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View Full Version : p0174 and p0171 caused by Ebay intake?



motomatt77
04-22-2015, 10:49 AM
I have a 2008 Audi A3 3.2L that I bought from an auction. It has a crappy ebay looking cold air intake on it (one of those cheap universal ones). It has also been throwing lean codes p0171 and p0174. I original cleaned the Mass air flow sensor and hooked it up to a OBII VAG reader I have and tested the MAF grams per second and at 6k RPM’s it got up to around 200. When it idles it reads about 5 for a little bit then goes to about 3.5 – 4. I clear the codes and it usually runs really rough / hard start for a little while (5 or ten minutes) then it will run fine for a few days until the code comes back. My fuel mileage is terrible and I experience a rough idle and lack of power intermittently. It also seems to shift rough but this could be a separate issue.

I have checked visually for vacuum leaks but have not found anything yet. I plan on doing a vacuum test with a kit my brother has this weekend.

Does anyone think this could be caused by just having that crappy ebay intake on there? My plan is to replace it either way. I can get a K&N 57I-9500 for $250 or it looks like to get a stock box and filter im’ looking at around $140 on ebay. I've seen mixed reviews on the performance intake.

Any suggestions on any of this would be helpful, I have read numerous forum posts and there is a lot of conflicting information out there. They only thing I have done so far is replaced the CPS. I bought new plugs and will put those in this weekend as well.

vacsimile
04-23-2015, 07:19 PM
Wow a 3.2 A3 huh? That's a rare bird you got yourself there. As far as your problem goes, the air filter/box could definitely be causing your issue. Hot-wire type MAF sensors can be easily fooled by changing air flow design before the sensor. Turbulence can cause air to 'stream' around the tiny portion of the sensor that actually measures air mass. Not to say there isn't something else going on with your car, too.

I'd start with getting the airbox back to factory. It may not fix your problem but it's the only way to truly rule it out. If no avail, I would check the crankcase breather valve. If failed, it will leak vacuum from the intake manifold into the crankcase and it will be very difficult to remove the oil filler cap while the engine is idling. After that I would look at value blocks 32 (long term fuel trim) and 33 (short term). If you have access to one a smoke tester is the best way to find intake leaks. If you've ruled out the entire air intake system you'll need to move on to testing and checking fuel delivery. Good luck.

corrado-correr
05-28-2015, 12:49 PM
FYI, the Carbonio Intakes come with a restriction plate that's intended to prevent MAF implausibility faults from setting.