2000 Trans Am Code P0171, has backfires between shifts when cold
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Teching In
Joined: Jan 2021
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2000 Trans Am Code P0171, has backfires between shifts when cold Thanks in advance. I am a relatively new F Body owner. Bought a 2000 Trans Am with 41K miles a couple months ago. Great shape, 6 speed manual transmission.
I live in northern VA and since I got it I have noticed it will backfire between shifts a little bit when first started and cold. Happens first couple shifts then goes away as it warms up. My 94 mustang would do that too so I thought nothing of it. It has the SLP bullet muffler exhaust too. No codes when I bought it and test drove it too. I checked this and put a few miles on it. I have changed the fuel filter with a new NAPA gold one, and I put a bottle of Liqui Moly fuel injector cleaner in the tank of gas currently in the car. I filled it up and added the injector cleaner. I have also changed the oil. No other engine maintenance besides that and swapping the K&N air filter for a stock one too. It has ram air. I do not like K&N filters and the one in it was very dirty.
Anyway, it drives fine, no power loss, but I got the code P0171 today when the check engine light came on. Says bank 1. I have done some research here and watched several youtube videos. Appears it could be a dirty MAF, O2 sensors, or an Idle Air Control valve problem, or perhaps something else.
Any suggestions or advice? I will get some MAF cleaner and clean that up first.
Thanks!
I live in northern VA and since I got it I have noticed it will backfire between shifts a little bit when first started and cold. Happens first couple shifts then goes away as it warms up. My 94 mustang would do that too so I thought nothing of it. It has the SLP bullet muffler exhaust too. No codes when I bought it and test drove it too. I checked this and put a few miles on it. I have changed the fuel filter with a new NAPA gold one, and I put a bottle of Liqui Moly fuel injector cleaner in the tank of gas currently in the car. I filled it up and added the injector cleaner. I have also changed the oil. No other engine maintenance besides that and swapping the K&N air filter for a stock one too. It has ram air. I do not like K&N filters and the one in it was very dirty.
Anyway, it drives fine, no power loss, but I got the code P0171 today when the check engine light came on. Says bank 1. I have done some research here and watched several youtube videos. Appears it could be a dirty MAF, O2 sensors, or an Idle Air Control valve problem, or perhaps something else.
Any suggestions or advice? I will get some MAF cleaner and clean that up first.
Thanks!
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
That's a good place to start. Change the fuel filter. You might also pull the IAC valve and clean it, especiallly if you notice a lot of carbon build up on it. Check for any vacuum leaks in the PCV lines.
TECH Resident
Joined: Mar 2012
Posts: 859
Likes: 402
From: Texas
THIS right here. I'll bet you have a leaking flange gasket.
WHen the O2 sensor sees the extra oxygen in the exhaust, it sees this as the engine running lean.
And backfire/ popping from the exhaus when you let off the gas is a common symptom of an exhaust leak.
