Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
how did you check for a restricted exhaust?
also what are you long term fuel trims at idle?
fuel trims will tell you if the maf sensor is working properly. the ignition timing is just what the showing what the computer is telling it to do. if it is retarding and not advancing it is sensing something in the fuel mixture that is telling it to due so. if your long term fuel trims are not 0 on both banks i would first try cleaning the maf or just replacing it.
these engines dont like an unplugged maf much at all. but just idle in park drive or anthing longterm should be 0.
also are you sure your transmission is not in limp mode? try if fuel trims are okay. unplugging the transmission harness and manually shifting through the gears while driving. it will be a bit harsher than normal but this will confirm whether or not you are in limp mode.
ok just wanted to verify
that seems a bit low they are normally higher than that i cant remember the exact speed. let me see if i can find a good spec on that.
i cannot find a proper spec on the stall speed for the converter however i did find a tsb regarding the torque converter. also do you have any reduced engine power codes?
if everything else test out then it is going to be your throttle body assembly. that or the gas pedal assembly. 90% of the time it is the throttle body.
give me a moment.
ok while looking for testing procedures i found a tsb for the condition you are experiencing. the first step is to call the dealer and make sure that this vehicle has the proper ecm programming. if not it will need to be updated. and if it does the tsb states the throttle body will need to be replaced. i will attach the tsb give me a moment.
one is the tsb with diag instructions the other is a recal warranty extension.
well not advancing properly and lack of power to me is a type of rough running. and gm has had issues with ecm programming throughout many years so i would start with making sure the ecm is updated to the proper vesion. a local airbag service can usually do this. and they will come to you. i would atleast verify the version first.