POP, RATTLE, & SHAKE ... cold start ups

[Aimee4588]

I currently have an 01 manual, base model with 76K miles, living in west Texas. We rarely get any cold weather, but lately every start up during the past week has been rough to my ears. I've had the car for only 5months.

It could be the cold weather, but everytime i start up the car, like the title, it shakes, rattles, and even shut down on me completely. The noise lasts for about 3 painful minutes. The car has a popping noise, definately in the engine area. Then it will start to rattle and shake. There are NO trusted repair shops around here that i've found and Dallas is a 3hr drive.

Any suggestions? I will upload youtube vid after class of the noise.

[gregdacat]

Once it settles down and starts running "normal" check and see if you can remove the oil fill cap while it is running. If not, or if it is difficult to remove (suction) it is most likely your AOS (Air Oil Separator) Mine had the exact same symptoms just before the AOS went south.

[milliemax]

My exhaust rattles when cold. The previous owner told me it was the converters. After they warm the noise stops.

[Aimee4588]

I was reading in previous posts that it does happen to other 986-ers but only for a few seconds. Mine lasts for at least 2 to 3 minutes.

I took it in to get a diagnostic and they couldn't find anything at all. Suggested that it might just be moisture build up due to the cold and to try using dry gas. Has anyone used that before? I don't want to pour things into my car that might just harm it even more.

@gregdacat thanks for the suggestion. I looked up AOS cost and repairs, looks like it'll be a pretty penny.

@milliemax: how long until the noise goes away from start up?

[jcb986]

Dry gas...??? Every time I stick my finger in gas it's wet. I would start with a good tuneup, new plugs for sure, timing check, coil paks removed and checked and the timing sensor checked. The sensor can cause your problems. Get a good indy who knows Porsche's.

[Dale_K]

Maybe disconnect the electrical connector at the MAF and see if the car runs well afterward. I've never done it myself but I've read here that the car's computer reverts to a lookup table when it looses communication with the MAF. In other words it doesn't hurt the car to temporarily disconnect the MAF as a diagnostic test. It's worth a shot since disconecting the MAF is so easy. I'm no expert, so take this with a grain of salt.

[milliemax]

The exhaust rattles until it gets hot. A few miles ? I hear it when I back out of the garage and when I get to my destination , it's gone. The noise is in the converters. Good luck with your car !

[jcb986]

I notice the guys keep saying converter, but if your engine is popping, "misfire", then it's a coil pak or timing sensor issue, so my question is the car misfiring and quitting or just the popping rattling noise.

[John99Boxster]

I get the normal "rattling sound" for 1 or 2 seconds when I start the car and then it is very smooth. The 1 to 2 sec. rattle comes from the tensioner.

Shaking and Popping is abnormal. I would look at 1) Spark Plugs 2) Ignition Coils