Turbo fluttering and dropping power...
 

Greetings All,

I have a 1999 Avant a4 1.8t, it has 160,000 on it and I am not sure the existing turbo is original or not. I have had the car for a year and had no issues at all. There has always been a minor fluttering in the turbo when it is spooling up. It has happened consistently from 2400 to 2900 RPM in second thru fifth gears.

What is new is that now when I am in second gear thru fifth if I put the pedal to the floor it sputters and kicks with some authority and looses 90% power. As soon as I come back to 1/2 pedal it stops bucking and choking and spools up just like it always had. It sputters up to 3000 rpm and then it won't sputter any more.

Any ideas? I thought it could be a little condensation in the fuel tank or a bad tank of fuel. So I got some dry gas and some injector cleaner with no changes.

Any ideas or postulations are welcome. Thank you in advance for your time and attention

When this happen does the CEL (check engine light) flash at all?

Might be worth it to check for fault codes with an OBDII reader or VAG-COM.

No CEL at all....

It still may be worthwhile to check for stored fault codes that didn't/haven't caused a CEL.

Another idea is the diverter valve is in poor shape and may need replacement.

I will get to a reader and see what is stored and share what I find. If it is a diverter valve how harmful is it to run the vehicle?

I'd say the worst thing is the effects of the bucking on the drivetrain.

How old are your spark plugs? It sounds like you're not getting misfires (CEL flashing indicates misfires), but I wonder if fresh spark plugs would improve this behavior. Also, same goes for primary oxygen sensor and MAF (mass airflow sensor).

Greetings. I have not gotten to check for codes but I can report that today the bucking and sputtering is about 50% less than yesterday. I am wondering if there is a injector or fuel flow problem as it feels like the engine is starving for fuel when I depress the acc. pedal and it will stop fluttering if I just ease up a little. Like I said it is less to day with about driving about 10 miles with the dry gas and injector cleaner in the tank. I hate putting any thing but fuel in my tank but it seems to have had a positive affect.

In that case, it could also be a clogged fuel filter. If it's never been replaced, then you should replace it ASAP!

You know i have this same problem! A4 B7, really wierd i don't want to take it in. But i can't seem to find the answer to the issue either.

Found a solution to my problem! Similar in what you explained, for me it was the spark plugs. Iridium no good, gap needs to be .032 or less. Hope it helps.Cheapest thing turned out to be the best fix :)