2003 Chevrolet Tahoe - rough idle, stalling, check engine, etc

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#1
We have a 2003 Chevrolet Tahoe, 37500 miles (1500 miles out of manufacturer warranty), we bough the truck back in March with 33k. About a month ago the check engine light came on, and we noticed it would be a bit rough at idle, but the problem was only intermittent and the check engine light went off for a bit. Last week the light came back on, and the same problem started again. Rough at idle, fine when we drive it, seems to be worse in cold weather. Then, a few days ago, it started stalling when idle. We took the car into the service center and they gave us 4 codes: p0101, p0171, p074 and p0300. However, they saw we had a K & N filter (which voided our extended warranty) and would not diagnose past that. They said 'oil from the filter has gotten on the mass air flow meter and caused symptoms,' and they offered to change the filter, clean the MAF meter and clear the codes. We said thanks but no thanks, changed the filter ourselves to a standard filter and bought MAF sensor cleaner and used that.

Nothing has changed or improved, and tonight the check engine light started blinking while I was idle. I found what I thought were related TSBs, but not to my specific year, so I'm sure they are not relevant. Any information or suggestions would be greatly appreciated. I've done some googling (how I found about about this website!) and found anything from the O2 sensor to spark plugs to fuel filters, etc. There does not seem to be one specific standard answer, but I have a feeling that just changing the sensors is not the answer. . . thanks so much in advance for any advice!
 
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#2
Oh I almost forgot, the engine is 5. 3L V8. It is the LT model. Thanks again in advance.
 

Gus

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#3
Flashing CE light, means the engine is misfiring...and if it is doing this at idle, you have a major misfire....

Since you did the work yourself, you did not clear the codes.....so now we don't know, outside of the misfire code, if the other codes are the problem.....usual procedure is to clear codes after the work is done and see if a code returns...you need a scan tool to do this...

Also a scan tool would tell you if a particular cylinder is misfiring, or if ALL cylinders are misfiring...

P0171/0174, indicate a lean condition, which may affect all cylinders.....you could have a major vacuum leak, a MAF problem, or even a MAP problem, or fuel pressure or secondary ignition problem.....These days, without diagnostic tools, like a scan tool to look at data, it's basically guesswork and you just become a parts changer, which can be costly, never mind the loss of time of your vehicle.....

They were correct about the K&N filter....but did you put it in, or was it there when you bought the vehicle?

The only TSB I saw was to check the operation of the MAP sensor, which could give the wrong data, which would cause the MAF readings to affect fuel mixture.....but once again, that is just a guess, without seeing data.....
 

nickb2

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#4
You seem to have a lean condition on both banks, which to me indicates maf,vacuum leak, air intake duck leak after maf. P0300 indicates multiple misfire. As said, scanner info is a must here. Codes p0301 to p0312 indicate respective cyl misfire. Injectors may also be clogged, causing lean condition. Beware those K/N filters in modern fuel injected engines. Water/humidity may freeze overnight on these exposed filters (if this is the case) and air deprivation will surley be a problem.
 
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#5
Re: 2003 Chevrolet Tahoe - almost fixed....

Thanks everyone for getting back to me so quickly. Fortunately, over the long weekend the problem seemed to just go away again. . . no blinking check engine light, bad idle, or stalling. We're going to put it in the shop this weekend to get a once over just to have a professional check it out. Could the new regular filter and cleaner stuff have just cleaned out the system and it be working fine again? Any other ideas as to why this problem happens, then goes away, then happens and goes away again? And to answer one question, no, we did not buy the car with the K&N filter, unfortunately we took some bad advice about how it was going to improve our cars' performance. We have since researched and learned and removed it. . . and it will not be going back in. Thanks again and I will come back with any other updates. Right now I'm just thankful we're in a position where nothing is wrong, and hoping we can do some preventative maintenance to keep it from happening again.
 
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#6
Hello i see is been awhile but i have the same make and modle tahoe with the same problem. Were you ever able to figure out what the problem was? Hope you see this thanks in advance
 

billr

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#7
You will be better-served if you start a new thread. However, by "same problem", do you mean you also have one of those super-duper aftermarket air filters?