Erratic Idle

[cammmy 1]

Hey Guys. For some reason once my car warms up, when I let the accelerator out the idle sits at 1500 for a while before slowly dropping down to 1000. I checked the accelerator cable and it was fine, everything is where it should be and the cable is not too tight or loose. Also I think the car runs rich. There doesn't appear to be any black smoke but there is always the smell of half burned petrol when I get out the car. Could this be something to do with the oxygen sensor? What would the likely culprit be?

 

Cheers

[Feeble 0]

What should the RPM be? Mine site at 700

[cammmy 1]

about 700 to 800 I guess.

[cybernck 402 1 Cars]

850 when warm i reckon.

 

however, pug tachos are so inaccurate that it hurts, lol.

[KRISKARRERA 2 1 Cars]

Yes they are just a bit!

The idle once warmed up is set at 850rpm, according to all the manuals. As Cybernck said.

[cammmy 1]

The previous owner said he had it tuned. I'm guessing thats why I gets me the petrol smell. So do I need to have the ECU re-mapped? Is there any way to just adjust the idle? How do I get an ECU re-mapped? Would a new induction system help draw in more air and allow a more complete combustion, or would I need an uprated intake manifold etc as well? Should I give the oxygen sensor a clean and see what happens?

 

Sorry for all the questions

 

Cheers

[cammmy 1]

Anyone?

[Guest turbolag]

what had he done to 'tune' it?

 

Don't muck about cleaning O2 sensors - for what they cost if you shop around, and the grief they cause if an old corroded one shears off, just buy another (you might need a special socket too - check firsts).

[Tony1345402284 0]

Cam

 

The idle control valve is a possible cause of this problem. This valve controls the idle speed by regulating the flow of air to the engine at idle when the throttle body is closed.

 

The valve is on top of the inlet manifold and has two hoses and an electrical plug connected to it.

 

The stepper motor controlling the valve wears with age and the valve itself gets sticky with a buildup of carbon and oil.

 

Disconect the hoses and electrical plug and remove the valve. Use aerosol carb cleaner to remove the crud. The port in the end is easy to spray into. The other port is blocked by the rotating shutter, move the shutter aside with something soft like an ice cream stick (don't dcratch it!!) so you can spray in there too. Drain and refit.

 

This may help the symptoms.

 

Also check that the throttle position switch is set up and working correctly.

 

Hope this helps.

 

Tony

[cammmy 1]

Okay cheers for the info, i'll give that a go this weekend. With regards to the tuning, no idea what he has had done, all the parts seem to be stock so I assume he did something with the ECU. I'll post the results when i've had a go at cleaning it.

 

Cheers

[cammmy 1]

With regards to the throttle position switch (this is where the large gaps in my automotive knowledge come in to play), I took the air box off and cleaned the butterfly's, they close completely when the accelerator is not depressed. Also secured the accelerator cable as it had a lot of free play (the sheathing around the cable moved with the accelerator not just the metal cable inside thanks to some missing clips) If that makes any sense.

[cammmy 1]

Okay, Removed the valve and gave the inside a clean with carb cleaner, couldn't move the valve but it was a little open at the top so I sprayed it in and it made it through. Have put the valve back on and am waiting just to make sure that the carb cleaner evaporates before I try it. Will let you know how it goes.

 

Cheers

Edited August 2, 2007 by cammmy

[welshpug 1,657]

carb cleaner wont harm the engine at all its pretty much the same as easy start spray

[cammmy 1]

Well it was "start ya bastard" but carb cleaner is easier to right. I just left it to dissipate as I figured it's better safe than sorry (used about 20 times more to spray it down than I would if I was using it to start the car) I'll have to get the garage to check out the ECU mapping or something

[cammmy 1]

Sorry didn't post the results. No change the idle still sits at 1500 after a bit of driving before dropping to about 1000 5-10 seconds later. Any ideas? New oxygen sensor maybe? Could I get one from another model like the SRI?

[cammmy 1]

any one?

[Guest jontg428]

I am having the same problem as well, cleaned the idle control valve and its working better for the moment. Could be that the actual idle air valve is bad. I could not find any other vacume leaks on my car, so I am guessing that that was my problem. Hope you get your pug back up and running happy soon,

 

Jon

[cammmy 1]

Yeah cheers. It's not too bad at the moment so next time i'm at Pick-A-Part i'll see if there are any control valves that are the same.