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My 2002 5.3 Silverado 90K. First code was replace MAS. After replacing the MAS the truck ran fine. 2 weeks later another code came up with 1 and 2 banks running lean. Replaced fuel filter with no change in code. What should i do next?

Submitted: 129 days and 20 hours ago.

Category: Chevy

Value: $23

Status: AWAITING EXPERT REPLY

Year: 2002
Make: Chevrolet
Make (other): silverado
Model: 4x4 extended cab
Engine: 5.3

Already Tried:
MAS, fuel filter

Posted by ase_master327 129 days and 20 hours ago.

Info Request

Hi, thanks for asking.. Are you using a air filter that needs to be oiled?

129 days and 18 hours ago.

Reply

I replaced the air filter with a K&N 33-2129 about 10K miles ago.

Posted by ase_master327 129 days and 18 hours ago.

Answer

Switch back to the stock filter, and clean your MAF. The oil on the filter sucks through and contaminates the element on the MAF and doesn't let it cool off enough. This makes the computer think that less air is entering the engine than actually is.

129 days and 17 hours ago.

Reply

How do i clean the MAF?

Posted by ase_master327 129 days and 16 hours ago.

Answer

Hi.. SOrry it took a while.. had to feed the kids.

Anyways.. to clean the MAF.. You can get MAF cleaner (carb cleaner works good too) from the auto parts store for like $8 or so.. CRC makes the one that I use. Then take it off, and the best way to do it (if you have security tip torx bits, you can take the sensor apart and clean it, but if not, just clean it out real good with the cleaner, and wait about a good 30 minutes for it to evaporate, before you plug it in.. If you shoot power to it while it is still wet, then you will find yourself needing a new one. So, just make sure it is completely dry.

Here is the MAF cleaner that I use though.

128 days and 17 hours ago.

Reply

I replaced the air filter and cleaned the MAF as you suggested. Cleared the codes for banks 1 and 2 and found another code for 0300 random engine misfire. No specific cylinder was identified. The truck seems to run fine except at idle it continues to run rough.

Posted by ase_master327 128 days and 16 hours ago.

Answer

Hmm.. Well it WAS running lean.. it may have burned out some spark plugs.. it is not uncommon for that to happen.

128 days and 16 hours ago.

Reply

I will replace the plugs. Any recommendations on plug brand model etc? If this does not resiolve the problem should i then replace the ignition wires? Plugs and wires are both OE. Thanks again for your help? I will be sure to accept your response and leave positive feedback. This service is awesome. "PITA" truck is Pain In The you know what.

Accepted Answer

Yes, actually plugs and wires should be changed as a set, anyways.

Here is the info on them:

View Full Image

If you need anything else.. I'll be around here somewhere.

Expert:	ase_master327
Pos. Feedback:	98.3 %
Accepts:	780
Answered:	11/12/2009

Shop Owner

+15 years experience with Chevrolet. Bumper to bumper diagnosis & repair.

127 days and 20 hours ago.

Reply

Sorry to be a PITA but I changed the plugs and wires out today. Still no change with rough idle at 700 rpm. No codes. Any ideas?

Posted by ase_master327 127 days and 20 hours ago.

Info Request

Hmmm.. DOes it only do it while idling? .. or get better or worse as the engine warms up?
How about the acceleration.. does it accelerate normally, or does it lack a bit of power?ase_master32740129.8586077199

127 days and 19 hours ago.

Reply

Seems to only doi it at idle. Accelerates well and and runs smoothly. I filled up the truck with gasand (did not top off) and ran the truck for 20 miles at 75 mph and the following 2 codes came back. 0134, 02 sensir CKT Bank1 sensor 1 and 0174, lean bank 2.

Posted by ase_master327 127 days and 18 hours ago.

Info Request

wow talk about a pita lol!
How many wires you got on the 02 sensors on this one?

127 days and 18 hours ago.

Reply

Must have been built on a Monday. The sensors before and after the CAT on the driver side have 3 wires. Blue black and white.

Posted by ase_master327 127 days and 18 hours ago.

Answer

Well, that makes things a bit easier.. but not really, bercause a scantool is needed to monitor that sensor. That lean running thing may have even eaten up the sensors.. But don't go changing them just yet.. Go through the diagnostic.. Here is the diagnostic for that sensor code. If it turns out that the sensor is bad on that side, then (90%) the other one will be messed up too. Running them lean like that really messes things up because it makes em run hotter like when you add oxygen to the cutting torch.

127 days and 17 hours ago.

Reply

I do not own a scantool and i may be getting in over my head. Any way to pull the sensor and take it in to have checked? Should i replace a sensor or sensors?

Posted by ase_master327 127 days and 16 hours ago.

Answer

Hi.. sorry for taking a while, things got hectic here for a while but those ribs were GOOOOD.
Anyways.. yes the sensors can be bench tested, but that also takes some special equipment..Snapon Modis.. or Solace (I forget which one does it).. but again, those things are both shop equipment.
I don't want to tell you to ochange them, and it be something in the wiring though.. but if they have never been changed.. it might be about that time anyways, especially if your fuel mileage has not been what it should.

127 days and 14 hours ago.

Reply

They are the original sensors and the truck is a gas pig. Are there only 2? Any tricks to getting them off and disconnected?

Posted by ase_master327 127 days and 12 hours ago.

Answer

Hi, there is one on each side of the engine.. SO you would only need to change 2 of them.. and then there is another for each catalytic converter.. but those sensors are different, they are actually catalytic converter 'monitors' and have very little effect on gas mileage.
So, if you were to change them, you would change the 2 front ones. To get them out.. nothing special really, they are a 13/16 size and there is a special socket for them, but it is a waste of money and it will do nothing but make you mad when it spreads out on you. I usually just put a box end wrench on them to loosen them.. and if it gets tight.. you know spray it with wd-40 and screw it back in to get the lube on the threads, etc, etc.. typical PITA stuff.. and then when you get it out, clean the threads, and make sure there is some copper based anti seize compound on the threads of the new sensor (this is so it is easier to get out the next time).. other than that.. its pretty much plug and play. but they can be a pain if they get 'seized' in the threads.. if it happens.. stay patient and don't mess up the threads.

127 days and 1 hours ago.

Reply

I sure miss my 71 Nova and 62 Belair. A lot easier to work on and a better investment then the stock market these days...Anyways I cant seem to find the sensors. I see the ones before the CAT and after the CAT. Do you find them from the engine compartment or underneath. I loooked on line and they identify the 02 sensors before and after the CAT. Sorry to bug you...

Posted by ase_master327 126 days and 22 hours ago.

Answer

You would be looking at the ones before the cat.. They would be bank 1 (and 2), sensor 1
You get to them from under the truck.. And they are right below the manifold.

View Full Image

Pull the little 'lock' out of the connector, and then you can separate it..

125 days and 21 hours ago.

Reply

Thanks. I replaced the 02 sensors with out difficulty. Turns out the driver side sensor was rubbing on the drive shaft leading to the 4x4. Burned through the wires. I had some transmission work completed about 6 mos ago and apparently they did not secured the harness completely. Truck runs great now.Thanks!! And lastly...when replacing the O2 sensors i ended up getting the ones for rthe flex fuel. The standard ones I originally purchased had a different connector (elongated oval) more PITA. Does that mean my truck is equipped for flex fuel? Should i even bother with flex fuel if so equipped?

Accepted Answer

Hmm... if the 8th VIN digit is a Z, then you have the flex fuel engine. Flex fuel just means you can run the E85. So, I would hope it is the flex fuel engine, lol!

Expert:	ase_master327
Pos. Feedback:	98.3 %
Accepts:	780
Answered:	11/14/2009

Shop Owner

+15 years experience with Chevrolet. Bumper to bumper diagnosis & repair.

125 days and 16 hours ago.

Reply

Thanks again for your help.

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Question

My 2002 5.3 Silverado 90K. First code was replace MAS. After replacing the MAS the truck ran fine. 2 weeks later another code came up with 1 and 2 banks running lean. Replaced fuel filter with no change in code. What should i do next?

Optional Information

Year: 2002Make: ChevroletMake (other): silveradoModel: 4x4 extended cabEngine: 5.3 Already Tried: MAS, fuel filter

Info Request

Hi, thanks for asking.. Are you using a air filter that needs to be oiled?

Reply

I replaced the air filter with a K&N 33-2129 about 10K miles ago.

Answer

Switch back to the stock filter, and clean your MAF. The oil on the filter sucks through and contaminates the element on the MAF and doesn't let it cool off enough. This makes the computer think that less air is entering the engine than actually is.

Reply

How do i clean the MAF?

Answer

Reply

I replaced the air filter and cleaned the MAF as you suggested. Cleared the codes for banks 1 and 2 and found another code for 0300 random engine misfire. No specific cylinder was identified. The truck seems to run fine except at idle it continues to run rough.

Answer

Hmm.. Well it WAS running lean.. it may have burned out some spark plugs.. it is not uncommon for that to happen.

Reply

Accepted Answer

Yes, actually plugs and wires should be changed as a set, anyways. Here is the info on them: View Full Image If you need anything else.. I'll be around here somewhere.

Reply

Sorry to be a PITA but I changed the plugs and wires out today. Still no change with rough idle at 700 rpm. No codes. Any ideas?

Info Request

Hmmm.. DOes it only do it while idling? .. or get better or worse as the engine warms up?How about the acceleration.. does it accelerate normally, or does it lack a bit of power?ase_master32740129.8586077199

Reply

Seems to only doi it at idle. Accelerates well and and runs smoothly. I filled up the truck with gasand (did not top off) and ran the truck for 20 miles at 75 mph and the following 2 codes came back. 0134, 02 sensir CKT Bank1 sensor 1 and 0174, lean bank 2.

Info Request

wow talk about a pita lol!How many wires you got on the 02 sensors on this one?

Reply

Must have been built on a Monday. The sensors before and after the CAT on the driver side have 3 wires. Blue black and white.

Answer

Reply

I do not own a scantool and i may be getting in over my head. Any way to pull the sensor and take it in to have checked? Should i replace a sensor or sensors?

Answer

Reply

They are the original sensors and the truck is a gas pig. Are there only 2? Any tricks to getting them off and disconnected?

Answer

Reply

Answer

You would be looking at the ones before the cat.. They would be bank 1 (and 2), sensor 1You get to them from under the truck.. And they are right below the manifold. View Full Image Pull the little 'lock' out of the connector, and then you can separate it..

Reply

Accepted Answer

Hmm... if the 8th VIN digit is a Z, then you have the flex fuel engine. Flex fuel just means you can run the E85. So, I would hope it is the flex fuel engine, lol!

Reply

Thanks again for your help.

Related Chevy Questions

Year: 2002
Make: Chevrolet
Make (other): silverado
Model: 4x4 extended cab
Engine: 5.3

Already Tried:
MAS, fuel filter

Yes, actually plugs and wires should be changed as a set, anyways.

Here is the info on them:

View Full Image

If you need anything else.. I'll be around here somewhere.

Hmmm.. DOes it only do it while idling? .. or get better or worse as the engine warms up?
How about the acceleration.. does it accelerate normally, or does it lack a bit of power?ase_master32740129.8586077199

wow talk about a pita lol!
How many wires you got on the 02 sensors on this one?

You would be looking at the ones before the cat.. They would be bank 1 (and 2), sensor 1
You get to them from under the truck.. And they are right below the manifold.

View Full Image

Pull the little 'lock' out of the connector, and then you can separate it..