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Discussion Starter · #1 ·
Hi everyone. As the title says I have a problem with my wifes Megane over revving and erratic idle. I have took off the throttle boy and given it a clean, but noticed that the throttle itself doesnt close fully. How are these throttle bodies meant to be? I have put it all back together and it still has the same problem, but also noticed that if i manually turn the throttle with the tip of a screwdriver i can stop the erratic idle. It seems as if the motor on the opposite side isn't actually closing the throttle enough. Will this be the problem or is that how it is meant to be?

Kind regards

Mike
 
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I'd imagine it should not completely close or you would get no air to the TB.

If it is over revving, then it is getting too much air, check that there are no leaks prior to the TB.

It is possible that your MAP sensor is busted, worth getting checked.
 

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Discussion Starter · #3 ·
I'd imagine it should not completely close or you would get no air to the TB.

If it is over revving, then it is getting too much air, check that there are no leaks prior to the TB.

It is possible that your MAP sensor is busted, worth getting checked.

Hi, I have done a search over the last few days, looking for info on why my Megane is over revving and surging at idle.
Up to now I have found various posts but none that are the same prblem as mine, or that have been solved.
When the car is started, the car idles around 1600 - 1800 rpm, no misfires or any other problems. Once driven the car still idles at high revs, but also surges from 1000rpm upto 2800rpm.
So far I have removed and cleaned the throttle body, checked and improved the throttle body to manifold seal, tried a different MAP sensor, tried a different set of coil packs, checked for any other air leaks on the intake system. All to no avail.

I have ordered an ELM 327 diagnostics able and software to check any fault codes and that should arrive tomorrow, my galletto arrived today!

Any help greatly appreciated

Forgot to mention its a 2004 1.4 16v megane, 54,000 miles

Mike
bloobloo Posts: 2 Joined: Sat Jun 18, 2011 4:50 pm
 

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Discussion Starter · #5 ·
No, I took out the seals and gave them a good clean. The first time i took it apart I used a gasket sealant but that made no improvement. I then went to the breakers yard and got another inlet manifold for £4.00 just in case the other one was cracked etc. I then took off the 1st inlet manifold, scraped and cleaned all the other gasket sealant off the lower inlet and replaced the top manifold. I will order new seals tomorrow and try that.
 
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If you were able to get them out to clean them I'd say they were OK. Usually they go flat and hard.

I'm sure I read on here about high revving, but I can't find it.
 

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Discussion Starter · #8 ·
Well, the ELM327 OBD2 came today and works great. I found a code logged P0638 which, according to a google search is - " The fault P0638 is generated when the ECU compares the position of the pedal to how open the butterfly valve is, and the two don't match up within the given tolerances."

So my 1st train of thought seems to be correct, the throtte is open too far on idle.
Anyone any thoughts on how to rectify this, or is it going to be a replacement throttle body & gubbins?
 

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Discussion Starter · #10 ·
A quick update for people with the same problem... it was the throttle body! I went and got a throttle body from a breakers yard this morning, threw it on as soon as I got back. Resut = car running perfect, no more p0638 fault code and idling evenly at 800rpm.
Hope this helps anyone present or future with the same problem.
 

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I have had the same problem, I disconnected the 2 wire connector on the alternator and this cured the problem, the alternator is still charging. seems the alternator sends a signal to the ecu saying it needs more power. well worth trying before you go to far.
 

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hi I have the same problem I cannot make my mind up what it is I think it maybe thotle idle valve or the thotle body sensor my car is 1.4 16 valve megane my mobile is 07968899403 if you want you to text me I will try and help best of luck mine only does it now and again mick or if you find solution please text me or e mail [email protected]
 

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Hi,

I had a similar problem with my 2001 1.4 Kangoo, high revving on start up and then revving up and down on idle all by itself, people looking at me like I was some impatient yobbo at traffic lights zebra crossings etc. It also seemed to be running cooler than normal.

Tried cleaning the throttle body, a new throttle sensor, no change, replaced the other sensor in the throttle body which made the idle speed even higher.

Eventually I found the problem was the larger of the two pipes from the rocker cover that leads to the plenum, just under the pressure sensor, had a broken connection. I replaced the tube with new rubber and the problem had gone!
 

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2001 Renault Megane BA11, K4M
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Eventually I found the problem was the larger of the two pipes from the rocker cover that leads to the plenum, just under the pressure sensor, had a broken connection. I replaced the tube with new rubber and the problem had gone!
Hi,
Can you please explain which pipe, the rubber one? If you can, please post picture of the part, either from google or ebay.. OR send me a PM.
Thanks in advance! :)
 

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Ive had the same problem. Replaced throttle body, new spark plugs, new air filter. New map sensor. Fixed mine by trying to lift accelerator pedal and noticing revs dropped. Gently forced it up with my foot under it until i got to 900 revs. Been right ever since. I get the odd splutter now and then but needs an oil change too. So it could have been a combination of things. I just slowly worked my way through everyone elses suggestions that i could do myself. Good luck.
 

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it just seemsuch a common problem ...mine revs from 2500 to 3500 in bursts and all the lights are on
Just work your way through the list starting with the common and cheap fixes then the more obscure. Mine had no management lights on, after i cleared them. Theres also a trick with taking the two wires off the alternator, but that didnt work with mine. Good luck youre in the right place to find the answer.
 
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