Misfire Issue In Low RPM

**Quattritude** · 04-27-2015 09:10 AM

Hey guys,

Lately I have been having a misfire issue. I have had misfiring in the past here and there but now there is a consistent problem and it happens only in idle when the RPM drops below 1000. If I rev the car higher than 1000 while at a stop, I don't get any misfiring but if I do not, then it misfires in cylinder 1 and 3. I have changed my spark plugs and coilpacks (to the red R8 ones) but the problem still persists. I even switched the new spark plugs and coilpacks around in case they were faulty as well but the problem did not follow those particular sparks or coils and still came back in cylinder 1 and 3.

Does anyone have any ideas what the issue can be? I am going to do carbon build-up cleaning this upcoming weekend, which I am sure is a factor due to my car having about 65k miles on it but just wanted to make sure it is not something else.

Any help would be great!

**Quattritude** · 04-29-2015 10:32 AM

Just purchased a PCV valve perhaps that will fix the issue

**Quattritude** · 05-06-2015 06:16 PM

Swapped out my PCV and did carbon build up cleaning. Car feels a lot better but I get the flashing CEL here and there when the car is at idle.

Any help would be great!

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**STA4** · 05-06-2015 09:35 PM

Any error codes? Injector issue?

**van462** · 05-07-2015 05:51 AM

Pull your sparkplugs and see if any are wet with gas. Possible fuel injector sticking.

**Quattritude** · 05-07-2015 07:32 AM

Originally Posted by STA4

Any error codes? Injector issue?

Before I used to get the typical P0303 Cylinder 3 misfire but now that I changed my PCV and did the carbon build up cleaning, the CEL just flashes at idle. I checked pending DTCs with VAG COM and it shows the P0303 Cylinder 3 misfire.

**Quattritude** · 05-07-2015 07:34 AM

Originally Posted by van462

Pull your sparkplugs and see if any are wet with gas. Possible fuel injector sticking.

Awesome, thanks I will try that today and report back. If it's sticking, is there a way to clean the fuel injector or do I have to replace it? Also, is it injector 1, 2, 3, 4 from the front of the car or from the fire wall?

**Quattritude** · 05-07-2015 09:46 AM

Just bought some of this stuff. It's an Audi multipurpose additive. It's meant to clean the fuel injectors (not carbon build up obv....which i don't need it to because i have done that already).

I am hoping i have some luck with this. Don't want to pull my manifold twice in a week lol

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**STA4** · 05-07-2015 10:28 AM

Good luck, I just ran a tank of Chevron Techron. I have a slightly rough idle...it didn't help. I think of it as preventative maintenance.

**Quattritude** · 05-07-2015 10:36 AM

Originally Posted by STA4

Good luck, I just ran a tank of Chevron Techron. I have a slightly rough idle...it didn't help. I think of it as preventative maintenance.

Yea, I'm thinking it is preventative as well but I am desperate at the moment and trying to avoid pulling the manifold again lol. Worth $10

**STA4** · 05-07-2015 10:43 AM

It's definitely worth the shot. Where did you pick that up, dealership?

**Quattritude** · 05-07-2015 10:53 AM

Originally Posted by STA4

It's definitely worth the shot. Where did you pick that up, dealership?

Got it from Downtown Audi. All Audi dealerships should typically have stock of it.

**Quattritude** · 05-08-2015 06:29 AM

I would like to confirm that the fuel additive didn't do shit lol. I think it is the injectors

**STA4** · 05-08-2015 06:55 AM

It's not an instant fix. You have to drive the whole tank to know as it takes time for the additives to clean

**Quattritude** · 05-08-2015 07:22 AM

Yea but I have done 3/4 tank and the car still idles like complete shit. I have doubts that in the last 1/4 tank the car is going to run like new

**STA4** · 05-08-2015 07:44 AM

You did 3/4 tank in 1 day?!

**Quattritude** · 05-08-2015 08:12 AM

LOL yea. I pumped up in North York and drove to Newmarket. From Newmarket, went to the Leslieville (downtown) and then from there went to Richmond and Peter St. From there went back to Newmarket. From Newmarket I went to Woodbridge. Then today from Woodbridge to downtown Toronto again. 50% of it in dense traffic and ripped it every time I got the chance

**Quattritude** · 05-08-2015 09:59 AM

So I just ordered an injector. I know they usually recommend replacing all four but I'm going to replace the one I believe is faulty for now.

There is an extended warranty in place for the injectors but with the mods that I have on my car, I'm scared they'll just send me out on my way and plus I would have to pay the diagnostics fee for an hour of labor which is $145 plus taxes. Instead, I ordered an injector for the same price along with the installation kit from ECS. I will report back once I have changed it.

**Quattritude** · 05-14-2015 06:06 PM

I changed the injector today and unfortunately nothing changed. I still have the misfiring in cylinder 3. I am truly out of ideas.

Any help would be great!

**Quattritude** · 05-15-2015 08:48 AM

BUMP

**Elliott** · 05-15-2015 11:01 AM

This is pretty odd. I would've guessed the injector would solve the problem. Is the misfire still only on cyl 3? Any damage to the wiring around the coil pack? Possibly a valve seal going bad?

**Quattritude** · 05-16-2015 11:13 AM

Originally Posted by Elliott

This is pretty odd. I would've guessed the injector would solve the problem. Is the misfire still only on cyl 3? Any damage to the wiring around the coil pack? Possibly a valve seal going bad?

Yea, I was hoping it would have as well. Yes, the misfire persists in cylinder three. There's no damage that I can see. I am taking my car in on Tuesday (it's the long weekend here everything is closed) to have my car diagnosed. They're going to do a compression test, etc. I hope it is something simple that I have missed as opposed to cylinder three being shot and having to do an engine re-build of some sort.

I'll keep everyone updated as I go along.

**mukixt** · 05-19-2015 07:46 AM

Update?

**Quattritude** · 05-19-2015 08:17 AM

Nope, not yet. I am going to the mechanic in the afternoon today for them to do a compression test. My mechanic is saying it could be the piston rings. We'll find out soon enough

**SDF1** · 05-19-2015 03:11 PM

http://wiki.ross-tech.com/wiki/index...7/P0303/000771

Do you consume oil?
If so, check with APR to do a flash back to stock and then have them do a consumption test. if it fails hope they cover new piston and rings.

**Quattritude** · 05-19-2015 03:40 PM

Originally Posted by SDF1

http://wiki.ross-tech.com/wiki/index...7/P0303/000771

Do you consume oil?
If so, check with APR to do a flash back to stock and then have them do a consumption test. if it fails hope they cover new piston and rings.

No, the car doesn't really consume oil. I put in like a quart of oil every 7-8000 km so I am guessing its not that bad?

My car is out of warranty, they wouldn't still cover it would they? My mechanic tells me chances are cyl 3's piston rings is fucked

**Quattritude** · 05-20-2015 09:18 AM

So the mechanic didn't do a compression test but scanned the car and saw it misfiring and looked at the rate it was misfiring and was quick to blame piston rings. I kept asking for a compression test but they never did one so i became a bit skeptical.

I bought a compression tester and tested the compression in each cylinder. Had the following results:

Cyl 1: 180
Cyl 2: 175
Cyl 3: 179
Cyl 4: 180

I don't think there is anything wrong internally. I think the connectors for the coil packs might be detective. I'm going to take my car to my fiancé's uncle's shop. I was avoiding it till now because it is over 100km away and i didn't want to drive it that far while it is misfiring. I just got CAA so I'm going to get it towed there.

Just an FYI for anyone who deals with something like this in the future...even if your CEL isn't flashing or solid at high RPMS or high speed and even if your car feels smooth at high RPM or high speed, chances are you're still misfiring even though the CEL is only flashing at low RPM or idle. I was able to see this first hand while I was data logging while driving. It wasn't misfiring as often as when i was idling but it still was misfiring a fair amount for me to be concerned. The fact that it wasn't misfiring as often at high RPM or high speed makes it smoother which is why we typically think it only misfires at idle.

Also, while data logging, cylinder 3 was constantly misfiring while cylinder 1 was misfiring every once in a while. Perhaps they're linked in some way? But, the car never picks it up or gives a CEL for cylinder 1.

Just to summarize so far what i have done (in this order):

- Spark Plugs
- Coil Packs
- Changed To Aftermarket Intercooler (didnt think it was linked...just a mod i always wanted to do and i swapped this after the issue started)
- Carbon Build Up Cleaning
- PCV Valve
- Injector for Cylinder 3
- Compression Test (180, 175, 179, 180)

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**STA4** · 05-20-2015 11:45 AM

Don't forget to add carbon cleaning to your list

**Quattritude** · 05-20-2015 12:19 PM

Lmao fuck my life that was the worst part. Adding to the list

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**inNout** · 05-20-2015 03:49 PM

I had this issue and it was bad gas.
But i think you already went through a whole tank of gas and refilled....

**Quattritude** · 05-20-2015 04:07 PM

Originally Posted by inNout

I had this issue and it was bad gas.
But i think you already went through a whole tank of gas and refilled....

You had misfires in one cylinder or all? Perhaps a bad fuel filter but i would think misfires would occur in all cylinders at that point no? Mind you it doesnt cost much...might just do it anyway

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**SDF1** · 05-20-2015 06:17 PM

could be intake manifold.

post a video.

**inNout** · 05-20-2015 06:20 PM

This was when i had bad gas.... The f'n engine trying to free itself from the bay.

**Quattritude** · 05-21-2015 10:33 AM

^ Mine shakes uncontrollably like that or perhaps even worse. I'll post a video later today.

I think it's the wiring for either coil packs or injector. Car will be in the shop next week Tuesday for now it sits and collects dust