Did I just Kill my 1.8t?

[aslusher]

My car burns oil. About a quart per 1k-1.5k miles. For this reason I keep a jug of fresh oil in the trunk until I have time after school is finished to properly diagnose and fix the problem.

Today I was driving on the highway without said oil jug, when my MIN oil light flashed. I got to a store (walmart) as fast as I could, but it was probably more than 5, less than 10 mins before I was able to get there. I have driven (VERY MINIMALLY) with the low oil light before just to get to a shop to buy oil, and have not had any issues. In these cases I don't push it and I watch the temp gauge like a hawk. Stupid of me, in retrospect.

But today, after filling up to the proper dipstick level, the car initially started right up without issue. I noticed the MIN oil light was still on, though, and then the engine suddenly stalled 30 seconds later. After that, I could not get it to start. It cranked over vigorously again and again, sometimes "catching" for a moment as if it was going to start up, but quickly sputtering off before any real start could occur. I pulled some fuses, and all were intact. The MIN oil light disappeared after pulling fuses.

I am worried that I may have burnt my engine internally. However, the tow truck driver says he got it to start after I left the garage that the car was dropped at. So what gives? How could running the oil out cause the car to only temporarily fail to start? I should note that I had about 1/8 tank of gas in it. Not a lot, sure, but shouldn't be enough to cause it to not start. I also depressed the fuel rail relief valve and found gas to squirt out.

Anyone have any insights here? What would a toasted engine look like in terms of symptoms? Can any critical sensors required for ignition fail because they were temporarily not bathed in oil?

The garage I took it to does not do Audi/VW electrics.. I just asked them to verify that my engine is mechanically OK. I am now wondering what to look for sensor-wise, etc. if their report is good.

Thanks in advance for any help.

[EuroxS4]

I doubt you cooked the engine. Are you sure it was a min oil light and not a oil pressure warning??Pressure warning is in red I think min oil is in orange color.My guess would be a failing fuel pump,clogged filter and relay on its way out.If you have cooked the engine it would be knocking when running.I would say your engine is ok but probably have a fuel pump thats on its way out.

[aslusher]

I doubt you cooked the engine. Are you sure it was a min oil light and not a oil pressure warning??Pressure warning is in red I think min oil is in orange color.My guess would be a failing fuel pump,clogged filter and relay on its way out.If you have cooked the engine it would be knocking when running.I would say your engine is ok but probably have a fuel pump thats on its way out.

Yes, certain it was min oil level and not oil pressure, which I've thankfully not (yet) seen in my car.

I changed my fuel filter last week, so that should not be an issue. I could absolutely believe that my fuel pump or relay has failed, though. It is just puzzling that the symptom would appear immediately after rolling around with no oil to spare. It would be almost too great a coincidence for me to believe. Unless somehow the two could be mechanistically connected?

[EuroxS4]

Yes, certain it was min oil level and not oil pressure, which I've thankfully not (yet) seen in my car.

I changed my fuel filter last week, so that should not be an issue. I could absolutely believe that my fuel pump or relay has failed, though. It is just puzzling that the symptom would appear immediately after rolling around with no oil to spare. It would be almost too great a coincidence for me to believe. Unless somehow the two could be mechanistically connected?

Not connected but you said you had a 1/8th of a tank correct??So not coincidence but rather failure.The reasons why these pumps fail cause most of us run the tank till it’s empty the pumps get hot when the level is very low.Im guilty of it myself I’ll admit it.The usual life span of one of these pump is between 100-130k miles.I know this because I’ve put in 3 pumps into my avant.


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[obaka]

Crankshaft speed sensor maybe?

[aslusher]

Not connected but you said you had a 1/8th of a tank correct??So not coincidence but rather failure.The reasons why these pumps fail cause most of us run the tank till it’s empty the pumps get hot when the level is very low.Im guilty of it myself I’ll admit it.The usual life span of one of these pump is between 100-130k miles.I know this because I’ve put in 3 pumps into my avant.


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I see your point. I still would find it highly suspicious that this all happened right after I played with fire regarding engine oil. I mean, a 1/8 tank level happens often enough that this was one of many opportunities for the pump failure to begin to show.

But assuming it is the pump, I just wanted to point out that, when I briefly pressed the fuel rail relief valve, there was a squirt of gas. Shouldn't this mean that there is at least something in there to get the car to start up? I don't know enough about the fuel delivery system..

[aslusher]

Crankshaft speed sensor maybe?

I stumbled across this when I did some initial googling/forum searching. Is there any way that a crankshaft speed sensor failure could result from oil starvation, or would this possibility for the failure point require coincidence for an explanation?

[EuroxS4]

I stumbled across this when I did some initial googling/forum searching. Is there any way that a crankshaft speed sensor failure could result from oil starvation, or would this possibility for the failure point require coincidence for an explanation?

No no way one would cause the other but also a possibility.At this pint it’s safe to say the vehicle needs to be scanned for faults.Crank sensor would cause a crank no start.Did you notice if the rpm needles was moving when you cranked but it didn’t start??


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[aslusher]

No no way one would cause the other but also a possibility.At this pint it’s safe to say the vehicle needs to be scanned for faults.Crank sensor would cause a crank no start.Did you notice if the rpm needles was moving when you cranked but it didn’t start??


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Did not look at the tach unfortunately. I guess you are right in that all I can do is hook it up to VCDS. Thanks for the input. Incidentally, my "car" laptop's hard drive failed a couple weeks ago..

[aslusher]

Mechanics weren't going to get to it today anyway, so I decided to stop by the garage on my way to class today and, sure enough, the car fired right up. This is good news to me in that the engine is clearly not dead..but on the other hand I am not any closer to diagnosing the problem. Based on your responses, I suspect fuel pump itself or an electrical short in fuel pump circuit or engine speed sensor circuit. Will post results of a VCDS scan as soon as I am able to do one..

[imnuts]

I have a 3.0 that goes through oil. For me, it's every 2-5k miles with no real rhyme or reason as to how long between the light coming on. I've driven 20+ min with the min oil light on before with no issues. As long as the engine wasn't making any mechanical knocking out screeching, you should be ok from a lubrication perspective. Good luck figuring out the no start issue.

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[aslusher]

I have a 3.0 that goes through oil. For me, it's every 2-5k miles with no real rhyme or reason as to how long between the light coming on. I've driven 20+ min with the min oil light on before with no issues. As long as the engine wasn't making any mechanical knocking out screeching, you should be ok from a lubrication perspective. Good luck figuring out the no start issue.

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Thanks for the input, that's reassuring.

For me I think my oil issue is turbo-related. A boost log showed spikes that make me think I need a new wastegate actuator. Not sure if perpetual overboost can explain the oil loss, but I think I'll start there. If that doesn't do it, then I guess I'll just live with it unless it gets much worse.

[eljay]

I know the car is at the shop, so it's hard to diagnose yourself at this point, but do get it scanned so you are not wasting time chasing ghosts.
When it comes to oil, did you previously look around the engine bay for any obvious oil seepage or dirt build-up? Either the oil is leaking out somewhere slowly or being consumed internally, in which case you would see some blue smoke on start up if it accumulates sufficiently during combustion. You could also pull out spark plugs and check them.

[aslusher]

I know the car is at the shop, so it's hard to diagnose yourself at this point, but do get it scanned so you are not wasting time chasing ghosts.
When it comes to oil, did you previously look around the engine bay for any obvious oil seepage or dirt build-up? Either the oil is leaking out somewhere slowly or being consumed internally, in which case you would see some blue smoke on start up if it accumulates sufficiently during combustion. You could also pull out spark plugs and check them.

I drove the car home last night without issue. Unfortunately, It's going to have to sit until I get through an exam tomorrow. chemistry > Audi problems.

I've never seen so much as a drop of oil under the car, and the splash guard is "clean"--other than grit and grease from spills over the years. I do get some residue on the bottom of the engine, but I have chalked that up to sloppy oil filter changes. No matter what that residue is from, it's not nearly enough to explain a quart every thousand miles or so.. I'll have to have someone drive my car while I ride behind it to look for smoke. From the driver's seat, I don't think I'd see fk all unless i had a plume of smoke behind me.

EDIT: While on the subject, I do get an easily noticeable oil/fuel stench coming from under the hood after shutting my car off. It smells like a mixture of partially combusted fuel and used motor oil. Thinking that's probably connected to the oil loss.