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First let me say hellow. Im a first time Lexus owner. I have 1990 LS 400. 225,457 miles. :) Runs lote a top, Or at least it did. :(

I bought the car about 2 weekis ago at auction for $1,400 abd drove it home. Seeing that it has a few miles i thought i would do some work on it. I did the front brakes, New rad, coolent hoses, drive belt, timeing belt, water pump, and tune up.

I got every thing done and started the car and it ran fine for about 2 MIN. I shut the car off, put the tires back on and lowered it off the jack stands.

I re-started the car and it seamed to rev up a bit. Then remembered to glug in the sensor on the bottom of the rad. I pluged it in and ite idle droped down and sounded good.

After about 5 MIN the engine started surging up to 1800 RPM and the exaust is geting vary hot.

I checked every thing and i dont see eney thing rong.

I realey love this car. Eney help would be grate.


Backfire Rabbit. :P

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Hello back and that's a great price.

The heat up may have something to do with the cooling system. What does the temperature gauge inside the car show?

1800 rpm is quite high and my car does this if its cold outside - usually below freezing. The temp gauge needle huddles at the bottom looking for warmth.

If all else fails maybe worth throwing in a hundred or so to the Lexus dealers for a diagnosis.

Good luck.

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Judging from previous posts, the NMAF is a very sensitive device.

There is a writeup here about testing it :

I will do a summary for you from the manual. It is from page EG-183 for 1996 LS400.


Resistance goes down as the temperatures go up. For normal temperatures (20 C / 68 F the resistance should be 2-3 KOhms.

This resistance is measured between the THA and E2 pins.

When looking at the male end connector while MAF is still on the car,

THA is third pin from the left

E2 is second pin from left.


--> Connect volt meter, positive to VG and negative to EVG.

When looking at the male end connector while MAF is still on the car,

VG is fourth pin from the left

EVG is first pin from left.

--> Turn ignition on, blow air into the MAF.

--> Voltage should fluctuate.

I found out how to get te codes with out a scaner. I hope this helps someone. It did for me.

I got a code 31. Mass airflow signal.

Will water hurt the sensor? It got rained on when i had it off.

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