S3RRO

Hi Guys,
I made a mistake and for the 2nd time in 2 months I got regular gas, instead of premium, I was tired and didnt check what I am getting at that moment.

I realized what I got after I tried to start the engine, cause it didnt start on the first try. I have an 2006 a4, now my engine light is ON, how big damage could it be? Should I empty the tank with some hose, and fill it back with premium ? I feel really bad. I am leaving it to the service on Monday, its under warranty but I am scared If they tell me some big damages happened to the engine and Its not gonna be covered under the warranty since I didnt use the requested gas type.

What do you guys say ? Its a 2.0 T a4

sonic

your just lowering the octane level. It really should not do any damage to the engine. You may get it to ping. Im actualy suprised the engine light went on. Its usualy not that significant a change to cause that to happen. If you want you can get "octane booster" and put that in the tank...i dont know how well that works or if its just a gimic. Still, im suprsed that it has made a check engine light go on. Im thinking that maybe the gas cap isent on all the way or something else.....

Can the grade of gas actulay make the light go on, on the new 2T??

1move

iTrader: (1)

Yes it can, I have read in some cases that misfires and inproper timing issues and it needs to be cleared, get someone with a vag com to scan it for you and check it all out.

986Jim

It is possible however unlikely as the fuel system is a non-return style system so the fuel that is in the line from the tank to the engine and in the rail during your start up will still all be whatever was in the tank before and it would take a minute to burn that before you got to new gas from the tank that you put in. So when the car started and coughed it was running then on your old gas still.

It's more likely that during your sleepy fill up you also forgot to tighten down your gas cap and the CE light came on as a result of that.

87 octane gas will run in any engine, even a twin turbo viper with 10,000 hp and nitrous, as long as you are not at wide open throttle. The only time octane has anything to do with it, is when you are really pressing on the gas, the turbo is at full boost and the computer goes into open loop. Open loop at WOT ignores the O2 sensors information and runs on a fixed timing and fueling map and will only see if there is knock to pull timing. When you first step on it timing will drop from 35-40 deg of advance (cruizing) to about 8-10 deg of advance then slowly build back to say 20-25 deg at WOT. If knocking is detected then it will drop the timing back or hold it steady.

During Closed loop, partial throttle driving the O2 sensor information is used the the fuel and timing maps are optimized to run the best fuel efficiency and timing is way advanced as a result. The load on the engine is so low that low octane gas will have no problem.

The only reason higher octane is even used is so that during wide open throttle operation at high RPM the gasoline has knock resistance. The higher the octane the less chances of pre-detonation. During partial throttle driving, pre-detonation is practically impossible as there is so little heat, rpm or anything else that causes pre-detonation present it's pretty well a non-factor.

Octane booster does work, but not like you think. If it' says Super 108+ octane or whatever, read the bottle it will increase octane 8 points. but remember that 10 points is 1 octane. So if you have 87 and you add that stuff you will have 87.8 octane not 95. You would need 10 bottles of that to raise it 80 points. So you increase your gas by 8 basis points or .8 lol. Big whoop...

calgaryBrian

Agreed with Jim...

But, if you're driving and hear/feel pinging or "knocking", pull over.

K04-S4

True... but you should not experience this effect in a newer Audi. The knock sensor(s) will have ECU pull timing in order to ride the threshold of optimum engine efficiency before serious knocking occurs.

rveino

Would the 2003 Audi A4 1.8T have a knock sensor? I experienced loss of power and weird noises when running regular in my car.

Or is it just different for Turbo's period that they required premium?

J Ozzie

Just grab a bottle of OCT booster. And then once your done that tank run all the way to E. Next time around throw some fuel system cleaner in there along with the good stuff and your good. I run my 1.8 T on 90 Mohawk