knfeparty

Just got back from 7 month deployment. Got my dad to drive it and crank it a few times but still had the same tank of gas in it. Drove it to work once and on the way back threw a CEL. I put a fresh tank of gas in it and honestly it seems to run pretty normally. Only thing that seems odd is that there is a lot of vacuum when I pull the oil cap off. I can get the cap off easily but there is a sound of rushing wind going into the crankcase when I pull the oil cap off. Car isn't blowing any smoke at all but I always idle it a bit before I shut it off. Going to get it scanned tomorrow by the local tech who has the Porsche scanner.
Thoughts? AOS?

Macster

Seven month old gas and probably the wrong blend for the climate can certainly explain the CEL. Did the CEL flash? Did you read the error codes?

With just a CEL and no other scary/odd engine behavior old/stale gas has got to be prime suspect.

(Drove an Infiniti EX35 with 7+ month old gas and while the CEL didn't come on the engine felt definitely flat. But I attributed it that being a characteristic of the car, although I kind of remember when looking into these cars before it was purchased they were kind of a hot rod. Anyhow I drove the car quite a bit and finally the tank got low and I filled up the tank with Shell premium. The change was quite remarkable and the engine really perked up. The gas was extremely stale.)

There is some vacuum at the oil filler tube cap. This is normal. What would not be normal is if while you could unscrew the cap you could not remove it against the pressure difference.

There is another possible explanation for the CEL. That the car sat 7 months it could have been visited by mice (or worse). I have seen several cars that have sat for less time with substantial though not on the surface obvious rodent damage. I have also come across several cars that have sat as long or longer (one sat unused for 3 years) and had no rodent damage. (The car that sat for 3 years though had to have its fuel tank, pump, fuel lines, injectors and other things replaced due to the gasoline simply turning into something nasty over that time.)

Get the car scanned, the error codes read. What the code are can influence what you do, or don't do, next.

Sincerely,

Macster.

Byprodriver

Welcome Home! & Thank You for your service! It's normal to have alot of vacum when the cap is removed. Gas goes bad within 6 months so the engine is not liking that & hopefully that is the only problem. You might want to disconnect the battery to reset the CEL & drive it to see if the CEL comes back on. Refill with gas often to further dilute the remaining bad gas.

Invius

Thank you for your service! I would put in some octane booster to get you through the rough patch, and as Bypro recommends, fill it as often as you can to start mixing better gas in.

knfeparty

Thanks and it's good to be home! Yeah I really hope that the amount of vacuum is normal and not AOS-related. As I said, the car runs pretty normally now that it has some fresh gasoline in it. I am getting the car scanned tomorrow. It's going to cost $95 but oh well.

I did put the car on a lift today to fix a loose swaybar droplink that was causing some noise. I didn't spend too much time looking but didn't see anything out of the ordinary. There was a bit of moisture from what looks like would be RMS seepage, but my RMS is only a couple of years old and it isn't dripping off the car any.

Well I won't try to clear the CEL since it is getting scanned tomorrow anyways. We'll see how it goes from there!

Driver5

$95 for a scan? Might want to try Autozone. They will do it for free. Save the $95 for new gas!

Invius

+1 for what Driver said, as well as Pep Boys, and most other national chains. I wouldn't let them work on my car, but if they could come up with what the CEL codes are, post them back here and we can chime in on what may be causing them.

C4CRNA

You can buy your own scanner for less than $95 and we can help you decifer the code!!

Macster

The car is probably free of rodents but just in case, for signs of rodent infestation look on top of the underbody trays/panels. Nest litter gets shoved out of the car and falls onto these trays.

Sincerely,

Macster.

Byprodriver

Octane is a measure of resistance to ignite, the higher the number, the higher the resistance to ignition, so raising octane will make the OPs problem worse.

knfeparty

Well the code was gross emissions leak (i.e. gas cap loose). Oddly enough the car's onboard diagnostic tests and the Porsche testing unit (PTS2 or whatever that thing is called) wouldn't complete all of the tests. Seth at Technical Dimensions reset the fault and test drove it some but it didn't come back. He told me to drive it a few days and see if the fault returns. He didn't charge me either! Hopefully it was just loose gas cap/crummy fuel.

wross996tt

The cars are very sensitive to this...When I first read this post I thought the tech took your car...LOL

Macster

Makes sense now. The car sat and the gas got stale and the cap o-ring either dried out/shrunk or the cap was loose to begin with.

You have a good tech. Buy him donuts!

Sincerely,

Macster.