nm3210

Hey guys, this is in regards to my wife's 1999 A6 (2.8L AHA), mine is thankfully still running very well. I'm going to cross post this to AudiForums too, so don't hate.

A little background so you can understand the situation: the car is still owned by her father (we're fresh out of college) and so unlike my car where I do all my own general maintenance it generally gets taken to a shop/dealer to get worked on. This includes oil changes which get done at a Mobil1 Lube Express - thankfully they've done a good job from what i've seen over the last 20k miles. They use 0w35 full synthetic and request to get it changed every 3k (which is pretty frequent with full synthetic these days). The last oil change however, was about 6,000 miles ago - not that big of deal if you ask me.


So we drive home for the holidays in her car and everything is fine. It's parked in my driveway for a few days and then when we try to start it Christmas morning it doesn't want to start. It fired once (a couple ignitions) and then just went flat. The starter could crank it just fine but since that first ignition there was nothing happening. I grabbed my computer to read any codes that might have come up (there was zero indication of anything wrong/bad on the dash) and there were zero within the engine module which was the only one i checked at the time. We proceeded to take a different car to continue on with our vacation and a few days later we came back, tried it again (same engine crank but nothing happening) and then got it towed.

I will leave out my choice words to the repair shop that it got towed to (again, not my car, not my choice), but the first day they say that they ran a compression test and two of the cylinders came back at 50psi (it should be 160psi). So first question:

Q.) Does low compression mean that something HAS to be wrong? Or could it just be a minor side effect of something else that's easily fixed? (honestly they could have done this wrong and/or lied about it)

The next day they say that they were trying to test the oil and noticed that it was low, they added some oil and that the thing just started up then (with no bother in regards to the low compression). The anecdotal evidence was that the "owner's daughter's friend's BMW doesn't start when the oil is too low so this audi probably has the same sort of system". This leads to my second question:

Q.) Does the engine refuse to start given low oil situations? I personally think this is BS because I have never heard of this before, and why would the engine still crank over??

So now I have a working car that just went through a really weird episode and I am not confident that the real problem was actually determined/fixed. The low compression has me slightly worried but the incompetence of this shop alleviates that quite a bit. The airbag light is on, but beyond that it is code-free.

Any thoughts/suggestions would be greatly appreciated!

4Driver4

I think you are leaving something out. I bet the car was parked for a while, then started briefly, perhaps to move it in the driveway to get another car in or out.

True?

And no, there is no oil level sensor that prevents the car from firing.

nm3210

Gah I just asked my wife, and yes it was moved in and out of the driveway briefly.

So what would cause it to act up like this because of that and what can I do to fix it next time? (What did the shop do to "fix" it?) I obviously know it's not good to quickly turn the car on and then off and I don't generally do it with my vehicles, but it seems I also don't know what actually happens to the car when it DOES happen and how to then fix it.

Thanks for your help :-)

jseklund

I believe 4D4 is referring to "car wash syndrome" or something like that, where the engine is started cold, flooded with fuel, and then stopped relatively soon after. i.e.- you start the car to move it out of the garage in order to wash it, and then stop it 10 seconds later. I believe this is how it works at least....

As for the low comopression - it could be an unrelated issue. Your car will start with compression on just 4 cylinders I believe. If you are concerned about it, why not check it yourself? Get a guage at autozone (rental) and remove the plugs and crank the engine. You may find the shop just screwed up. Or maybe it had to do with too much fuel in the cylinders? I don't know if that would cause a problem or not.

nm3210

Isn't it supposed to start up after waiting a while though? (so the engine can 'de-flood'?) It still didn't start days later which I thought was weird. What are you supposed to do when it's like that?

4Driver4

Yes.

And while most people think this "feature" is due to flooding, I disagree. Think it is high viscosity oil at start-up hyper inflating the lifters and causing a loss of compression.

Regardless. Usually you can start the car again by pushing the throttle pedal to the floor and cranking until the car starts. Usually this will cause a bunch of misfires and the car will run poorly at first, but eventually all will be well.

SloopJohnB@mac.com

Interesting take. I'm too lazy to pull the plugs and look for wet plugs and/or run a compression test.
But it shouldn't be too hard to pull one plug....

4Driver4

Compression has been verified as low in the past. I think both parties agree on that. At issue is the cause: is it excess fuel washing down the rings and causing a loss of compression, or hyper extended lifters.

The lifter thing was not uncommon on the mid eighties VW 1.8 engines.

Just Me

My quick comments:
1. good idea s it may be, it will; run with no oil
2. i would suspect the hydraulic valves never fully filled for the compression test
3. i might also suspect some degree of flooding in a car that was shyt down cold, maybe started (the shorter the worse for cold fuel in cylinders), shut down cold, and left. Bzzt.

Anyway, good luck.

6k is not long for synthetic.

I have never heard of 5w35. Wooly mammoth blood maybe?

G