1990 LS400 175K - idle at 200 and then stalls

The 1UZFE EGR Delete Kit is available for sale here.

Terry in Va Beach

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30
Location
Virginia Beach, VA
Took it in to the dealer and they saw code 31. Diagnosis is replace with a new MAF sensor at $1004. Then step 2 is recheck system and see if problem still exists. I assume the next step is to replace the idle speed control valve at $600. The car has gradually gone down in idle over the last year to the point it is now. With air conditioner on idle stays at 400 rpm and does not stall. Any ideas or suggestions?
 
Damn.. MAF for 1000? and ISC for 600. Try to adjust your TPS. Its a spoon shape black color attach to the throttle body. The are two screws. Just loosen the screws and rotate it. I think its clockwise to increase rpm. Secondly, you might want to check the throttle cables and other accessories.
 
Doing some trouble shooting.

I did some research in my factory repair manual and found the following concerning my trouble code 31. Code 31 goes into the ECU memory which then "makes the ECU operate in the fail safe function, keeping the ignition timing and fuel injection volume constant and making it possible to drive the vehicle."
First thing was to reset the trouble code. Simple thing to do by removing the EFI fuze for at least 10 seconds.
Second thng I did was to clean the throttle body which was really nasty. Third thing I did was to adjust the throttle position sensor (TPS) clockwise to increase idle rpm. (Thanks Lextreme for that tip).
Idle is now at 700, but need to get it up to normal operating temp to ensure it is at 650 rpm with no load on ie; without the air conditioning on..
This is looking promising and keeping my fingers crossed. Thanks for the tips.
 
Terry,

What make me mad is that Lexus Dealer sell u 1600 worlth of part/labor and not solve the problem. I would take my car back to the dealer and demand for refund. U should not pay for something that is NOT broke or none functional. I would only pay for things that is the cause of the problem. I would not pay for something that they just guess.

Besides the TPS, u can always try to reset the ecu and you also can adjust the throttle body cables or stopper. That will help.
 


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