Ok guys, tired of banging my head on the wall, so I'm asking for help.
My daughter has a 2002 Chevy Impala with 130k miles. Two weeks ago when she was driving home from college, it started hesitating really bad on the highway. She limped it on home, and I enlisted the help of my brother so we could troubleshoot and fix it.
After a test drive, I was convinced it was fuel related. Idles perfect. No codes. Drives around the neighborhood perfect. But as soon as you step on the gas to get above 25 mph, it falls on its face. Lurches, hesitates, doesn't shift right, chugs like a train, etc.
Go to parts store and pick up fuel filter, fuel pump, and fuel pressure test rig. Replace the fuel filter because why not. Then test fuel pressure. It's within spec. So it's not the pump. Test drive. No good. More research, decide to check MAF. Pull the MAF sensor, test drive with it unplugged, and it runs just fine. Gets up to speed, shifts normally, no issues.
Return fuel pressure test rig and fuel pump, pick up a reman MAF (only one they had). Put it in, runs crappy again. Spend more money for OEM MAF, same thing.
In my research, the things that came up were MAF, clogged catalytic converter, crank position sensor, and throttle position sensor. Ruled out the TPS because we watched it real time with the OBD2 on the test drive. CPS, maybe. But why would it run well without the MAF? Catalytic converter should make it run bad all the time. And again, no codes.
She has to head back to college tomorrow, and I'd like to have the car fixed, rather than let her keep driving it with the MAF unplugged.
TL;DR: 2002 Chevy Impala. Runs like crap with a brand new OEM MAF. Runs great with it unplugged.
My daughter has a 2002 Chevy Impala with 130k miles. Two weeks ago when she was driving home from college, it started hesitating really bad on the highway. She limped it on home, and I enlisted the help of my brother so we could troubleshoot and fix it.
After a test drive, I was convinced it was fuel related. Idles perfect. No codes. Drives around the neighborhood perfect. But as soon as you step on the gas to get above 25 mph, it falls on its face. Lurches, hesitates, doesn't shift right, chugs like a train, etc.
Go to parts store and pick up fuel filter, fuel pump, and fuel pressure test rig. Replace the fuel filter because why not. Then test fuel pressure. It's within spec. So it's not the pump. Test drive. No good. More research, decide to check MAF. Pull the MAF sensor, test drive with it unplugged, and it runs just fine. Gets up to speed, shifts normally, no issues.
Return fuel pressure test rig and fuel pump, pick up a reman MAF (only one they had). Put it in, runs crappy again. Spend more money for OEM MAF, same thing.
In my research, the things that came up were MAF, clogged catalytic converter, crank position sensor, and throttle position sensor. Ruled out the TPS because we watched it real time with the OBD2 on the test drive. CPS, maybe. But why would it run well without the MAF? Catalytic converter should make it run bad all the time. And again, no codes.
She has to head back to college tomorrow, and I'd like to have the car fixed, rather than let her keep driving it with the MAF unplugged.
TL;DR: 2002 Chevy Impala. Runs like crap with a brand new OEM MAF. Runs great with it unplugged.
