Engine Performance problem
2003 Chevy Impala 6 cyl Front Wheel Drive Automatic 78500 miles
My car keeps getting a code of PO121. The rpm's will go up. It take's for ever for it to shift out of first gear. And when you push on the gas it wont go into passing gear. Its just dead. I have replaced the Throttle position sensor twice, replaced the idle air control sensor, and the speed sensor on the transmission. I wrote to one of your tech's about three weeks ago and this is what he told me:
start with the basics, check these first; Vacuum hoses disconnected, damaged, or incorrectly routed
Ã¢ï¿½ ¢ MAP sensor seal missing or damaged
Ã¢ï¿½ ¢ Restrictions in the MAP sensor vacuum source
Ã¢ï¿½ ¢ Intake manifold vacuum leaks
you also have to check for a 5 volt reference at the tps as well as see what the MAP sensor is doing, the PCM will use the manifold absolute pressure (MAP) sensor to determine if the predicted operating range of the TP sensor is correct. If the PCM detects that the TP sensor voltage is out of the predicted range DTC P0121 sets. Start here first, post back with what you find.
I replaced the map sensor, replaced the pcv valve, the two o rings inside where the pcv valve is and the holder that holds the map sensor in place. And checked all the vacuum hose's. And it run good for two days and started with the bad running problems again and the same code of PO121.I have always cleared the code when I put a part on. I started with the easiest first since I have no ideal how to check for the voltage like the other tech said to do. And if I did. What would I do if the voltage was off. Since I've already replaced four sensors, I cant keep replacing sensors (because Im out of work) can you please help me with this. Thank You
have the same problem?
Sunday, February 21st, 2010 AT 7:21 PM