High Idle

[DIYheadache]

Thanks to everyone that helped with my last problem with the purge valve, but I'm affraid the car has developed another related issue.

Peugeot 206 1.4 Auto (Y/2001)

On starting the engine will idle at 2,000. Sometimes it goes down by itself after about 10 seconds othertimes it will come down when the brake is pushed. The car drives fine, sometimes it will hold high revs when you come to a stop but this is rare. The engine will start at high revs once turned off then re-started about 10-15 minutes later, but not as high as when cold.

I have checked all vacuum lines for signs of cracks etc. I used a vacuum gauge to measure manifold vacuum, it was a steady 16inchs when cold, I have not tested when warmed up yet but this seems normal to me?

Could the brake booster have a split diaphram?
Could it be the temperature sender?

Many Thanks

Peter

 

[Jimmyjaffa]

More than lightly be the idle speed control valve full of soot. just remove the throttle housing and then remove the idle speed control valve and give them both a good clean.refit and all should be good. The control valve may need to be adjusted a little by hand so you may have to remove it a few times.

 

[DIYheadache]

Thanks Skippster

The Idle valve was replaced last time it had a hunting problem, which turned out to be the purge valve not closing. Although, I do think it could be a possibility. Will get some carb cleaner and give it a good clean.

Thanks

Peter

 

[Jimmyjaffa]

Give the trottle flap a good going over as well around the pivit point.

 

[tinytom]

it might be something to do with temparature, as long as your not losing power it that is, when it is cold it will sound like your revving, and vice versa when warm, all cars will become quiter 1-5 mins of running just when the engine has warmed (sorry if im just stating the obvious)

tom

 

[Avocet]

Have a really good check for any air leaks in any of the breather hoses - or the convoluted rubber one that goes from the airflow meter to the throttle body. They can sometimes cause a high idle.

 

[DIYheadache]

I gave the throttle body and ICV a good clean with some carb cleaner and left the battery dis-connectted overnight. Car was fine for about a week and then started to do the same thing again, when engine cold.

I took all the vac hoses off and gave them a close inspection. The green rubber o-ring inside the PCV has a small split on the inside of it. If this is leaking could it cause the high idle?

Thanks

Peter

 

[TeamLemon]

I had a similar experience with my Pug 106 1.4 petrol. It just would not idle and even cleaning the ICV didn't help it. I cleaned all the pipes, checked the breathers but to no avail so I changed the ICV and Voila!! It started and ran as it should.

If you have taken the battery off, you need to reprogram the ICV to the engine. I can't remember the exact procedure but I think it's something like: Turn the ignition key to second position and leave for 30 seconds (don't start the engine), switch off for 30 seconds, switch back to second position for 30 seconds, switch off for 30 seconds again and finally, start the engine and it should run normally.

Hope this helps

 

[DIYheadache]

The car no longer idles high when started but will hold the revs high when you take your foot of the gas pedal. Went for a drive today and it was accerlerating with my foot off the gas pedal, revs only lowered as I braked. It only seems to do it when the engine is below temperature, when warmed up it seems fine. The car drives really well and there is no hessitation or dead spots in acceleration.

I have replaced the PCV and breather hose but this has made little difference. What else could it be?

Thanks

Peter

 

[DIYheadache]

Just did a few tests:

If I rev the engine hard (>3500) a loud hissing noise is heard when I take my foot off the gas pedal - it sounds like it's coming from the back of the inlet manifold. Is this a leak or is it just high velocity air rushing in through the throttle by-pass.

Also, when I do this, the response is quick on the way up but slow on the way back down to idle. It starts to fall quickly then slows down in steps, is this the idle control valve taking over control?

The brake booster vac hose comes off the back of the manifold, there are no obvious leaks in the hose so it could be from the o-ring seal in the connector and is only leaking badly under high vacuum (over-run). Does this sound plausable?

Many thanks

Peter

 

[DIYheadache]

UPDATE:

Decided to live with the problem, as could not find anything obvious. Went in for a major service a couple of weeks ago and the problem has gone!!!

Garage replaced air,oil and fuel filter, spark plugs and new oil. Which one of these could have caused the high idle? Could crappy oil cause sticking valves and cause a funny idle?

Thanks

Pete

 

[Burnerman]

Got a feeling in my water that this may come back, Pete.....
Still think you have an air leak somewhere, but best of luck anyway!
John

 

[DIYheadache]

John, if you're right, it may come back when teperatures dip below double figures again!! Until then, I'm optimistic. That reminds me:

An optimist will say the glass is half full.
A pessimist will say the glass is half empty.
An Engineer will say the glass is twice as big as it needs to be!!

Pete