I love my 09 CGTS which had been rock solid, except for one problem. It seems to be very sensitive to vapor leak/gas cap tightness. Because of this, I replaced the gas cap with an aftermarket solid aluminum one a couple of years ago. But the problem keep on coming back. I am diligently tightening it to a point that I put a lot of pressure and it won't move anymore, but still the same. I have a Durametric and reset it once in a while.. although lately I am just letting the CEL go away (after driving for 100 miles).

Vehicle is out of warranty and my indy mechanic does not have a clue why it keeps happening.

Does anybody experience the same?

Any clue why this is happening, could this indicate an underlying problem?

The vehicle drives great and this does not seem to affect it's performance.

Thanks in advance for any input.

 

Yes they can be. So, ditch the expensive "PORSCHE" aluminum cap and drive down to your dealership and buy the correct cap. The propper cap doesn't need (and can't be) to be overtightened. That may end the problem.

 

I've been having the same issue on my '05. I just bought a new cap figuring it's possibly the gasket on the old one. I haven't put it on yet but I'll let you know if it fixes it. Wasn't very expensive either, at least not for my year.... http://www.ecstuning.com/Porsche-200...earch/Gas_Cap/

 

More often than not, it's the fuel vapor purge valve getting stuck open that causes the EVAP leak fault. There are other possible causes too, but it's not just limited to the fuel cap.

 

Thanks Tim will keep that in mind. Is the valve easy to replace? On mine anyway when the code has popped up I'd retighten the gas cap and it went away. I put the new cap on last night and it did seem to be a bit tighter feel to it.

We'll see I suppose. If I get the code again I'll look at the valve!!

 

I ran Durametric, got
8110 - No signal/communication
9410 - Value below limit
8004 - Value below limit

anybody familiar with these codes?

 

Yes, it's very easy to replace. It's on top of the motor, under the driver's side coil cover.

 

Cool will keep that in mind. So far with the new cap no more CEL.

 

it just dawned on me - could these CEL issues be secondary cat bypass and cold air intake related? I have both. I will bring the vehicle to a local indy shop who specialize in Porches (PIWIS equipped) and will consider GIAC ECU as well

 

I don't think these would contribute to your problem. Many people have these mods installed (including me) with no CEL issues. The cap or the fuel vapor purge valve sounds like the culprit to me.

 

I suspected it was cold air intake related and took it out. I reinstalled the factory air box and used the OEM filter initially... CEL did not come back for a week (it used to re-appear within 10 kms after I reset the code with my Durametric). I replaced the OEM filter with a K & N drop-in 2 days ago and has put in almost 1,000 kms since - still no CEL and I honestly think it runs better now (maybe effect of Sprint Booster I just installed).

I think I will go ahead with an ECU tuning soon to complete the package

 

Well I hope you found it. The new cap seems to have done it for me. No codes since I put it in several weeks ago!!