audi tt, 1.8 T, 225 HP - rpm variations at deceleration and other problems

Hi everybody,

Please take a little time for my rather long story, but consider the fact that I' am struggling with this matter for more than a year. I've bought a Audi TT 1.8 Turbo, 225 HP and soon I have discovered that the turbine (turbocharger) is broken - was throwing oil in the exhaust system and the effect was a black smoke. I've changed the turbine, then because VAG-COM reported a error I've changed the Lambda oxygen sensor everything was OK in respect with the VAG-COM, or at least I got no more errors.

Then I have noticed ( I don't remember if this happend before I changed the turbine) this strange behaviour: whenever I relase too suddenly the throttle pedal I hear a noise in the air filter area (some kind of rattling) and the engine rpm drop dangerously to a 400 -

600 rpm. Sometimes in slow speed corners the engine stops.

For this I have changed the throttle body with a new one, after many calibrations and cleanings - no difference.

Recently I have changed the debitmeter with a new one and everything got crazy. First the car worked almost as before - with a small lack of power when I begun to press the acceleration pedal. When I stoped after few kilometers I received the error:

Control Module Part Number: Component and/or Version: 1.8L R4/5VT 0001 Software Coding: 05710 Work Shop Code: WSC 00000

1 Fault Found: 16486 - Mass Air Flow Sensor (G70): Signal too Low P0102 - 35-00 - - - Intermittent

Then I cleared this error, made another few kilometers and I got:

Control Module Part Number: Component and/or Version: 1.8L R4/5VT 0001 Software Coding: 05710 Work Shop Code: WSC 00000

1 Fault Found: 16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit P0130 - 35-10 - - - Intermittent

I cleared also this error, I have callibrated the throttle body and I got again the Lambda error. I have cleared again the Lambda error and then the car became not stable when I started it. It didn't start at the first few tries, I got a huge rpm variation, I got explosions in the exhaust etc...

I had to disconnect the debitmeter (pulled of the power cable) and the car worked different in the sense that it was the first time I didn't experienced rpm drops, although the noise in the air filter area was still persistent. But, I couldn't go over 3500 rpm - it was clear that this was not the fix.

In the next morning I have connected the debitmeter back, got difficulties when I tried to start the engine but I have hepled the engine to start by pressing hard the throttle pedal. Whenever the engine passes the first phase, with the acceleration help it goes to a "normal" behaviour.

Because I got again the Lambda error I have put it out and clean it, although it was allready clean. From then on I received no more Lambda errors.

I have drove the car, with a difficult start, but then it worked fine, on the highway with 130 - 160 km/h. When I got off the highway, after couple of kilometers with 40 - 100 km/h, the ESP warning on bord lighted up. I have stoped and I have seen that I had the new error:

Control Module Part Number: Component and/or Version: 1.8L R4/5VT 0001 Software Coding: 05710 Work Shop Code: WSC 00000

1 Fault Found: 16487 - Mass Air Flow Sensor (G70): Signal too High P0103 - 35-10 - - - Intermittent

Even though I have cleared the error in the next 100 km it appeard again a couple of times everytime announced by the ESP on bord.

I stoped, cleared the error, didn't start the car for few days then I made around 300 KM - normal rode and highway. I had dificulties to start the car but then it worked almost like before I changed the debitmeter and ... I got no more errors! The next day, after a difficult start I drove around 10 km but again no errors.

What I have noticed and I believe it is important is that whenever I have dificulties to start the car, in the "001" Measuring Blocks field in VAG-COM I got at "HOS2 Control" a constant "25%" value. Anytime else I got a constant variation from -7% to +10%.

Well, that's the story... If it not clear please indicate me what else should I do and what other data may I offer you. Maybe based on your experience you can help me clarify:

- why the car is producing a rattling noise while decelerating in the air filter area? I believe that it is relared with the "cut-off" valve but how can I decide it is broken, what experiments should I make, what data in VAG-COM should I follow?

- why is the rpm droping when I take the foot off the pedal?

- is the new debitmeter broken, or is the old one but in such manner that it hides some of the car's vices?

- what do you think I should do to solve the problem or make it clear?

Reply to
florinman
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What's your g/s reading at idle in measure value block 2 zone 4, a/c both on and off? With the engine running (in neutral), quickly hit the throttle and try to get the load% reading in zone 2 close to or around

100%. How many g/s do you see now?
Reply to
Madesio

I have changed back with the old MAF but I can give you a LOG I've made yesterday on my way home. First column is the RPM, the second is the g/s:

840 3.83 800 3.83 840 3.86 840 4.17 840 3.97 840 4.08 880 4.14 880 3.92 840 3.83 880 3.92 880 3.94 880 3.94 880 3.5 880 3.44 880 3.22 880 3.25 840 2.97 840 3.06 840 2.97 840 2.86 840 2.86 840 2.89 840 2.97 840 2.94 840 2.97 840 2.94 840 3.03 840 3.08 840 3.28 840 3.19 840 3.14 840 3.22 840 3.58 840 3.33 840 3.28 840 3.31 840 3.33 840 3.33 840 3.33 840 3.33 840 3.33 840 3.33 840 3.25 800 3.25 840 3.28 840 3.39 840 3.44 840 3.44 840 3.5 840 3.72 840 3.56 840 3.53 840 3.58 840 3.61 840 3.53 840 3.58 840 3.61 840 3.69 840 3.61 840 3.58 840 3.56 840 3.64 840 3.56 840 3.58 840 3.56 840 3.53 840 3.42 840 3.44 840 3.44 840 3.44 840 3.42 840 3.42 840 3.36 840 3.42 840 3.42 840 3.42 840 3.44 840 3.42 840 3.31 840 3.33 840 3.33 840 3.39 840 3.36 840 3.33 840 3.33 840 3.33 840 3.33 840 3.33 840 3.31 840 3.31 840 3.33 840 3.25 840 3.31 840 3.36 840 3.33 840 3.33 840 3.28 840 3.31 840 3.28 840 3.33 840 3.33 840 3.31 840 3.31 840 3.33 840 3.31 840 3.33 840 3.28 1000 11.53 2080 23.03 2440 37.69 2520 51.36 2560 61.28 2440 68.14 2440 75.28 2880 114.75 3320 127.92 3680 121.56 3840 5.78 2760 7.94 2600 66.67 2800 80.33 3000 59.67 2720 9.17 2480 0 2120 5.25 1760 0 1440 11 1080 3 760 3.78 560 6.78 1920 7.56 2840 16.31 2760 26.81 2720 14.19 2840 21 2920 30.89 2880 0 2520 9.86 2200 1.83 1960 12.83 2000 13.28 2040 11.72 2040 13.25 2040 12.42 2080 12.97 2120 12.42 2120 10.42 2120 9.17 2080 0.19 2080 7.67 2040 8.94 2040 9.47 2080 9.39 2080 8.56 2040 3.5 2040 1.5 2040 4.31 2040 9.81 2040 14.83 2080 24.47 2160 33.89 2200 31.28 2240 23.78 2280 22.72 2280 0 2360 69.36 2320 14.92 2400 11.61 2360 9.75 2320 12.25 2320 11.31 2280 4.36 2280 2.58 2240 2.28 2200 1.42 2160 1.28 2160 10 2160 24.33 2160 10.44 2200 16.03 2120 12.47 2120 2.92 2080 1.19 2120 11.94 2120 11.44 2120 12.58 2120 15.31 2160 20.56 2200 34.14 2240 37.83 2320 11.53 2240 4 2280 38.86 2240 0 2240 1.53 2200 11.22 2280 18.61 2240 22.14 2320 27.94 2360 32.33 2440 27.75 2480 16.5 2480 15.39 2520 17.89 2560 27.67 2600 14.53 2600 17.64 2640 9.33 2600 42.75 2600 0 2600 27.72 2640 20.5 2640 14.61 2600 8.75 2560 15.53 2600 7.86 2560 4.69 2520 1.36 2520 0.58 2480 2.86 2480 6.64 2440 9.69 2440 11.83 2440 12.61 2440 11.97 2480 12.47 2440 7.36 2400 5.94 2400 11.31 2360 11.11 2360 6.36 2320 3.92 2320 1.61 2280 1.17 2280 5.5 2240 7.5 2240 6.03 2240 6.03 2200 7.44 2240 9.11 2200 8.25 2200 8.53 2200 7.69 2200 6.33 2200 6.86 2200 8 2200 9.75 2200 9.61 2200 9.31 2200 10.47 2200 10.64 2200 10.64 2200 11.06 2240 10.53 2240 9.61 2240 9.44 2240 9.47 2240 10.47 2240 9.31 2240 10 2240 9 2240 10.08 2280 9.78 2280 9.28 2280 9.69 2280 10.39 2280 9.61 2280 9.28 2280 10.56 2280 10.44 2320 8.25 2240 6.61 2240 5.47 2240 2.64 2200 1.06 2200 2.03 2160 6.17 2160 8.19 2120 9.42 2080 4.64 2120 5.67 2080 10.58 2120 11.03 2120 9.17 2040 2.92 2080 7.64 2040 9.61 2000 7.33 1920 5.19 1880 1.53 1800 1.06 1760 1.03 1680 4.22 1600 3.72 1480 6.44 1360 5.28 1360 4.44 1400 10.5 1400 13.86 1440 14.42 1480 19.25 1480 17.94 1560 15.69 1560 12.89 1560 1.56 1560 9.64 1520 2.42 1520 2.03 1480 1.92 1440 3.78 1440 3.06 1400 4.86 1360 4.58 1360 4.44 1320 4.67 1320 3.75 1280 3.67 1240 3.56 1200 2.89 1200 2 1120 2.06 1040 2.03 960 2.06 880 2.39 800 2.31 760 3.28 760 3.28 840 3.14 880 2.97 880 2.86 840 2.83 1240 10.86 1480 14 1160 12.11 1240 9.42 1280 14.31 1360 16.67 1440 14.97 1520 16.17 1640 27.06 1680 27.31 1840 26.78 1960 29.08 1960 35.72 2000 0 1960 13.75 1880 1.56 1800 0.92 1680 1.61 1520 3.25 1400 6.69 1120 4.97 840 3.28 640 3.83 680 17.06 1720 22.64 1440 19.69 1600 23.36 1720 25.56 1840 29.75 2000 36.56 2160 52.14 2280 13.81 2080 34.25 1840 17.86 1560 10.31 1560 16.44 1640 12.03 1680 15.08 1680 15 1680 1 1640 14.53 1640 0.92 1640 2.78 1600 2.19 1560 3.31 1560 2.89 1520 4.31 1480 4.89 1480 4.83 1440 4.56 1480 5.78 1440 8.08 1440 6.89 1440 3.64 1440 3.33 1440 1.92 1400 2.64 1360 1.97 1360 1.83 1320 2.03 1280 2.19 1280 2.19 1240 2.31 1240 2.36 1240 5.94 1240 12.75 1280 11.36 1280 7.53 1240 5.5 1280 5.81 1280 5.94 1160 2.08 960 1.64 800 4.03 760 3.53 800 3.92 840 3.08 880 3 880 2.78 840 2.75 840 2.69 840 2.75 840 2.97 880 2.94 880 2.86 840 2.72 840 2.64 880 7.61 1720 10.78 1520 12.42 1520 10.17 1560 9.28 1600 8.69 1600 7.08 1600 8.17 1560 2.69 1560 3.44 1560 10.42 1560 3.42 1520 4.64 1520 4.75 1480 4.56 1520 4.97 1480 4.42 1480 5.06 1520 6.56 1480 5.86 1480 5.64 1480 4.69 1480 4.58 1400 3.33 1440 2.75 1400 2.86 1360 2.81 1320 2.14 1280 2.64 1240 2.61 1240 4.08 1200 5.39 1200 6.61 1240 6.81 1240 4.75 1240 4.89 1280 4.22 1280 15.92 1360 12.92 1440 13.56 1520 14 1600 17.25 1680 21.47 1800 23.08 1920 23.92 2040 16.78 2080 1.08 2080 42.5 1960 0 1960 3.17 1880 3.22 1840 3.42 1760 1.42 1720 4.72 1640 4.64 1600 3.56 1560 4.56 1560 10.42 1560 5.08 1520 4.67 1520 2.89 1480 2.94 1440 3.69 1440 7.25 1440 7.92 1480 6.94 1480 6.67 1480 5.08 1520 5.5 1480 3.94 1480 3.28 1480 2.75 1440 3.08 1440 2.61 1400 2.83 1360 3.83 1360 3.47 1320 3.47 1320 3.44 1280 4.86 1320 5.39 1280 5.36 1320 5.47 1320 6.14 1320 5.25 1280 3.11 1320 2.56 1240 2.44 1240 4.97 1280 4.39 1240 3.72 1240 5.56 1240 7.81 1280 7.53 1280 5.5 1320 4.5 1320 3.81 1320 3.72 1320 3.5 1280 4.31 1280 5.67 1280 5.31 1280 4.78 1280 4.69 1280 4.67 1280 4.36 1280 3.44 1240 2.42 1240 2.58 1200 2.72 1160 2.61 1120 2.58 1080 2.5 1040 2.56 1000 2.56 920 2.67 800 2.67 760 3.19 840 3.47 840 3.17 840 3.11 840 3.11 840 3.14 840 3.14 840 3.22 840 3.39 840 3.42 840 3.39 840 3.36 840 3.36 840 3.42 840 3.61 840 3.47 840 3.56 840 3.53 840 3.53 840 3.53 880 3.39 960 5.33 1280 7.67 1800 7.5 2120 9.19 2440 9.58 2480 6.94 2360 5.39 2240 5.25 2080 4.42 1880 4.67 1560 3.33 1360 3.22 1160 2.92 1000 2.47 840 2.64 800 3.25 840 2.92 1240 10.69 1800 18.31 1920 18.72 2200 35.61 2360 8.11 1680 6.36 1200 22.03 1120 7.53 880 2.39 560 5.83 560 9.78 1000 7.36 1040 10.5 1000 3.28 1000 1.17 960 2.78 920 2.92 880 3.28 840 3.78 840 3.67 840 3.92 840 3.67 840 3.94 840 3.97 800 4.03 840 4.22 840 4.06 840 4 840 4.08 840 4.25 840 4.28 840 4.22 840 4.14 840 4.06 840 4.31 840 4.17 840 4.22 840 3.56 840 3.47 840 3.36 840 3.42 840 3.25 840 3.08 840 3.28 840 3.14 840 3.08 840 3.08 840 3.17 800 3.33 840 3.33 840 3.53 840 3.53 840 3.47 840 3.44 840 3.44 840 3.44 840 3.47 840 3.44 840 3.47 880 3.44 840 3.25 840 3.22 840 3.22 840 3.22 840 3.17 840 3.19 840 3.17 840 3.11 840 3.06 840 3.14 840 3.08 840 3.17 840 3.14 840 3.14 840 3.14 840 3.17 840 3.11 840 3.28 840 3.22 840 3.22 840 3.19 840 3.14 920 13.47 1800 16.31 2120 23.61 2480 27.67 2520 22.42 2000 13.11 1600 12.31 1920 26.61 2280 19.47 2440 19.25 2680 22.44 2640 0 2280 24.94 2120 38.86 2280 37.64 2240 36.97 2200 43.67 2320 45.81 2480 29.31 2600 29.86 2720 26.28 2840 26.83 2960 26.36 3040 25.28 3120 26.08 3080 7.67 2840 0 2520 28.28 2240 46.67 2320 48.89 2360 10.78 2320 12.72 2360 55.69 2360 0 2360 13.67 2320 11.22 2280 5.92 2280 6.42 2280 9.36 2280 8.89 2280 8.42 2280 9 2280 8.06 2280 7.5 2280 14.67 2320 15.17 2320 12.97 2360 14.19 2360 12.69 2400 12.53 2440 30.14 2480 36.78 2560 45.64 2640 33.06 2680 23.61 2720 23.56 2760 17.67 2800 20.61 2840 27.94 2920 67.06 3000 104.83 3120 113.28 3240 127.14 3360 135.89 3480 128.17 3560 118.53 3560 5.22 3560 8.08 3520 4.36 3480 0 3440 11.5 3400 15.75 3320 9.83 3240 1.19 3120 1.56 3040 4.72 2920 1.81 2840 1.17 2760 3.83 2720 7.11 2640 8.11 2560 7.11 2520 7.61 2440 5.67 2440 4.97 2400 3.08 2360 2.28 2320 1.25 2280 0.94 2240 1.67 2200 1.06 2120 1.89 1920 1.56 1560 4.56 1280 5.89 1040 5.19 840 3.08 720 3.69 720 2.75 840 3.17 1040 0 1000 2.33 920 2.97 880 2.89 880 2.64 840 2.69 840 2.64 840 2.81 920 8.75 1720 14.97 1720 15.83 1720 21.53 1840 26.61 1960 33.19 2160 41.94 2360 48.56 2520 51.5 2680 30.72 2760 27.67 2680 0 2320 0 2000 0 1560 10.44 1280 4.94 960 2.5 560 3.06 560 7.61 1080 4.33 1120 4.58 1120 5.11 1120 2.61 1080 2.75 1000 3.42 960 3.67 880 3.28 840 3.19 840 3.03 800 3.03 840 3.42 800 3.33 800 3.28 800 3.31 840 3.58 840 3.53 800 3.56 880 10.72 1320 14.06 1160 15.03 920 10.75 960 10.67 1000 10.86 1040 12.08 1120 14.28 1240 17.06 1360 18.94 1440 18.94 1600 24.11 1720 25.14 1840 67.53 1960 17.86 1800 0 1480 4.47 1240 11.06 920 6.75 640 5.78 480 7.39 1040 9.33 1080 7.47 1080 3.17 1040 2.78 1000 4 960 3.03 920 3.44 880 3.39 840 3.36 840 3.39 840 3.44 840 3.42 840 3.44 880 3.47 840 3.53 840 3.56 840 3.5 800 3.5 800 3.5 800 3.72 800 3.78 840 3.86 840 3.94 840 3.94 840 4 840 4.03 840 3.94 840 3.17 840 2.25 800 2.92 840 3.14 840 3.06 840 2.86 840 2.92 840 2.94 840 2.89 840 2.89 840 2.89 840 2.83 840 3.06 1120 10.06 1640 9.78 1440 0.61 1120 2 1040 2.33 920 2.89 840 2.78 800 2.58 800 3.03 840 3.03 840 2.92 840 2.86 840 2.86 840 2.89 840 2.92 840 3.06 840 3.03 840 3 840 2.97 840 3.11 840 3.22 840 3.17 840 3.08 840 3.11 840 3.08 840 3.14 840 3.11 840 3.11
Reply to
florinman

since I get back to the old MAF the MAF and Oxygen Sensor errors dissapeard. Anyway I still have rpm drops and the sound on deceleration (someoane on a forum reffered to the same sound I believe as "Darth Vader exhaling" ). I have two suggestions related to this sound:

  1. Diverter Valve - which I have allready ordered (The Forge one)
  2. Turbo Waste Gate Actuator.

What do you think?

Sience I have the old MAF back I also experience a new problem: The engine is not running well after 3000 rpm, like there is sime kind of blockage. Other thing I have discovered using VAG-COM and field 115 in Measuring Blocks is that the Actual Pressure and Requested pressure grow verry slow and are nt related with the rpm only but with the rpm/time i.e. if I increase the rpm slowly, no matter how much rpm the engine is producing I have a requested pressure around 990 and actual pressure around 10000. If I press the gas pedal violently then I have some normal values - bigger than 1200...

Reply to
florinman

Typical of a 1.8 diverter, usually a bit noisier than other makes and models of vehicles. The new Forge valve should sound the same if not slightly noisier. In the meantime make sure that the vacuum connections from the throttle body to the turbo are free of any leaks.

I'd suggest putting the new MAF back in the equation and driving hard to re-adapt the new values into the ECM. Generating a readiness code while not necessarily needed in this case could definitely speed up the computer's re-learning process. Even newly replaced MAFs will hamper performance under load as the ECM was already used the prior faulty values. It is not uncommon for some O2 and misfire faults to pop up; just clear them. You are re-adapting the throttle right?

Reply to
Madesio

Yes, I have re-adapted the throttle after every change or cleared code. With the new MAF that was generating errors I drove more than 500 KM on normal rodes and highway up to a 180KM/h. In lower gears was a mess. In 4, 5 and 6 it worked fine... until it gave me the errors above. Still whenever I stoped the car, to start it again was a nightmare.... You are saying that I should put it back after I replace the DV?

Reply to
florinman

Yes, and drive hard under loaded conditions for a while until you feel it smoothen out. Accelerate up hills hard in lower gears etc.

Reply to
Madesio

Hello,

Well I have finally replace the DV. The resoults are good: the noise dissapeared or at least is hardly noticeable and the rpm drops are now smaller and rarely appear. But... to be able to use the car untill I got the DV I have put back the old MAF and I have returned the new one (I descriebed the problems related with the new MAF in my first post). Since then I experience a engine power loss. I am still hearing the turbo but the car lacks power. Please see the VAG-COM log file in which I have also generated a graph:

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I suppose is that there is a problem with the turbo pressurebecause the actual pressure (@Intercooler) (with the red color), isallways less than requested presure - yellow. In fact the pressureonly incerases if I press at once and very hard the gas pedeal. If Ipress it gredualy nothing happens. Is this normal? With blue are therpm. With green are the verry slow values recorded by the MAF. What doyou think about these measurements?

Reply to
florinman

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