Clean97a6

So I'm having an issue with my 97 a6 quattro wagon trying to get the car to accelerate in any gear. I had the car in storage for a month When I pulled it out it started having issues. When I floor the car I have power untll I get to about 3000 rpms, it feels like I'm pulling a semi behind me, it struggles to even hit red line in neutral. I have no codes, but the only thing I could see on the live stream was that it looked like the car was fuel pressure being out of limits and the mass read that it was only getting 17 inch pounds of air? Ever since this issue I've replace the fuel pump, checked screen in tank, injectors, fuel filter, checked all the fuel lines, replaced fuel pressure regulator, spark plugs, mass, map, even the tps. I've checked all of the vacuum lines and replaced a few, I even checked the secondary butterflys they open up about 4500 rpms. I have no clue why this car all of a sudden started doing this out of the blue. Does anyone have any idea what could possibly be the problem? I'm out of ideas what it could be.

Rusty Spokes

I have seen a few of our older A6-C4 cars that over the years have picked up rust and junk in the fuel tank.

I would do the test for fuel volume..fuel pump too. There is a screen on the inlet of the in-tank fuel pump that can become clogged up.

The volume test is easy..I have attached a copy of the test below. Report back your findings?

Clean97a6

When I replaced my fuel pump with a new aem 320 lph fuel pump, I took the container that the original fuel pump sat in and cleaned the screen and the rest of the junk that was in the tank. I made sure that there was nothing in the tank or sending unit that was restrictive, I even tried to clean the electrical connectors and checked the voltage again to make sure that every thing was fine. I haven't done a fuel pressure test yet, I am going to do that today. Even thought i haven't done a fuel pressure test yet, I'm starting to think that the problem is more electrical and has something to do with timing. I checked the timing marks, it has not jumped timing.

Rusty Spokes

Checking the fuel pressures and volume is a good place to start..a new fuel filter too..it dosent happen often but fuel pressure regulators will go bad too.

Clean97a6

I've replace the regulator with 4 different ones and I've replaced the filter. But when I do the pressure test, how much psi should I see when I do the test?

Clean97a6

So I did a fuel test before the fuel rail, at idle warm it showed 65 psi, normal opp range is 40 to 50. I expected this I put a pump in that is almost 100 lph higher than stock, so fuel isn't an issue. I did some more tests today and found at idle my timing will go from 0 to 13.5 degree advanced and around 4500 will go up around 35 to 40 degrees advanced timing. I believe timing is my issue but I'm not 100% sure if timing is my issue what could cause my high rpm problem

Rusty Spokes

Be careful with your tests..AIRC the fuel pressure test is done engine off (vacuum on the pressure regulator changes the readings)..should be specified value: 3.8 to 4.2 bar (55 - 61 psi) engine not running..if the FP is too high you can have problems..see the attachment.

Timing will move around alot..35 to 40 degrees is okay at 4000rpm..engine load will adjust that around too.

Air leaks? they will make havoc with the engine running..usually you get a code though..which is odd that you do not..which is why I suspect the fuel pressures.

boxerfan1

My engine loses power at approximately 4000rpm. I have replaced a couple of vac hoses, fuel filter, O2 sensors, spark plugs, cleaned the MAF, removed the intake and cleaned it and the hoses to the valve covers along with the throttle body by just hitting it with carb cleaner.

The running has has improved but the basic symptom of losing power remains unchanged.

My code reader says I have an issue with the catalyst and oxygen sensor resulting it saying there is a ending code to come.

Is there an an easy way to see if the cats are blocked?

Rusty Spokes

Use a vacuum gauge on a direct port to the intake manifold. Most have instructions how to read.

And do check the throttle second stage vacuum changeover pot, part number 078133159a. If it is not working then the secondary throttles will not open. Use a mini vac pump to test.

Rusty Spokes

Use a vacuum gauge on a direct port to the intake manifold to test the Cats. Most have instructions how to read.

And do check the throttle second stage vacuum changeover pot, part number 078133159a. If it is not working then the secondary throttles will not open. Use a mini vac pump to test.