Hi there. I have a '03 A4 1.8t. So far, I've had the timing belt/water pump, thermostat, crankcase breather tube, suction jet pump, and the pcv valve at the intake replaced. We also replaced a few check valves that looked that they had been beat to death. After replacing alot in the pcv system, I noticed that my acceleration was seriously lagging. My turbo won't kick on until at almost 4,000 rpm and sometimes not even at that. Normally it kicks on at around 2500-3000 rpm or so. Well my CEL was on, but the code it was throwing was the same one it was throwing before we replaced all the pcv valves, P0171. A week or so after replacing the pcv valve and breather tube, my brakes started acting weird. My ABS light and brake warning would turn on intermittently. It came on one time so I checked the engine, and sure enough my Suction jet pump had blown apart. Ever since we replaced the SJP, my ABS and brake warning has NOT been coming on, but the CEL won't clear. I had to have a wheel bearing replaced, so while at the shop, I had them run a diagnostic. They couldn't find any problems with the pcv, so they checked the stored codes and found:

P1136-001 Fuel trim bank 1 system too lean
P1479-008 Brake boost vacuum system mechanical failure
P1128-001 Fuel trim bank 1 system too lean
P1111-002 Oxygen sensor regulation bank 1 system too lean intermittent

They tested the areas, and found the MAF sensor was out of calibration, and the vacuum pump internally not operating causing large loss of vacuum during acceleration. I was told I need my MAF replaced and my Vacuum brake booster pump replaced. They cleared the CEL at the shop and it has yet to come on. I'm worried that the MAF and vacuum pump may not be the problem. I'm now skeptical because they said on my statement that I told them that I had no power after 4000 rpm. Thats not what I said, at all. I told them I didn't get power until 4000 rpm. Also, I had told them that I had my bushings replaced by another mechanic (long story) and I wanted them to check the suspension while they were replacing the bearing. On the invoice write up, it said that I had my Motor mounts replaced at another mechanic and I wanted them to look and check if they were secured. They reported: Motor mounts look new and in good condition. YEA, I haven't had those replaced yet, and was told by the same mechanic doing the diagnostic that they needed to be replaced last time I came in. Sooooo, is there anything I need to check for before we go and replace the pump and MAF, because by the incorrect statements on the invoice I am starting to doubt that is the problem area. Repairs would profit the shop $800 but we would be doing it ourselves. Sorry so long.


Oh forgot to mention, when letting my foot off the gas, it loses power really fast, and hiccups a little. It's like it wants to stay in idle range, and its pushing itself to go above 1500 rpm. I have around 126,000 miles on my car.

 

Ok just to update this. I did a manual brake pump test that I saw multiple times in the threads, and everything seems to be working normal. I am not having any issues with my brakes. Main issue is the acceleration lag, and lack of turbo. I stared at my car very hard for a little while and noticed areas where there should be clamps. They were missing. 2 clamps missing on the hoses to/from the pancake valve (combi valve?) on the back of the motor. There is another one missing under there too but I didn't have the right size clamp, will put on later. The was another one missing on the metal pipe leading from the (combi valve?) towards the TIP area. Not sure what that pipe is. Possibly an oil line? Anyhoo, put a clamp on there. Ran the car around the block and tested it on the interstate for a moment. It's not hiccupping anymore, and seems to lag a little less. However, the turbo is still not kicking on. Its almost like it won't shift to the right gear, is how it feels. And it pulls when I coast at idle pretty bad, like it doesn't want to go in a lower gear. I don't think its a gear problem, but my turbo is not there and something is causing it to lag. When I step on the gas to accelerate, it will go, but you can hear all the engine pulling, and no boost all the way up to 5000 rpm. I remembered some things I had read and decided to follow the pcv system to the turbo area, and what it lead to next. It leads to the diverter valve. We are going to test the valve and possibly replace it. Does this sound like it may be the problem? I also noticed the pcv pancake valve at the TIP is missing. Someone removed it, and placed the hose directly into the TIP. There is screw clamp on there, like the ones at autozone. Could that be the culprit?

 

Welp pretty sure that is the problem. Gunna check the pancake on the combi valve, and put a pancake back on the TIP. I don't know who the h*ll removed that, but the pancake on the combi had a date on it, 09.01.06. I am only the second owner on my car and didn't by it until 07 soooo that narrows it down. If that is not a date, I sure didn't have any work done in that area during my time with her. Thanks to everyone who answered this....oh wait.

 

still not sure if thats where the cprv goes, but Im just going to leave it alone. the whole acceleration problem was from the crappy spark plugs we used. Kinda ruled it down to spark plugs when the rpms were bouncing at idle. Pulled them and they were burnt up. Those were replaced last year, but didn't realize how specific they needed to be. $64 for spark plugs later, and its running good again