Right, here goes my 2nd problem thread.

When I bought my 2.5 v6 Miggy a month ago on the cheap, the baffle had gone in the back box and there was a bit of a misfire situation...

After replacing the back box and changing the plugs (one of the plugs was cracked) she sounded far better, gained some "ooomf" but she still sounds a bit... well rough.

More or less like a V8 would.

She drives quite well and loves cruising above 50mph, but below this she just grumbles...

I've been told to check/replace the Lambda sensors if the baffle in the back box went due to any excessive exhaust back pressure...

Should I continue with this or are there other things I should look at too?

Hi Welcome to the forum

You don't say what year the car is but first easy thing to do is the paperclip/pedal test.  This will show any stored codes. I'll have alook for the link.

Here it is http://www.omegaowners.com/forum/YaBB.pl?num=1189022687

Had the link for the "paper clip" test, will be trying it out tomorrow afternoon after work, guessing this a pretty nifty trick?

And she's a 1999 model, less than 65k on the clock

Yes it is, saves £££'s.

Have a look under the bonnet tonight while it is dark for any arcing on the plug leads or DIS paclk which is conveniently located right down the back of the engine under the bulkhead. Single plug misfire could well be a failed  plug lead. Multiple is more likely the DIS Pack

Another thing to look for in the morning is oil in the plug wells . Very common problem with the V6's is failed cam cover gaskets. If yours have failed use genuine VX /Opel only. pull the plug leads they should all be 100% dry.

evilClive wrote on 11. Nov 2010 at 19:38:

Had the link for the "paper clip" test, will be trying it out tomorrow afternoon after work, guessing this a pretty nifty trick?

It's basically a free diagnostic, doing it and putting the results on here will either rule out an awful lot of things and possibly give you the exact problem.

Welcome by the way, there are some Very knowlegable people on here and a couple of very good mobile spannerwielders.

evilClive wrote on 11. Nov 2010 at 19:27:

Right, here goes my 2nd problem thread. When I bought my 2.5 v6 Miggy a month ago on the cheap, the baffle had gone in the back box and there was a bit of a misfire situation... After replacing the back box and changing the plugs (one of the plugs was cracked) she sounded far better, gained some "ooomf" but she still sounds a bit... well rough. More or less like a V8 would. She drives quite well and loves cruising above 50mph, but below this she just grumbles... I've been told to check/replace the Lambda sensors if the baffle in the back box went due to any excessive exhaust back pressure... Should I continue with this or are there other things I should look at too?

If it sounds like a v8,shouldent that be a good thing. :D 8-)

Thanks very much for this info guys, very welcomed :-)

I'm not used to such modern cars with engine management malarky! I prefer old mk2 Golf Gti's, so much easier to work on.

Anyway, checked under the bonnet with the engine running and there is not flashing indicating any arching, even blipped the throttle cable to make sure.

I admit sounding like a v8 isn't a 'bad' thing, but she feels underpowered... no quicker than my old Golf or the 2l Renault Espace this Miggy has replaced lol.

heavier car than both mentioned for a start and rwd as opposed to fwd so wil be different. Try the sport button if its auto ans then see the difference. ;D ;D

Its worth checking the two small rubber hoses from the manifolds to the SIA piping, they sometimes split ;)

perhaps update your profile to tell us where you are:  maybe someone close to have a look for you.  could be a multitude of things: multirams, blowing SAI pipe but it may be nothing.

suffice to say that with a little "fettling" I'm sure that below 50 it will still impress