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Posted

Car type: lexus SC400 1993

Guys, I Just changed an altenator, and thermostat with o ring. after that install, I turn the car on , after it warms up in neutral the idel starts to set between 1000 rpm and 2000 rpm , it goes from low to high every 3 seconds. I dont understand, I took it to the shop , they said it was the mas air flow sensor and it would be $1100.00 retail from lexus, I picked one up off of ebay with the same numbers. put it on, and that is not the problem at all. Any suggestions would be greatly appriciated.

chewin my nails waiting for an answer. :wacko:


Posted

i had a power steering leak cuasing internal leaking of the fuild into the engine .. and then cuase the air control vavle to work properly.. i did cahnge my alternator just like you .. but its becuase ps fuild leaked into it... on neutral my rpm is at 2000, and wont go pass.. its a ari control vavle problem or mas air flow sensor .. just lean the control valve... took it to lexus they estimate 1300 for parts and labor... that is becuase the whole thing cost alot. when they only have to just clean the vavle... instead of cleaning it they wanna make sure it works.. so they jsut install a brand new vavle

open your intake system, and look inside of that chamber, the air control valve is under the traction control box... if its black, dark brown.. or dirty... claen it up.. take the whole thing out and clean it

Posted
i had a power steering leak cuasing internal leaking of the fuild into the engine .. and then cuase the air control vavle to work properly.. i did cahnge my alternator just like you .. but its becuase ps fuild leaked into it... on neutral my rpm is at 2000, and wont go pass.. its a ari control vavle problem or mas air flow sensor .. just lean the control valve... took it to lexus they estimate 1300 for parts and labor... that is becuase the whole thing cost alot. when they only have to just clean the vavle... instead of cleaning it they wanna make sure it works.. so they jsut install a brand new vavle

open your intake system, and look inside of that chamber, the air control valve is under the traction control box... if its black, dark brown.. or dirty... claen it up.. take the whole thing out and clean it

Is your A/C not working? my a/c compressor kicks on and off sometimes and it will change the rpm's by cycling off. Try just turning your whole air system off and see what it does then.

Posted
i had a power steering leak cuasing internal leaking of the fuild into the engine .. and then cuase the air control vavle to work properly.. i did cahnge my alternator just like you .. but its becuase ps fuild leaked into it... on neutral my rpm is at 2000, and wont go pass.. its a ari control vavle problem or mas air flow sensor .. just lean the control valve... took it to lexus they estimate 1300 for parts and labor... that is becuase the whole thing cost alot. when they only have to just clean the vavle... instead of cleaning it they wanna make sure it works.. so they jsut install a brand new vavle

open your intake system, and look inside of that chamber, the air control valve is under the traction control box... if its black, dark brown.. or dirty... claen it up.. take the whole thing out and clean it

Sounds Simular to my symptoms, I will Try the air control valve cleanning. (not the mass air sensor) but the air control valve, it is two different things right? btw thank you..

Posted
i had a power steering leak cuasing internal leaking of the fuild into the engine .. and then cuase the air control vavle to work properly.. i did cahnge my alternator just like you .. but its becuase ps fuild leaked into it... on neutral my rpm is at 2000, and wont go pass.. its a ari control vavle problem or mas air flow sensor .. just lean the control valve... took it to lexus they estimate 1300 for parts and labor... that is becuase the whole thing cost alot. when they only have to just clean the vavle... instead of cleaning it they wanna make sure it works.. so they jsut install a brand new vavle

open your intake system, and look inside of that chamber, the air control valve is under the traction control box... if its black, dark brown.. or dirty... claen it up.. take the whole thing out and clean it

Is your A/C not working? my a/c compressor kicks on and off sometimes and it will change the rpm's by cycling off. Try just turning your whole air system off and see what it does then.

A/C is working fine , just changed compressor also, and had system off .. definitly a sensor of some kind, tps might be suspect also. Thanks again .
Posted

Im Not sure , If , U are talking about the Mas Air flow or the Air control valve, Is there such a thing?(air control valve)? I changed the mas air flow sensor between the air cleaner and throttle body.

  • 2 weeks later...
Posted
One suggestion:  Did you check the 2 vacuum lines that go from the Power Steering pump to the top valve cover?    :cheers:

Yes I did and guess what ? they had leaks in them, they were part of the problem..

Thank you for your information, it was greatly appriciated.

Ken

Posted
Im Not sure , If , U are talking about the Mas Air flow or the Air control valve, Is there such a thing?(air control valve)? I changed the mas air flow sensor between the air cleaner and throttle body.

yeah buddy ,, I changed it.. ohmed it out and it was bad,, so got another one ,, its within range.. but that wasnt the problem.. (even though my other didnt ohm out right, so it needed to be changed) Thanks for the Information and all your help.

Ken

Posted
i had a power steering leak cuasing internal leaking of the fuild into the engine .. and then cuase the air control vavle to work properly.. i did cahnge my alternator just like you .. but its becuase ps fuild leaked into it... on neutral my rpm is at 2000, and wont go pass.. its a ari control vavle problem or mas air flow sensor .. just lean the control valve... took it to lexus they estimate 1300 for parts and labor... that is becuase the whole thing cost alot. when they only have to just clean the vavle... instead of cleaning it they wanna make sure it works.. so they jsut install a brand new vavle

open your intake system, and look inside of that chamber, the air control valve is under the traction control box... if its black, dark brown.. or dirty... claen it up.. take the whole thing out and clean it

looks like it turned out to be a combo of things. mass air flow, ISC, vacume lines from poersteering pump. Thank you for your help..

Ken

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