So today I was driving my A6 and for fun decided to step on the gas for a minute. Well, the car started taking off, and then the rpms quickly climbed to 5 to 6 thousand. And the gauge kept bouncing up and down, while the transmission seemed like it couldn't decide what gear to shift into. Well, the car then stalled and shut off. Went to restart and i stalled again with a battery light indicator on. Popped the hood for a second, couldn't smell anything burning or notice any problems besides my intake hose popping off. So I put the hose back on, and let the car sit for a second, and it started back up without a single problem and drove just fine. I had new transmission fluid put in it back in July when I bought the car, but have not replaced the filter. Could it possibly be that, or something much worse?

 

Wouldn't be the filter.

Sounds like when the intake popped off it allowed air to bypass the MAF changing the fuel mixture which thus made the vehicle run lean. Some cars(not sure about Audi's) have settings built in that shut the vehicle down when something occurs which could damage the engine such as running rich or running lean.

Tighten those clamps up, check the codes with your reader and if nothing shows my only diagnosis is leave the racing to the Pros and drive normally.

By the way? You wouldnt happen to have one of those Cold Air Intakes would you? They're notorious for doing that.

 

Yeah, sometimes I get that slight itch to push my vehicle. Not usually a good idea. But nope no cold air intake, and I'll need scan it tomorrow after work. Hopefully that was all it was.

 

I'd be willing to bet thats all it was. Especially if you tightened it back up and then it started and ran fine.

Just make sure thats all tight before you decide to do that again. If this is the first time its done this during hard revs then it might be a sign that your motor mounts are worn and allowing too much play in the motor. Next time you're under there take a little peak and make sure everythings good and strong in there.

 

Its not the first time the rev thing happened, but it is the first time it stalled. Hopefully thats all it was. I replaced the squeeze clamps? with worm clamps and tightened them down. I seriously hate those clips though ugh. And how would I go about checking my engine mounts, and if I have to replace the how do I do that? Is it something I can wrench on my own, because with help I have succesfully completed a timing belt.

 

Did the hose pop off before?

I wouldnt use those silly little plastic clips. Go down to Home depot and get the screw clips. Its a little belt that has a screw on the end and as you turn the screw it tightens the belt. Its all metal, wont break and it'll be tight like crazy. Put it this way, my engine was completely submerged last year for about 15 minutes while I was crossing a pond and got hung up on some rocks, those clips are what I trusted to keep water out of my engine.

As for the motor mounts they look different on every car but you always look for the same thing.



You'll notice there the rubber bushing fills the hole completely. This design has a small movement groove in it but dont concern yourself with that. What you're looking for is the rubber will be dry, cracked, sometimes protruding from one side of the bushing.

Now, if it wasnt the air bypassing the MAF like we had first thought then it could be a couple things. I'm new to Audi's specificly so someone will have to help me out on this but I can tell you what I'd test in my Jeeps or other vehicles.

Fuel pump(Because of your symptoms specifically this is the first I'd check)
Crank position sensor
Throttle position sensor
Cam position sensor(s)

Those are the likely culprits from something like this. Throttle position sensor wont throw a code until its completely undriveable so the idiots at the shop will say its fine because their stupid little machine says so. Until ofcourse it revs your engine to redline for no reason and completely fails and then you're unable to drive it to the shop if its an Auto, or you're in for a REALLY rough and annoying ride if its a manual. So you're going to have to test it with a volt/AMeter. There are tutorials online for this.

Maybe someone else will pipe up and let us know how likely a TPS, CKS or CPS would be.

Edit: Worry about this problem first, we can discuss replacement of engine mounts later. Its detailed... lol

 

It definitely sounds like the behavior of a faulty (or bypassed) MAF sensor. My wife's car ('99 a6) was having a MAF problem and had very similar symptoms, it even stalled a few times when I was playing with it. Just make sure everything is tightened down and you really should be fine. If you see these symptoms in the future look into replacing your MAF.

The motor mounts is a somewhat legitimate diagnosis (i mean WHY did your hose come off???), but you would also be noticing a lot more vibration in general. Depending on how long you've had your car you might just be used to this, however. Definitely worth looking into.

 

If it were like below yes.


However you can have slightly worn motor mounts that have just softened too much and allow too much play in the engine. Its still thick enough to dampen vibes. My brother in laws 350 chev equiped Impala Police interceptor had this problem when he brought it to me. All the same symptoms. I took one look at the K&N intake that the dealer put on for him and diagnosed the MAF/Worn out engine mounts. The engine mounts allowed the motor to move 5cm more than it should have which then caused the cheap *** K&N setup to disconnect.

I should clarify, do not change those sensors until you've tested them. No point in spending money pointlessly. Most probably the MAF but if it hasn't been leaking substantial amounts of air beyond the MAF then it wouldnt cause the symptoms.

 

The easiest way to check the mounts is to put it in drive, stand on the brake and slowly bring up the R's and look at the engine. When I say slowly I mean a couple seconds and only hold it for a couple seconds. It builds a lot of heat in the fluid to just brake stand it that way and hold it.

It should torque to one side a little but not excessively. Then let it idle and try it in reverse.

Every engine mounting system is different but if you can't figure out if it's too much or not get someone else to double check you.

Usually it is the engine torquing too much and pulling the hose loose but it could be someone was in there and didn't get it back on right or didn't get it tightened down too !!

 

I wouldnt really recommend this method, different vehicles torque different amounts. and if you have poly bushings vs rubber bushings that will also make a difference. Your best bet is to look under and check it. It'll be fairly obvious if its worn.

But he makes an excellent point as to why I'm the only one working on my vehicles. you never know what some dim whit is doing under there.