expidia

Started last week. After 30 sec runs fine again. Added some dry gas last week, but stumble still there. Anyone ever experienced this. Connected a code puller this afternoon and codes are clear.
Thanks

Bob Petruska

Many things can cause this.

On my 2014, 2.0T, Q5 when I get that initial stumble, I reset my throttle body. The stumble/hesitation goes away immediately, and stays fine for many months. When it comes back I just do it again.

Throttle Body Alignment (TBA) - Ross-Tech Wiki)

Again, you may have one of the other 101 items that can cause this

You need a Ross-Tech VCDS unit to do this

expidia

Ok thx for that quick reply.

MurrayA4

Bob's right.The price of a VCDS approx.$300 will pay back fast.It gives you dealer level access, just not the programing power.Get one, perform a "complete scan" and you'll likely find an entrance point to solving your problem.

expidia

Thanks. I figured it will be at least a $200-300 investment going the VCDS route. If I go to the dealer I know they wil hit me up for $150 first just to hook it up to the computer. I know I'm probably looking at a $300-400 bill knowing how dealers run up their revenue for each bay. This Q5's been great. Picked it up 3 years ago as a CPO. We are going to sell it and buy a 2019 Q5 over the summer, so I have to get this stumbling issue solved. But I'm not thrilled at the thought of investing $300 in a device that will potentially become obsolete a few years from now.

I might sell both of our cars for 2019's which would put both SUV's back under warranty negating an investment in a VCDS. But there are 6 cars in my extended family, so I probably could put it to use again in the near future since we currently have 5 vehicles out of warranty.

Just a thought. What are the chances its the 5 year old battery as a possible cause?

expidia

Thought I'd update my issue since some of you responded to my original issue:
Brought it to the dealer for their recall of them installing a re-designed after run coolant pump. Took them a year to re-design a replacement. The had me go there a year ago as some were catching on fire so they unplugged it until they had a replacement.
While it was there I asked them to diagnois the stumbling when starting cold issue. He said it would be an hour labor or $150. They came back with no codes but since the SUV was 5 years old it should have the plugs changed even though it only has 28k on it. We have only owned it 3 years. And then of course they wanted to change the brake fluid too. I'm surprised he did not say the old fuel injector cleaning treatment too.

So I told him I would do the plugs myself. Ordered a cabin filter $15 and air filter $17 and 4 platinum plugs off Amazon. $33 for the plugs. My local Advanced Auto wanted $53 for the same plugs (amazing).

I installed all items today. Plugs were black (I was hoping to see a nice light brown coloring) At least it was all 4 and not just one. I suggested to my Wife that she run 91 octane for awhile and then I'll re-check a plug again to see how clean they are running. Maybe from mostly city driving and using mid grade 89 octane gas they got that black. Filters were pretty grundgy too.

I took it for a test drive around the block and it had the full power we enjoyed after we first bought it. At idle can't even tell the engine is running. Tomorrow AM I'll see if it still stumbles at start up. I doubt it will but it was a lot cooler outside a few months ago when the issue started. In the 70's now.

Edit: 7:50 AM 51 degrees. Started up with no engine stumble! Thanks again for your above responses

MurrayA4

Boy that's a sooty plug.Do you/your wife do a lot of city (like all) driving and idling ? If not there's something going on there.Might want to change plug's temperature range.Any good parts shop should be able to set you up.I'm a big fan of NGK.

expidia

Exactly. All city the past 3 years she has owned it, short 2 miles back and forth to her job. I thought about changing the heat range when I saw them. I'll pull one in a few weeks to see if they are still loading up. She is also now only using the 91 octane. Ditto on the NKG's.

expidia

Update: Its been almost a month since the new plugs. The stumbling is starting to re-appear again. Its brief and the engine still has full power when I drive away. I noticed when I started it up the other day the tac was jumping between 1000 and 9000 until it settled down and it felt like it was going to stall which is what my wife says happens to her when she leaves work.

Over the next day or two my plan is to pull a plug and see if its sooty again. If it is I might increase the heat range as Murray A4 suggested . I figure for anoher $33 for a set of 4 hotter NGK plugs is cheaper than going back to the dealer, losing hours of my time and paying a minimum of $150 to put the car back on their computer. I did ask them to check or adjust the throttle body but they said it looked OK on their computer.

So I used NGK 1675 . . . what NKG number do you recommend as a hotter plug and how much hotter looking at those black sooty pics above?
Thx

apoelistas

Vcds is out of the question?? One dealer visit worth is what it costs no??