leaving behind a cloud of smoke at stoplights

**AWD Addict** · 02-03-2016 01:17 PM

Lately I've been noticing that if the car's at running temperature and I've been sitting a few minutes at a light, when I drive off again I'll look in the rear view and see a healthy cloud of exhaust. Wondering if this is normal for a cat-less RS4 running a full exhaust and a 91 octane tune?

**komseh** · 02-03-2016 01:19 PM

No, it's not normal. Ever changed your PCV?

**AWD Addict** · 02-03-2016 01:20 PM

I've never replaced it.

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**komseh** · 02-03-2016 01:22 PM

I believe FWP was having the same symptom and a new PCV was the solution.

**AWD Addict** · 02-03-2016 02:23 PM

thanks komseh

**Quattrors4** · 02-03-2016 02:30 PM

Originally Posted by AWD Addict

thanks komseh

spray the inside of your pcv oil seperator with carb clean or soak it in fuel for a few hours,should fix it,those separators are expensive like 300$ i think

**Mr. Corey** · 02-03-2016 05:31 PM

I had this issue when my valve stem seals / guides failed ..... I know its more common of the BHF S4 engine. I've never heard of it happening with a RS4 so hopefully its just your PVC.

**NYC_Legacy** · 02-03-2016 05:51 PM

Originally Posted by komseh

No, it's not normal. Ever changed your PCV?

I third this, friend and fellow owner was experiencing the same symptoms. PCV was the fix.

**AWD Addict** · 02-03-2016 06:40 PM

Originally Posted by Quattrors4

spray the inside of your pcv oil seperator with carb clean or soak it in fuel for a few hours,should fix it,those separators are expensive like 300$ i think

When the car had a carbon clean about 5K miles ago we also installed JHM's Oil Separator Heater Bypass. Is that a different part?

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**BenSti** · 02-03-2016 11:58 PM

Originally Posted by AWD Addict

When the car had a carbon clean about 5K miles ago we also installed JHM's Oil Separator Heater Bypass. Is that a different part?

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Yeah, normally coolant flows through the oil separator, the JHM setup just bypasses this making the manifold easier to remove. The separator is a black plastic piece in the back of the manifold.

**FWP!** · 02-04-2016 08:35 AM

Originally Posted by komseh

I believe FWP was having the same symptom and a new PCV was the solution.

A new PCV lessened the smoke, but it was definitely still there. I'm thinking it's the valve seals because it's still doing it, getting estimates from some shops to see how much it would be to replace them.

**sandspeed** · 02-05-2016 01:48 AM

It definitely sounds like it's blown. I'll buy it for $3.50 and can pull it myself.

**AWD Addict** · 02-05-2016 03:48 PM

Thanks FWP. A bad PCV can lead to bigger things if left unchecked so I need to get on this. Is it accessible on our engines or does it involve intake manifold removal or the dreaded $ervice mode?

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**JimmyBones** · 02-05-2016 05:17 PM

It is possible to replace the PCV valve without removing the intake manifold but the secondary air injection hose is in the way and a bitch.

**FWP!** · 02-05-2016 05:30 PM

Originally Posted by AWD Addict

Thanks FWP. A bad PCV can lead to bigger things if left unchecked so I need to get on this. Is it accessible on our engines or does it involve intake manifold removal or the dreaded $ervice mode?

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Yea as JimmyBones said, it's not easy. I've done it probably 15 times now so it takes me 1 hour from start to finish swapping the PCV out, but you do have to loosen and then move the SAI tube out of the way enough to get the bottom torx bolt bolting the PCV valve to the intake manifold.

**AWD Addict** · 02-07-2016 10:41 AM

Ok good to know. Is there a way to test the PCV for problems before I make the effort to remove it? I'd hate to do all of that and it doesn't fix it.

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**FWP!** · 02-22-2016 08:59 AM

I have a new theory..

So I get the smoke after idling for a while and then taking off, but it only happens maybe every 1 or two weeks where it'll do it once, and won't do it again for a long time.

What if it's a sticking injector? The injector sticks open, washes down the cylinder, and then when I take off, all of that gas and oil gets burnt off? The smoke has always smelled slightly like burning oil, but A LOT like the engine is running REALLY rich. Reminds me of when I had an injector go bad on an old car of mine.

I need to find some time to get my injectors sent out to have them cleaned and flow matched.

**AWD Addict** · 02-25-2016 01:34 PM

Sounds like a good theory. Seems pretty consistent with everything I'm experiencing too. I'm not getting smoke every time I cold start the car or every time I pull away from a long light. Was in Tahoe last weekend and I never saw it happen once.

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**FWP!** · 02-25-2016 06:45 PM

Originally Posted by AWD Addict

Sounds like a good theory. Seems pretty consistent with everything I'm experiencing too. I'm not getting smoke every time I cold start the car or every time I pull away from a long light. Was in Tahoe last weekend and I never saw it happen once.

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I got 6 of my injectors out and took them to a shop I found in Phoenix that does cleaning and flow matching for FIS injectors. I tried getting the last 2 out, but they were nearly welded in place and ruined them getting them out, so I have two on order from rockauto that should be here tomorrow, then I'll take them over to the shop so that all 8 can get flow matched and also so we can compare new injectors to my OEM's. They're also giving the fuel rails a bath in the ultrasonic cleaner. Looking forward to getting it all put back together to see how she runs.

**komseh** · 02-25-2016 06:47 PM

FWP, do you have buildup in your fuel rails or something? Or just getting them cleaned for sake of completeness?

**FWP!** · 02-25-2016 06:54 PM

Originally Posted by komseh

FWP, do you have buildup in your fuel rails or something? Or just getting them cleaned for sake of completeness?

There was a very slight "grey-ish" film we saw on the inside of them and they're doing them free of charge so I figured why not.

**AWD Addict** · 02-26-2016 12:18 PM

Looking forward to hearing the results FWP!

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**FWP!** · 02-26-2016 05:06 PM

Report for the 6 OEM injectors. They said #2 was leaking and wouldn't hold pressure initially, but it was ok after cleaning. Could be the cause of my issue. Will put it all back together tonight.

**AWD Addict** · 02-27-2016 06:37 PM

Notice any difference yet?

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**Seattle squash** · 02-27-2016 11:33 PM

Just did mine, and way less smoke! Will watch oil consumption as well!

**FWP!** · 02-29-2016 11:21 PM

Originally Posted by AWD Addict

Notice any difference yet?

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No smoke yet, car runs great, even "smells" better. Only driven about 50 miles, so I'll report back in a few weeks. Hoping the cause was a leaky #2 injector.

**AWD Addict** · 03-02-2016 06:51 PM

Cool. I'll be crossing my fingers!

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**Striddy** · 03-21-2016 07:16 PM

What ever happened with this?

**FWP!** · 03-22-2016 10:35 AM

Originally Posted by Striddy

What ever happened with this?

It's been a few weeks since I did my injectors and no smoke at all. The car runs better, starts quicker, doesn't "stink" as bad (catless downpipes). I think it was my leaky #2 injector that was causing the issue.

**Striddy** · 04-21-2016 01:51 PM

Originally Posted by FWP!

It's been a few weeks since I did my injectors and no smoke at all. The car runs better, starts quicker, doesn't "stink" as bad (catless downpipes). I think it was my leaky #2 injector that was causing the issue.

Thank you, looks like I'll be doing the same. Was your EPC light on?

**AWD Addict** · 04-22-2016 02:47 PM

So I paid to have the leak down and compression checked. Everything was within the acceptable range which, I'm told, likely means it's a defect in the head that's causing the oil to burn.

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**FWP!** · 04-22-2016 03:18 PM

Originally Posted by AWD Addict

So I paid to have the leak down and compression checked. Everything was within the acceptable range which, I'm told, likely means it's a defect in the head that's causing the oil to burn.

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Have you replaced the injectors yet?

**AWD Addict** · 04-22-2016 03:23 PM

Mechanic said the injectors were fine. That's why we did the leak down and compression tests first.

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**komseh** · 04-22-2016 04:10 PM

How does the mechanic KNOW the injectors are fine?

**your daddy** · 04-22-2016 06:00 PM

crystal ball

**AWD Addict** · 04-23-2016 03:42 PM

He said there would have been a significant loss of pressure

**komseh** · 04-23-2016 04:34 PM

I'm not convinced a leakdown test is going to reveal leaking or poorly flowing FSI injectors. I may be thinking about this incorrectly so someone please correct me if I'm wrong.

If I were you I would replace or clean the injectors. It's a lot cheaper than going down the path the mechanic suggested. You could do it next time you carbon clean to save on the labor.

Guessing games are no fun on the wallet when it comes to repairing cars, but in this case it's an educated guess since you are having identical symptoms to at least one other forum member. It's also a member that went through just about all the possible fixes for the symptoms before targeting the injectors.

**AWD Addict** · 04-23-2016 04:35 PM

What the fuck did I just pay $400 for then?

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**komseh** · 04-23-2016 04:39 PM

Well, you know your motor is in good shape. The compression and leakdown numbers came back good, right?

**AWD Addict** · 04-23-2016 08:36 PM

Yes the tests showed everything was in the acceptable range. Maybe I was asking the wrong questions. He couldn't give me a print out so we talked through the results and what it could likely be.

FWIW I'm not using up a lot oil. In fact I would say it's the exact same consumption rate as it was BEFORE the blue smoke.

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