Hello Scotty,
I was wondering if you can help me find a solution to my cars lean code. I know it's not any issue related to the fuel pump because I got the code at a low speed. I think it has to be a specific vacuum leak somewhere. I am not sure where it is. Also, I changed my cars MAF sensor and airbox. Likewise, I tried using one of the methods you used to check if it was my manifold gasket leaking but that does not seem to be the case. I'm looking into using a smoke machine to detect leaks, do you suggest doing this as the best route to solving my issue. Before I do anything, what do you suggest I look at first before investing in a smoke machine.
Best,
Juan
Did you install an OEM MAF sensor? Aftermarket sensors frequently do not work. Seeing as how a faulty O2 sensor can cause this code you might want to check your upstream O2 sensor output. A smoke test to find vacuum leaks is not a bad idea but you can also use something like carb cleaner to look for leaks.
https://www.obd-codes.com/p0171
https://www.youtube.com/watch?v=9CPqbaSgcok
