3.0 misfires but no codes??

[Garf]

All symptoms point to a misfire when I was driving the car home today but hooked up the VAG505 and no codes??? but the car still misfires...

[19jdog]

Can you give more info, symptoms you are experiencing? My 3.0 misfires but there is no change in performance, it very annoying TBH.

[Garf]

The symptom is a misfire when I am driving. Not my first experience getting a misfire. I normally plug in the VAG505 to see which cylinder is the culprit and just change out the coil. This time I am stumped because it did not throw a code at all.

A misfire is not good for your catalytic converter from what I am told and besides I don't think it is healthy for the engine. Annoying would be my last concern.

[QuattroVAG]

I recently performed a "tune up" on my 3.0 that eliminated 95% of my random misfires. Most of my misfires would occur at idle and most times would not be logged in VAGCOM. My car is now running great and stopped consuming oil.

-Clean MAF
-Clean throttle body (didn't remove it- I used a mirror to spray and wipe it down while still connected to manifold)
-Clean PCV valve
-BG EPR oil treatment and BG 44k fuel treatment (change oil after)

EDIT- Does your misfire occur when accelerating or is it totally random while driving? If during acceleration i'd guess a coil pack is going bad

[SJorge3442]

I recently performed a "tune up" on my 3.0 that eliminated 95% of my random misfires. Most of my misfires would occur at idle and most times would not be logged in VAGCOM. My car is now running great and stopped consuming oil.

-Clean MAF
-Clean throttle body (didn't remove it- I used a mirror to spray and wipe it down while still connected to manifold)
-Clean PCV valve
-BG EPR oil treatment and BG 44k fuel treatment (change oil after)

EDIT- Does your misfire occur when accelerating or is it totally random while driving? If during acceleration i'd guess a coil pack is going bad

How did you clean the pcv?

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[Garf]

I recently performed a "tune up" on my 3.0 that eliminated 95% of my random misfires. Most of my misfires would occur at idle and most times would not be logged in VAGCOM. My car is now running great and stopped consuming oil.

-Clean MAF
-Clean throttle body (didn't remove it- I used a mirror to spray and wipe it down while still connected to manifold)
-Clean PCV valve
-BG EPR oil treatment and BG 44k fuel treatment (change oil after)

EDIT- Does your misfire occur when accelerating or is it totally random while driving? If during acceleration i'd guess a coil pack is going bad

Thank you! I will take a look at those areas first thing tomorrow.

[QuattroVAG]

How did you clean the pcv?

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I removed it and filled it with carb cleaner a few times until the liquid coming out was clear. My valve and PCV lines were pretty clean to begin with but the spring mechanism seems to move smoother after the cleaning. In total this is a 15minute job.

DIY to remove it
http://www.audizine.com/forum/showth...CV-Replacement

[QuattroVAG]

Thank you! I will take a look at those areas first thing tomorrow.

No problem. If you do the on-car TB cleaning like I did turn the ignition on and put a brick on the gas pedal. The butterfly valve will now be opened so you can clean both sides.

[Garf]

I removed it and filled it with carb cleaner a few times until the liquid coming out was clear. My valve and PCV lines were pretty clean to begin with but the spring mechanism seems to move smoother after the cleaning. In total this is a 15minute job.

DIY to remove it
http://www.audizine.com/forum/showth...CV-Replacement

Which is the best carb cleaner to use? Are they all the same using the same chemicals. I would hate to melt or screw up my PVC valve cleaning it. The weather is cold here so I will warm up the engine slightly so that the plastics on the PVC and clips won't be brittle and crack in the cold. I also saw a pic of it and it looks like it can be taken a part and snapped back together. Would it not be better to clean it that way instead of drowning the insides of it?






Also when you do the on-car TB cleaning. Is the carb cleaner you spray into it going to cause other issues in the future? I am assuming the engine will just burn out the carb cleaner and shoot it out the exhaust as smoke.

[QuattroVAG]

Which is the best carb cleaner to use? Are they all the same using the same chemicals. I would hate to melt or screw up my PVC valve cleaning it. The weather is cold here so I will warm up the engine slightly so that the plastics on the PVC and clips won't be brittle and crack in the cold. I also saw a pic of it and it looks like it can be taken a part and snapped back together. Would it not be better to clean it that way instead of drowning the insides of it?






Also when you do the on-car TB cleaning. Is the carb cleaner you spray into it going to cause other issues in the future? I am assuming the engine will just burn out the carb cleaner and shoot it out the exhaust as smoke.

Carb cleaners are all pretty much the same. I wouldn't let it soak for an extended period of time. Mine wasn't that dirty so I didn't even consider taking it apart - there's a big spring in it that could cause a problem reassembling.

No issues with cleaning the TB on the car. It took about 15sec of cranking to start the car after but no issues since.

I realigned the TB with vagcom after cleaning but I believe there is also a way to do it without vagcom


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[SJorge3442]

Hmm. I'm not sure how I feel about about all that gunk going into the manifold/engine. I know its just carbon, but at the same time, I'd rather just get that all off and not push it through the block. Pulling the manifold on our engine really instead that hard and would give you a clear shot at the TB and you can also check other aspects (PCV lines, coolant cross over, fuel injector o rings) while you're in there.

[QuattroVAG]

Hmm. I'm not sure how I feel about about all that gunk going into the manifold/engine. I know its just carbon, but at the same time, I'd rather just get that all off and not push it through the block. Pulling the manifold on our engine really instead that hard and would give you a clear shot at the TB and you can also check other aspects (PCV lines, coolant cross over, fuel injector o rings) while you're in there.

Well it's not carbon - it's blowby oil residue. Unless your car has been ill maintained it should be minimal - N/A engines have much less blowby than a turbo engine.

You only use the carb/TB cleaner to wet the surface then you wipe the residue away with a rag.

But if your motivated to completely remove it by all means go ahead.

The BG oil and fuel treatments seem to have made the biggest difference for my car. I believe my misfires was due to a leaky injector. The oil treatment completely silenced my cold start lifter noise.


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[SJorge3442]

Well it's not carbon - it's blowby oil residue. Unless your car has been ill maintained it should be minimal - N/A engines have much less blowby than a turbo engine.

You only use the carb/TB cleaner to wet the surface then you wipe the residue away with a rag.

But if your motivated to completely remove it by all means go ahead.

The BG oil and fuel treatments seem to have made the biggest difference for my car. I believe my misfires was due to a leaky injector. The oil treatment completely silenced my cold start lifter noise.


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Gotcha. I've never tried to blindly clean the TB so I was unaware of your tactics there. I agree with the BG stuff though. Its awesome stuff and I try to run a can of 44K every year or so through my car. Recently got my dad using it on his cars too. I need to try to the oil treatment to see if I can get ride of my cold start lifter noise. Was you rnoice just a quick rattle/tap for a second or so until oil pressure was built up? I might do that treatment prior to my next oil change.

[QuattroVAG]

Gotcha. I've never tried to blindly clean the TB so I was unaware of your tactics there. I agree with the BG stuff though. Its awesome stuff and I try to run a can of 44K every year or so through my car. Recently got my dad using it on his cars too. I need to try to the oil treatment to see if I can get ride of my cold start lifter noise. Was you rnoice just a quick rattle/tap for a second or so until oil pressure was built up? I might do that treatment prior to my next oil change.

I rarely had the 1 second noise a lot of people talk about. My car had a slight knocking sound that would last for about 30sec.


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[Garf]

Which BG product did you use for the oil?

[QuattroVAG]

Which BG product did you use for the oil?

BG EPR


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[Garf]

BG EPR


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I forgot to mention that I use only Motul and LiquiMoly oil. Is BG EPR still needed?

[imnuts]

I forgot to mention that I use only Motul and LiquiMoly oil. Is BG EPR still needed?

EPR is used right before an oil change. Regardless of oil used, it may still help clean junk out of the engine. It could also break up gunk that is keeping things from leaking, but that's the chance you take with something meant to dissolve varnishes and such.

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[Garf]

EPR is used right before an oil change. Regardless of oil used, it may still help clean junk out of the engine. It could also break up gunk that is keeping things from leaking, but that's the chance you take with something meant to dissolve varnishes and such.

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My A4 B6 is vintage like all other A4 B6's on the road. I would hate to cause a massive hemorrhage leak and destroy engine just to make it cleaner.

[imnuts]

I used it and didn't notice any ill effects. The oil was quite black coming out afterwards, so it seemed to clean things out, but otherwise I'm not sure what it did. I figured I'd put that warning in there just so you're aware ahead of time. Odds are that you'll be fine, but there is always a chance.

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[Garf]

I used it and didn't notice any ill effects. The oil was quite black coming out afterwards, so it seemed to clean things out, but otherwise I'm not sure what it did. I figured I'd put that warning in there just so you're aware ahead of time. Odds are that you'll be fine, but there is always a chance.

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I am not burning oil and use only Motul or LiquiMoly only. More TLC can't hurt.

Just did a search on reviews for the BG 109. I am surprised with the great reviews on it. I think I will give it try.

According for user say is the use BG109 just before you change the oil for 15 mins. Rev the engine up to 1200 rpm. Can you drive around for 10-15mins but keep the revs down to around 1200 - 1400 rpms. Once you change the oil, will the residue BG109 hurt the engine till the next scheduled oil change??

[Garf]

I am not burning oil and use only Motul or LiquiMoly only. More TLC can't hurt.

Just did a search on reviews for the BG 109. I am surprised with the great reviews on it. I think I will give it try.

According for user say is the use BG109 just before you change the oil for 15 mins. Rev the engine up to 1200 rpm. Can you drive around for 10-15mins but keep the revs down to around 1200 - 1400 rpms. Once you change the oil, will the residue BG109 hurt the engine till the next scheduled oil change??

Oh.... someone just told to use LiquiMoly engine flush instead...

[pablolizarraga]

I recently performed a "tune up" on my 3.0 that eliminated 95% of my random misfires. Most of my misfires would occur at idle and most times would not be logged in VAGCOM. My car is now running great and stopped consuming oil.

Maybe this should be in the dumb question thread but if misfires don't appear on VAGCOM (or VCDS-lite), how can you tell difference between misfires you only feel at idle and bad engine mounts?


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[pablolizarraga]

Here's another dumberer question, how do you know (other than seeping valve gaskets) that this is not working?


Or better yet, how do you know it IS working?

I've heard of the "glove test". The part (PCV?) works when the glove blows up like a balloon at cold start or when engine is at normal temp?

I've been noticing burning oil smell shortly after "spirited" driving and I've noticed an increase in oil residue toward firewall end of both valve covers.


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[Garf]

Here's another dumberer question, how do you know (other than seeping valve gaskets) that this is not working?


Or better yet, how do you know it IS working?

Mine had a cracked internal diaphragm after opening it up for inspection.

How do I know it was not working??? Well my A4 drove like all six ignition coils were blown. If my wife was in the car, she would swear I forgot how to drive a manual transmission how violent the car was jerking when I accelerate.

I replaced it with a new one, and the car now purrs.