VikingTrad3r

hi guys. what would the symptoms look like on a L98 if the egr was allowing a bit of exhaust gas through its passage at idle?

would it idle high? low? low and rough? high and rough?

thnx.

mlm0

Rough idle

cardo0

I believe you can lift the valve up with a screwdriver to see for yourself. Be careful you don't bust the diaphragm though.

C409

Or just use a hand vacuum pump like a brake bleeder deal . Mityvac .

pcolt94

What is your actual problem?

Other than the main seal leaking, there is a internal valve also. This is part of the EGRs operation when acceleration. There are a few tests for the EGR and all can be good but the EGR still might not work correctly if the inner valve does not work properly. This valve is overlooked many times in testing and even with a test it may not catch a bad valve.

There are positive and negative pressure EGRs and tests explained in internet. If it tests OK and the valve is bad, it might cause a slight hesitation.