amallah Posted January 30, 2011 Share Posted January 30, 2011 I have a 2005 LGT. My turbo recently blew because of the banjo bolt screen clog. When I got the car back, the CEL/Cruise lights have been consistently on and I am seeing a P0171 code. There is no visible effect to me (idle is not rough), car accelerates/boosts just fine, fuel economy is typical, etc. Based on other posts on the forum, common causes are dirty MAF (sprayed the crap out of it with MAF cleaner and no luck, unless I am cleaning the wrong part, which is a possibility) and possible vacuum hose leak. I have checked every hose I could see and even took off my intercooler and checked the hoses under it, including the blue T connection. Everything seemed fine. So, I'm trying to figure out what to look at next. I suspect the next step is O2 sensor, but I'd like to be as sure as I can be before I spend the money to replace them. Is there some kind of diagnostic procedure I can perform to identify which O2 sensor is bad? I have access to an OBD cable and a laptop, would datalogging give me any hints? If the MAF sensor could be beyond "cleanable", is there a way to identify that with datalogging as well? Or does anyone have a picture of a "clean" MAF to compare? Link to comment Share on other sites More sharing options...
cheerio Posted January 30, 2011 Share Posted January 30, 2011 been having the same problem on a stage 2 setup... i already changed both my O2 sensor and check for vacuum leaks already... but theres a thread on the NASOIC forum but im feeling lazy and too hungry to look it up for u right now.... Link to comment Share on other sites More sharing options...
ehsnils Posted January 30, 2011 Share Posted January 30, 2011 Cleaning of the throttle body may help, but you may actually have a bad injector too. Datalogging would give you an indication if it can be a problem with the O2 sensor. But look at this thread too: http://legacygt.com/forums/showthread.php/p0171-cold-idle-problems-154213.html The manifold gaskets seems to shrink or at least be sensitive to cold so replacing them can actually be a remedy. And if they did take off the manifold during the repair it's a good chance that they failed to replace them - or that they mixed up two hoses. The PCV valve can also be a culprit. As for MAF sensor - there are two gray resistors inside the MAF sensor, you can see them faintly in the hole in the pic below. One is cold the other one hot, and the hot resistor will get some residue over time. It's usually brown or similar and can effectively double the size of the resistor causing it to give a skewed measure. If both resistors looks identical you are OK. But don't touch them with any tool, just wash them with MAF cleaner. http://3.bp.blogspot.com/_ycqwcbb6wEo/TQKXFy7IgLI/AAAAAAAAH08/W6yz5zpbhus/s1600/DSC04074.JPG http://www.sparkys-answers.com/2010/12/1999-lexus-es-300-code-p0171-stored.html Link to comment Share on other sites More sharing options...
Mega Users paintpollz Posted January 30, 2011 Mega Users Share Posted January 30, 2011 my car is throwing this code as well. The intake manifold gasket is leaking causing the left bank to run lean. gasket is getting replaced as we speak "Remember Danny - Two wrongs don't make a right but three rights make a left." Link to comment Share on other sites More sharing options...
Yamarocket630 Posted January 30, 2011 Share Posted January 30, 2011 Since this happened after the turbo was replaced, my #1 suspect would be the turbo inlet tube was damaged or not properly installed. Link to comment Share on other sites More sharing options...
cheerio Posted February 1, 2011 Share Posted February 1, 2011 paintpoll did ur code clear up? Link to comment Share on other sites More sharing options...
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