Old gas leading to misfires?

**trailertravis13** · 01-27-2008 02:17 PM

Hey guys my A4 has been basically sitting for the past few months and was probably last driven around October or so. I took it out for a drive yesterday after jump starting the battery and got misfires anytime I would put the car into boost. I changed the oil, put new NGK BKR6E plugs in the car and am still having the misfire issues. I haven't ruled out a bad coilpack or the ICM but the car ran fine before it sat so I suspect it might be the gas but I have never owned a car that has sat for a few months.

What do I need to do to weed out whether its the fuel that has been sitting or coilpack/ICM? I have a CEL due to either my Labree HFC or a bad O2 sensor (haven't gotten that far in the resoration process yet, O2 sensors are in the mail) but I pulled the codes to see if I had any others and had random cylinder misfires and also cylinder 4 misfires.

I currently have about 1/4 tank a gas. Should I add some new gas or should I try to run the current fuel out first? Is it worth adding Seafoam or something like that or am I wasting my money?

**ILoveT** · 01-27-2008 02:23 PM

We had that problem also. We just added some of that cheap octane booster and it ran better. I think that is the only time it should be used though.

**trailertravis13** · 01-27-2008 02:32 PM

Alright maybe I will give that a shot. I was thinking about adding some Seafoam and someone on Audiworld suggested BG 44K but it doesn't seem like that is readily available at Advance Auto Parts or Autozone and would need to be ordered. Thanks for the help.

**sbghms** · 01-27-2008 04:10 PM

How do you know if a car misfires?

**trailertravis13** · 01-27-2008 04:56 PM

If you are getting a lot of misfires you might get a CEL or even a flashing CEL depending on how bad they are. I don't really know how to describe what it feels or sounds like. The only way to know for sure what is going on if you think you are having misfires is to hook your car up to a vag-com. It will tell you if its random misfires or a specific cylinder.

**whoace** · 01-28-2008 04:22 PM

Bad gas would definitely cause misfiring. Gas has a shelf life of 30 days before the octane rating starts dropping. Our cars are rated for 91 octane. I'd say fill up with the highest octane u can find and that should fix it.

**A4Rollin** · 01-28-2008 06:22 PM

well after reading this I have a question.
I havent driven my car for about 2 months now. Im pretty sure there is a half tank left and its filled with 93 octane (always). When i go start it in a couple days should I use some octane booster before i start it? I dont want to deal with any misfiring issues, and would like to know what to do before i drive off.
Any help would be much appreciated

**whoace** · 01-28-2008 06:39 PM

You should be ok if you don't give it hard. pre-ignition (which is what's causing the misfire) is more likely to happen on heavy load. I'd say just fill up on 93.

**Militant-Grunt** · 01-28-2008 06:59 PM

Originally Posted by A4Rollin

well after reading this I have a question.
I havent driven my car for about 2 months now. Im pretty sure there is a half tank left and its filled with 93 octane (always). When i go start it in a couple days should I use some octane booster before i start it? I dont want to deal with any misfiring issues, and would like to know what to do before i drive off.
Any help would be much appreciated

My car is hard to turn over if it sits over a week without being started, I guess thats a clogged fuel filter though. Ideally you should start the car once a week.