zulujams

I started using 91 but the pricing is almost the same and I switched over to 93. I bought used and can only hope the previous owner was running 91 or 93. I've heard from others that 'misfires are normal' but didn't have much else to go on besides that. I just didn't know if the log files were showing me of a pending problem or just something 'normal'. Thanks.

SkidroweS4

I've had the same issue show up 3 times. It's always an entire cylinder bank and all 3 cylinders show the same timestamp for the misfire. The first time, it threw a cel and I took it to the dealership. They told me to stop using crappy gas. I only fill up with Shell and Chevron, but I do only have 91 octane available to me here in California. The last time, I saw it with my vag-com cable. I just emailed it to the dealership and asked them to note it in my "file" and then cleared it. I haven't seen it since I got tuned 3 months ago. I researched it a lot and have seen about 5-10 people who also had identical misfires across an entire cylinder bank and almost all of them never saw them again or felt a rough idle.

-Skid

GR8-LIFE

I'm going to need to find how to read the codes. Might as well check now while she's still young

zulujams

Sorry, not trying to make you paranoid. And I swear I don't work for Ross-Tech, but I do promote their product as I find it pretty amazing. The price tag seemed a bit high at first until I started playing around with it and learning from others. with the cable, all I did for reading these faults (or events?) was go to auto-scan and let it run for 5 or so min and got the output. PM me if you want a full scan file emailed so you can see what it checks. Beyond some settings changes and scanning, there is real time logging of parameters--over my head for now but others know about it and can share.

socfan12

I've had two misfires recently, one on the street about a month ago and another on the track just 2 days ago. The one one the street was 'silent', no CEL and if I hadn't been scanning for codes, I would not have known (engine was not rough). On the track two days ago, my EPC light came on and car went into limp mode. Pitted in and scanned for codes: cylinder misfire in cylinder 4 and the ECU disabled it. Let it cool down, put in some 100 Octane just for yucks, and finished the day doing the last session and still driving hard.

This is third time going into limp mode on the track due to cylinder misfires, very annoying. But the dealer cannot find an issue with my fueling system, just blamed it on crappy gas. I've been using Shell pretty much exclusively since they told me (almost 5 months now) but I still got this misfire and limp mode. Debating whether to take it back to the dealer or a shop who can really diagnose the problem.

I don't mind the silent misfires, it probably happens every once in a while, but to get into limp mode is quite annoying, especially on the track...

GR8-LIFE

One thing I cant stand is when dealers blame it on crappy gas because they cant find out whats wrong. Thats not only a cop out and a sign of poor service, but it also insults my intelligence. A letter to AUDI (Johan de Nysschen, himself if necessary) would be in order if that ever happened to me. One thing I always do is introduce myself to the shop formean and I try to arm myself with TSB awareness. Long ago shops had an advantage over owners but nowadys, TSB information is everywhere on the Net so a dealer only makes hmslef look bad when he ignores an issue or attempts damage control by pretending he has never heard about the problem.

Recently I had a leak from the flanges near the rear diff. My SA says "hmmm . normally we dont have leaks form the S4. Are you sure its the S4 and not another one of your cars?" I reply "Not Only am am I certain is the S4, but therr is a TSB out on the leak" Boy, I am certain he felt like an idiot, especially when the technician acknowledged the leak and applied the TSB to fix it!

SukiS4

I've asked about misfires either on here or AudiZine in the past, and at a shop. All I got was what's been discussed here recently, and it all comes down to the gas quality...I guess. The shop even went further saying that he thinks it's because we have to use 91 octane out here in CA, and not 93 octane. Well, I guess that's now debunked as the person here is having the same problems while on 93 octane.

I try to put in 93 octane from time to time, but I really have to go out of my way to get it. A local 76 station 5 minutes away from me sells VP Racing 100 octane, so I just mix it with 91 octane until I get the ratio right to 93 octane.

Muhtish

I have posted in a thread titled "misfire" about my experience. If you would like to read it, do a search under my screen name, I'm not sure how to navigate through this website yet (joined today).
​​​​​​But the bottom line in my case was the bad/burnt spark plug. Easy fix and took care of my problem. Hope it helps you guys out .