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Chevy Tahoe Maintenance and Repair

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  • Hey guys,

    I have 2003 Tahoe Z71 with 99000 miles on it. I have kept it in GREAT condition, oil changed every 3-4k miles, all the services done on time, tires rotated etc etc.

    In the past 2 weeks my car has been idling rough, almost shaking at about 300-500rpm. It usually only happens when I have it in Park or Neutral. Recently it does it when I'm stopped at a light or just started the car and waiting to warm up a bit.

    I brought it in to the dealership (yeah, I know) and they said it was the Throttle Positioning Sensor so they replaced it, in addition to all the spark plugs, air/fuel filter and spark plug wires. 2 days after getting it back, it started doing it again.

    My check engine light came on the other day . They ran the computer and found the following codes:
    P0171
    P0174
    P0300

    What is up here? PLEASE, someone help.

    Thanks y'all
    Alex
  • arriearrie Posts: 312
    I think P0171 and P0174 indicate lean condition in bank one and bank 2 oxygen sensors, i.e. it sees too much oxygen in the exhaust.

    P0300 is a misfire code and perhaps could be caused by the condition setting the two first codes.

    Could be a MAF sensor problem, i.e. mass air flow sensor sees less air flow than actually enters in the engine. This can happen when the sensing wires in the MAF get dirty.

    MAF can be cleaned but I'm not sure what to use. Them small sensing wires are so tiny. Perhaps you want to replace the MAF. It cost about $150. I replaced mine as I think I had a intake air temperature problem, which is built in the MAF.

    Arrie
  • when the car dies, absolutely wverything goes dead. the guages drop to zero, all the electrics reset. but i have one question, does the battery cause the car to start, then slowly die. let me detail that one, when it starts, the engine makes a few revolutions then slowly drops back down to zero. in other words, when it would start normaally, the engine would rev to 900 rpm, then settle to an idle a little lower than that. when it does it thing, it revs up to that point, then descends down to zero. i'll agree with you that the radio has nothing to do with the main computer, but this dying is what happened to my mom's old bronco, w/o the elictrics goin nuts.
    oh wait, i can think of a way the the computer has to do wiht the radio...if the brain controlls all the electrics, and the radio is electric, wouldnt that mean that if the computer is messing up then the electronics mess up???
  • arriearrie Posts: 312
    I don't believe the radio is in any way controlled by the car's computer.

    Also, I don't think driving lights are either. There are other 'brains' for these.

    If I was you I would get a new battery just to rule it out as a possible problem source. A good battery can be purchased for about $60 so it is not a huge loss even if it would turn out not to be the problem.

    Batteries can really mess up the car and be intermittent problem. They are also difficult to diagnose when it is an internal problem with the battery.

    Of course the problem could be the PCM but it sounds weird that all electronics goes out when the car stalls. Problem with the PCM should not kill all electric power.

    Arrie
  • I checked out the MAF's and found one at Napa for $140 (see below). Maybe I'll just replace that and see what happens.

    The guys at the dealership just keep telling me that they're "doing some research on it".

    Any hints on replacing one?

    Any other thoughts, feel free to keep 'em coming.
    Thanks for your help man. 'preciate it!

    Alex
    -----------
    Item#: NECMAF68411
    Price: $140.99
    tax and shipping not included
    image"
  • arriearrie Posts: 312
    To change the MAF you only need a screw driver as it is held in place with two hose clamps. First remove the flexible hose from engine side then remove the MAF from the duct of air filter box. The sensor has three holes that probably are for mounting screws in some other model vehicles than mine but at least in my '04 Tahoe the MAF is fastened with a hose clamp on both sides of it.

    Before you go to buy one you could try to clean it as it is very easy to remove from the intake air duct. Buy some spray grease solvent with no oil in it. I guess they are alcohol base chemicals, the kind electrical component workers use. Sorry I don't know any brand names here.

    As you can see in the picture you attached those 3 small wires are so tiny you would not want to actually touch them.

    The built-in intake air temperature sensor is that 'hump' on the rim at 5 o'clock position in the picture (right at wire harness connector).

    The problem you have could also be temperature reading problem as it together with MAF signal tells the PCM how much oxygen flow you have going in the engine. If temperature is reading way too high it keeps your engine running lean.

    The problem could also be bad connection at the wire harness causing wrong readings. Simple disconnect and re-connect maneuver can also help.

    For diagnosing these issues I purchased a Car Chip from Auto Zone. It is a data logger you connect to the OBD II port in the car and you can record some variables as you drive and then analyze it in a PC computer. I think it cost about $100. For example the intake air temperature is one of the variables you can monitor.

    Arrie
  • 73shark73shark Posts: 325
    By chance are you using a lo-restriction, oiled air filter aka K&N? GM recommends against these as they tend to "coke" the MAF during the cleaning (burn-off) cycle.
  • jmalikjmalik Posts: 10
    Hi there. I own a 2003 Tahoe LT. I LOVE the 20" chrome wheels available on the 2007 Chevrolet Tahoe, and i inquired with a local chevy dealer (the parts dept) and he said that in order to fit 20" wheels on my 2003, I would need a suspension/lift kit upgrade, total you're looking at $7K (he wasn't trying to sell me on it, he was basically saying it wasn't worth it). He said that the maximum wheel size a 2003 can take is 17". Anyone know anything different about this?
  • jmalikjmalik Posts: 10
    73shark - Can you please elaborate - what do you mean by "coke" - what are the implications of coking an MAF?. I have a 2003 Tahoe and I'm considering a K&N and cold air induction kit. Thanks,
  • Thanks for the tips. I'll try taking it out this weekend and clean it with the spray grease solvent (no oil).

    Let you know what happens.

    Alex
  • yea i kinda thought about that electrical thing lol...i dont even see how i would have thought that

    but is it impossible for the battery to be shorting out the computer, and possibly destroy it?
    also, if say it wasnt the battery, what else could it be?
  • arriearrie Posts: 312
    Did you replace the battery yet?

    Arrie
  • well not yet no
    i told him he needs to do it very quickly
  • 73shark73shark Posts: 325
    Periodically the computer causes a hi current (burn-off) to go thru the wire in the MAF to burn off any contaminants that may have got on it. Oil from an air filter causes more contaminants to stick to it and when heated, carbonize (coke) and make matters worse. GM recommends that oiled air filters not be used for this reason.

    Here's an alternative:
    http://www.trueflow.com/product.php

    Be aware that most of these CAI kits state up to 10+ hp gain, the ones I've seen that document it show the gain at hi RPM where most of our driving is not done.
  • jmalikjmalik Posts: 10
    Good info 73 Shark, I'll check it out (the true flow)...many thanks
  • Oiled air-filter elements were first used in the 19th Century on locomotives. Who(which)supplier is using this technique?
    Carryover of oil mist...small droplet sizes in the 1-10 micron diameter size has always been a problem using this technology.
  • i have a 98 2 door tahoe that for now i want to squeeze some 33`s into until i have enough money to do my full lift and tires i was wondering which would be smarter .... crank up my torsion bars or just get the leveling kit any help would be much appreciated
  • 73shark73shark Posts: 325
    K&N for one.
  • sdoo25sdoo25 Posts: 25
    We live in FL and have had no problems w/our sunroof during the summer rainy season on our '07 Tahoe.
  • sasz71sasz71 Posts: 14
    I have a 2002 Tahoe Z71 with 20" American Racing rims and 285 50 Yocahoma tires. They fit fine with no lift.
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