LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

Replace your 20 - 30 year old MAF Sensor

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Old 08-02-20, 12:52 PM
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YODAONE
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Default Replace your 20 - 30 year old MAF Sensor

CRC Mass Air Flow Sensor Cleaner (Use 1995-2000 LS400 only) helps restore functionality to MAF sensors.





However, no matter how clean the sensor elements, their capacity diminishes through age or use.

On my 1999 LS400, routinely clean the MAF sensor with CRC Mass Airflow Sensor Cleaner each air filter change.

Recently a MAF trouble code arose and so cleaned MAF again.

The code dissipated, but after 178,000 miles, replaced the 21 year old MAF sensor with new purchased from Lexus....$200

Efficiency has improved appreciably, easily 15-20% with in city driving.

Not inexpensible, but payback over about 8,000 miles @ $3.00/gallon for premium and average 21 MPG

The engine is happier too...(catalytic converters, oxygen sensors, engine oil, valves (deposits), emissions system, etc.)

Transmission shifting feels more behaved.

Now seeing average 25 MPG. (Highway is 29 - 30 MPG despite LS400 has an LS430 engine transplant.)

Note: The MAF Sensor purchased from Lexus did not include the necessary rectangular rubber sealing gasket...although it is supposed to.
On information, Toyota is sorting this out.
As it is not sold separately, have Toyota/Lexus. parts counterman open the MAF box before purchase.

MAF sensor gasket


Old 08-02-20, 02:06 PM
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RA40
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Good tip. I'm making a list of parts to buy since factory ones are becoming scarce. The car passed smog but readings are increasing so I'm considering that some of the fuel and EFI related items may be at the verge of needing replacement.
Old 08-02-20, 08:47 PM
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Losiracer2
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Would replacing this be a benefit if I’m only seeing about 15-16mpg city? Or would you try cleaning first? 99’ with 157k. I average 28-31mpg hwy but city is pretty horrible. It has been extremely hot lately, averaging 110-115 for the last 2-3 weeks, so AC is working nonstop.

Or would this be typical of severe/extreme weather causing the fuel coming drop?
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Old 08-02-20, 09:24 PM
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YODAONE
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Originally Posted by Losiracer2
Would replacing this be a benefit if I’m only seeing about 15-16mpg city? Or would you try cleaning first? 99’ with 157k. I average 28-31mpg hwy but city is pretty horrible. It has been extremely hot lately, averaging 110-115 for the last 2-3 weeks, so AC is working nonstop.

Or would this be typical of severe/extreme weather causing the fuel coming drop?
Try using CRC cleaner, but experienced better results with city MPG using new MAF sensor.

Last edited by YODAONE; 08-02-20 at 09:29 PM.
Old 08-03-20, 12:30 AM
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In city ours does that 15-16 too. Worst has been 12 with really bad crawling traffic.
Old 08-03-20, 12:41 AM
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Worst I've seen from a tank is 17mpg during the summer with A\C running. Dense city driving <40mph, tons of traffic. Typical city is 18-20mpg. Mixed tank is usually 23 or so.

Highest I've seen is 32.5 on a half tank with a tail wind and a thousand foot elevation loss. Highest "normal" I've seen is 28.2.

However, I'm at altitude, which helps things slightly.

Last edited by 400fanboy; 08-03-20 at 12:45 AM.
Old 08-03-20, 01:21 AM
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Yoda- I know the 95-97 models used a different MAF sensor than the 98-00. If it can be cleaned as you stated using the CRC cleaner then they're not the Karman Vortex AFM, correct? Please confirm. Thanks
Old 08-03-20, 06:05 AM
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JohnAndic
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Originally Posted by Superfast1
Yoda- I know the 95-97 models used a different MAF sensor than the 98-00. If it can be cleaned as you stated using the CRC cleaner then they're not the Karman Vortex AFM, correct? Please confirm. Thanks

I believe it is the 1st gen that have the AMF.
Old 08-03-20, 07:03 AM
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sdls
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Originally Posted by JohnAndic
I believe it is the 1st gen that have the AMF.
the 1990-1994 have the karman vortex air flow meter; the 95-97 have a hot wire mass air flow sensor. The KV AFMs of the 90-94 should not be cleaned.
Old 08-03-20, 08:00 AM
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That's what I thought. Thanks guys
Old 08-03-20, 09:42 AM
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Wonder if this will help the issue I have where it wants to turn off after start up when hot. Doesn't do it when car is cold or outside temp is cold
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Old 08-03-20, 11:27 AM
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I use CRC Electrical parts Cleaner to clean MAF sensor. It works fine.
Old 08-03-20, 12:12 PM
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Originally Posted by Sin1UZFE
Wonder if this will help the issue I have where it wants to turn off after start up when hot. Doesn't do it when car is cold or outside temp is cold
If you use CRC please keep us posted
Old 08-03-20, 12:29 PM
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Originally Posted by EthanS
If you use CRC please keep us posted
Wasn't planning on it. Was just gonna replace maf
Old 08-03-20, 12:43 PM
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Originally Posted by FloridaCam
I use CRC Electrical parts Cleaner to clean MAF sensor. It works fine.
CRC offers offers both Electrical Parts Cleaner (which I have) AND Mass Airflow Sensor cleaner which I purchased to clean the MAF

What do you see as the difference?


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