1988 3.2 crappy idle and shakes

[Tyson Schmidt]

I've seen a few fuel pressure damper and fuel pressure regulator diaphragms blow out, causing fuel to be siphoned into the intake. Ethanol damage. Dries out the rubber and it cracks.

Easy to check. Pull the vacuum hose with it running and check for any fuel present. Or put a vacuum tester on them to see if they hold.

Not super common, but something to check if you run out of ideas.

[almostordinary]

Originally Posted by mikedsilva

Sounds like that disconnected vacuum line might have been responsible for a lot

My thoughts exactly. There's a lot going on behind the intake, one vacuum leak and these motors let you know there's a problem immediately.

My brake booster and my oil cap were leaking simultaneously when I first rebuilt my car, a cheap smoke machine from Amazon paid for itself.

I've also had that exact vacuum hose come off, luckily with my heat delete it was easy enough to track down.

Enjoy the new driving experience!

[Snitzler]

He did mention the part about gas leaking out of the fuel pressure damper and fuel pressure regulator diaphragms blut there was no gas.

[pmax]

Curious how the vacuum line got disconnected at the regulator.

I suppose some work was done around that area or is it due to some "blow out" event ?

[Snitzler]

Finally an answer... For a number of reasons I sold my 911. The new owner wants to do some work and was curious as to why the engine was running so rough. Pulled the engine and started a tear down and found that all the intake gaskets were falling apart.
One was in pieces. This is interesting as the engine had a recent smoke test done and no smoke leaks. The car ran better when cold and got progressively worse as it hit operating temp. So maybe the gaskets worked better when cold and the heat caused them to open up?

[Cairo94507]

Thanks for circling back with the end result.