toledotom

I have a and bought used from 2013 Audi Q5 2.0L Premium Plus with 68,975 miles. Have owned the car for 3 years a Audi/Mercedes-Benz Dealership I bought my E350 Mercedes from. It had 39,875 miles on it used when i purchased the vehicle for my Wife. i am a very GOOD Mechanic and this car is a Lemon if you ask me. With-in a year and 4,000 miles the dreaded Chain tensioner or stretched chain or plugged oil path from the oil screen and a broken vale rocker I am out over $3,500. Now, I am having a long crank start issue. Car starts fine and runs for about 3 seconds and drops RPMs to 800 and bogs like going to stall, but stays running really rough.
I lost my interior lights, door, under dash, glove box, under seat lights. Funny thing is? The interior lights and all door lights came back on by themselves. Yesterday I lost my MMI and NO Radio, Navigation, Telephone or Media on my MMI. Nothing. But today the MMI radio and screen come on but stay on for only about 20 seconds and Go OUT! Oh Yea, No Cruise Control either?? I pulled the cover to the ECU on the driver's front cowl and checked ALL the fuses. ALL good and Connections to ECU showed NO water or corrosion. I have gone through all 3 fuse boxes, Driver's side, Passenger side and right rear luggage area. ALL fuses Fine. I even bought a $20 Premium Digital Automotive Circuit Tester. I had 2 (Now 3) circuit testers! I have Purchased a New CAN Bus Gateway Module for info Here and other sites favor replacing this Module. Audi has had problems with this unit but more so on 2018 -2022 because of placement under rear seat! I hope this is it? I am going after it on the right side under das having to remove glove box. Supposed to be right there? Any HELP regarding these Electrical Gremlins or Similar Issues? PLEASE HELP!

tomaszp72

Did you check the battery? You symptoms could be pointing to the bad battery.

S4'ed

Try replacing the plug-in relays, one at a time, located on the rear fuse/relay panel (right side of cargo area), and some located in the water-tight ECU box (located under the cowl cover, driver side, base of the windshield).
Likely suspects are the "Terminal 15" relay and the "Load Reduction" relay.

silver_tt

All good advice. I would also scan with VCDS to see if there are any codes (can also check your battery health).

Sorry about the broken valve rocker, that is pretty rare. Unfortunately on the 2013 the timing chain and cam bridge screen are an issue and need to be addressed.

Regarding your long crank issue you didn't finish your sentence but most likely culprits are timing (but you said you already did this) and HPFP.

Since my 2014 engine hit 100K+ miles I am dropping my OCIs down from 5K miles to 2-3K miles. The rings in this engine will clog with carbon if you don't change your oil frequently with a high quality oil.

toledotom

Yes, I have Ross Tech - VCDS 22.10. Just downloaded and installed. Been using VCDS since 2004 on my 2004 VW Jetta TDI.I said I was a Very Good Mechanic.
1. Battery has been charged up to 100% (6 months old) Yes, Batteries can cause some problems but first thing I checked and Alternator.
2. S4'ed Thanks for the response. Your info seems useful but I can't fully understand what you are telling me? Ok, understand locations but Terminal 15 and Load reduction Where at? More precise might help? I have ALL 4 fuse boxes open and the Glove Box down. Going to replace my 8R0 907 468 F CAN Bus Module. Staring here and going back to left side of cargo and take apart the Audio Units and check for fuses, loose wire and any corrosion?
3.ECU gets opened next. Removing the 2 pesky screws. I have a pinpoint torch to heat them, might have to cut a slot in them to use a regular screw driver. Checking for and wires broke or CORROSION - I believe it all is right here?
4.Going to run a small cable down my sunroof drains and clip the rubber grommets on the end so water will flow out easily, I believe water is coming in and my main culprit.
5. I am looking for anyone who had a similar problem? Chasing this bad connection down is a lot of work and tedious. Broken wires, bad fuses, bad grounds and corrosion in wire connectors is a PITA.

SMac770

Rough idle, could be the PCV (if you cover the hole on the backside of the round cap on the PCV, does it smooth out?), could be HPFP, could be the injectors, or plugs, or coils. You have the flex fuel engine CPM (CPMA for 2013)? Could be bad fuel quality sensor (so it has an incorrect assessment of the gas/Ethanol mix). As you have VCDS, do a full auto scan and post the complete log here. Easier for everyone to work from the same information base.

If you have water intrusion, the normal locations will be in the left rear, messing with the radio and amp, depending on what equipment you have. Or the right rear, messing with the J393 and other components. Or under the dash, left end, the J519 BCM. The central electrics that manages all the interior lighting. It would seem odd for the J533 CAN Gateway to be at issue, especially if the scan tool is talking to it (the OBD port goes directly to the J533; the J533 does all the talking to the rest of the car on the scan tool's behalf).

Luckily, this is a 2.0T, not a 3.0T or 3.0 TDI, so no stop/start system to deal with (as I understand it). As such, the B8.5 A4/A5 2.0T wiring layout is likely the same enough for the B8.5 Q5 2.0T. But yeah, could be a corroded ground point. Though that'll be easier to analyze once a an actual group of devices whose 12v to ground pin is not showing a 12v drop is determined.




Check the voltage values in blocks 14 and 18 of the J533. 14 has alternator output commanded voltage. 18 has battery monitor measured voltage. Engine running, the values for 14 and 18 should be within a few tenths. If not, check that by testing the voltage at the alternator (B+ to housing), at the jump start posts, and at the battery posts. Find the point where there's excess voltage drop. And then carry that on from the battery to each fuse column and make sure there's not a voltage loss getting from the battery to each fuse column. Note, fuses 1-4 on left brown are differently wired (1 and 4 are not wired, 2 and 3 are wired from the J271 relay).