2003 Silverado Mis Fire

[ianfaber1]

I have a 2003 Silverado with a 5.3L a 3" strait pipe for an exhaust installed just behind the cats. For the last couple days my check engine light starts flashing when I accelerate getting on the expressway. Today I turned ion my computer and it read out mis fire on several cylinders as well as a mass air flow error. I have been noticing a small rattle noise possibly coming from one or both cats for the last month or so. I am looking for any suggestions on where to start before I start dumping too much money into fixing the problem.

Thanks

Ian

[nickvrebel]

1. start with cleaning the MAF sensor (takes a special cleaner, follow the instruction and don't try to go cheap and use anything else).

2. clean the throttle body with carb/ throttle body cleaner, thoroughly

3. inspect the catalytic converters - if it's rattling then it's bad - you can LIGHTLY tap on each one with a rubber hammer to check them.

4. inspect the plug wires and spark plugs. how many miles on them?

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It would really help if you could give us the actual p codes, instead of just telling us it was a maf code, or a misfire code. The misfire code will be p0300, but there are multiple maf codes.

[ianfaber1]

It would really help if you could give us the actual p codes, instead of just telling us it was a maf code, or a misfire code. The misfire code will be p0300, but there are multiple maf codes.

The codes that came up were

 

P0101 mass air flow circuit

Reading 5.8 -6.2. Lb/m at 68mph

 

B0103 not recognized

 

P0175 - system too rich bank 2

 

P0300 - random/multiple cylinder misfire detected

 

I cleaned the MAS and went for a short drive and haven't had the MAS code come up yet. But the misfire code still comes up.

Then after about 15-20 miles the MAS error came back. And a new code appeared B2575.

I plan on checking the cat this morning.

[Stevens03]

Are you running a K&N intake?

 

If so swap it out for the factory intake and be sure to reset the PCM. I had that same issue with my S10 and the intake was the issue.

[ianfaber1]

Are you running a K&N intake?

 

If so swap it out for the factory intake and be sure to reset the PCM. I had that same issue with my S10 and the intake was the issue.

 

I am running a k&n filter with the stock intake.

[ianfaber1]

I found out that I had a bad CAT on the passenger side and replaced it. The truck is running fine now with a noticeable difference in horse power in low end acceleration. Thanks for all the help.