Unplugging egr valves?

[skene]

Hi lads,

I have an '04 Vectra 1.9 CDTi 150 which has been running a bit rough at idle. On advice of a few people on the owners club I have unplugged the egr valve and now it's running much better and a lot smoother.

Is there any harm caused by doing this? The last time I unplugged it for a while not long after I reconnected it the small exhaust pipe that connects the egr valve itself and the exhaust manifold burst leaving me with a fairly significant bill. Was this just a coincidence?

Also I run an enclosed air filter (Pipercross) on it and no matter how long you let it idle for the turbo to spool down, when I shut the engine off you can hear pressure chattering back through the filter, which it didn't do before unplugging it.

Any ideas?

[aw51 121565]

You're making your engine produce more Oxides of Nitrogen, as the combustion temperature will be hotter under certain critical circumstances (cruising, from memory). This is A BAD THING in terms of providing one chemical contributing to photochemical smog, and you should be ashamed . (If you had a Renault DCi you'd also be risking the turbo getting overheated and emotional and spewing oil vapour into the incoming air followed soon after by a "runaway".)

In the real world outside places (like the Los Angeles basin) that 'trap' air pollution and have strong sunlight year round, you'll possibly cause an orange "service" light to glow (and this can be worked around) but the car will pass its MoT as normal on the emissions (particulates) test .

So - go for it !

[wheedler]

Easier to drop in bucket of diesel and cleaning it

[twink]

Just seen your post on Vectra-C.

It'll be fine as others have said. Fiat even supply a blanking plate for it (is a Fiat engine) which may help if you're concerned about leaving it unplugged. You can get it mapped out too if you have the car remapped. A lot of people have gone down this route. It'll be saving your inlet manifold too.

With regards to the exhaust manifold blowing, just a coincidence.

[Rob P]

Is that the same engine as a Saab 93?

If it is I did 45k miles with it unplugged, no issues other than the management light being on all the time.

[twink]

Rob P said:

Is that the same engine as a Saab 93?

If it is I did 45k miles with it unplugged, no issues other than the management light being on all the time.

Yup. It's in some Alfas too.

[FFSport]

I have the Saab 9-3 1.9TiD Vector Sport(150) I think it does have the same engine, had problems with my EGR and the EML on all the time, Turns out my inlet manifold & actuator had seized up. That left me hefty bill of around £650+, 90% of people I know have been quoted £800 to do this work, I took mine down to a place called Vauxcare and they do a diognostic for £54 but if they carry out the work for you its -£54 off your bill. Bonus!

But I would say its bad keeping it off the car, Give it a good clean and get it back on the car, Carbon spray also does the trick give it a little tap and bang and watch how much st comes out of it, If this doesnt work go out and see if you can get a new one cheap. If that doesnt work, get yourself to somewhere to have a look incase it gets costly for you!

[martin mrt]

Remove it, along with the inlet manifold, clean it all out, bypass it then remap it out.

Then how much better the car drives without it, and will continue to do so

[thinfourth2]

wheedler said:

Easier to drop in bucket of diesel and cleaning it

But more fun to drop the bucket of diesel in the car and then light it

[lance1a]

Wih EGR valves I've found that cleaning them with Alloy Wheel cleaner (such as the stronger version of Wonder wheels available in the trade) is far more effective than using most other methods.

[cirian75]

Did it to my XUD9 1.9 TD 306

got rid of the dip in the power instantly

also on the XUD it was linked to conrod failures

[Dr Doofenshmirtz]

aw51 121565 said:

You're making your engine produce more Oxides of Nitrogen, as the combustion temperature will be hotter under certain critical circumstances (cruising, from memory).

Nope - EGR valves only operate under low inlet manifold pressure conditions - for instance, when you open up the throttle to accelerate. As soon as manifold pressure stabilises, the EGR valve will close.
They do not operate at cruising speed, idle or when the engine is cold.
If plugging the EGR fixes a rough idle, then chances are the EGR valve is sticking open allowing exhaust gas into the inlet manifold all the time.