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Uneven Idling And Stalling Cured


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:D Finally cured the above, and it cost me only a call out charge of £60

You may have seen prevoius posts regarding my GS300 Mk1 (1997 with 127k), which started, but wouldn't run when cold, and idled erratically when warm, typically at 500 to 600 rather than 750 to 800 rpm.

I thought my mechanic had fixed this by thoroughly cleaning the throttle body and idle air valve (cost of an hours labour and two cans of carb cleaner). It was certainly better, but not right.

Chris, my mechanic, said he needed some help, especially as Lexus had had it in for diagnostic work, and charged £150 to say they couldn't find the fault. He rang Martin, a mobile auto electrician, who offers suport services to local garages, and has all of the latest diagnostic gear.

Martin didn't even hook up to his p.c., just listened to the fault, checked that the engine management light was not on, and in 3 minutes fixed the problem.

Here is what he did.

On the front of the throttle body are two sensors. One is the idle air control valve, the other Martin described as the "Throttle Pot". If you look from the front of the engine the idle air controller is on the left hand side, and has a grey electrical connector, and the "Throttle Pot" is on the right hand side, and has a black electrical connector.

The Throttle Pot is secured by two screws, one of which, at the top of the unit, has an elongated slot, allowing some positional adjustment, Martin loosened this half a turn, and moved the unit anticlockwise about a millimetre; the idle speed increased by 350 revs. He switched the engine off, and left it off for 10 secods, and re-started the engine, which still revved at around 1100 rpm. He switched off, left for a few seconds, and moved the unit clockwise by less than half a millimeter, and tightened up the securing screw. The engine was restarted, and idled perfectly. Marin then started and stopped the engine 10 times to ensure that the ECU had "learned" the new setting, and hey presto, solved. No £500 idle air valve, no £300 throttle controller, just 15 minutes, and 30 years experience. I have pictures of the unit, and will be happy to send them to anyone who has this problem.

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  • 1 year later...
  • 1 month later...
Dear member,

I am having the same problem and will appreciate step by step instructions and photos if possible, my car is GS300 SE 1998 MK-II,

Problem rose just after engine cleaning,

Regards

Had the same problem after changing plugs and cleaning the inlet manifold but mine was idling @ 1500, tried giving it a blast down the road then disconnected the Battery for 5 mins, still no good, pulled off the grey plug and idle settled to normal so new it was something to do with the TPS. It was going into Lexus for a check the next day so left it for them to sort, by the time i drove there it was fine, they checked it and all was back to normal. Pretty sure ecu has self learning mode, just seemed to take longer than i thought, maybe i have a thick car

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  • 4 months later...

  • 7 months later...
:D Finally cured the above, and it cost me only a call out charge of £60

You may have seen prevoius posts regarding my GS300 Mk1 (1997 with 127k), which started, but wouldn't run when cold, and idled erratically when warm, typically at 500 to 600 rather than 750 to 800 rpm.

I thought my mechanic had fixed this by thoroughly cleaning the throttle body and idle air valve (cost of an hours labour and two cans of carb cleaner). It was certainly better, but not right.

Chris, my mechanic, said he needed some help, especially as Lexus had had it in for diagnostic work, and charged £150 to say they couldn't find the fault. He rang Martin, a mobile auto electrician, who offers suport services to local garages, and has all of the latest diagnostic gear.

Martin didn't even hook up to his p.c., just listened to the fault, checked that the engine management light was not on, and in 3 minutes fixed the problem.

Here is what he did.

On the front of the throttle body are two sensors. One is the idle air control valve, the other Martin described as the "Throttle Pot". If you look from the front of the engine the idle air controller is on the left hand side, and has a grey electrical connector, and the "Throttle Pot" is on the right hand side, and has a black electrical connector.

The Throttle Pot is secured by two screws, one of which, at the top of the unit, has an elongated slot, allowing some positional adjustment, Martin loosened this half a turn, and moved the unit anticlockwise about a millimetre; the idle speed increased by 350 revs. He switched the engine off, and left it off for 10 secods, and re-started the engine, which still revved at around 1100 rpm. He switched off, left for a few seconds, and moved the unit clockwise by less than half a millimeter, and tightened up the securing screw. The engine was restarted, and idled perfectly. Marin then started and stopped the engine 10 times to ensure that the ECU had "learned" the new setting, and hey presto, solved. No £500 idle air valve, no £300 throttle controller, just 15 minutes, and 30 years experience. I have pictures of the unit, and will be happy to send them to anyone who has this problem.

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:D Finally cured the above, and it cost me only a call out charge of £60

You may have seen prevoius posts regarding my GS300 Mk1 (1997 with 127k), which started, but wouldn't run when cold, and idled erratically when warm, typically at 500 to 600 rather than 750 to 800 rpm.

I thought my mechanic had fixed this by thoroughly cleaning the throttle body and idle air valve (cost of an hours labour and two cans of carb cleaner). It was certainly better, but not right.

Chris, my mechanic, said he needed some help, especially as Lexus had had it in for diagnostic work, and charged £150 to say they couldn't find the fault. He rang Martin, a mobile auto electrician, who offers suport services to local garages, and has all of the latest diagnostic gear.

Martin didn't even hook up to his p.c., just listened to the fault, checked that the engine management light was not on, and in 3 minutes fixed the problem.

Here is what he did.

On the front of the throttle body are two sensors. One is the idle air control valve, the other Martin described as the "Throttle Pot". If you look from the front of the engine the idle air controller is on the left hand side, and has a grey electrical connector, and the "Throttle Pot" is on the right hand side, and has a black electrical connector.

The Throttle Pot is secured by two screws, one of which, at the top of the unit, has an elongated slot, allowing some positional adjustment, Martin loosened this half a turn, and moved the unit anticlockwise about a millimetre; the idle speed increased by 350 revs. He switched the engine off, and left it off for 10 secods, and re-started the engine, which still revved at around 1100 rpm. He switched off, left for a few seconds, and moved the unit clockwise by less than half a millimeter, and tightened up the securing screw. The engine was restarted, and idled perfectly. Marin then started and stopped the engine 10 times to ensure that the ECU had "learned" the new setting, and hey presto, solved. No £500 idle air valve, no £300 throttle controller, just 15 minutes, and 30 years experience. I have pictures of the unit, and will be happy to send them to anyone who has this problem.

Hello My name is Harry and I have been experiencing the same problems as you did...Lexus have put the car on diagnostics and had no errors codes showiing.They have cleaned the throttle body and is better but im still getting idling problems and stalling too.

Can you please email me some pictures on your fix you spoke about..It would be a great help to me...

My email add is: h4real@hotymail.com

Thanks in advance

Harry

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:D Finally cured the above, and it cost me only a call out charge of £60

You may have seen prevoius posts regarding my GS300 Mk1 (1997 with 127k), which started, but wouldn't run when cold, and idled erratically when warm, typically at 500 to 600 rather than 750 to 800 rpm.

I thought my mechanic had fixed this by thoroughly cleaning the throttle body and idle air valve (cost of an hours labour and two cans of carb cleaner). It was certainly better, but not right.

Chris, my mechanic, said he needed some help, especially as Lexus had had it in for diagnostic work, and charged £150 to say they couldn't find the fault. He rang Martin, a mobile auto electrician, who offers suport services to local garages, and has all of the latest diagnostic gear.

Martin didn't even hook up to his p.c., just listened to the fault, checked that the engine management light was not on, and in 3 minutes fixed the problem.

Here is what he did.

On the front of the throttle body are two sensors. One is the idle air control valve, the other Martin described as the "Throttle Pot". If you look from the front of the engine the idle air controller is on the left hand side, and has a grey electrical connector, and the "Throttle Pot" is on the right hand side, and has a black electrical connector.

The Throttle Pot is secured by two screws, one of which, at the top of the unit, has an elongated slot, allowing some positional adjustment, Martin loosened this half a turn, and moved the unit anticlockwise about a millimetre; the idle speed increased by 350 revs. He switched the engine off, and left it off for 10 secods, and re-started the engine, which still revved at around 1100 rpm. He switched off, left for a few seconds, and moved the unit clockwise by less than half a millimeter, and tightened up the securing screw. The engine was restarted, and idled perfectly. Marin then started and stopped the engine 10 times to ensure that the ECU had "learned" the new setting, and hey presto, solved. No £500 idle air valve, no £300 throttle controller, just 15 minutes, and 30 years experience. I have pictures of the unit, and will be happy to send them to anyone who has this problem.

Hello My name is Harry and I have been experiencing the same problems as you did...Lexus have put the car on diagnostics and had no errors codes showiing.They have cleaned the throttle body and is better but im still getting idling problems and stalling too.

Can you please email me some pictures on your fix you spoke about..It would be a great help to me...

My email add is: h4real@hotmail.com

Thanks in advance

Harry

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Hello My name is Harry and I have been experiencing the same problems as you did...Lexus have put the car on diagnostics and had no errors codes showiing.They have cleaned the throttle body and is better but im still getting idling problems and stalling too.

Can you please email me some pictures on your fix you spoke about..It would be a great help to me...

My email add is: h4real@hotmail.com

Thanks in advance

Harry

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  • 4 months later...

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