Osmosis

Well, I've finally had my 2000 2.7t A6 up and running. I purchased a new stock intake boot so I could put all the plastic on the engine to make it look nice. I had a cheap 20$ silicone boot that worked well, but changed it. Anyway, as of recent, I had noticed a huge air whoosh sound when I got into the boost and it has become worse. I also noticed that the car seems slow during certain RPM's when trying to get into the boost. I also heard a funny sound from one of the turbos a few times but have not heard that noise in a while. What I did to find the problem was I purchased the parts to make a boost leak tester. I put shop air to the system and I find a nice slit in the stock style intake boot I put on Not happy. At this point, I think Easy fix! I have my old silicone intake boot so I'll just throw that on and I'll be good right? Wrong! So here is the problem. I put the old intake boot on that has no leaks. Go and take the car for a spin and the car falls flat on it's face anytime I put my foot into it. Part throttle, runs OK, but not right. WTF? After checking for leaks with the old intake boot on which was not damaged, I found no leaks with the boost leak tester. I did multiple test runs with no changes with the intact intake boot on the car. The car continues to run flat on it's face @ WOT. I then think, hey, I wonder what the car will run like if I change the intake boot back to the ripped stock one. I swapped in the torn intake boot and the car runs way better with the ripped boot. WTF???

So, I'm puzzled as of why the car falls flat on it's face with the intact intake boot. I checked for leaks via boost tester and water/soap spray bottle and ears, seen and heard nothing.

Yet, the car runs OK when it has the intake boot with the tear in it.


No codes other than the SAI and pre cats as I removed them both. My next step was to omit them via nefmoto software.

I cleared the codes via torque pro and then disconnected the battery for 15 minutes, no changes to the test run with the good intake boot.

I"m at a loss here guys, no codes, runs like crap with a good intake boot, but runs OK with a damaged intake boot. I'm finding no boost leaks other than the leak I found with the torn intake boot. Wondering if it's a bad turbo? I have no clue and I desperately need help.

Sorry if I"m redundant here, just frustrated and currently on pain meds. Just had bilateral knee surgery so I'm not happy about having to mess with my car at this point.

Thanks for the help!

johnkk

Strange that it runs better with the leaky intake hose. Fuel, air or spark? I would take another look at vacuum hoses off the back of the intake. Boost testers test the boost side, but the throttle plate blocks most of the pressure to the vacuum side. Connect some air pressure to the brake booster hose to check for leaks that your boost leak tester might miss. Fuel pressure regulator hose is a suspect.

With the leaky boot are you still able to hit full boost? You mentioned whoosh, so you should be able to feel the loss of boost. Is your pressure sensor tight in the top of the new throttle boot?

How's the fuel pressure? Is filter good?

Osmosis

Johnkk, All great thoughts, fuel, spark, air. I too was thinking that path as it leads to all answers, or at least most answers to car problems. I did spray brake cleaner on the engine @ idle. The car idles perfect..perfect???

So far, this is what I found and did. First thing yesterday, I put the good TBB boot on the car. I then swapped tunes. I've an APR stage 1 tune and stock tune on my ECU. I swapped the tune back to stock, drove it and It drove fine. There is a obvious flat spot in the RPM range of 25-50 when I go WOT. The flat spot is almost exactly @ 40-50 mph. It pulls, then stops pulling hard and just ok in this area. I swapped back to the APR tune and the same thing happens. Otherwise, the car now is normal. Pulls hard if I get on it @ 50mph or 15mph. Just that vague area of 25-35 WOT, it hits a flat spot @ 40-50.

No codes, no change on rpms while I spray brake cleaner on the vacuum hoses. I'm gonna figure out how to data log and try and figure it out.

Metronet

How many MAP sensors do you have? like when you swapped the TBB boot did you also change the pressure sensor together with it or the same one is installed? Data log and emission delete with Nefmoto sounds like a good plan, I am guessing 2000 is a ME7.1/APB?

Osmosis

Exactly right! 2000 ME7 APB. I'm not sure how many map sensors I have in the car, not too familiar with Audi's but I"m getting there. No codes so far. I used the same pressure sensor, no need to change. I've not had a chance to attempt to learn the nefmoto data logging as of yet, let alone drive it much. I figure for starters' I'll do the Ross Tech lite, then later get more detailed data log's from nefmoto ME7 logger.

clancy

I would guess (emphasis) you still have an intake leak. Some hose is likely split where you cannot see it. Only opens up under hard acceleration. I had a leak that I looked and listened over and over, without finding. Finally decided to start replacing hoses anyway. Found it after someone here suggested this hose. It was a split on the bottom that I could barely see even after removing and looking at under a good light. If I remember correctly it was that one from the fuel pressure regulator on the driver's side that went under the intake manifold in the center to something (?) on the passenger side. Anyway, the idea being that I had no way of inspecting it without removing it. And, I couldn't hear any leak because it was hidden and it didn't leak except under pressure when driving. Maybe pressurizing the system would have pointed to it, but I still would question whether you would be able to hear it leaking.

Osmosis

There are definitely no boost leaks. I've yet to hook her up to my computer, too many projects at hand
I believe my suspicion of a turbo going out is in the process. I hear one of the turbos periodically making the sound of a "dentist drill". If I put my my foot down, accelerate, I hear it once in a while. If I do hear the sound, I pull my foot out of the throttle and it goes away. Power does have a flat spot around 40 mph. As for now, I've no choice but to address other priorities. I figure next spring, or sooner, I yank the motor and rebuild the turbos Right now, I have some ...OK, a lot of home projects and my F 350 needing work

Osmosis

Some 3 years later....Yep, it was the turbo I bought 2 used turbos on ebay, not the fake chinesium ones, and the turbos were unusable. I put my stock ones back in and they are leaking oil....bad. So, I was going to trade my A6 in for a brand new Camaro SS as they have 426hp and get 27mpg on the hwy. Buuuut, my daughter just got accepted to a 4yr school, so money will be tight. So what next? Instead of a new car.....Time for a rebuild I'm gonna stick with stock KO3 turbos as I want to keep this project cost under control. I may go with a stage 2 program and delete the rest of the Cats. I removed the pre-cats and hogged them out last time, So, I may just cut off the big bread box cat and straight pipe it to the mufflers. No emissions here