses back. The thing is, there are other tests here that indicate it IS airtight because it doesn't fail the other tests. So it leaves me confused. There is a video here on the topic if anyone is interested.

Do I have to be driving to test the trims? Or can I just pinch the hose, and then press the brake while parked, like I was doing earlier?

You can do the test without driving around. You do not have to step on the brake during testing. Just compare the fuel trims while the hose is pinched to those when the hose is not pinched. You may want to test at different rpm.

Hi. I tried pinching a few days ago with only a negative short term fuel trim around -2-3%. So I assumed it wasn't the problem. But I only did this at idle while parked.

So I guess I should try different combinations. For example, In Park, rev with it pinched, or press the brake with it pinched, etc.

The total fuel trim is what you have to look for. Short term trim only at 2or 3% could be anything, good or bad, it depends on the context - in this case LTFT.

Well I'm looking at the short term at that moment because isn't the short term essentially the live data, vs where the long term is the average of the live data?

For example, I just pinched it, and pressing the brake I can still bring the short term to 10-20%. Not sure why if it's pinched. Maybe bad vise grips? Bought them for 3 dollars.

But I will try the test again looking at the total fuel trim as you suggest.
Is this a good test to report back with?
w/o brake booster pinched
Fuel Trims at Idle
Fuel Trims at 2500 RPM

w/ brake booster pinched
Fuel Trims at Idle
Fuel Trims at 2500 RPM

Hi. So I tested the car today parked. I didn't drive today, just let the engine warmed up. The long terms weren't that high as usual.

IDLE, NOT PINCHED
STFT Bank 1: -1.56%
LTFT Bank 1: 12.50%
Total Bank 1: 10.94%
STFT Bank 2: -0.78%
LTFT Bank 2: 14.06%
Total Bank 2: 13.28%

3000 RPM for 30 seconds NOT PINCHED
STFT Bank 1: 0.00%
LTFT Bank 1: 14.06%
Total Bank 1: 14.06%
STFT Bank 2: -3.91%
LTFT Bank 2: 15.63%
Total Bank 2: 11.72%

BACK TO IDLE AFTER 30 SECONDS, NOT PINCHED
STFT Bank 1: 0.00%
LTFT Bank 1: 11.72%
Total Bank 1: 11.72%
STFT Bank 2: 0.00%
LTFT Bank 2: 13.28%
Total Bank 2: 13.28%


IDLE, w/ BOOSTER PINCHED
STFT Bank 1: 0.00%
LTFT Bank 1: 12.50%
Total Bank 1: 12.50%
STFT Bank 2: -0.78%
LTFT Bank 2: 13.28%
Total Bank 2: 12.50%

3000 RPM for 30 seconds w/ BOOSTER PINCHED
STFT Bank 1: 1.56%
LTFT Bank 1: 14.06%
Total Bank 1: 15.62%
STFT Bank 2: 0.78%
LTFT Bank 2: 15.63%
Total Bank 2: 16.41%

BACK TO IDLE AFTER 30 SECONDS, w/ BOOSTER PINCHED
STFT Bank 1: -1.56%
LTFT Bank 1: 11.72%
Total Bank 1: 10.16%
STFT Bank 2: 0.00%
LTFT Bank 2: 13.28%
Total Bank 2: 13.28%

:blink: :blink: :blink:

The results of your exhaustive tests reflect a general fuel delivery problem:

It is NOT bank specific, both banks are affected.

The slight differences between booster hose pinched and not pinched do not point to a mayor leak there, though there might be "A" problem as indicated by the pushback of the pedal when shut off.

The needed percentage to compensate for the lean condition is almost consistent over the tested load/rpm ranges. A skewed MAF sensor often misreports worse under higher loads and rpm than under light loads/idle. The reported air mass at idle seems to sit at the low end. You already changed this sensor to no avail, although the replacement came from a junkyard. .

Possible other reasons for fuel delivery problems may be insufficient fuel pressure and fuel volume. This could be anywhere from the pump up to the inyectores. A pressure test seems in order to me at this point, depending on your tooling you may want to have a look at the pump's voltage and ground while working, as well as it's current consumption. There are more things to consider regarding fuel delivery but this is a starting point.

The O2/AF sensors are also critical for correct mixture adjustment. Though not probable that both upstream sensors fail at the same time in the same manner you could force lean and rich conditions by introducing 'false air's at one time and extra fuel ( carb cleaner ) at another and see if the sensors respond accordingly.

Lexus cars of this vintage probably will report 3.2 volts as lambda 1. Higher voltages display a lean mixture and lower than 3.2 would be rich.


I'd be interested in the manifold vacuum at idle and your altitude as well. Does the car feature a true baro/map sensor (I don't think so...)?

Well the maf either the junkyard is also just underperforming as well...or it is fuel like you said. I could try and order an OEM maf from rockauto, but if it's not the issue I heard returns are a bit of a pain...

Sometimes I do smell a gas smell when I start the engine, usually around the front. I thought it went away when I repaired a fuel vapor line, but I smelled it again the other day. Maybe a leak somewhere? The front 3 injectors have this sort of staining on the engine bay. I was alarmed by it when I saw it, but was told it's normal...it usually doesn't feel wet...

Unfortunately the car does not have a normal schrader valve to pressure test. I have to get some adapters then find where to tap into to pressure test. I see two connectors to tap into here at clamps 23841B and 23842A. A bit annoying because to attach the tester, gas is gonna leak everywhere into the engine bay. I think another attachment MIGHT be in the back near the tank but requires lifting the car. Though I can't find it in any diagrams showing it. I have a simple voltmeter and the test light probe. The injectors I see some testing to check the resistances. But the other 3 injectors are under the intake...

Both upstream A/F sensors I usually see around 3.3V. Never tested them introducing lean or rich conditions, but one of the banks I did test a long time ago by just measuring the resistance of the sensor according to the documentation and it was according to spec. Is that enough to rule out the theory of both going bad?

I do not believe there is a MAP or baro sensor. My current altitude is 4m/13ft

EDIT: I measured the resistance of injectors 2, 4, and 6 (corresponding with the cylinder numbers). The spec expected is 11.6-12.4 ohms at 68F. It's 50F today but I got 12.1-12.2 ohms on all 3. The others I cannot and other tests I cannot perform yet.

Hi. An update. I got a fuel pressure tester kit and the adapters to tap into the system. I will probably test tomorrow. In the meantime, I tested the resistance on injectors 2, 4 and 6 and all seem in spec.
Also my scanner shows a reading for a baro sensor, around 100-101kpa.

Here's something interesting. My friend was joking if I had a spider issue with the car. He saw a spider on the outside a few weeks back when I was at his place. I've seen 2-3 on the outside during the night. Tonight, I saw approximately 3-4 near the trunk area. One got inside but I killed it. It seems they are yellow sac spiders. I read they are attracted to the smell of gasoline, and to the point Mazda and Honda did recalls as they would get into the evap systems and cause problems...but what are the chances this is the actual reason the car is having issues...the smell of gas, lean trims, and the spiders on the exterior. I mean though I thought evap causing lean would just be from the solenoid.

Hi. I did the test today. Originally got sent the wrong adapters. I tested at the front between the fuel rail and the lines that run from the back to the front.

Engine start PSI: 52 psi
Idle: 52 psi
Shutdown: Immediate jump to 45 psi
After 5 minutes of shutdown: 41.5 psi

Toyota Documentation:
Fuel pressure:
304 to 343 kPa (3.1 to 3.5 kgf*cm2, 44.1 to 49.7 psi)

---

❌
• If the fuel pressure is greater than the standard
value, replace the fuel pressure regulator.

---

❌
• If the fuel pressure is less than the standard
value, check the fuel hoses and connections, fuel
pump, fuel filter and fuel pressure regulator.
Stop the engine.
(o) Check that the fuel pressure remains as specified
for 5 minutes after the engine stops.
Fuel pressure:
147 kPa (1.5 kgf*cm 2, 21 psi) or more

---

✔️
If the fuel pressure is not as specified, check the fuel
pump, pressure regulator and/or fuel injectors.


I mean the PSI wasn't far off from the max on the spec, and wouldn't higher pressure being causing a rich condition as opposed to lean? Maybe the gauge is just not spot on...anyways maybe this points to both MAF's just being bad?
A summary to previous tests. Injectors 2, 4 and 6 resistance is in spec. Car does seem to have a barometer reading 100-101kpa.

I induced a lean condition and both A/F sensors went to 4.45-4.5V

I also saw at 120k miles for the car, (I'm at 134k miles) the dealer recommended the last owner to do a MOC fuel system decarb, but it was declined.

OH. As for the spiders. When I went to the fuel pump under the seats, I lifted the lid and there was one there! They have to be nesting in the area? I had to close the lid quick to prevent any of the spider's friends from entering the interior of the car.

Bump