February 24, 2010hey guys i just purchased an 02 Silverado 1500 Z71(pics are on the way) and now every morning i go to crank it up it idles erracticly and the check engine light comes on, this will last for about 10 to 15 minutes and then once the truck warms up it runs excellent the rest of the day. I took it to Advance and it threw these codes P0171,P0174, P0300. He said it sounds like a vacuum leak but he wasnt sure, the previous owner of the truck installed dual exhaust but he cut out the muffler and ran straight pipes(not sure if that matters or not with the problems im having) any help will be greatly appreciated. thanks
February 24, 2010Welcome to CTW!!!
Clean your MAF sensor with MAF sensor cleaner and see if that works.
Also when the previous owner installed the Straight Pipes did they remove the Cats????
February 24, 2010the previous owner left the Cats in he just took out the muffler. this maybe a stupid question but what is the MAF and where is it located?
February 24, 2010even if they did cut the cats, it wouldnt make your truck shake that way! mine has the cats off and it just makes the check engine come on, no side affects.
February 24, 2010Check out this pic of the MAF.
If someone removes thier cats and they dont do something with the O2 Sensors YES it will cause problems. The engine detects a richness in the Back o2 sensor and Leans out that bank to Compensate for the rich fuel mixture it is getting.
February 24, 2010they only took out the muffler not the CATS. Where is the MAF located?
February 24, 2010Up next to the air filter box...JohnB
February 24, 2010ah well shows how much i know. lolsorry man thanks for correcting me!
February 24, 2010No problem Buddy, Thats what we are all here to do is learn!!
February 24, 2010P0171
Fuel trim bank one condition
â€“ The powertrain control module uses the oxygen sensor to calculate the air/fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.
1. If bank one and two codes set together suspect fuel pressure or MAF (Mass Air Flow) Sensor
2. Oxygen sensor defective
3. Ignition misfire-repair
4. Fuel injector problem
Fuel Trim Bank Two Condition
â€“ The ECM has detected a rich or lean air/fuel ratio condition on engine bank two
1. If bank one and two are set together suspect a fuel pressure condition or MAF sensor fault
2. Failed HO2S21
3. Ignition misfire condition
4. Fuel injector problem
5. Engine mechanical condition
Cylinder misfire detected- Random cylinders
â€“ The powertrain control module monitors the crankshaft speed and has detected a misfire condition
1. Ignition system fault-spark plug(s), ignition wires, coil
2. Vacuum leak
3. injector fault
4. high or low fuel pressure
A good site for trouble codes.....
February 24, 2010should i start with cleaning the MAF sensor? should i replace the O2 sensor as well? what can i clean the MAF sensor with and how do you clean it?
February 25, 2010Clean the MAF sensor first.... go to the parts store and get MAF Cleaner! Do not use carb or brake cleaner, it can leave a seridue on the sensor that will not help the problem!! Does it have a K&N air filter? If you over oil this after cleaning it can cuase similar problem. Since injector pops up as a posible cause on all of these codes it may not hurt to get a can or two of sea foam and put one in the gas tank and use half of the other on the brake booster (vacume lines) cleaning trick..
Question... does your SES (Service Engine Soon) light stay on "solid" or "blink" and for how long of interval?