reisjdmd

car ran perfectly until it jerked intermittently on freeway. cel came on. i don't remember the code, but the mechanic replaced the bank 1 sensor 1 with a denso. it ran well for 30 miles, then started intermittently jerking again at hy speeds. otherwise it is perfect in all respects. cel showed P0171. mechanic cleaned the maf sensor, and this helped a little. i took it home and gave the maf a real thorough cleaning and it helped a lot, but it still occasionally intermittently jerks after about 15 miles of driving, and the cel comes on [p0171]. i replaced the maf with a cheap new one, but there is no effect. so far, the thing that helped the most was my thorough cleaning of the original MAF sensor.
here is exactly what it is doing wrong now. clear the code. everything is perfect. drive about 15 miles at 55MPH. give a very slight gas pedal presssure, to increase speed gradually from about 55-58 mpg. it jerks. take foot off gas and let it slow down. stops jerking after 3-4 seconds. except for this problem, it runs great. the code comes on [P0171]. could this be a TPS problem, since it only happens intemittently with very slight gas pedal presssure with mild slight acceleration from 55-58MPH? sorry this post is so long.

Lexmex

What do you mean by jerking?

The car moving side to side, back and forth or is it some kind of hesitation?

Baetke

P0171 is a pretty generic trouble code. It refers to a "system too lean Bank 1" condition. Here are the recommended areas to investigate according to the diagnostics manual.

reisjdmd

by jerking, i meant stuttering, like some serious ignition "missing" for a few seconds, and then it kicks in again and the car jerks forward. this is hard to describe exactly, but it's like the thing shakes for a few seconds. however, not side to side, not steering. definitely related to gas pedal movement. does anything sound like a throttle position sensor that is faulty at the range of pedal pressure just above idle. this only happens at cruising speed. it accelerates from a stop, and shifts, normally. if i'm cruising along and floor it to pass, it does just great. it happens only with very slight pedal pressure, while cruising, and then only intermittently. my mecanic checked for vacuum and exhaust leaks. i used injector clearner a few months ago, many weeks before this problem started, just as a preventive measure. we have not yet replaced the bank 2 sensor 1, because there i have to replace the whole exhaust manifold, because the old sensor is taking the threads out with it when we try to remove it. we are stumped..