EGR valve problem?

My volvo 740 1990 broke down recently after hesitating and stalling on me
for a couple of days. I replaced the oxygen mirror and the car ran but
still with some hesitations and sputtering. I had a full tuneup
(sparkplugs, rotor, distributorcap, wires, fuelinjector cleaining,
airfilter) done (at mechanic) with only minor improvments as result. I was
told by a friend that tuning the EGR valve could help? Does not this alter
the emission and can cause teh car not to pass inpsections? Other ideas
and tips anyone? Also one gasket at the interface between engineblock and
exhaust pipe system has a minor leakage. This happend when the car
initially broke down. Can this effect the performance and cause the
problems i describe? Thank you for your input.

 

The EGR can cause poor idle if the valve doesn't close completely.
Perhaps what your friend was referring to doing was cleaning it to make
sure that it was working correctly.

An exhaust leak where you describe allows air to get sucked in at
certain times due to the pulsing nature of the exhaust. This fools the
oxygen sensor (oxygen mirror??) into believing they mixture is too lean,
with the resulting overly rich mixture which can cause poor idle and
hesitation.

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

I was pondering about the exhaust leakage and I thought that it could have
a negative effevt. Thank you for conferming my thoughts.

The next question is of course how to fix it. I am almost certain that it
is only the gasket that is broken. It seams like a lot of work to remove
and replace the exhaust manifold just to replace the gasket. Is there any
reliable good way to seal the leak without removing the exhaust manifold?

 

No, the only way is to remove the manifold. It's not too hard on a
non-turbo, on a turbo it's more work, and also make sure you heat every
nut cherry red before attempting to remove them (8 manifold to head, 3
turbo to front exhaust pipe or you'll be breaking studs!

--
Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)