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Chevrolet Tahoe Engine and Performance Problems

mom_of_three1mom_of_three1 Member Posts: 1
edited April 2014 in Chevrolet
I am about to strangle someone at GM if they can't fix the "reduced engine problem" on my 2004 Chevy Tahoe. (The "reduced engine power" notice appears and the truck cuts down to about 2000 RPM's and either goes 5-10 MPH at most or completely dies out and we loose power and brake functions - this happens anywhere from taking it out of park, or going 65 MPH). We had the throttle sensor replaced last year when it occurred and everything was fine until 3-4 months ago when it started back up again. But guess what? They say their diagnstic shows nothing wrong, and they give it back to us. We took it in over 3 times....mostly because we have 3 small kids and when it dies out on the expressway we feel like we are about to be killed! Now after 3 months it is getting worse, there are pinging and knocking noises and I am going crazy. We took it to another place and they say they can't find the problem with the reduced engine power, but our U-joints need to be replaced! I have a few questions....what is wrong with my truck? AND could the U-joint damage been caused by the power cutting out so much?
Someone please help!


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    kiawahkiawah Member Posts: 3,666
    Well the worse the problem gets, the easier it is to find the problem and fix it. When it rarely fails, it may be hard to catch it in a failed state. You could have one of the sensors bad, and the computer is trying to compensate by adjusting the timing and mixture to the point that the engine is pinging. Is it a dealership that you have had it to? If so, try a different dealer, and make sure the service advisor is aware of the previous attempts to fix.

    Can't see how any joint damage could be related.
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    arriearrie Member Posts: 312
    I have an '04 Tahoe LT myself and have had to do quite a lot of work with it.

    First of all, forget the U-joint job. It has nothing to do with engine performance. That shop is just trying to make money on you with probably unnecessary job with U-joints. It could need service too though but engine performance it has absolutely nothing to do with.

    Engine acting like you explain is probably some sensor related. There are several sensors and most of them can fail without engine performance loss but a sensor can also start sending wrong input, which the on board computer does not necessarily see as failed sensor because it is getting a signal from it. Usually sensors are seen failed when they just stop working or the signal from the sensor is out of the range where it should be at. In cases like this you will get SES (Service Engine Soon) light, the one with engine picture.

    There are a couple of sensors that probably will not cause SES light to come on before they totally fail but could cause big problems with engine performance. One of them is the Crank Shaft Position sensor. This sensor reads crank shaft speed and position and is one of the key sensors for engine spark timing. If GM shop is not able to help you with the engine performance problem this sensor it the one I would start myself with. I have changed it myself in my own truck. The sensor cost about $80 but of course the installation is extra if you cannot do it yourself.

    Problem with this sensor change is that it is located behind starter motor on right side of the engine block. Starter motor must be taken off to gain access to the Crank Shaft Position sensor. Sensor itself has only one bolt on it and is very easy to change but that starter motor takes a bit more to remove and re-install. It could also be a bad wire connection to this sensor but to get your hands just to the wire harness of this sensor the starter motor must come down first.

    The other sensor that works exactly the same way is the valve position sensor. This sensor is located on top of the engine behind the intake manifold. I is in quite difficult location but I think it can be changed without taking anything else off of the engine. I have not changed this sensor so I don't know how much it costs.

    I believe above two sensors both will not cause any fault code in car's computer unless they completely fail working but before they do they can cause very severe engine performance problems.

    And as I said I would start with the Crank Shaft Position sensor. This sensor is quite common to fail probably due to its location in very hot engine oil environment.

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    carolyn9776carolyn9776 Member Posts: 3
    Have any of you ever had the engine cooling fans so loud that you can hear them cooling 25 feet away? GRRRRRRRRR
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    robertshawrobertshaw Member Posts: 1
    Ok guy I have the answer to your problem. there is a recall out about the wires going to the throttle sensor on of the can break about 1 to 8 inches from the connector harness. mine was the yellow wire i just cut away 5 inches and rewired and no more problems. Hope this works for you.
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    rodonnellrodonnell Member Posts: 37
    Has anyone connected to the OBDII connector to see what the computer is saying?

    I would think there is most likely some codes getting thrown. Is your Check Engine Light lighted?

    Before you go changing components willy nilly, you probably want to know what the engine management system is saying.

    You can take you Tahoe to almost any auto parts store, or for that matter AAMCO and they will read the codes for free. Worth a shot.

    As for the U joints. I agree, not related, but if they are bad, you need to replace them. Get under the truck and wiggle the driveshaft(s). If you see any play in the U Joints or hear any noises out of them, they need replacement.

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    wishiknewwishiknew Member Posts: 2
    Hey all, I've got a '97 GMC suburban K1500(I know, GMC and all, but I figured that Chevy and GMC have the same exact engine) at 203,000 miles. Just the other day I got back from 2,000 mile trip with it and it started giving me an issue. I'm getting a sort of tickering sound when it idles and the fan is unusually loud. It's become very noticeable since yesterday when I got back. Any ideas? I'm not exactly car-savvy.
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    momto5momto5 Member Posts: 2
    Our 2007 Suburban has 35500 miles and has blown white smoke numerous times now.
    The dealer said they replaced the top of the engine, the heads per a Chevy bulletin.
    The problems still exists.
    Our radio made the same sound you hear when an ampifier is unplugged.
    the dealer replaced the radio per a Chevy bulletin.
    The problem still exists.
    When putting the vehicle into reverse after overnight it is jerky and hesitates.
    The dealer said they reprogramed the transmission per a Chevy bulletin.
    The problem still exists and appears to be worsening.
    Any suggestions?
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    kiawahkiawah Member Posts: 3,666
    Take it back to the dealership and indicate that you still have the problem, or take it to a different dealership? You want to get those definitively resolved before the warranty runs out.

    If they 'fix it', and it's still doing it, then they didn't fix the right thing.
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    momto5momto5 Member Posts: 2
    That's where it's at right now! My husband took it in again today.
    The dealership called earlier and said everything checked out just fine on the machines. They can't find anything wrong.
    One of the service techs volunteered to take it home for the evening and see if he could experience the "backing up issue" from his house!
    We declined his gracious offer.
    I'm not convinced they were able to "fix" anything. Though things seemed fine when we picked it up. It was probably about 50-100 miles before things weren't working properly again.
    This is the second time major issues have come up in a couple hundred miles.
    We were told a 12 month 12k warranty went with the latest work.
    Today, my husband was told the engine, transmission and drive train have a 5 year 100k mile warranty.
    Does that sound right to you? It depends on who you ask as to the answer you get.
    Thanks again.
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    kiawahkiawah Member Posts: 3,666
    I own a 2007 Suburban, and the warranty is 3 years, 36 months. There is a thin warranty book with your owners manual, which details exactly what is covered and is not.

    Unless you bought an additional warranty thru someone, I believe your warranty is about to expire. Unless there was a marketing change mid-year (or in 2008 models) to carry a longer warranty, I think you'll find a 3/36 warranty.
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    rockman59rockman59 Member Posts: 250
    I have an '06 and the factory warranty is 36 months/36,000 miles on the entire vehicle with the exception of the smog gear which I believe is covered up to 50,000 miles per EPA regulation. Here's GM powertrain warranty for '07 and '08:
    Covered for five years/100,000 miles*
    General Motors will warrant each 2007 and 2008 model year passenger car, light duty truck or van for 5 years, or 100,000 miles/160,000 kms. with no deductible, whichever comes first, from the original in-service date of the vehicle, for warrantable repairs which are required as a result of defects due to material and/or workmanship to the Powertrain.

    Both the '07 and '08 models have the full warranty on everything for 36month/36K miles.
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    kiawahkiawah Member Posts: 3,666
    Well that is interesting, where did you get that info that the powertrain warranty is 5 years? That doesn't match my warranty book, nor my understanding of the warranty when I bought the vehicle.

    I also just pulled out the marketing/sales brochure and have it in my hands, and it clearly indicates 3years/36000 miles (rust thru 6years/100K miles).

    I'm hoping you are right!
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    steverstever Guest Posts: 52,454
    Edmunds says it's 5/100k on the drivetrain too.

    2007 Chevrolet Suburban Standard Warranty
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    kiawahkiawah Member Posts: 3,666
    Well that doesn't crossfoot with published Chevy documentation.

    I'm wondering if the warranty was improved at some point mid model year. Perhaps a call ot the Chevrolet Customer Assistance Center Monday is in order!!
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    steverstever Guest Posts: 52,454
    Looks like they did it starting with the '07 model year - probably didn't get your warranty book updated or there's a TSB out to put a sticker or something in it.

    GM Strengthens Warranty

    The date on GM's press release is 9/6/06.
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    rockman59rockman59 Member Posts: 250
    Well that is interesting, where did you get that info that the powertrain warranty is 5 years?
    Info came right off the GM website....check it out for yourself. Just Google "GM Warranty" and then click on the GM site that comes up.
This discussion has been closed.