audiq7peoria

Hi Folks,
I own 07 Audi Q7. I live in Peoria, Central illinois. Now its 3 F (-16 C) freaking cold. I tried to start the car the other day. It made rattling noise and then stopped in 2 seconds and it sounded like the air was going out of the balloon for a minute underneath the car.It's like coming from the exhaust pipes. I didn't figure out. After that I didn't dare to start again. It had happened before. But I waited for the weather to warm back up and it started with very low idle for 2 seconds and then running fine.
I just replaced my battery with Exide 5L/49 AGM and changed the oil for Liqui Moly Synthoil Premium 5W40
I filled the tank with 87 octane gas by mistake. I don't know if it matters.
I bought this car a month ago I drove a couple of times. Its so embrassing. I need your help.

lentiman

This is a gasser and not a diesel, correct?

audiq7peoria

3.6 L FSI Gas engine.

audiq7peoria

It's gas engine 3.6L

M3 Ninja

So you changed your oil and battery after you had this mysterious starting issue?

audiq7peoria

I was gonna change the oil and the battery anyways. But this issue had happened before I changed the oil and the battery. Today I tried to start again. It was cranking but, it wouldn't start. It was 18F when I tried.

D3Audi

How long did it crank for? Sometimes in colder weather it takes a couple of cranks to get going, I've had my V8 Q7 crank about 6-8 times before it started on a really cold morning (-30°F). can you get the car going at all and drive it somewhere? Take it to Auto zone and have a scan run on it, they will do it for free, or run a scan your self if you have the tools. I'm sure it's throwing codes.

audiq7peoria

maybe it cranked for 10 seconds. I tried 3 times. I didn't get the car going. I have a diagnostic tool icarsoft 908. It didnt throw any codes. Maybe I should check it after I start the car. Btw I filled the tank with 87 octane gas. Does it matter?

Clues

You may have gotten a bad tank of gas with high water content (some gas stations have leaky storage tanks which allow water to mix with the gas). The water content can freeze in extreme conditions and then clog up your fuel lines/engine. And then in warmer weather the car drives fine because your ECU can compensate with engine timing/detonation adjustments. This has happened to me a few times. You can get gas line antifreeze from any auto parts store and many gas stations - use 1.5 bottles for the Q7 as our tanks are BIG. Also top off your tank with fresh premium gas from a different gas station (to help offset the effects of the bad gas).

Your mistake of using 87 gas should not prevent the car from starting - at worst you might get some knocking or pinging.

audiq7peoria

I ordered bg44k online yesterday. Will it also work? I know it was stupid to fill with 87. I didnt get any knocking but, next time I will get high octane gas anyways. Thank you for your advice.