Just checking back. Anything new to report?

 

Heat shields?

 

Heat shields is the suspected cause but has not been definitively confirmed yet.

 

It really does sound like a heat shield issue. Regarding the 194 temp constant turn the car off and it still reads 194 one would think it would spike a little up to 200 or so after shutdown if you have been driving it hard.I have never seen a 195 reading.

 

there is a good reason for this- it's an idiot light. Porsche has fixed the reading so that it reads no greater than 194 unless the car is overheating. Probably prevents questions and service appointments

 

I need to keep bumping this until we find a definitive fix. It sounds so crappy. Very un-Porsche.

 

Bad direct fuel injector?

 

Well with temperatures down around -15c in Toronto this week I'm going to do some cold weather testing and see if temperature changes anything. If it is the HEAT SHIELD vibrating against something at a certain resonant frequency, maybe cold weather will change that.

If anyone else has any further learnings post 'em up.

 

I had a vibration that turned out to be in the exhaust system at one rpm range. I found it by using something (broomstick) to apply pressure on various parts until it stopped. A very crude but effective approach.

 

Explain your discovery technique in full detail I'm curious. Was it on lift? Did a friend help?

 

I'm curious, do you have SC? I'm wondering if clearances are effected by one or the other.

ChuckJ

 

I used a crude method . I had a loud metallic rattle at 1150 rpms. While still cool I had may wife hold rpms at 1150 wearing a pair of gloves and using a short broomstick as a prod I pressed down on the heat shields and various exhaust bits. I managed to put my hands on everything in less than two minutes. Watch out for spinning belts and pulleys ect. I came up from underneath without an answer. Just as an after thought I put my shoe lightly on the tailpipe bingo the noise stopped. I removed the right hand exhaust tip, and cleaned it, put it back on and was greeted with the proper sound. This obviously would not work if the car has to be in gear rather than park . Also don't tick off your wife before laying underneath the rear. This is probably 14 different ways of wrong for most people. :-)

 

Always wise advice.

 

Yes I do have SC.

 

Hi guys, I think I may have had a little bit of a breakthrough here.

I had a hunch that maybe if the noise was a vibration or weird resonance between the heat shield and something else on the engine/exhaust, that maybe it might go away if the temperature was much colder than normal. Metals expand and shrink with heat and cold and I thought if the noise is indeed outside the engine that the noise might go away.

Well tonight I got my chance to test my hunch.

It's -17c outside right now (1F) so I drove around for about 30 minutes to let the engine warm up to operating temperature and then I brought it up through the rev range to where it always makes the noise. For me that's at exactly 3,100RPM under throttle. I did this over and over again in 1st, 2nd and 3rd gear on an empty stretch of road.

Well, for the first time since I bought the car the noise wasn't there. I could still here the tenor of the engine note change, but there was no harsh vibrating resonant noise.

This leads me to believe it truly is something to do with a heat shield somewhere and not something more complicated inside the engine or gearbox. Still needs to get fixed, but at least now we may know where it is.