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[perfferle]

Hi,
Just made the first proper run in my miggy 180 miles - since i replaced the DIS pack, leads, plugs, serviced breathers, Cleaned ICV and replaced cam cover gaskets.
At idle the engine is very smooth and after about a minute the RPM suddenly dives below the 500rpm mark and sputters before righting itself. What do you think is the matter? Crank sensor? ICV?
Regards, :-/

[Mike Collins]

Did you lubricate the ICV after cleaning? Thin machine oil may help.

[perfferle]

Yep mate, did that, even operated the valve manually  - it moves freely. Do these ICV's get 'weak'? It is dread if i have to replace it only to see if that is the problem. :-/

[JasonH]

What state is your battery in?

Does it do the same when you wind down a window?

I've seen Omegas do this when the battery is quite flat. It's the load from the alternator.

Check the battery volts before you start the car in the morning. Below say 12.3V and that could be your problem.

[perfferle]

Good point. I do have a fairly new battery. You can see a difference especially when the electric fan/s switches on and this mildly affects the idle - but not in a major way. The problem is quite pronounced and is noticabely different to the effect of electrical loading as i discovered while sitting in traffic today. It seems that the idle simply drops to a critical low RPM with no additional electrical being switcjed on, when the engine suddenly seems to 'catch itself' and rev back to normal idle 500-600 RPM. - Really odd. :-/

[JasonH]

Mine did that missing a beat thing until I replaced the battery.

Definitely worth checking the battery volts after the car has been stood overnight.

[perfferle]

Will do - first thing tomorrow

[cem_devecioglu]

EGR can also do it (if you have) and if its blocked ..

if EGR not blocked try cleaning it ..

[perfferle]

EGR never cleaned... I will look for a maintenance thread on how to do this.
Thanks.

[Phil B]

I've had the same problem since I had the car. My EGR is free to move as it pleases, but I blanked it off just to be sure and it still does it.

The RPM seems to very slightly decrease momentarily accompanied by un-smoothness, then it suddenly dips, revs and settles back to normal. Mine will do it about 3 or four times, usually when hot.

[jasonxr2racer]

Could be a vac leak?

[cem_devecioglu]

in later models they drop the EGR from design..Because its a headache..Nox measurement not used in most Europe countries..Also in UK..Also here..

And even if you block it , somehow effects the car..I use extra gasket under , this  reduced its effect a bit but not totally.. by design when engine become hot it starts working .. :-/

you can test its work on a park place.. let the car idle and become hot ..You will see the idle start playing at periodical times when EGR comes into play..

[perfferle]

Can i simply un-plug the EGR??

[Phil B]

If you unplug it I think you will get an ems fault light.

Try undoing the two torx bolts and check the valve moves freely. If it doesn't then clean up with carb cleaner and try it again. If it does move alright you can trace the outline of it's gasket onto a flat peice of beer can and cut a new one out without the holes, and put it all back on to see if it makes a difference

I tried that on mine and I could have sworn it was still doing it, but sod's law I can't make it do it now! I'll see what it does on the drive home and post back