Cold start idle problems
01-25-19, 06:39 AM
#1
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Cold start idle problems
When I start my car when cold and shift into gear the RPM’s are around 1000 and seems fine. As I drive the car for a minute or so the RPM’s increase to the point where I am going 40 MPH without touching the gas peddle. If I shift it into neutral the RPM’s goes up to 1200 or more at a stop light. This can last for 20 minutes or more. Not until the car is fully warmed up does the idle return to normal. I have cleaned the Mass Airflow Sensor but still have the problem. I’m thinking maybe the IAC valve but not sure of it’s location.
01-25-19, 08:21 AM
#2
My car behaves that way, as well, for at least the first 10-15 minutes if the temp is below 50°. That's regardless of the gear I'm in. It's annoying to me, to say the least.
01-25-19, 11:01 AM
#3
If you want the idle to be lower when the engine is cold, put it in ECO mode.
01-25-19, 11:01 AM
#4
Lexus Test Driver
When I start my car when cold and shift into gear the RPM’s are around 1000 and seems fine. As I drive the car for a minute or so the RPM’s increase to the point where I am going 40 MPH without touching the gas peddle. If I shift it into neutral the RPM’s goes up to 1200 or more at a stop light. This can last for 20 minutes or more. Not until the car is fully warmed up does the idle return to normal. I have cleaned the Mass Airflow Sensor but still have the problem. I’m thinking maybe the IAC valve but not sure of it’s location.
Your engine idle is working absolutely perfectly... The engine idle is based on the ECU receiving input signals from many different parameters - from air temperature, coolant temperature, engine oil temperature, exhaust temperature, etc., etc.
01-25-19, 11:25 AM
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Sorry about the duplicate post,new to site. I have 2 Lexus’s and the other runs fine during cold weather. I understand the electronics of how it operates. The high Idle actually increases as you drive. I have to use both feet on the brake at stop lights and when the light turns green I don’t even have to give it gas and the car goes up to 40. Also when I’m stopped and put it neutral it races up to 1800 RPM ‘s. Sometime on the the highway it will be doing 70 without touching the peddle before it’s fully warmed up. Then about 1in 10 times the car will operate just fine.
01-28-19, 02:32 AM
#6
Sorry about the duplicate post,new to site. I have 2 Lexus’s and the other runs fine during cold weather. I understand the electronics of how it operates. The high Idle actually increases as you drive. I have to use both feet on the brake at stop lights and when the light turns green I don’t even have to give it gas and the car goes up to 40. Also when I’m stopped and put it neutral it races up to 1800 RPM ‘s. Sometime on the the highway it will be doing 70 without touching the peddle before it’s fully warmed up. Then about 1in 10 times the car will operate just fine.
Last edited by VA75067; 01-28-19 at 06:40 AM.
01-28-19, 05:16 AM
#7
Lead Lap
Yeah, you need to take it to the dealer.
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01-28-19, 08:19 AM
#8
Sorry about the duplicate post,new to site. I have 2 Lexus’s and the other runs fine during cold weather. I understand the electronics of how it operates. The high Idle actually increases as you drive. I have to use both feet on the brake at stop lights and when the light turns green I don’t even have to give it gas and the car goes up to 40. Also when I’m stopped and put it neutral it races up to 1800 RPM ‘s. Sometime on the the highway it will be doing 70 without touching the peddle before it’s fully warmed up. Then about 1in 10 times the car will operate just fine.
01-28-19, 08:22 AM
#9
Racer
01-28-19, 08:50 AM
#10
Lexus Test Driver
OP - If you are suggesting that it is difficult for your brakes to prevent the car from moving forward when stopped ... or it is difficult for your brakes to slow the car down once you get to [say] 40 mph, then that is not normal. However, something tells me you are not in danger of your car racing out-of-control as-if there was a heavy foot controlling the accelerator.
Normal elevated cold engine idle speed has very little uummph behind it - in other words, it's not going to produce the kind of power needed to climb even a moderately steep driveway at walking speed. It's lollygagging...
Normal elevated cold engine idle speed has very little uummph behind it - in other words, it's not going to produce the kind of power needed to climb even a moderately steep driveway at walking speed. It's lollygagging...
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