Can low octane rated gas be the reason for 3 cylinders to constantly misfire?


Asked by Nov 10, 2014 at 01:59 PM about the 2004 Audi A4 3.0 quattro Sedan AWD

Question type: Maintenance & Repair

I bought my 2004 Audi A4 3.0
quattro two weeks ago, i have used
premium (93 octane) gas ever since,
but two days ago i put in basic
unleaded (87 octane). Just a day
later my CEL turned on while driving
and the car began to noticably
vibrate. I realized this was most likely
a misfire issue. A diagnostic
computer showed that my 1st, 3rd,
and 4th cylinders are constantly
misfriring. I have changed the spark
plugs cleaned air intake, and added
an octane booster, injector cleaner,
and 1/2 tank of premium (93) gas to
the 1/2 tank left of the basic (87) gas.
I have diven the car about 60miles
since to no avail. Is this enough to
eventually sort out the problem, or
could this be more than a fuel/air
related misfire issue?

4 Answers


Nope this is a fuel issue. Basically the car is made to run on the highest octane gas you can buy. Lower octane gas will foul out your spark plugs and cause other parts to misfire. My advice to you is to drive the car till the tank is almost bone dry then refill it with high octane gas after replacing the fuel filter and redoing the plugs again. Do not cheap out and use ngk plugs. Use the best Bosch plugs you can buy roughly costs about 89 $ for a full set. ONLY replace the plugs after you have all the old gas used up. Your car once its been driven a while after you have used up all the old gas and have the new high octane in it it should eventually even out and start running smooth again. And this is why you don't use regular gas in a vw or audi as it will only cost you more in the end then the gas is worth in savingings.


Oh and be sure to replace the fuel filter and then run the car for about 15km to make sure the old gas is fully out of the system before doing the plugs.


Thank you. I was just wondering why this only affected 3 cylinders and not the other 3?


i would assume it only affected one side of the engine right ? it may just seem to have only affected one side of the car but really it has affected all your plugs. The fuel does not fire correctly because the engine expects the best gas as its more refined. All vw and audi engines work the same and i think it also has something to do with there completely pressurized systems.

Your Answer


Looking for a Used A4 in your area?

CarGurus has 12,429 nationwide A4 listings starting at $1,500.


Audi A4 Experts

  • #1
  • #2
    Tom Demyan
  • #3
View All

Related Models For Sale

Used BMW 3 Series
963 Great Deals out of 33,201 listings starting at $1,000
Used Audi A6
132 Great Deals out of 7,779 listings starting at $2,200
Used Audi S4
24 Great Deals out of 1,542 listings starting at $3,850
Used Audi A3
107 Great Deals out of 6,418 listings starting at $3,400
Used Mercedes-Benz C-Class
584 Great Deals out of 25,555 listings starting at $1,950
Used Honda Accord
540 Great Deals out of 94,361 listings starting at $1,300
Used BMW 5 Series
401 Great Deals out of 16,252 listings starting at $1,650
Used Ford Mustang
291 Great Deals out of 38,369 listings starting at $1,995
Used Audi A8
42 Great Deals out of 1,450 listings starting at $3,499
Used Mercedes-Benz E-Class
440 Great Deals out of 20,659 listings starting at $1,999
Used Honda Civic
347 Great Deals out of 52,617 listings starting at $1,200

Used Cars For Sale

2018 Audi A4 For Sale
5 Great Deals out of 6,323 listings starting at $28,691
2017 Audi A4 For Sale
33 Great Deals out of 865 listings starting at $18,995
2016 Audi A4 For Sale
13 Great Deals out of 207 listings starting at $17,220
2015 Audi A4 For Sale
33 Great Deals out of 984 listings starting at $14,499
2014 Audi A4 For Sale
16 Great Deals out of 673 listings starting at $13,900

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.