Misfire = Bad fuel injector? HELP!

[airbornerifleman]

UPDATE IN POST #6


So, I’ve been having misfire issues (not every time, but the colder the temp. the higher the chances of occurrence) under cold start up for the past 3-4 months. In rare occasions the CEL blinks. All the symptoms goes away after engine hes been running for more than 5 minutes.

Last Friday, when I hit the gas (appx. 40% load) from a stop, my engine started shuttering and the CEL was blinking, I immediately let off the gas and coasted until the blinking stopped, at which point the CEL was solid. I scanned it with vag-com and found random misfire and cylinder 2 misfire. Thinking this is a coilpack issue, I took it to the dealership to have the perform the recall campaign. The dealer changed the coilpacks and send me on my way. I started getting the same issue but on a more consistent basis now. I took it back to the dealer today and they told me that it was due to my spark plugs, so I had them replaced. Tech takes it for a road test and comes back and says that the car is only misfiring on cylinder 2 and that they swapped coilpacks and plugs to be sure, so they are thinking it may be a clogged injector and want to perform an injector cleaning but they can't guarantee that it will fix the issue. I told them thanks for all your help but I will have to pass on the injector cleaning. The symptoms are encountered on both stock and APR 91 mode.

Has anyone come across this kind of issue before? What are your thoughts/suggestions?

If I do have to replace my injectors, would it be advantageous to upgrade to the S3 injectors vice OEM? I will upgrade my stock exhaust but not turbo in the near future?

FYI
2006 A4
2.0T
Quattro Tip
K&N cone air filter
Custom intake pipe
APR 91, 93, 100
88xxxKM/54xxxMi

Thanks in advance

[Tusin]

not sure how hard it is to remove our injectors.... But could you take the injector out of 2 and put it in a different cylinder and see if the mis-fires follow? That should pretty much rule out the injector if it doesn't.

[airbornerifleman]

not sure how hard it is to remove our injectors.... But could you take the injector out of 2 and put it in a different cylinder and see if the mis-fires follow? That should pretty much rule out the injector if it doesn't.

Swapping the injectors is a great idea, thanks. I hope someone chimes in with a DIY on how to remove the injectors.

[Tusin]

When I get home I will look it up in ElsaWin for ya.

[airbornerifleman]

Sweet! Thanks.
I searched and found this, but it's for the 1.8T http://www.a4mods.com/index.php?page...injectors.html

[airbornerifleman]

I am updating this thread because, there has been a few threads WRT missfires.
I ended up changing all 4 of my injectors with new ones, at in indy shop, the problem was fixed.

After doing some hard reSEARCH, I ended up using the oem injectors instead of the S3 or RS4 ones. The S3/RS4 ones will make the engine run rich with out some serious custom ecu re-mapping and plus I'm only at APR Stage 1 with factory HPFP. If I was at Stage II+, I would seriously consider it.

This may not be good news for some, but at least you know what to fix now.

[rs6]

Check your cam follower. I had the same problem, put in new injectors, fixed the problem and car ran OK.

Still, I checked the cam follower and found it was totally shot, as was the HPFP and cam.

[b7kevin]

this issue sounds carbon related to me. Sounds like the valves are gunked pretty good. Run a can or 2 of sea foam through the an vacuum line on the intake mani. Also throw a can in the gas tank. This will run you no more than $30 and it requires maybe 15 minutes of your time.

[Tanner]

I say throw in a can of fuel cleaner the next time you fill up, and once the engine is warmed up run the engine hard (get on the highway and do 70kmh if you can, throw it in sixth gear and floor it until you get to at or above highway speeds). I used to have a bit of stumbling at the mileage you're at but no CEL, and did this and it seemed to have helped. But the misfires came back 20,000k later and I ended up getting the intake valves cleaned out at 103,500km.

[A4_Joe]

there is two possible change of car misfiring. lean misfire or rich misfire. Go for 20 mile drive and take the spark plugs out on cylinder 2 to see if you see any fuel residue on the cylinder if you don't it's not rich condition. The best thing to do is really remove and swap injectors around to see if misfire is move to different cylinder. I think all you have to do is remove the intake manifold and you should be able to have access to fuel injectors.

[rs6]

I thought my misfiring was carbon deposit related also. Had the intake deposits cleaned up, replaced the injectors, but it was really the cam follower in the end.

[Tanner]

Yeah, I'd check cam, plugs, injectors ... all the simple stuff before doing the intake cleanup.

[airbornerifleman]

Mike, can you PM the price for the carbon cleaning? I assume you took it IT.

[airbornerifleman]

Check your cam follower. I had the same problem, put in new injectors, fixed the problem and car ran OK.

Still, I checked the cam follower and found it was totally shot, as was the HPFP and cam.

I figured it was needless to mention. But, I did have the follower changed, when they were swapping the injectors. I also had the fuel filter changed before I ran into this issue.

[Swerve]

I had the same problem. I took my car to the dealer and they replaced the fuel injector on the missfiring cylinder. I still had a missfire. i asked about the cam follower, and the tech said that he checked that first and it looked fine. They tore apart the head, and took it to a machine shop. There was a significant amount of carbon buildup. They cleaned everything up and are putting the block back together. I should have an update on how everything goes by the end of the weekend.
My extended warranty has a loophole that states anything that is caused by carbon buildup is not covered. So I found out just now that I get to pay for all this out of pocket. FML.

[Tanner]

My extended warranty has a loophole that states anything that is caused by carbon buildup is not covered.

Audi CPO warranty?

[b7kevin]

I may be newer to this community but I do not understand how a follower could be the issue causing specific cylinder misfires. This would be highly improbable if not impossible. The follower is a wear part that protects the HPFP from directly contacting the cam lobe, its pretty much 100% or nothing. Theres no real gray period for make cylinder x misfire more than cylinder y, thats just completely makes no sense to me.

plug or coil yes, gunked valves yes, injector maybe. follower in a state prior to failure completely no.

plus op posted end result, injector failure all replaced.

[airbornerifleman]

I agree with you, Kevin.

[88mu88]

my car was idling very roughly after i changed the stock injector to a 386 cc injectors, will this be caused by the ecu not adapting or injector defect even when it was new

any thoughts guys?

[viziers]

my car was idling very roughly after i changed the stock injector to a 386 cc injectors, will this be caused by the ecu not adapting or injector defect even when it was new

any thoughts guys?

Did you replace it with a FSI injector or a standard injector??? I ask because the FSI injectors are not referred to as 386"cc" but OEM FSI, S3 or Rs4 injectors....



vizi

[88mu88]

Did you replace it with a FSI injector or a standard injector??? I ask because the FSI injectors are not referred to as 386"cc" but OEM FSI, S3 or Rs4 injectors....



vizi

sorry to mention that my b7 had a 1.8t in it being a european version we get in new zealand, so i replaced it with a 386 cc.

[viziers]

sorry to mention that my b7 had a 1.8t in it being a european version we get in new zealand, so i replaced it with a 386 cc.

Ahhh , makes sense now...lol




vizi