Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: TheHood on 30 August 2008, 17:39:24

Title: Whistling Plenum
Post by: TheHood on 30 August 2008, 17:39:24
Hi  :D I've got a very sick 2000 2.5v6 cdx  :'( It's missfiring badly and there's a whistling noise coming from the rear of the plenum.

Any ideas before I have to submit myself to "Oh, Omega, £500 quid for starters"

Thanx in advance, and for the maintenance guides which have saved me on a few occasions  8-)
Title: Re: Whistling Plenum
Post by: johnnycboy on 30 August 2008, 17:42:56
have u had plenum off recently may just need new plenum o rings.  take it off and check the rings first.  hth
Title: Re: Whistling Plenum
Post by: TheHood on 30 August 2008, 17:55:36
Well I was going to replace the rocker box gaskets, fuel bridge gaskets, plugs, leads and the o rings etc but that lot adds up to a tidy sum. So I thought I'd ask first in case there's a mechanical part that would need replacing at the same time.

I always  tend to finish a job that means talking half the engine apart only to be told "Ah, you should have replaced XXXXX while you were at it!"  ::)
Title: Re: Whistling Plenum
Post by: dbug on 30 August 2008, 18:05:19
Whistling noise sounds like an air/vacuum leak.   Check all pipes around rear of plenum are attached and have no holes.  If ok then likely to be plenum seals (o-rings)
Title: Re: Whistling Plenum
Post by: Lazydocker on 30 August 2008, 18:23:01
As above... All the symptoms are for a vacuum leak at one of the mentioned locations :y :y :y
Title: Re: Whistling Plenum
Post by: tunnie on 30 August 2008, 18:35:06
replace the 6 O-rings on the top of the fuel injection system.
Title: Re: Whistling Plenum
Post by: MutantCav on 30 August 2008, 18:48:09
Whistling noise will be the small o ring with the stirrup kind of thing that seals the airbox on top of the plenum where it pushes into the plenum itself...however rough running may also be o rings on plenum needing replacing...

However if you have rough running may also be leaking camcover gasket which you can tell by oil in the spark plug wells...
Title: Re: Whistling Plenum
Post by: TheHood on 30 August 2008, 18:53:27
Cheers everyone, I was just having a nose around and thers a hard plastic tube (vacume type) that isn't connected to anything. There doesn't seem to be any obvious connection for it to go to?

Just found it in FAQ, auto gearbox, sorry I'm a numpty

Just pricing up the parts to do a lead and gasket change so perhaps it will become obvious when it all comes apart  :-X
Title: Re: Whistling Plenum
Post by: Marks DTM Calib on 30 August 2008, 19:27:26
Hmmm.....beware of advice that says change this, that and the other, always correctly diagnose anything before changing things as all you do is add more unknowns into the equation  :y (new parts and extra work can be wrong or faulty!)

The ideal would be to do a vac test and then start looking for leaks.

The O rings on the injector assembly dont just fail although they can be damaged following poor assembly.

The most common point of failure is the brake servo pipe rubbing on the aircon pipe at the rear right of the engine following poor fitment after work has been done.

Also be aware that there is a breather pipe at the rear of the plenum on autos for the gearbox which shouldn't attach to anything (it vents to atmosphere)

Also be aware that you do get some hissing as the ide air passes through the mostly closed idle valve and the breather also hiss a small amount (check it is not excessive though)
Title: Re: Whistling Plenum
Post by: TheHood on 01 September 2008, 14:59:32
On further investigation there is a vacum valve on the rear of the plenum that doesnt seem to operate at all, the one on the multiram snaps open sharply when a bit of throttle is applied but the one on the plenum seems dormant

Is this usual or indicative of a fault?

Sorry to be a pain bit I'm completely skint and can't afford make mistakes or pay a garage £200.00 to tell me thay don't know what's wrong

Thanks for your patience and help  :)
Title: Re: Whistling Plenum
Post by: TheHood on 01 September 2008, 16:20:10
paperclip test,
although I didn't have a management light on I did the paperclip test
and got a 33-Exhaust Gas Recirculation (EGR) Valve Voltage Low

 and... well it flashes 9 then a little break then 1 and then 2 and repeats this three times now if that's a 93-Hall Sensor Voltage Low
wold this make sense to anyone?

33-Exhaust Gas Recirculation (EGR) Valve Voltage Low
93-Hall Sensor Voltage Low