Originally Posted by bowtie4ever
No coolant leak, just slight rough idle. Been doing it for about 5 years ( spare car barely driven ). Have done all the normal stuff= plugs wires ect. Can the egr port leak vaccum on the inside?? Thanks.
Here'* the problem in a summary.
The EGR stovepipe comin in through the upper intake manifold touches the plastic walls of the upper intake manifold around it. Adjacent to that EGR port are the throttle body coolant passages. The heat cause the plastic to become brittle and crack over time, which can potentially cause a severe coolant leak. Its a ticking time bomb.
The revised upper intake manifold includes a revised stovepipe which has a smaller opening, allowing a pocket of air around the pipe itself so that it doesn't directly heat up the plastic and cause it warp, crack, etc.
Try cleaning your mass air flow sensor. Does the idle bounce around in the revs, or is there just a vibration in the car? A broken engine mount can cause excessive vibration to be transferred to the chassis instead of bein absorbed by the mount.
EGR ports don't leak vacuum. The purpose of EGR is to allow exhaust gasses to flow back into your intake. The purpose of this is to mix air coming through the throttle body with exhaust gasses, which cannot be combusted as fuel. This artificially lowers the effective displacement of your engine, causing your fuel economy to decrease, along with depositing carbon on the intake runners over time. The fact that it is exhaust gas is what causes that stovepipe to get so hot and cause damage long term. You should be able to confirm if you have the revised stovepipe by removing your throttle body and shining a flashlight in there.
2005 Pontiac Bonneville GXP - For Sale ----- 1995 Buick Regal GS(X) - L67 madness
2000 Buick Regal GSE - Stock...for now
----- 1987 Jaguar XJ-* V12 - 12>8