2005 Chevrolet Tahoe P0171 Code: Poor Idle After MAF Sensor Cleaning - What's Next?

Check fuel pressure and flow — these are common causes of P0171 in 2005 Tahoe models. If the issue stems from a weak fuel pump or clogged fuel filter, you may also notice poor high-end performance. In my experience with a similar vehicle, I found it difficult to pass other cars on two-lane roads due to engine hesitation. The RPM limiter would briefly shut off the engine during passes. Although no codes were present at the time, after replacing the fuel filter and testing it by blowing into it, I detected significant back pressure — indicating restricted flow. After the replacement, passing became smooth again. For a rough idle with P0170/P0171 symptoms, vacuum leaks are a strong possibility. These can originate from cracked or leaking vacuum hoses, but also include a stuck or faulty PCV valve. To test a PCV valve: blow air into one end — it should block airflow completely; then blow into the other end — air should pass freely. This simple check might help diagnose the issue even if it's too late for your current situation. It could serve as useful guidance for future users.

You have probably fixed the problem by now. BUT, from my experience, if it were fuel pressure and flow, like from a weak fuel pump or dirty fuel filter, you would also be noticing poor top-end performance. In one vehicle that I own, I was unable to pass vehicles on a two-lane road like I had used to, to the point that the RPM limiter in my vehicle shut the engine down for a few seconds as I was passing. Although there were no trouble codes at that time, shortly after my trip, I changed the fuel filter. When I took out the old filter, I blew hard continuously into it, and I could feel back pressure that the air from my mouth was not flowing through it freely, my next trip on a two-lane road passing was a breeze, like it had used to be. With a rough idle symptom, my suspicion would be that it was a vacuum leak, I am tracking down a P0171 myself. A vacuum leak can be anything from a broken / leaking vacuum hose, but can also be a sticking or totally faulty PCV valve. With a PCV valve, blowing into it from one end should entirely BLOCK air from going in, blowing into it from the other end should entirely PERMIT air to go in freely. If this is too late to help you, maybe it can leave bread crumbs for the next person...