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Old 5th February 2010, 23:32   #1
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Default Sudden, unexplained RPM shoot-up in brand new car

Hi,

Facing a weird issue, which 2 rounds of workshop visit haven't been able to fix. This is regarding my new Logan 1.4GLX. In about 1 month of ownership, the problem has randomly appeared 8-10 times, and it happens absolutely without any warning or prior symptoms. While shifting gears generally from higher to lower (from my observation), with feet already "off" the accelerator, and foot all the way on the clutch (& break) s.a. just about to arrive at a speed-breaker, the RPM shoots all the way to 6000/7000, and then stays there for about 15 seconds, and then slowly comes down to about 3000 range in another 10 seconds. Pressing accelerator in this situation does seem to pump-up the RPM again. Sometimes, the only way to turn things to normal is to turn ignition off and back on, and after that the car runs perfectly.

The control-wire for accelerator has already been changed for a brand-new one, by workshop once, but problem persists. Since this has happened in various situations s.a. while I am travelling at 15kmph through internal colony roads, and even at around 60kmph on main road, I am quite worried.

Anyone else seen this problem with a Logan ?

cheers,
BD
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Old 6th February 2010, 01:19   #2
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Originally Posted by bdutta View Post
with feet already "off" the accelerator, and foot all the way on the clutch (& break) s.a. just about to arrive at a speed-breaker, the RPM shoots all the way to 6000/7000, and then stays there for about 15 seconds, and then slowly comes down to about 3000 range in another 10 seconds.
Please see the 2 attached pictures to prove the point. Picture#1 shows the RPM still overing over 2000, Picture#2 shows my feet as being only on clutch, and accelerator being completely unengaged.
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Old 6th February 2010, 01:43   #3
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Have they checked and cleaned the throttle body?
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Old 6th February 2010, 09:11   #4
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Have they checked and cleaned the throttle body?
Hi Zappo,

I am pretty sure they haven't, as the accelerator control cable job was done in about 20mins or so. Will definitely ask them to do so.

This started happening in the car when it was about 10 days old, and had run about 200kms on Odo, and till date, done about 700kms, i.e. after another 20 odd days. What kind of problem can be expected on throttle body, so soon ?

regards,
BD
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Old 7th February 2010, 11:17   #5
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Babu,

Many Logan owners have reported this issue of the accelerator getting stuck - dangerous

I believe this has got to do with either the accelerator cable or the idling control valve(IACV)
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Old 7th February 2010, 11:29   #6
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Check the idle control and throttle body, ensure both these are working well and smooth. Also check for any leaks in the intake system.
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Old 7th February 2010, 12:26   #7
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whoa!!!
thats a serious issue there.
its a shame we will rave about toyota and honda recalling cars due to stuck acc peds and all.. but we wont do much if it happens in our country.
i suggest you take it to the dealer and refuse to take delivery until the problem is sorted. you should demand a new ECU and new accelerator pedal with its electronics.

just a small doubt, does the RMP stay as high as you mentioned when it is in gear; i mean will the car accelerate hard in such scenario???
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Old 8th February 2010, 13:15   #8
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Originally Posted by vigsom View Post
Babu,

Many Logan owners have reported this issue of the accelerator getting stuck - dangerous

I believe this has got to do with either the accelerator cable or the idling control valve(IACV)
Hi Vigsom,

That's strange, because in my rather painstaking search through the Team-BHP archives and general google search outside of TBHP, haven't come accross any reports of this problem. Of course, sticky-pedal is getting a lot of publicity thanks to Toyota in US. Are you sure you are not mixing those reports ?

Thanks for the tip, will get the accelerator control cable and ICV checked.

regards,
BD
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Old 8th February 2010, 13:23   #9
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whoa!!!
thats a serious issue there.
Agreed, and it always freaks me out when it happens. So far hasn't happened in high-speed, high-traffic situations, but if it does, will be really scary.

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i suggest you take it to the dealer and refuse to take delivery until the problem is sorted. you should demand a new ECU and new accelerator pedal with its electronics.
Hmm... are the dealers in this country that customer friendly ? I can surely give it a shot though.

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just a small doubt, does the RMP stay as high as you mentioned when it is in gear; i mean will the car accelerate hard in such scenario???
[/quote]
Good question... in my observation during normal driving (i.e. when problem hasn't happened), I manage to do 60kmph @ around 1600-1700rpm, and about 80kmph @ around 2100rpm, all on 5th gear. So far, on purpose I've never gone above 3000rpm... infact drive mostly around 2000rpm or lower, until the run-in period. However, without gear engaged (i.e. on neutral) the mechanic who fixed/replaced control cable had demonstrated no issues when he revved up to around 6000rpm. When the problem does happen, it is always with gear on neutral or clutch-pressed. I've tried to press the accelerator in this situation, i.e. car is already in this freaky mode with revs doing around 3000rpm w/o accelerator pressed, and the accelerator does respond by pushing up rpm higher.

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Old 8th February 2010, 13:24   #10
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Check the idle control and throttle body, ensure both these are working well and smooth. Also check for any leaks in the intake system.
Will do. Making a list of all things to get checked. However intake leaks -- isn't it too darn early for the car to have those ? This is just about a month-old car.
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Old 8th February 2010, 13:57   #11
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As the others mentioned, it does point to the throttle body. While its definitely too early to require it on a new car, its better you get that checked first so you can eliminate that as a reason. You can search using this term on the forum, and you'll find threads with similar symptoms.
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Old 9th February 2010, 14:54   #12
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Originally Posted by bdutta View Post

Good question... in my observation during normal driving (i.e. when problem hasn't happened), I manage to do 60kmph @ around 1600-1700rpm, and about 80kmph @ around 2100rpm, all on 5th gear. So far, on purpose I've never gone above 3000rpm... infact drive mostly around 2000rpm or lower, until the run-in period. However, without gear engaged (i.e. on neutral) the mechanic who fixed/replaced control cable had demonstrated no issues when he revved up to around 6000rpm. When the problem does happen, it is always with gear on neutral or clutch-pressed. I've tried to press the accelerator in this situation, i.e. car is already in this freaky mode with revs doing around 3000rpm w/o accelerator pressed, and the accelerator does respond by pushing up rpm higher.

I understand you are running in your engine that you dont take it beyond 3k rpm.

"When the problem does happen, it is always with gear on neutral or clutch-pressed" ---> okay. is it either or both?
does it happen a few minutes after driving?

Very strange that the accped does not respond during the bad spell. after pressed a certain amount, it should take the engine beyond the point it is stuck.

Will it be possible for you to verify the air mass sensor? sometimes they tend to misbehave.

The dealer is equiped with a diagnostic tool. You should ask him to plug it in and check the ECU status. Get this done in front of you.
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