MAF = .01 (just learning this stuff)

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Jan 24, 2022 | 08:17 PM

Xeus430

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From: CA

MAF = .01 (just learning this stuff)

I'm thinking the MAF @idle is reading way too low, and it does not increase much with driving. I'm just learning this stuff, but I suspect the starting point will be clearing it, and then replacing if necessary, but I don't know....

Conditions: 2006 LS 430.
Mileage: 93,000, TB replaced 55,000 miles ago (previous owner)
The car is in good shape.
I've noticed some slight and brief hiccups infrequently occurring during acceleration. I think the higher speed gas mileage MAY be lower than usual, but I live in big, hilly territory, so that is hard to say for sure.
The engine air filter was replaced with Lexus OEM last week (I never looked at this MAF until now).
Idle = 750 RPM
LOAD_PCT = 26.7 (this is a bit high, yes?)
ECT = 199.40 (seems OK)
SHRTFT1 (%) = 0.0
LONGFT1 (%) = 7.8 (after driving a bit, a bit negative and positive, both these jump around a bit, but the net is even tighter).
SHRTFT2 (%) = 0.0
LONGFT2 (%) = 9.4 (like I said, after driving, these tighten up)
IAT = 132.80

I am not sure which of these numbers may be the most relevant or relative, but thought I would I include them since MAF is a relational equation.

There are no warnings/ no codes appearing, but I just thought the MAF was way out of whack. I believe my next steps are to clean it with CRC, and then possibly replace it.

Ideas? Thanks.

Jan 25, 2022 | 06:11 AM

Peacebay

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MAF replacement is a prudent thing to do if it is original. Maybe it’s just me, but I have not had good luck cleaning the MAF sensor on these cars. Plus, the IAT sensor is in the MAF, and that temp reading seems high, especially for this time of the year (unless you’re in Florida, taking these readings sitting at idle for a while or something?)

The long term fuel trims at idle are high, but consistently high across both banks. This means there is unmetered air entering the intake somewhere (I.e. a vacuum leak) OR your MAF is underreporting the air flow.

Jan 25, 2022 | 08:09 AM

Xeus430

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From: CA

Good deduction

Yep, I’m in So Cal and it had been idling for a while. Definitely thanks for your input.

Jan 25, 2022 | 01:00 PM

Aus430

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From: New South Wales

Ltfts have a tendency to jump around a bit in these cars. More than some other types of cars that I've worked on.

How are your vacuum hoses? If they are original they are likely to be getting hard and brittle and likely to start leaking air in, especially noticeable if ltfts are positive at idle reducing to 0 or even negative above 2000 rpm

MAF,s are super important to the running of an engine. When I first started diagnosing my car I tried cleaning it, then replaced it with a new Denso sensor. It didn't fix my problem but a new sensor gave me confidence that the readings were correct and the problem was elsewhere in the system. (and I now have a known good sensor which came in handy when a friend bought the same sort of car). Turns out that these sensors were used in a heap of toyotas/lexus products so if you have a friend who is willing to let you swap in their sensor for half an hour it can save a lot of guessing (and buying unneeded parts) to known that your sensor is working well or not.

Jan 25, 2022 | 01:05 PM

Aus430

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From: New South Wales

Also, is there an operational problem that you are trying solve as such? Or more just wanting to stay on top of things?

Jan 25, 2022 | 06:16 PM

Xeus430

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From: CA

Staying on top

Just staying on top of things and using the projects to learn more.

all good ideas. Thanks.

Jan 30, 2022 | 07:01 PM

Xeus430

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From: CA

Update on MAF

Well, to show how a person learning can do potentially stupid things, I was using a reference of someone who quoting for the MAF grams per second when my scanner was reading LBS per second. Problem solved. Or no problem. Still, I cleaned the sensor and have noticed an immediate improvement in smoother idle (although it wasn't that bad). My mpg immediately improved 2-3 mpg, especially on the highway. The MAF Sensor was completely black on one side, and mostly black on the other. That's better now, although not completely clear. The CALC LOAD % dropped 6 to 7 points. So, it was definitely worth it.