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Hi all. I copied my posting from a different section and wanted to come to the correct section for Q5s. I am new to the forum. I have a 2010 Q5 3.2 V6 that is having CEL and EPC, Shuttering, Limp Mode issues. It first started as a CEL. Autopart store ran scan. DTC were P0302(Cylinder 2 Misfire), 7119((Cylinder 4 Misfire), 6351(Cylinder 2), 6371(Random Multiple Misfires), 6036(Bank 2 CMP Sensor) and 7948 (cylinder disabling). I replaced the Bank 2 sensor. CEL came back on. Mechanic checked and replaced plugs and #2 coil. Day and a half later CEL back on, but now the EPC light accompanied the CEL. At this point, the EPC and CEL did not cause car to go into limp mode. EPC light would go out after a few shut offs but CEL would stay on and still show Cylinder 2 misfire. I ended up purchasing an OBDeleven scanner. Same Cylinder 2 misfire detected as well as MAF upper motor limit exceeded code. Back to mechanic and replaced injector. Drove 3 miles from mechanic and CEL and EPC back on. This time, full limp mode, shutter/shake and no power. Back to mechanic. Says he needed to reprogram injectors. Get to shop, start car and CEL on again. He said it was clear for multiple test drives. He said there was some carbon build up when he replaced cyl 2 injector and told me to run 3 consecutive tanks of high test with SeaFoam to clean. Drove it home with no CEL or EPC light. Drove to office this am which is 10 miles and CEL came back on. I reset and on the commute home the CEL and EPC came back on with shutter/shake limp mode. I can't keep "trying" things to fix this.

Mechanic is going to do a compression test next Tuesday. I spoke with another mechanic who told me that SeaFoam won't work on direct injection for carbon build up. Says he hasn't heard of same misfire after common fixes (plugs, coil, injectors). This is only happening after the car is warmed up. When I clear the faults it drives fine. But I am noticing a pattern after doing this a few days now where the car will drive fine. Peppy off the start, no shutter, shake, etc. But when the car gets warmed up I notice that I can accelerate from a stop just fine, but when I get into 4th gear, the car will start to shutter slightly when feathering the gas to maintain speed. Feels similar to when driving a manual and you need to downshift for more power. It is shortly thereafter that the CEL will come on then followed by the EPC light and limp mode. Rinse and Repeat. Clear the codes, it's fine then the same process every time. I would love some suggestions here because I just don't know what to do next.

Sorry of the long first post, but I don't know if it is time to mechanic shop or is it really this difficult to truly diagnose this issue. Thank you for any additional suggestions. I asked him to do a compression test also next and told him I'm not paying for that.

m1964

Is the mechanic an audi specialist?
if he is, my next step would be a dealer. If he is not look for a specialist who is familiar with Audis.
A year ago my wife's q5 stalled in the middle of the street without any warnings. A mechanic changed all the coils because his scanner showed multiple misfires at all cylinders . It worked. BTW, he was not an Audi specialist.
I'd try the other mechanic who told you that seafoam will not work on direct injection engines.
the new coil could be defective, and, since originally there was a code for multiple misfires, I would change all the coils. There is a slight possibility that the main compouter went bad...
Please, let us know of the solution .
We have the same car so I would like to know what the problem is in case of it happening with our car.

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He is supposed to be very good with imports. That's all he does. That doesn't mean he can figure this out. It was more of a convenience for me to go there because he was close to the dealer where I bought it. That said, he is doing the compression test today. If he can't figure it out I will definitely be going elsewhere. I just don't get it. It just shutters and shakes even without the CEL and EPC lights on. So frustrating. The initial CEL light indicated multiple misfires, however, the last few weeks it has been specific to Cylinder 2. Even after the plugs, coil and injector.

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So the compression test was done and the pressure was 145 in Cylinder 2, 150 in Cylinder 1 and 153 in Cylinder 3. All within specs apparently. He moved coil and plug from 2 to 1 and the misfire still shows up for Cylinder 2. He is now believing that the ECU is the culprit but is going to consult a colleague.

gk1

Unfortunately the 3.2 is notorious for carbon buildup similar to the NA 4.2 in the RS4. There is no compressor (turbo or super) and carbon buildup on the intake can cause the types of issues you are seeing. You may just have to get a full carbon cleaning...either walnut shell blasted or manually with a pick and brushes.
How many miles do you have?
FWIW my old A6 3.2 needed manual cleaning due to misfires at just 18k miles. I never made it to 36k with that one so who knows if it ever came back, but there were no issues when I traded it in at 32k miles.
At the time they also did a TSB that they claim changed the valve overlap to mitigate the issue, but who really knows for sure...they may have just lowered the sensitivity to misfires.

Love It or List It

I bought it used with 117,000 miles on it. I have read where the carbon buildup could be an issue, but several videos and posts suggest that it would be more attributed to cold start CEL. My CEL/EPC only comes on after it is driven for a little while after clearing the codes.

gk1

117k on a 3.2 is a heck of a lot of miles to not have a carbon buildup issue so it is very high on the list of potential candidates that doesn't mean you could not have another issue as you are investigating electrical or otherwise.
Did you try an Italian tuneup and see how much black soot comes out of the tailpipe when you floor it? (Sometimes easier for a person following to see or at night when another cars headlights can light it up.)

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I don't disagree. I have not had anyone follow me to see if there what comes out the pipes. Worth a shot I suppose. Mechanic still has the car so I will ask him what he charges for a cleanup. Thanks for the posts gk1. Appreciate any input at this point.

sooany

My audi q5 do not have carbon build up issues (I removed intake manifold and check it). Current mileage is just over 120,000kms. Our Q5 3.2 has slightly different engine compare to A6 3.2 (improved for carbon buildup issues)

If you have misfire issues when it is hot, it is most likely leaky injector issues. When the engine is cold, more air comes to the cylinder and burn excessive fuel but when the engine is hot, less air comes to the cylinder which is not enough to burn excessive fuel.

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The last call I had a few moments ago was the mechanic telling me something about solenoids for the 3.2 v6 that are matched with the cylinders that could be faulty. I'm not sure I heard him right though. He said that a colleague mentioned they could go bad so he is going to switch them out tonight to see if the fault follows whatever he is talking about.