2000 Chevy 1 ton 454 problems

[glewis]

I have a 2000 Chevy 1ton dualley with the Vortec 454 engine. The service engine soon light came on and I had the codes read at an auto parts store. The code was 071, 072, ( I think ) which when printed out said "Right bank too lean" and "Left Bank too lean". The engine runs crappy until it is well warmed up, then it runs ok. I have 81000 mile on the truck, replaced the fuel filter - no change, The auto parts people said it is probably the O2 sensor, but looking it up states it takes 2 of them and at $100.00 a pop, I don't want to replace them if there is something else that may be the cause. I want to look at all the options first. I have a K&N air filter on it, which I just cleaned about 2000 miles ago. I read a few articles where the K&N air filters make your engine run poorly.
I will appreciate any and all help.

[silverado122775]

If you put too much oil on the filter it can get on the MAF sensor giving bad stats, but if you keep the sensor clean then the filter should not be a problem. When you oil the filter you want just enough to turn the filter red, you do not want the oil to be dripping down, plus you need to let it dry for about 6 hours before you put it back on.

About your codes. if you have never replaced your o2 sensors then it would not be a bad idea to do so. However you may want to clean out the throttle-body as well. You could also have a bad injector or fuel rail. I would pray that it is just an o2 sensor.

[taillight]

Put the old air filter system back on. You will have a lot less problems like this.

[n8zdogg]

Originally Posted by taillight

Put the old air filter system back on. You will have a lot less problems like this.

I respectfully disagree a K&N filter will not cause these headaches....

I've encountered the same problems on a 99 454 and after $800plus in diagnostic work and two new fuel injectors (same codes as you got) it turned out to be the fuel pressure regulator. $40 and hour later, problem solved.

[fillupread]

It seems temp related. Check your intake where it meets the heads. Give it the ole spray test when its cold.

[glewis]

To all
Thanks for the responses.
About the K&N air filter, It has been a year since I cleaned it, I do not beloeve I sprayed too much oil on it and I let it dry overnight before I put it back in.
What is the old spray test?

I do not know what the furel pressure is, but when I changed the fuel filter, there was a lot of pressure in the line. I just had a problem with a buick dealing with the fuel injectors, this does not seem to be the same symptoms.

This truck also is totally fuell injected - no throttle body carb.

As for temp related - Do you think the heater on the O2 sensor may have gone bad, so it is not reading correctly until everything is warmed up?

Again thanks for all the advice.

[maxwedge]

Low fuel pressure, a vacuum leak, skewed MAF inputs can all cause this code and symptoms. Have the FP tested, look for intake vacuum leaks, scan it for maf and o2 sensor inputs, long term fuel trim, this is the way this should be diagnosed. Yes a MAF contaminated by K and N oil can cause these symptoms, I would at least clean the maf.

[777stickman]

I would say the o2 sensors are telling the truth since both sides are saying the same thing. Heater problems with the o2 sensors will bring up different codes.

The codes you refered to are (p0171) fuel system trim lean bank 1 and (p0172) fuel system trim rich bank 1. But you said the printout indicated both 1 & 2 banks lean. So if both banks are lean (believe the o2 sensors) then it could be a fuel pressure related problem.

Like MAX says at least clean the MAF with brake cleaner and see what happens.

It could also be the coolant temp sensor not sending the right signal to the PCM on cold starts since it runs ok when warmed up.

Let us know.