Since I built this engine three years ago (B230F)it has had an issue with a surging idle for about one minute after a cold start in sub 40F weather, annoying yes, bothersome no. The more bothersome issue was the hot start stall that would require holding down the gas pedal a bit for two or so minutes at idle on a hot engine restart in weather above 70F.

Well, thanks to all the good advice on the BB I checked for vacuum leaks, even isolated the brake booster, no leaks were found anywhere and the problem persisted. I finally got fed up with the issue and pulled the intake manifold to inspect the gasket. the gasket was intact but oddly enough the center two intake runner gaskets showed staining at the bottom of the openings... hmm, very small leak. For the heck of it, I checked the flange of the intake for flatness where it mates to the head. The finding was quite stunning in that the bottom of the center runners were warped to 0.068" at the maximum!

At this point I pulled the intake manifold from the car and had it refaced at the machine shop. I reinstalled everything with a new manifold gasket, have driven it for a month and surprise of all surprises, the idle problems are gone!

Please note that the intake manifold on this car is modified as it has been ground, ported, and polished inside and out to a mirror finish. I'm not sure if this caused the manifold to warp or not as I didn't even think to check it for flat when I installed it three years ago. If there is a take-away from this one, if the intake manifold gasket is leaking, check the manifold for flatness before reinstalling.

Hope the above helps someone avoid repeat intake manifold gasket leaks! And thanks to those of you that pointed me in the vacuum leak direction!

jorrell
--
92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!