siitech

My 2013 base 991 runs fine and gets decent gas milage about equivalent to the EPA listed numbers. However, there is heavy unburned gas smell from the exhaust after cold start in the morning and during warm up. Drive it a few blocks and then it would be fine, and the smell seems to be gone once the engine is warmed up. I did not notice it for quite a while because most of the time I would be inside the car and drove away, but if I cold start the car and walk out the door, the whole gargage area would smell bad even though the garage door was open. I plan to schedule an appointment with my local dealer, but just want to make sure this is not normal, and checking that if anyone had the same issue.

991carreradriver

Not normal. I would have it checked out.

jimbo1111

The cold start or auto choke is normal for the first 30 seconds or so. Car sounds raspier on startup as well. Seems normal to me. No service light right?

siitech

No service light. But the strong smell does not seem to be normal. I made an appointment to bring in the car to my dealer tomorrow, I will leave it overnight so they can check cold start in the following morning. I will report back.

dflowerz

How is your gas mileage. Wondering if you might have a sticky injector.

siitech

I generally get about 17-20mpg in the city, 26-28 on freeway, according to the trip computer. Seems normal. On the other hand, the strong smell from exhaust would be mostly gone soon as the car warms up a little, so maybe most of the time the car runs normal and that was why I did not notice drop in mpg.

997s07

It's completely fine. All 991 cars do this. It's running rich to get the engine up to temperature. Unfortunately running rich is inefficient use of fuel since it goes unburned and the cats can't catalyze the oxidation of the fuel. So you smell fuel.

Edit: If you warm start it and it smells like fuel, I would take it in.

LexVan

Agree.

I am the Walrus

In the morning do you start the car and drive off, or do you sit and let it "warm up?"

siitech

I generally drove off immediately after cold start. I did not notice the smell for quite a while until my wife told me the garage smell really bad after I drove off with the 991, she was wondering if there was a problem with the car, then I looked into it and I smelled it easily too outside the car.

Anyway, I drove to my local dealer today and talked with my SA, he was pretty sure it was normal for the 991 as long as there is no warning light or fault code, he told me the 991 would run rich after cold start just as the same stated by 997s07 and LexVan. So he did not bother to check in my car for inspection.

I am glad to hear it is normal. By the way my car has CPO warranty till 2019 so I am not worried.

LexVan

Sitech, when you start your car, watch the tach. In runs on high idle, about 1,200 rpm, for about 60 seconds. Then the rpms drop to about 800. The car just runs rich this way as part of the thermal management for EPA stuff and fuel economy. Start and go. You'll be fine.

siitech

Yes, I noticed the high idle after cold start. It seems my car runs pretty normal. I always drove off immediately, and I drive gently until the engine is fairly warm.

This is my first Porsche, so i am uncertain about a few things. Although I am not that young and had quite a few Audies and BMWs, so it is not like a new hobby. I am sure most cars are set to run rich during cold start and warm up period, but I did not had any previous cars that emmits such strong unburned gas smell so my initial doubt. Thanks guys for your help!

Here is an unrelated issue: I have been trying to eliminate some noise from the rear side of the car. It seems to come from the rear panesl or rear folding seats, it is not mechanical noise, but like something was loose and vibrates. It does not happen all the time, but more when car was going over rough surfaces. I checked and could not find anything. And it is hard to locate the noise when I am sitting in front driving. Any suggestion?

Stil_1

If it helps any it's not just the 911 that does this. My old F80 M3 did this as well at cold start. Ran rich and sounded like a diesel truck for 30 seconds (unless you open the valves on start) so not only a thing Porsche does.

thomnellie

Mine doesn't.

CSK 911 C4S

A raw fuel smell is odd.

Mine smells sweet when started.

Post up what the dealer finds.