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Old 18th December 2009, 15:39   #1
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Default High idle RPM issue.

I am facing this issue for sometime now. Whwnever I start my car after it has been at rest for a few hours, idle RPM rises to around 1500 rpm and RPM remains relatively high for all the gears. But shutting down and then re-starting brings idle RPM to routine 700-800 RPM. Any guesses what could be the culprit here.
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Old 18th December 2009, 16:45   #2
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Are you sure its not idle RPM advance at work for cold starts at work? Oh, which car is this? Is it a FE engine or Carb?
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Old 18th December 2009, 19:23   #3
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It is perfectly fine to have high RPM for cold engine initially.
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Old 18th December 2009, 19:25   #4
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Quote:
Originally Posted by Jaggu View Post
Are you sure its not idle RPM advance at work for cold starts at work?
Even if its because of Idle Rpm Advance at work, it should not be as high as 1500rpm.
Also taurian mentioned that it happens in all gears. How could it happen in all gears. I mean no one would start in 2nd, 3rd, 4th or 5th gear.
May be he has misunderstood something.
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Old 18th December 2009, 19:55   #5
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can it be a faulty oxygen sensor?
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Old 18th December 2009, 20:02   #6
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@taurian: If its a MPFI petrol car, this is absolutely normal.
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Old 18th December 2009, 20:18   #7
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Ablolutely normal. I done even need to press the accelerator for some time, even while comming out of a incline parking. Once the engine temprature reaches half way everything is normal.
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Old 19th December 2009, 03:36   #8
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All this is done in order to heat up your catalytic converter. Once it has reached its light off temperature you car will become normal. Your ECU will try to load the car till then, which is what you are feeling as high rpm in every gear.
I guess yours is a port fuel injection car, which is fitted with a 3 way catalytic converters (here onwards will be called cat) . These engines are designed to run strictly at Lambda(relative air fuel ratio) = 1. The Cat has a light off temperature of 350. Upon reaching this temperature this will effectively control the NOx emissions.
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Old 20th December 2009, 00:32   #9
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Hi,

Get the Throttle Body removed and serviced. It is most likely that the IACV valve is stuck due to the carbon deposits from the fuel.

They should not be charging you more than Rs. 30 bucks for this job. Ensure that the IACV is removed and serviced and not just the Carb Cleaner sprayed in the trottle body externally.

Cheers!!!
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Old 23rd December 2009, 16:36   #10
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Guys I was off sick, so could not reply earlier.
Problem occurs when car is ar rest for a few hours and then upon first ignition RPM rises. Stays high till I deliberately shut down the car again and upon restarting RPM's drop to normal. Mine is an MPFI.
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Old 23rd December 2009, 16:59   #11
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Next time this happens check the temperature gauge also, if the engine is absolutely cold RPM will increase a bit (fast idle) for engine to heat up faster, in MPFI cars.
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Old 26th December 2009, 01:41   #12
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What happened ? Did you check the temperature guage ? I think I need more information about your problem.
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Old 19th May 2010, 16:19   #13
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I am facing this issue in my Esteem (2001) MPFI.

1. During cold starts, the rpm goes high (1600 or so).
2. I start driving off after say 15 seconds and rpm is still high.
3. Even after the car is driven for a few kms, the rpm remains high
4. If after the engine becomes hot, it is switched off and started, the rpm comes down to 800-900 (normal). However, it stays high if I do not restart (even after the engine has become hot).

However, if during a cold start, idle for about 4 minutes, and do not start driving, the rpm comes down to around 900.

How does the driving/not driving make a difference? Shouldn't the rpm come down automatically once the engine reaches the desired temperature?

Note: It has got Pow Steering and I can hear the rpm increasing when the steering is turned while standing still. Tust this is normal?
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Old 19th May 2010, 16:36   #14
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Quote:
Originally Posted by Jeep View Post
I am facing this issue in my Esteem (2001) MPFI.

1. During cold starts, the rpm goes high (1600 or so).
2. I start driving off after say 15 seconds and rpm is still high.
3. Even after the car is driven for a few kms, the rpm remains high
4. If after the engine becomes hot, it is switched off and started, the rpm comes down to 800-900 (normal). However, it stays high if I do not restart (even after the engine has become hot).

However, if during a cold start, idle for about 4 minutes, and do not start driving, the rpm comes down to around 900.

How does the driving/not driving make a difference? Shouldn't the rpm come down automatically once the engine reaches the desired temperature?

Note: It has got Pow Steering and I can hear the rpm increasing when the steering is turned while standing still. Tust this is normal?
Its normal for pre 2002 mpfi engines its because of the chock sensor
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Old 23rd May 2010, 22:56   #15
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Quote:
Originally Posted by manikjeet View Post
Its normal for pre 2002 mpfi engines its because of the chock sensor
Did you meant O2 sensor ?
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