AO

As I re-read this, I think we need more information. What do you mean "fall on its face"?

Does it continue to run when this occurs? How's the idle?

What did the dealer find/do?

How does it come back to life? By istelf? Or do you need to re-start?

tylenol

Thanks for the advice...I was driving in 2nd at about 2500rpm and it just stopped accelerating didnt die but quit pulling. Kept my foot in it and it came back to life?? The dealer put the rebuilt maf in and flushed the gas tank did vac checks and sent me on my way.

AO

Still too vague for me. While it could be the ignition side like I said previously, a weak fuel pump, or overheating relay (FP, LH, Ignition - u-pick) could also cause similar issues.

When this happens, how long does it last? Does it come back right away? Do you have a chance to put it in neutral and rev the engine / let it idle?

How often does it happen? All the time, once a day, once a week? If you push the car harder is it more apt to do it or less?

VehiGAZ

And then...???!!!???

Dude - we need DETAILS and CHRONOLOGY and CAUSES and EFFECTS. This momentary snapshot you have provided is not very helpful for diagnosing something as complicated as a 928 S4 - over an internet forum.

"It came back to life" - meaning it was running fine immediately afterward?

Was it running OK when you brought it to the dealer? Did they improve anything?

Will it hold idle?

Will it go up a hill?

Do the gauges give any indication of what's going on in the engine?

What else doesn't work in the car? (leave no detail unmentioned - did you know that your hatch motor may not work if one of your interior lights is fried?)

If you do not have the patience for a complete explanation of the circumstances of the failure, you are unlikely to get a helpful consensus answer.

VehiGAZ

I see AO & I are on the same page!

tylenol

This is what it was doing about 2 weeks after I replaced the Lh. at first it would act like it was cold when I started it (didnt matter if it was cold or hot) I would have to feather the clutch and accelerator until it acted like it warmed up maybe 2 to 3 minutes. Then finally after doing this for a month or so it finally just quit spit and sputtered and would not run at all. Had it towed to dealer they diagnosed the bad maf flushed the gas tank ran good for about a week.

Took the car and washed it got about a mile down the road and it stalled but do not die pushed in the clutch feathered the gas and it came out of it.

Thought something got wet?? Took it out a couple days later ran good when in and got beer came back out took off and thats when it stalled kept my foot in it and it came out of it. Have not drivin it since. It just seems to me that the symptoms are all very similiar?? And the fixs have all been different (LH, ran for a while MAf, ran for a while) I have know doubt these parts needed replaced because after they were the car ran fine. But the symptoms are all the same??? AT a loss

tylenol

Sorry more detail when I mean came out of it or came back to life yes that means it was running fine. And this latest time it stalled for about a minute did not die and then was running fine. One more thing when I got home I shut it off. Let it sit about 5 minutes started it back up sounded good held idle and then after ridleing for about 2 to 3 minutes started to spit and dropped idle i could keep it running by feathering the gas but if I let off it would die??

Thanks

tylenol

everything else works on the car the only thing that I thought was at all out of the ordinary is when driving hot or cold (outside temp) the heat gauge will jump between the 2nd white line and the third line. Never going over the third??

AO

I'm curious, why the dealer felt it neccesary to flush the tank if the problem was in the MAF. The two are very unrelated????

Also, why did you replace the LH? Did it do it before you replaced it?

Anyway, I'm now starting to think either a problem with the new LH or that your problem was/is a relay. Specifically... naw... I'll just leave it vauge.

auzivision

Me still thinks fueling... either poor metering or starvation… especially if it runs smooth down low.

Poor Metering could be many things, bad MAF, bad LH, bad sensor (O2, hall, knock, TPS, CPS.), or bad electronic connection. Then again most of those sensors (except O2) affect ignition timing, not fueling. Sure retarded timing will reduce power, but not “flat on its face”. If this means still runs, but way down on power. Does it hold RPM, but not gain? That sounds like fuel in my book.

If the metering is off and it’s too rich, you should notice black smoke out the exhaust. If it’s too lean, well that basically the same as starvation… not enough fuel for given amount of air.

Fuel starvation could be pump related or maybe even a plugged fuel filter (but I think many a changed fuel filter never really fixed anything). For the most part the critical items in the system are pump, relay, and LH signal… plus of course any connections. If the problem goes away when the relay is jumped, think relay or LH. If it’s doesn’t think pump or something else. You can rule out the pump with pressure gauge (free rental at Autozone).

Ignition, sure maybe a loose or bad wire or ground strap somewhere. Easy enough to check and fix. Clean ground straps at coils and rear of engine block. Inspect plug and coil wires, look for crack and spritz with water to see if you can make it run worse. Typically, an ignition that is missing (not firing on all cylinders) is going to cause shakes and vibrations (even at idle).

Big question, how does it run at idle? Is it smooth and steady or sputter and/or fluctuate?

VehiGAZ

What does this mean?

VehiGAZ

So the dealer did fix it, if only temporarily.

VehiGAZ

Don't toy with the boy, AO, you KNOW why the dealer did that - to make a bunch of money without knowing what's wrong!!

tylenol

Hey I just wrote a book here dont leave me hangin....I was about 60 miles away after buying the car when it just quit I mean I was going 65 mph outside of minneapolis and boom nothing would turn over but not run. Had it towed to courtny truck service in minneapolis. It took them about a week to discover it was the LH said it was extremly flooded. They put the new Lh in and I had it shipped to Kansas City. The dealer drained the tank because they said the gas smelled like turpintine. Like I said the car has been doing a lot of sitting.

auzivision

Wow, a lot has been typed since I started working on my last reply. I'm even more convinced now than ever it's related to your fuel pump. Why, because what you are describing is basically exactly what happened to me at SITM (more or less).

My fuel pump first started acting up just like you described… long before SITM. Swapped a relay and all was well for some time… like a few thousand miles. Then it started acting up again on the way to SITM, thought it was the MAF, swapped it and yes it worked... just not for long… maybe 15 miles

Then we messed with relays and LH… got it working again, but this time not for long again… only a couple miles. Let it sit (on the back of a flat bed) for a while, drove it right off and it ran fine. I’m sure it would be okay for at least a few more miles. We replaced the fuel pump even though it was running absolutely fine again the next day. I drove 500 miles home without incident.

The way you describe your symptoms, sounds just like mine. Way down on power, could keep it running if I feathered throttle, then bang back on again for a while, then drop flat on it’s face.