Rough Idle

[mikechristie 0]

Hi, having originally joined the forum a few years ago with all the enthusiasm you might expect from acquiring a 205CTi from a ten year hibernation in a local barn......I had high hopes......

I met the usual "rough idle" problems with a nonchalant "common problem, not too difficult to fix....."

£600 later having changed all the expected problem areas with little or no change I drove it into the garage (100 yards from it's 10 year incarceration) and forgot about it for another two years....

Now with enthused vigour I'm having another go. Any suggestions before I start stripping the head? I have replaced - breather hoses (silicone) and filter, plugs, leads, dist cap, rotor, air filter, tried second hand inlet manifold and injectors, SAD valve, MAF meter, idle valve. Although starting it still runs rough up to about 2500rpm when the performance is all that could be expected (apart from the odd pop).

I do know the valve seats have never been converted for unleaded, could this be the problem? It's what I intend trying next, along with a head recon.

Any suggestions would be greatly appreciated.

Mike

[2-Pugs 57]

I don't think taking the head off is going to help, unless you know there's a problem with it. Valve seats are all ok for unleaded. No modification required. Do a compression check by all means but don't rush into taking the head off would be my advice as i doubt very much that that is the cause of your problem.

 

One thing to try replacing. Coolant temperature sender to the ECU. Located on the back of the head and costs less than £10 so worth a go.

 

Another thing worth doing if you haven't already is to remove the throttle body and throughly clean it with carb cleaner or similiar. There are some small bypass holes and so on which all need to be clear for decent running at idle.

 

When you say idle valve, what do you mean by that?

 

There is also a bolt into the right hand side of the manifold in the vicinity of the oil filler nozzle. Make sure it's there otherwise unmetered air will be getting in which will cause poor running (I speak from experience and have Simes to thank for pointing it out to me!).

 

On a similiar note it's worth checking for air leaks between the air flow meter and cylinder head for the same reasons.

[Simes 248 2 Cars]

There is also a bolt into the right hand side of the manifold in the vicinity of the oil filler nozzle. Make sure it's there otherwise unmetered air will be getting in which will cause poor running (I speak from experience and have Simes to thank for pointing it out to me!).

 

That was years ago! I still remember!

[steve@cornwall 100]

Also worth checking the elbow pipe between the throttle body and afm they can split where the other breather hoses join. Check the breather on the cam cover is clear. Mine idles high, no matter what adjustment is made, but will come down when the throttle on the throttle body is "wiggled". I suspect the shaft is worn and not allowing the butterfly to fully close.so also worth a check.

[toolie72 67 1 Cars]

Also worth checking the elbow pipe between the throttle body and afm they can split where the other breather hoses join. Check the breather on the cam cover is clear. Mine idles high, no matter what adjustment is made, but will come down when the throttle on the throttle body is "wiggled". I suspect the shaft is worn and not allowing the butterfly to fully close.so also worth a check.

"shoogle" test is FAR more accurate on components being tested!!

[steve@cornwall 100]

Shoogling tends to be too gentle for this. But don't 'wodge" it or it could break

[mikechristie 0]

Thanks to everyone who took the time to offer advice - much appreciated. With the better weather arriving (tempting fate?) I'll try all the suggestions. Thanks again - some valuable info!