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Yesterday I pulled out onto a highway where I had to accelerate briskly, and then there was a light I had to stop at a few hundred yards down the road. Just after the acceleration, as I was slowing down to stop, I felt the engine get rough (around the 2k RPM range), and the MIL came on, flashing. I wasn't at a point where I could pull over, so I drove as carefully as I could. In that time, the MIL went solid, and the EPC came on (or possibly was already on, and I just didn't notice).
I had an appointment to get to, so I decide to drive it. Idle was/is extremely rough. Acceleration from stop is extremely sluggish and jerky - until the RPMs get up >2k. On my 5 mile mostly residential drive I discovered symptoms diminished to the point of not being noticeable as RPMs increased. So then I switched to tiptronic and held RPMs in the 3-4k range, and basically drove as normal otherwise - and you would think the car was fine until I had to slow down to start/stop.
I pulled the codes and have 4 Engine Faults found:
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 2
Mileage: 272794 km
Date: 2024.07.20
Time: 14:42:41
Engine RPM: 1621.50 /min
Normed load value: 11.4 %
Vehicle speed: 11 km/h
Coolant temperature: 90 °C
Intake air temperature: 74 °C
Ambient air pressure: 1010 mbar
Voltage terminal 30: 13.499 V
Unlearning counter according OBD: 40
Mean injection time: 1.612 ms
Engine operating condition: Part throttle
Engine operating condition-Test_Program_Channel 87: 6
A/C compressor: load current: act. value: -199.50 A
Torque request: A/C compressor: 793.6 Nm
4105 - Bank 1; System too Lean at Idle
P2187 00 [01100000] - -
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 1
Mileage: 271630 km
Date: 2024.06.23
Time: 17:33:24
VCDS
Diagnostic Trouble Code Report
Control Module Part Number: 8R1 907 115 B
Page 3
Engine RPM: 806.50 /min
Normed load value: 31.0 %
Vehicle speed: 0 km/h
Coolant temperature: 96 °C
Intake air temperature: 41 °C
Ambient air pressure: 1010 mbar
Voltage terminal 30: 12.910 V
Unlearning counter according OBD: 2
Mean injection time: 2.804 ms
Engine operating condition: Idle
Engine operating condition-Test_Program_Channel 87: 5
After some research I was thinking coils/plugs - but I just replaced all of them (based on mileage, wasn't having any issues) about 18 months/ 20k miles ago. Other info on the car in case it matters...I have owned it for 10 years & since 17k miles were on it, and have a total of ~170k miles on this vehicle now. I have always done all the maintenance (and oil/filter changes using German Castrol originally, then LiquiMoly when that became difficult to source @~5k miles and/or when the low oil light comes on - since from about 30k miles it has always consumed oil at the rate of about 1qt per 3-5k miles). Most recently the oil was changed about a month/1k miles ago.
Same just happened to me my 2017 CYMC 2.0L turbo, 20k on OE plugs (60K total) from rock auto I DIY'd it at 40K, misfire and cylinder disable fixed by replacing 1 plug, which looked like it was rusting, but no oil in plug tube etc, electrode end looked fine. I moved coils around as well, but was plug after only 20K, start there, easiest. Compression check was fine...
No 4 plug after 20K, which was the misfire, #3 for comparison
which was fine:
Last edited by Mesquite77; Jul 23, 2024 at 02:16 PM.
MY13 Q5 will have a Gen2 flex-fuel CPMA engine. Plugs/coils are certainly a possibility, but with the lean, and being a Gen2 CAE/CPM, PCV is the first thing I'd look at. If you put your finger over the vent hole on the backside of the round cap on the PCV, does the idle stabilize?
Thanks for the tip SMac. I have also replaced the PCV previously - about two years ago (probably 30k-ish miles). But before taking things apart I tried your suggestion. Unfortunately no luck w/ the hole plugged & still rough idle. I'm not sure how the cylinders are numbered, but when I was testing the PCV it definitely sounded like the front most piston was the rough one. I guess that could be 1 or 4 - hopefully it's 1, and that's the issue.
The plugs and coils I ordered just arrived, so I'm going to give those a go. Fingers crossed that's it.
Yep, you guys were right. I'm thankful it was a quick/cheap/easy fix!
I just finished pulling all the plugs/coils. Plug #1 was the worst (shot), as expected - but all the plugs were pretty bad. I've previously run plugs a lot longer, I guess with age the engine it's just leaving more carbon/build up. Probably doesn't help that I also just did a LiquiMoly fuel system cleaner about 1k miles ago. The coils themselves all seemed fine.
I attached a picture of all the plugs (#1 by itself, and then #1-4 from left to right - with a new plug there just for comparison).
I had previously purchased the plug/coil pack from FCP, so I guess I'll give their Lifetime Warranty (credit) a try.
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MIL & EPC Lights - ROUGH idle/accel @ low RPM - 2013 Q5 2.0T - VAG codes
