2006 A4 Avant 2.0T Troubles

[LanceSupersad]

Bought this car knowing that, when "cold", kindof misfires (it will be clear what I mean as this goes along). When I bought the car, there was a P0303 misfire code; I reset it for eTest, and it hasn't come back in two months. I was kindof hoping the code came back, but it didn't.

Sometime in the last ~1.5 years (before I got the car), the 4 coils were replaced, but apparently this didn't completely solve the issue I am mentioning. At that time, the plugs were replaced as well.

Here's what I've observed: In the first ~2 minutes of the car running, it feels a LOT like it's misfiring like crazy (I've only had one car that acted like this, and it was a 4 banger Corsica, and it's coilpack was dying). After around two minutes, the Audi works fine (as far as I can tell). I was told by the previous owner that "it does that until it warms up; doesn't really do it in the summer". On a "hot" day, where the engine temp starts rising in like 10 seconds, vs a "cold" say where it might not start rising for a minute, both instances I am waiting about 2 minutes and all is good. Also, it seemed to be more dramatic/last longer when it was raining, but it has only rained once since I've had the car, so it's not much data to go on.

A bit more info, it has a Unitronics program on it that is a "93 octane" program. When I got the car, I was running 91 octane for about 300 km (I conveniently forgot the 93 octane requirement), but has since been 94.

Any insight on where I should look first? The sparkplugs "look" pretty good, and have a stamped code (I think date) of 09-14 on them, and they're OE plugs. I find it very funny I am getting no codes, when the car is obviously running poorly, and most people complain these cars throw codes for seemingly no reason. Car has 266,000km, if that helps. Car was also brought to a track quite a few times post-Unitronics "chipping".

[vce1232000]

Maybe needs carbon cleaning done

[LanceSupersad]

Maybe needs carbon cleaning done

Is that something that someone who has worked on cars for many years would be able to do on his own? I am presuming this is in the intake, but I don't know.

[vce1232000]

Yes you can . a diy http://www.audizine.com/forum/showth...B7-A4-2-0T-3-2

[aluthman]

1. You can't run OE plugs with a tune and not expect misfires. You need a heat range colder plug. Set the gap to 0.028"-0.030".
2. Unitronic tunes suck. Get literally anything else.
3. Do a carbon cleaning.

[LanceSupersad]

1. You can't run OE plugs with a tune and not expect misfires. You need a heat range colder plug. Set the gap to 0.028"-0.030".
2. Unitronic tunes suck. Get literally anything else.
3. Do a carbon cleaning.

1. Did not know this; thank you. Are there any suggested plugs that Audi people think are worth it? FWIW, I did not pick these plugs.
2. I assume all tunes are garbage, since they're generic, but thanks for letting me know this one is notably worse. FWIW, I did not pick this tune.
3. I plan to; thanks !

[LanceSupersad]

Yes you can . a diy http://www.audizine.com/forum/showth...B7-A4-2-0T-3-2

So, looks like my options are:
1. pull the intake manifold and try and play dentist with the valves (4 hrs for intake, and apparently 8ish hrs of scraping the valves thru the ports, which seems like a lot of time)
2. pull the head, yank the valves, and clean them (R&R cyl. head is 8 hours, according to Mitchell ... apparently 12hrs to reface valves, resurface seats, clean guides, and adjust valves ... adjusting being the only thing I don't already know how to do).

Sounds like a "fun" weekend. Hopefully the hours spent on option #1 are exaggerated; I can't imagine spending 1 hour cleaning a single valve, even if I was being insanely meticulous.

[vce1232000]

1. Did not know this; thank you. Are there any suggested plugs that Audi people think are worth it? FWIW, I did not pick these plugs.
2. I assume all tunes are garbage, since they're generic, but thanks for letting me know this one is notably worse. FWIW, I did not pick this tune.
3. I plan to; thanks !

1. 1 step colder plugs NGK BKR8EIX
2. Not all are created equal. Unitronic works for some. But not many
3. +=

[o1turbo30v]

I would do a throttle body reset and intake runner adaptation since you don't have any other fault codes. You will need vag-com.

[LanceSupersad]

I would do a throttle body reset and intake runner adaptation since you don't have any other fault codes. You will need vag-com.

A good friend has one; I need to hit him up to try and figure out my reverse sensors anyways. Thanks!

[LanceSupersad]

So, plugs was step one; made the car run better, but still definitely not awesome. I've heard you have to "break in" plugs (maybe this is an old "fact", or was never true, but whatever), so maybe after this trip I'm going on, they'll be even better.

I have a boost gauge on the way so I can monitor that, but next is the runner adaptation and TB reset. I have a new code as well, but I assume it's probably a misfire on cylinder 3 like before.

Once that doesn't work, I'm gonna consult VAG-COM and see if it has any input, otherwise it's going in for some (does this sound right?) walnut and dry ice media blasting for the intake valves.

[Theiceman]

Soda blast or walnut shells all journey need is a shop vac. A piece if rad boss to shame to the Port. Cut a slice in the rad hose for the blasting wand and you done in 5 minutes a port.
Just need to borrow or rent a blasting machine. Get new gaskets.

So, looks like my options are:
1. pull the intake manifold and try and play dentist with the valves (4 hrs for intake, and apparently 8ish hrs of scraping the valves thru the ports, which seems like a lot of time)
2. pull the head, yank the valves, and clean them (R&R cyl. head is 8 hours, according to Mitchell ... apparently 12hrs to reface valves, resurface seats, clean guides, and adjust valves ... adjusting being the only thing I don't already know how to do).

Sounds like a "fun" weekend. Hopefully the hours spent on option #1 are exaggerated; I can't imagine spending 1 hour cleaning a single valve, even if I was being insanely meticulous.

[Okedokey]

Check for vacuum leaks, PCV etc, make sure you have adapted all the engine throttle and intake settings, change fuel filter and check cam follower.

[aluthman]

Soda blast or walnut shells all journey need is a shop vac. A piece if rad boss to shame to the Port.

Autocorrect fail lol

[pezgoon]

Lol.

I would start with carbon cleaning before digging for vacuum leaks, although it could be that, these cars are KNOWN to need it at many less miles/km's than what's on it, and if it hasn't been done ever then it most certainly needs it. And not doing it, causing a bunch of other issues, especially while tuned

[Okedokey]

Not saying carbon clean isn't needed but checking for basic stuff is quicker and easier than removing manifold.

[LanceSupersad]

Hey all, I made an appointment for the walnut/whatever blasting; should be sorted in a few weeks.

However, something random: I changed my oil, and when I went to start it to re-fill the system, the car ran like GARBAGE (after the initial 1/4 second of clacking as everything refilled). Turned it off, and I checked everything; all good, except I had the oil cap off when I started it. Once I re-installed the cap, it ran perfect. I've never seen anything like it, is that normal? Maybe a sign of something being very broken?

Also, had a fun time trying to decrypt Theiceman's post; I don't see how a shop vac and a rad hose are going to help me in any way. I am unable to find anyone local that "rents the machine" (I was thinking you meant a walnut blaster, but it seems you meant to turn a shopvac into one ... somehow).

[Low and Behold]

Yeah if the oil cap is off it will run rough for sure because of the vacuum at idle. It's normal


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[ballinb5]

i had this same issue and it ended up being solved by replacing the intake cam, hpfp, cam chain tensioner and chain as they wore because the cam follower failed...

[Older_not_Wiser]

Have you been able to check for codes yet? If this only happens when cold it could be intake flap motor related. If so there would be related codes.

If there are codes for IFM, there is a TSB for this and you could get it replaced for free if it has not been done for your car yet.

[LanceSupersad]

Some updates: So, I had the walnut blasting done; valves were bad, but it didn't fix anything. Had a friend do the intake runner thing as well; I was gone for the weekend, and he did it. No effect, though I am not sure if he did it properly. I opened up the pipes to the intercooler, and a decent amount of oil spilled out; no idea about that, but the car doesn't "burn" oil, so I'm hoping it's the PCV.

I'd given up on dealing with the car until recently; getting embarassing having to take it easy on the car for fear it'll misfire like crazy ... used to be fun racing everyone in what looks like an old woman's car.

Anyhow, I've noticed that, recently, the car starts like garbage after fuelling; apparently indicative of PCV issues. Again, the only code I have is a misfire on Cyl. 3; it's not the injector, or the coil, so I dunno. However, it's definitely misfiring on a other cylinders as well, but the computer seems to have a hard-on for the 3rd one.

Can't wait to see what the actual problem is :). Should I bother with a new PCV, or just get a catch can? Seems like you can get a LOT of PCVs for the price of a catch can ...

[pezgoon]

Only after fueling? Or you mean even though the car is hot, when you refuel it starts like garbage? Have you pulled the plugs to see what they look like? Lean, rich, burning buckets of oil, normal etc?

https://goo.gl/images/0zDM8O

Although the coils have been replaced, try switching them around, see if the misfires follow

Does it have a silver valve cover? If so those are know the split inside and suck in oil, maybe it's just eating so much oil it's misfiring, a friends corolla was doing that as one cylinder was burning oil and it was causing misfires because of it (solved it by totaling it lol)



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[LanceSupersad]

Only after fueling? Or you mean even though the car is hot, when you refuel it starts like garbage? Have you pulled the plugs to see what they look like? Lean, rich, burning buckets of oil, normal etc?

https://goo.gl/images/0zDM8O

Although the coils have been replaced, try switching them around, see if the misfires follow

Does it have a silver valve cover? If so those are know the split inside and suck in oil, maybe it's just eating so much oil it's misfiring, a friends corolla was doing that as one cylinder was burning oil and it was causing misfires because of it (solved it by totaling it lol)

Only after fueling, though I suppose this means the engine is always warm (the closest gas-station that has 93-94 octane is far enough my engine would be warm). Normally, it might "turn over" 3 times (basically, 3 compressions) to start (from cold), and maybe 1-2 when warm. After fueling, it takes probably 8-9, and sputters and sometimes stalls on the first go. If I am running around doing errands, so the car is going through a bunch of start-stops of varying durations, it will not do this.

Plugs look perfect; I replaced them per this thread's suggestion a few months ago ... the plugs that came out looked good, and these new ones look the same now (I pulled them a week ago "just to see"). Car does not "burn" any oil; I did an oil change about 4k ago, and it's still well within the "ok" range. The oil in the intercooler pipe may have been there for years for all I know.

No matter where I move the coil, the misfire stays on cyl. 3 (according to the computer). I can tell you that the car is misfiring on at LEAST 2 cylinders when it's behaving poorly. Also, it has to misfire for like a week for the code to be set; seems the computer is super forgiving for some asinine reason.

Valve cover is silver, yes. I don't believe it's cracked, I just think the car runs so poorly, that the "weakest link" is the 3rd cylinder. Maybe it has slightly shittier airflow or something, but it seems there is an "underlying" issue that is causing problems BASICALLY across all cylinders.

I'm not sure WHEN this was done, or what was fixed while they were in there, but the cam that the fuel pump rides on was replaced at some point. The previous owner gave me a cam chain kit (I think?); he did the timing belt, and was going to do that as well while he was in there, but never got around to it. Currently, the follower and pump look good; I check it every couple months. This engine is a little clackety, but everyone I've shown this to says this is completely normal.

[pezgoon]

Only after fueling, though I suppose this means the engine is always warm (the closest gas-station that has 93-94 octane is far enough my engine would be warm). Normally, it might "turn over" 3 times (basically, 3 compressions) to start (from cold), and maybe 1-2 when warm. After fueling, it takes probably 8-9, and sputters and sometimes stalls on the first go. If I am running around doing errands, so the car is going through a bunch of start-stops of varying durations, it will not do this.

Plugs look perfect; I replaced them per this thread's suggestion a few months ago ... the plugs that came out looked good, and these new ones look the same now (I pulled them a week ago "just to see"). Car does not "burn" any oil; I did an oil change about 4k ago, and it's still well within the "ok" range. The oil in the intercooler pipe may have been there for years for all I know.

No matter where I move the coil, the misfire stays on cyl. 3 (according to the computer). I can tell you that the car is misfiring on at LEAST 2 cylinders when it's behaving poorly. Also, it has to misfire for like a week for the code to be set; seems the computer is super forgiving for some asinine reason.

Valve cover is silver, yes. I don't believe it's cracked, I just think the car runs so poorly, that the "weakest link" is the 3rd cylinder. Maybe it has slightly shittier airflow or something, but it seems there is an "underlying" issue that is causing problems BASICALLY across all cylinders.

I'm not sure WHEN this was done, or what was fixed while they were in there, but the cam that the fuel pump rides on was replaced at some point. The previous owner gave me a cam chain kit (I think?); he did the timing belt, and was going to do that as well while he was in there, but never got around to it. Currently, the follower and pump look good; I check it every couple months. This engine is a little clackety, but everyone I've shown this to says this is completely normal.

Hmmm well the airflow thing would generally be attributed to carbon cleaning, if it doesn't move with the coil packs then I'd look at the injector as the next culprit, it may be clogged or just not working in general, I'm guessing you've tried running something like seafoam or Techron through the gas tank?

The bit with you filling up and it not starting I'm not totally sure about since it doesn't happen when you are stopping overall. I don't know what to do in regards to that department as I don't know much about the fueling system before the engine, maybe charcoal canister?

When the intake manifold came off for the carbon cleaning did you (or the mechanic) clean the injectors whilst they were out?

I will say this, your crank cycle sounds just like mine in regard to the cold and warm thing and mines got only 45k on it so I would say it's "normal" but I know I need spark plugs and to change the fuel filter so I may have an issue with mine needing normal maintenance

Maybe it's related to the unitronic tune as well

Edit: also did you ever pull the head off to clean/inspect the valves? I highly doubt that in 300km anything would've happened from running the wrong octane but it is possible ¯\_(ツ)_/¯ I'm kind of at a loss here besides the possibility of the injectors being bad/dirty


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[wriscolf]

Only after fueling, though I suppose this means the engine is always warm (the closest gas-station that has 93-94 octane is far enough my engine would be warm). Normally, it might "turn over" 3 times (basically, 3 compressions) to start (from cold), and maybe 1-2 when warm. After fueling, it takes probably 8-9, and sputters and sometimes stalls on the first go. If I am running around doing errands, so the car is going through a bunch of start-stops of varying durations, it will not do this.

Plugs look perfect; I replaced them per this thread's suggestion a few months ago ... the plugs that came out looked good, and these new ones look the same now (I pulled them a week ago "just to see"). Car does not "burn" any oil; I did an oil change about 4k ago, and it's still well within the "ok" range. The oil in the intercooler pipe may have been there for years for all I know.

No matter where I move the coil, the misfire stays on cyl. 3 (according to the computer). I can tell you that the car is misfiring on at LEAST 2 cylinders when it's behaving poorly. Also, it has to misfire for like a week for the code to be set; seems the computer is super forgiving for some asinine reason.

Valve cover is silver, yes. I don't believe it's cracked, I just think the car runs so poorly, that the "weakest link" is the 3rd cylinder. Maybe it has slightly shittier airflow or something, but it seems there is an "underlying" issue that is causing problems BASICALLY across all cylinders.

I'm not sure WHEN this was done, or what was fixed while they were in there, but the cam that the fuel pump rides on was replaced at some point. The previous owner gave me a cam chain kit (I think?); he did the timing belt, and was going to do that as well while he was in there, but never got around to it. Currently, the follower and pump look good; I check it every couple months. This engine is a little clackety, but everyone I've shown this to says this is completely normal.

Try replacing the Relay under the ECU. I was having that start up problem because of it. its the 614 one or what not. It has been revised to 644? dont quote me on that i forget the number. I posted a tread on it. One of the two relays is power and the other is for fuel i believe. (i would change both) its relatively inexpensive part from audi. Only thing is getting wiper arm for me was a PITA. I didnt know whether i had a misfire or not. I didnt have a CEL. I bought the car like this.

Reason i think its that is because of the symptoms of cold vs warm. I would make sure LPFP and Filters are done. Dont remember if you did that yet. Thats my next move although my car is fine.