a4 1.8 loss of power and poor performance

[natloz]

Hi, I need your help here: my car is a A4 1.8 petrol APT engine code, W Reg. (2000). It has been suffering from loss of power and poor acceleration for a while now and has poor performance in general. With cold engine, it starts with roughly 1200 RPM, and is really shaking the whole chassis and after a minute, it settles about 700-800 RPM. When stationary; such as in traffic jam or red light, the rev is fluctuating. Taking over is also a challenge as it feels as if one less cylinder is actually working but it might be that it is misfiring. Consumption has gone up as well but the oil level is not affected and there is no smoke from the exhaust. I have replaced the petrol filter and the lambda sensor as they were my first call but no affection. The local garage fitted a new Cat as allegedly it was gone but the problem still exists. No engine fault light on the dashboard. Cleaned out the intake manifold valve as much as i can and the MAF sensor seems to be OK as well. I have hooked it up with the VAG software and the read error codes are below:


Component: 1.8L R4/5V MOTR 0002

10 Faults Found:
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-10 - - - Intermittent
17536 - Fuel Trim: Bank 1 (Mult): System too Lean
P1128 - 35-00 - -
17545 - Fuel Trim: Bank 1 (Add): System too Rich
P1137 - 35-00 - -
17924 - Intake Manifold Valve (N156): Open Circuit
P1516 - 35-10 - - - Intermittent
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
18001 - Altitude Adaptation: Signal Out of Tolerance
P1593 - 35-10 - - - Intermittent
16946 - System Voltage Too Low
P0562 - 35-10 - - - Intermittent
17927 - Camshaft Adjustment: Bank 1: Malfunction
P1519 - 35-10 - - - Intermittent
16885 - Vehicle Speed Sensor: Implausible Signal
P0501 - 35-10 - - - Intermittent
16518 - Oxygen (Lambda) Sensor B1 S1: No Activity
P0134 - 35-10 - - - Intermittent
Readiness: 0000 0000

I had found threads suggesting that the cause can be failing crank position sensor, a leaking air guide below it or the coolant temp sensor? BTW is it true that on this car there is no EGR valve fitted as previously it only was on diesel ones?

Any soggestions?

Thank you very much

[iwaters]

That's a nastly little collection of DTCs.

I think a lot are connected. Certainly the MAF sensor and the fuel trim and latitude adapation. I suspect you either have a vaccum leak somewhere or your MAF is dud.

Check all the vacum hoses for cracks. Did you use VAG-Com to get the codes? If so there are some other checks you can do on the MAF, PM your email address and I can send you the info.

You are correct no EGR valve. This engine uses variable valve timing to adjust the overlap of the valves opening and closing. This is used to leave some exhaust gas in the combustion chamber, having the same affect as an EGR.

[natloz]

Hi there, thank you for the suggestion. I am just a layman who happens to love his car and determined to eliminate those evil DTCs and restore her original glory:) I have checked the vacuum hoses already but will go through them just in case. Do you think that if there is a leak somewhere in the thick pipe which runs from the front off side, includes the MAF and ends in the air guide (which leads the crankcase gas back to the engine) underneath the throttle valve can result such faults? Also the info the EGR valve is also appreciated and will PM you about the info on the MAF sensor as I had used the VAG-Com software indeed.

[natloz]

iwaters: i cannot PM you until the number of responses reaches 10. I trust the people not to abuse it so i provide you my email address here: [removed]
cheers

[iwaters]

Ah, there is always something.

I will send the info tonight. I have made a note of your email so if you want you can edit the post and remove your address now.

Cheers

[natloz]

very nice of you! cheers