2012 Q5 3.2 rough starts

[sferraro]

Hey, fellas.

Since mid-August, my wife's 2012 Q5 Premium Plus 3.2 has experienced random rough starts where the idle hovers very low. We turn the car off and then back on and all is good. We've never gotten an error code or CEL and we've even had it at the Audi dealership so they could take a look. But they say they can't reproduce it and since it isn't popping a code, they say they can't do much.

To me it screams carbon issue that the engines are known for, but the dealership says they need the code before they can do anything. The dealership has encouraged me to track the rough starts so that perhaps we can talk with AoA about pursuing a carbon cleaning despite not having an error code or CEL pop up.

Dates of rough starts: 8/11, 8/14 (2 times), 8/17, 8/21, 8/22, 8/23, 8/25, 8/26, 9/5, 9/6, 9/10, 9/14, 9/23, 9/29 (2 times) and 10/3. At this point it's more embarrassing/annoying than anything to have a luxury vehicle that randomly starts and idles rough.

Anyone have any other thoughts about what may be causing the rough starts that I'm overlooking since I'm convinced it's the carbon buildup? Car has just over 50,000 miles. Appreciate the help.

Cheers.

[hc_TK]

i got the exact same problem! iv'e been in and out from the dealer a lot and they cant figure it out. they had the car for weeks back and forth to try to figure whats wrong. I have mentioned carbon deposit issues, they say they have checked the valves with endoscope, but it apparently looked okay. they have changed spark plugs, changed intake valve, changed fuel ECU.
I talked with the technician who said it might be a high fuel pressure leak or something. im tracking the fuel pressure with an OBD reader, but im not sure if this is it.
They also struggle with getting this error at the dealer.. The problem seems to be most frequent when the car has been driven, then left for like 45min-1hour before starting it again.

[slee22]

Add me to that list...55,000 miles; no codes, and it's hit or miss whether it sits overnight or I've just driven it.
Once I put it in gear and drive off it's fine.

[sferraro]

Add me to that list...55,000 miles; no codes, and it's hit or miss whether it sits overnight or I've just driven it.
Once I put it in gear and drive off it's fine.

I don't know if it matters whether ours sits for a while or not - can't remember to be honest since my wife drives it mostly.

We haven't tried shifting into gear while it's idling rough, we've always just turned it off and restarted and it's always fine.

I think we're going to work with our SA and get the list of our rough starts to AoA to see if they'll approve work.

[ThunderDent]

Man I hate to see it for you guys. The 3.2 NA engine just wasn't a very good design.

So much carbon build up problems.

[A U D I]

Man I hate to see it for you guys. The 3.2 NA engine just wasn't a very good design.

So much carbon build up problems.

I'd have to disagree. The 3.2 motor is really reliable with only the carbon build up issue effecting the secondary air system, which Audi will warranty for 120k miles because of emissions. Other then that, it's a solid motor.

As far as carbon build up goes with Audi, all of the motors with direct injection have some level of build up that effects the motors performance. That said, we all still own Audis :)

[A U D I]

For the 3.2 random rough starts, have you guys checked with the techs about cleaning the throttle body ? If not, it's worth a go. They will get dirty and slowly mess up mileage, HP and also idle but not show codes for a while.

[sferraro]

I'd have to disagree. The 3.2 motor is really reliable with only the carbon build up issue effecting the secondary air system, which Audi will warranty for 120k miles because of emissions. Other then that, it's a solid motor.

As far as carbon build up goes with Audi, all of the motors with direct injection have some level of build up that effects the motors performance. That said, we all still own Audis :)

I'd have to agree. We picked up our Q5 knowing about the carbon issue and felt comfortable with it because of the extended warranty. We definitely won't keep it beyond the warranty but at just over 50,000 miles that's a while still. I of course am knocking on wood as I type this.

[hc_TK]

As mentioned above, all direct injection motors suffers from carbon build issues.
I know this also goes for the 4.2 v8 fsi and also the 2.0 tfsi.

[hc_TK]

any updates?

[ABOMB]

Just had this issue with my 3.2. I was throwing misfire in cylinder 1 and had real shaky idle at low rpm. thought it was coil packs and plugs, but replacing those didnt fix the issue. It ended up being a bad injector in cylinder 1. Car runs smooth now after replacing it.

ps. got the carbon cleaned out while the injectors were off. My mechanic said they had bad build up.

[jchen527]

I bought an audi Q5 about a month ago and it's amazing! There is one thing that started happening recently though. When I pushed the key into the ignition to start, I could see the RPM go up and drop back down to 0. After waiting a couple of seconds, I would do that again and RPM would be stable. I do not notice any performance issue after the car is on. What would be the cause of that?

[SQive]

It's called gauge sweep. SQ5's do it stock, and the others can with a simple VAGCom mod. Nothing to worry about.

[hc_TK]

if it goes up and down and then to 0, you got the same rough start issue. this happens to mine also.
after starting the second time you can smell fuel, so dont think that the injectors and fuel supply is the issue.

[hc_TK]

Any updates on your issues?

[hc_TK]

Ive read that this might be at least in my case, caused by internal leakage in the fuel injectors and not carbon build up.
http://www.audiworld.com/forums/q5-s...oblem-2776121/

[sferraro]

Any updates on your issues?

We're approaching the 55,000 mile service in the next few weeks so our dealership thinks plugs may correct the issue. I don't, but we'll get the service done so we can rule it out. We're up to 31 rough starts dating back to mid-August. Actually had one today.

I've been tracking them so that if new plugs don't correct the issue I can talk with AoA about okaying a carbon cleaning despite not getting any fault codes.

[sferraro]

Ive read that this might be at least in my case, caused by internal leakage in the fuel injectors and not carbon build up.
http://www.audiworld.com/forums/q5-s...oblem-2776121/

Interesting. The way this person described it is exactly how it happens for us. And about the same frequency. I'll have to bring it up when we go in for service. Thanks for sharing!

[hc_TK]

Interesting. The way this person described it is exactly how it happens for us. And about the same frequency. I'll have to bring it up when we go in for service. Thanks for sharing!

Yes, the same here as well.
I have noticed that if driven warm and left for about 45 min to 1 hour, it occurs more often.
As with the linked thread, i dont get any warning or fault codes.
And for some reason this never have happened at the Audi dealer, even though they have had the car for several weeks combined to find out whats wrong.

[sferraro]

Yes, the same here as well.
I have noticed that if driven warm and left for about 45 min to 1 hour, it occurs more often.
As with the linked thread, i dont get any warning or fault codes.
And for some reason this never have happened at the Audi dealer, even though they have had the car for several weeks combined to find out whats wrong.

Our dealership hasn't been able to reproduce the problem either. We'll replace the plugs at 55,000 miles and I'll bring up the possibility of fuel injector leakage. Those are the last options before I escalate to AoA in the hopes they'll approve the carbon cleaning.

[hc_TK]

they checked my air intake and valves with an endoscope and didnt find any carbon build up.
They have also changed plugs, coils, ECU and intake valve. none of these things helped ;)

[A U D I]

Hey guys, have any of you had the throttle body cleaned and reset ?

(If they get gummed up or carbon build up they will give issues and will not show up as codes.)

My suggestion would be to do that and if not have them check the flow of the secondary air to see if that's starting to get blocked by carbon but not enough to throw a code. The thing with that is you would notice it on cold starts also not just randomly because the secondary pump would need to be active at the times of problems and revving the motor would not correct it.

[One Nice Audi]

Funny you said that since both my work van having this idling problem. I took out the throttle body and there's a layer of gummed up stuff there. Work amazing after!

[hc_TK]

yes, mine was changed. no improvement in this case.

[A U D I]

yes, mine was changed. no improvement in this case.

I read that you said the Intake Valve was replaced but I don't think that is referred to as the throttle body. Can you double check that ?

[hc_TK]

yes, my bad. i was meaning the throttle body and not intake valve.

[A U D I]

How many miles are on yours now ?

Where is the temp gauge at when you start the engine with problems ? ( C or H or in between )

[hc_TK]

the car has 41k miles
temp gauge is at minimum, so cold engine.
I also think this happens more often of the outside temperature is not to low (bellow freezing) or too hot (20*C)

[One Nice Audi]

Have anyone tried seafoaming the engine?

[hc_TK]

Have anyone tried seafoaming the engine?

Nope, carbon build up doesnt seems like a problem for me at least according to the audi dealer.
As i mentioned, they checked the intake valves with endoscope.

[A U D I]

Have anyone tried seafoaming the engine?

I would never use Sea Foam on a Audi motor. That product is made more so for older US motors not German designs.

[A U D I]

the car has 41k miles
temp gauge is at minimum, so cold engine.
I also think this happens more often of the outside temperature is not to low (bellow freezing) or too hot (20*C)

I would suggest you have is the start to carbon build up in the Secondary Air System. It's not showing the code yet because it's not heavy enough. It will not show up having carbon in the Intake side because that is not where the problem is. This is why the motor is affected when the secondary pump is active. If you want to check it at home for yourself when the problem start happens go to the front passenger side foglight area and listen for the secondary air pump to be running. It will sound similar to a soft hair dryer. This will confirm the cause.
The secondary are fault seems to be more actively set in temps above 32° F - 80° F. The ECU management also has a harder time with it when the temp of the engine is not on a 100% cold start. (Engine has been starter and driven, allowed to cool some but not completely then restarted and the Secondary Air System is reactivated with the idle being slightly higher then normal(around 1k).

[hc_TK]

I would suggest you have is the start to carbon build up in the Secondary Air System. It's not showing the code yet because it's not heavy enough. It will not show up having carbon in the Intake side because that is not where the problem is. This is why the motor is affected when the secondary pump is active. If you want to check it at home for yourself when the problem start happens go to the front passenger side foglight area and listen for the secondary air pump to be running. It will sound similar to a soft hair dryer. This will confirm the cause.
The secondary are fault seems to be more actively set in temps above 32° F - 80° F. The ECU management also has a harder time with it when the temp of the engine is not on a 100% cold start. (Engine has been starter and driven, allowed to cool some but not completely then restarted and the Secondary Air System is reactivated with the idle being slightly higher then normal(around 1k).

what component exactly would be affected by this? Where could this be visually inspected or checked?

[A U D I]

You won't be able to see them because the air flow goes into the motor and carbon up the valves on the exhaust side.
Tech only can see the fault code for the system and check the operations of the air pump and valves to make sure the flow is correct. Once that is checked, then fault the motor for carbon build up. Since Audi is warranting this cleaning due to it affecting emissions, dealers need the check code to warrant it to Audi for reimbursement. They should call AOA and request this cleaning for your motor to get it done with out the check code stored.

(My guess is 2012 has a different ECU parameters to not be as affected by this issue to give the motor more time before it produces a code.)

[hc_TK]

so youre suggestion is carbon build up on the exhaust valves?
Im also not located in the US so the US extended warranty does include me

[A U D I]

so youre suggestion is carbon build up on the exhaust valves?
Im also not located in the US so the US extended warranty does include me

It's considered carbon build up on the exhaust ports of the Secondary Air System.
I'm not sure for the country your in, so check to see if they have that warranty coverage in yours. If not at your current mileage you should still be covered to have them fix it no matter what it is. (though I'm not for sure how it works in other countries)

[hc_TK]

Finally i got a rough start at the dealer!
Since this doesnt cause any codes, its most likely the fuel injectors.
But the dealer isnt have with replacing all, how can the faulty one(s) be identified?
They want to get another rough start and then oven up the engine to see which cylinder(s) that are wet.

But my question is, after a rough start, wouldnt all cylinders contain fuel?
My take on this would be to driver the car, let it sit for a couple of hours and then open up the cylinder to see which contain fuel. Is this leak would be fuel leaking from pressurized injectors to inside the combustion chamber. Do you agree?

I also asked about the secondary air system, and this is supposed to be monitored by sensors and would cause a fault code.

[S4'ed]

A problem in the Secondary Air Injection system can NOT cause a rough idle, it only effects the emission control performance during cold starts (more air pollution). Also, the carbon build-up problem, inside the SAI passages, is a totally separate issue than carbon build-up on the intake valves of DI engines.

Your rough idle is either a leaking injector, a spark plug (or coil), carbon deposits on the back of the intake valves, or a bad check-valve in the fuel system that causes a loss of residual fuel pressure (when the engine is off). A dirty throttle body can also cause the throttle blade to bind/stick, which can then cause a low idle and rough running till it gets itself unstuck (so that the ECU can properly adjust the throttle opening to maintain the correct idle speed).

[A U D I]

A problem in the Secondary Air Injection system can NOT cause a rough idle, it only effects the emission control performance during cold starts (more air pollution). Also, the carbon build-up problem, inside the SAI passages, is a totally separate issue than carbon build-up on the intake valves of DI engines.

Your rough idle is either a leaking injector, a spark plug (or coil), carbon deposits on the back of the intake valves, or a bad check-valve in the fuel system that causes a loss of residual fuel pressure (when the engine is off). A dirty throttle body can also cause the throttle blade to bind/stick, which can then cause a low idle and rough running till it gets itself unstuck (so that the ECU can properly adjust the throttle opening to maintain the correct idle speed).

Sorry, but you are incorrect about the Secondary Air System not being able to give a rough idle.
It can or will give a rough idle once activated if there is a blockage, restriction, or another part of the PCV system has failed or is in need of replacement/repair. It can also give misfires during this time also. The systems flow can also be checked to see if it is working properly to rule out a pre carbonization condition exist.

You are correct at assuming a injector(s) could be failing. The spark plug or coil pack would not be probable due to no codes have been stored that he has been told of and these are usually what techs toss in to rule out problems instead of actually checking them. The throttle body possibly is also correct but he has had his throttle body unnecessarily replaced/reset.

Hopefully he will get some better information this time from the dealer and or have it fixed.

[S4'ed]

Sorry, but you are incorrect about the Secondary Air System not being able to give a rough idle.
It can or will give a rough idle once activated if there is a blockage, restriction, or another part of the PCV system has failed or is in need of replacement/repair. It can also give misfires during this time also. The systems flow can also be checked to see if it is working properly to rule out a pre carbonization condition exist.

You are correct at assuming a injector(s) could be failing. The spark plug or coil pack would not be probable due to no codes have been stored that he has been told of and these are usually what techs toss in to rule out problems instead of actually checking them. The throttle body possibly is also correct but he has had his throttle body unnecessarily replaced/reset.

Hopefully he will get some better information this time from the dealer and or have it fixed.

There is no connection between the SAI and the PCV system.