IDLE adjustment -- HOW?
02-18-2002, 11:14 AM
#1
Senior Member
Thread Starter
Join Date: Mar 2001
Posts: 1,812
IDLE adjustment -- HOW?
Hello again!
Thanks to everyone that offered some suggestions on my "RPMs jump wildly" post -- especially JeepRage!
Anyhow, after I cleaned my throttle body, I, like many others, am experiencing higher idles...
That said, how do I adjust the idle back down? I know that some folks say "reset your computer", others say "It'll come down after the computer figures it out" and some say "adjust the idle down using the idle adjustment screw (?)".
OK, so, How do I adjust my idle? Where is the idle adjustment screw?
Thanks to all.
best,
FLO_BOY
Thanks to everyone that offered some suggestions on my "RPMs jump wildly" post -- especially JeepRage!
Anyhow, after I cleaned my throttle body, I, like many others, am experiencing higher idles...
That said, how do I adjust the idle back down? I know that some folks say "reset your computer", others say "It'll come down after the computer figures it out" and some say "adjust the idle down using the idle adjustment screw (?)".
OK, so, How do I adjust my idle? Where is the idle adjustment screw?
Thanks to all.
best,
FLO_BOY
02-18-2002, 02:41 PM
#2
Member who somehow became The President of The SE-L Club
iTrader: (19)
Join Date: Jun 2001
Posts: 16,033
Do this when your car is nice and warm.
The idle adjustment screw is on the throttle body right by where the throttle cables attach. (left side looking from drivers side) There is a small phillips head screw with a locking nut. The nut is 8 or 6mm.
Engine off - Disconnect the throttle position sensor plugs, there on the oppiside side of the cables on the throttle body. (right side) My 99 had 2 plugs, you may only have one.
Start the car and observe the RPM's. Losen the lock nut and turn the adjustment screw counter clockwise to lower the idle speed. Set the speed to approx. 750 RPM in Park or Neutral. No lights on, no A/C on and no radio (no accessories at all).
Turn off the engine and reconnect the TPS sensor.
Start your car and things should be all back to normal.
The idle adjustment screw is on the throttle body right by where the throttle cables attach. (left side looking from drivers side) There is a small phillips head screw with a locking nut. The nut is 8 or 6mm.
Engine off - Disconnect the throttle position sensor plugs, there on the oppiside side of the cables on the throttle body. (right side) My 99 had 2 plugs, you may only have one.
Start the car and observe the RPM's. Losen the lock nut and turn the adjustment screw counter clockwise to lower the idle speed. Set the speed to approx. 750 RPM in Park or Neutral. No lights on, no A/C on and no radio (no accessories at all).
Turn off the engine and reconnect the TPS sensor.
Start your car and things should be all back to normal.
02-18-2002, 05:36 PM
#3
Donating Maxima.org Member
Join Date: Jan 2002
Posts: 245
I might add what I read in another thread recently.
"Maximas with Auto Transmissions should idle at 600 in drive
and Manual Transmission cars should be about 600 rpm in neutral."
Is that about right?
Thanks,
White96MaxSE
"Maximas with Auto Transmissions should idle at 600 in drive
and Manual Transmission cars should be about 600 rpm in neutral."
Is that about right?
Thanks,
White96MaxSE
02-18-2002, 06:03 PM
#4
you are describing the idle stop screw (on the throttle body) which is pre set at the factory and should NOT be adjusted. The idle adjustment screw is on top of the IAC valve (right rear of the upper intake manifold)
Originally posted by njmaxseltd
Do this when your car is nice and warm.
The idle adjustment screw is on the throttle body right by where the throttle cables attach. (left side looking from drivers side) There is a small phillips head screw with a locking nut. The nut is 8 or 6mm.
Engine off - Disconnect the throttle position sensor plugs, there on the oppiside side of the cables on the throttle body. (right side) My 99 had 2 plugs, you may only have one.
Start the car and observe the RPM's. Losen the lock nut and turn the adjustment screw counter clockwise to lower the idle speed. Set the speed to approx. 750 RPM in Park or Neutral. No lights on, no A/C on and no radio (no accessories at all).
Turn off the engine and reconnect the TPS sensor.
Start your car and things should be all back to normal.
Do this when your car is nice and warm.
The idle adjustment screw is on the throttle body right by where the throttle cables attach. (left side looking from drivers side) There is a small phillips head screw with a locking nut. The nut is 8 or 6mm.
Engine off - Disconnect the throttle position sensor plugs, there on the oppiside side of the cables on the throttle body. (right side) My 99 had 2 plugs, you may only have one.
Start the car and observe the RPM's. Losen the lock nut and turn the adjustment screw counter clockwise to lower the idle speed. Set the speed to approx. 750 RPM in Park or Neutral. No lights on, no A/C on and no radio (no accessories at all).
Turn off the engine and reconnect the TPS sensor.
Start your car and things should be all back to normal.
02-18-2002, 07:03 PM
#5
Member who somehow became The President of The SE-L Club
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Join Date: Jun 2001
Posts: 16,033
Confused - That procedure is taken directly from a shop manual. It never mentions the screw in the IAC valve for idle speed adjustment.
Can you support your theory on idle speed adjustment please?
Can you support your theory on idle speed adjustment please?
02-18-2002, 10:20 PM
#7
Senior Member
Join Date: Nov 2001
Posts: 606
Originally posted by Confused
absolutly but i'm not looking for a p*ss*ng contest here...
FSM, Page EC-34 (or thereabout depending on year)diagram/procedure H
Haynes.. p 4-12, picture 16.8 is an excellent reference.
absolutly but i'm not looking for a p*ss*ng contest here...
FSM, Page EC-34 (or thereabout depending on year)diagram/procedure H
Haynes.. p 4-12, picture 16.8 is an excellent reference.
02-19-2002, 05:20 AM
#8
Junior Member
Join Date: Feb 2002
Posts: 27
The exact same thing happened to me this weekend after cleaning my throttle body and changing my knock sensor. My idle in park was around 950. I warmed the car and turned it off. Disconnected the TPS sensor and started the car. Using the screw on the IACV I set the rpms at 700 in park (no a/c or accesories on). Turned the car off and reconnected the TPS. Upon restarting the car the rpms went back up to 950. I repeated the whole thing again but I before starting the car I reset the computer (pulled out the codes: came out 0505 and then erased the codes . The car is smooth as silk now idling in park at 700 and at 600 in drive. With the a/c on it idles at 850 in park and 650 in drive. No vibrations at all.
02-19-2002, 05:43 AM
#9
Member who somehow became The President of The SE-L Club
iTrader: (19)
Join Date: Jun 2001
Posts: 16,033
Originally posted by Confused
absolutly but i'm not looking for a p*ss*ng contest here...
FSM, Page EC-34 (or thereabout depending on year)diagram/procedure H
Haynes.. p 4-12, picture 16.8 is an excellent reference.
absolutly but i'm not looking for a p*ss*ng contest here...
FSM, Page EC-34 (or thereabout depending on year)diagram/procedure H
Haynes.. p 4-12, picture 16.8 is an excellent reference.
I'm not looking for a p*ss*ng contest either, this is all very good information!
02-19-2002, 04:29 PM
#10
Donating Maxima.org Member
Join Date: Jan 2002
Posts: 245
Originally posted by njmaxseltd
Confused - Thanks for the info. I read that as well. Being we are seeing the idle change after cleaning the throttle body, I feel the adjustment which needs attention is at the throttle body, not the IAC Valve. Just more of a logical choice, being it's what we are working on here.
I'm not looking for a p*ss*ng contest either, this is all very good information!
Confused - Thanks for the info. I read that as well. Being we are seeing the idle change after cleaning the throttle body, I feel the adjustment which needs attention is at the throttle body, not the IAC Valve. Just more of a logical choice, being it's what we are working on here.
I'm not looking for a p*ss*ng contest either, this is all very good information!
"Caution: Do not attempt to adjust the idle speed with the idle stop screw on the throttle body. The idle stop screw is preset at the factory and should not be tampered with."
The Nissan dealer recently told me when I told him I was going to take the throttle body off to make sure and check the service manual because he has known of people that will adjust the idle stop screw and that there is no way to correct their mistake and you end up buying a new throttle body!
White96MaxSE
02-19-2002, 06:40 PM
#11
I guess it depends on your train of thought. For me the screw should be constant... there is another variable that is out of spec... our job of course... find it.
interesting addition about the dealer whitemax...
floboy.. i would start by resetting the ecu... its an easy way to start... drive it around for a while and see what happens.
just a note, when i was having similiar trouble i took off the iac valve and cleaned out the passage way.. cleaned up the valve a litte with a dry rag... it should not be submerged in any fluid since it is an electical part.
every car is different... i want high idle for the blower..
interesting addition about the dealer whitemax...
floboy.. i would start by resetting the ecu... its an easy way to start... drive it around for a while and see what happens.
just a note, when i was having similiar trouble i took off the iac valve and cleaned out the passage way.. cleaned up the valve a litte with a dry rag... it should not be submerged in any fluid since it is an electical part.
every car is different... i want high idle for the blower..
Originally posted by njmaxseltd
Confused - Thanks for the info. I read that as well. Being we are seeing the idle change after cleaning the throttle body, I feel the adjustment which needs attention is at the throttle body, not the IAC Valve. Just more of a logical choice, being it's what we are working on here.
I'm not looking for a p*ss*ng contest either, this is all very good information!
Confused - Thanks for the info. I read that as well. Being we are seeing the idle change after cleaning the throttle body, I feel the adjustment which needs attention is at the throttle body, not the IAC Valve. Just more of a logical choice, being it's what we are working on here.
I'm not looking for a p*ss*ng contest either, this is all very good information!
05-15-2002, 07:39 AM
#12
Senior Member
Join Date: Mar 2001
Posts: 179
Originally posted by Confused
I guess it depends on your train of thought. For me the screw should be constant... there is another variable that is out of spec... our job of course... find it.
interesting addition about the dealer whitemax...
floboy.. i would start by resetting the ecu... its an easy way to start... drive it around for a while and see what happens.
just a note, when i was having similiar trouble i took off the iac valve and cleaned out the passage way.. cleaned up the valve a litte with a dry rag... it should not be submerged in any fluid since it is an electical part.
every car is different... i want high idle for the blower..
I guess it depends on your train of thought. For me the screw should be constant... there is another variable that is out of spec... our job of course... find it.
interesting addition about the dealer whitemax...
floboy.. i would start by resetting the ecu... its an easy way to start... drive it around for a while and see what happens.
just a note, when i was having similiar trouble i took off the iac valve and cleaned out the passage way.. cleaned up the valve a litte with a dry rag... it should not be submerged in any fluid since it is an electical part.
every car is different... i want high idle for the blower..
10-19-2020, 10:45 AM
#13
Member
Join Date: Feb 2008
Posts: 121
[QUOTE=maxnewbie;829473]How is the IAC valve removed? Will it trigger a Check Engine Light when removed? How difficult is it to remove?[/QUOTE
Getting back to square one... what is the design perpose of the IAC valve? ...ok...understand it controls air to adjust the idle speed...how ever basic question if i may... why was it necessary to put in that control in the first place?
How simply things were when you just had an idle screw to the carb...
Having trouble with IAC valve ( 94 gxe Maxima) idle drops below 500 rpm...and runs rough...have to keep foot on gas pedal all the time to keep idle up...just to move car around driveway.
Getting back to square one... what is the design perpose of the IAC valve? ...ok...understand it controls air to adjust the idle speed...how ever basic question if i may... why was it necessary to put in that control in the first place?
How simply things were when you just had an idle screw to the carb...
Having trouble with IAC valve ( 94 gxe Maxima) idle drops below 500 rpm...and runs rough...have to keep foot on gas pedal all the time to keep idle up...just to move car around driveway.
10-21-2020, 07:33 AM
#14
Member
Join Date: Mar 2007
Posts: 227
[QUOTE=Starrider;9229920]
like other suggested, use IACV screw and follow procedure per FSM for idle adjustment.
There are so many factors affecting idle: PS pump, AC compressor, electrical loads: defrost/fan/radio/lights/wipers. Nissan has simplified to one device IACV, one screw. So keep it a linear behavior. Turn it CW to lower idle speed, CCW to higher. Don't try compensate bad part by changing good part. A low idle could become 'Crank, No Start' issue.
Assume your car has 4th gen IACV assembly, open 2 Phillip screws to remove the sensor and its plunger. The other 3 screws are for shielding the internal circuit, nothing to clean in there.
How is the IAC valve removed? Will it trigger a Check Engine Light when removed? How difficult is it to remove?[/QUOTE
Getting back to square one... what is the design perpose of the IAC valve? ...ok...understand it controls air to adjust the idle speed...how ever basic question if i may... why was it necessary to put in that control in the first place?
How simply things were when you just had an idle screw to the carb...
Having trouble with IAC valve ( 94 gxe Maxima) idle drops below 500 rpm...and runs rough...have to keep foot on gas pedal all the time to keep idle up...just to move car around driveway.
Getting back to square one... what is the design perpose of the IAC valve? ...ok...understand it controls air to adjust the idle speed...how ever basic question if i may... why was it necessary to put in that control in the first place?
How simply things were when you just had an idle screw to the carb...
Having trouble with IAC valve ( 94 gxe Maxima) idle drops below 500 rpm...and runs rough...have to keep foot on gas pedal all the time to keep idle up...just to move car around driveway.
There are so many factors affecting idle: PS pump, AC compressor, electrical loads: defrost/fan/radio/lights/wipers. Nissan has simplified to one device IACV, one screw. So keep it a linear behavior. Turn it CW to lower idle speed, CCW to higher. Don't try compensate bad part by changing good part. A low idle could become 'Crank, No Start' issue.
Assume your car has 4th gen IACV assembly, open 2 Phillip screws to remove the sensor and its plunger. The other 3 screws are for shielding the internal circuit, nothing to clean in there.
Last edited by saig; 10-21-2020 at 07:36 AM.
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