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Chevy Tahoe

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  • I find that the 5.3 in my Z71 has enough power to tow the 6000 GVWR trailer I tow. When I do tow, I always use tow/haul mode, even though it kills the gas mileage. I figure the GM engineers put it there for a reason, and figure that reason is to protect the transmission, so I use it. Also, when not towing, I find the Z71 to be very powerful.
  • I do the same as far as the tow mode is concern. And your right it does eat up the gas. The RPM goes up from 1600 Rpm’s to at least 2200 Rpm’s and stays there as long as you have it in Tow mode and are towing. That is until you have a little incline or any other drag, bumps in the road, wind, etc comes along, then the Rpm’s go up to 3000 JUST TO KEEP UP THE SPEED OF 60 mph. So the gas mileage obviously sucks and goes down to around 6 mpg as the engine works harder and RPM gages tacks over 3000. As far as the power goes when not towing, I also agree with you for the argument of a 5.3-liter engine in this extremely heavy SUV. I love my Tahoe, I just wish now after going for a ride in my brother in-laws F-250 Diesel that the Tahoe had a diesel engine. They are noisy, but they get a lot better gas mileage. My brother in-law just towed a very heavy load and doing 70 plus mph on Hwy 5 he averaged 20 mpg. In my Tahoe on the same Hwy I kept my cruise control set at 60 and once in a while I had to slow down to 55mph towing my 18' Prowler. I averaged 10.8 mpg over 320 miles. This is better than my Ford Explorer did on the same route with the 5.0 liter engine it got an average around 7 mpg. Obviously and I'm sure you would agree, we would rather get 20 mpg while towing. But the reality is this won't happen no matter how many adjustments or after market products we put on our Tahoe. It is a great vehicle for 4 wheeling and it does have a lot of torque for towing & 4 wheeling. A person just can not expect to get good gas mileage in the Tahoe. I normally keep my speed control set at 60 mph with the maximum speed of 70 mph on the Hwy. At this speed so long as the wind is not blowing I average approximately 15/18 mpg, depending on how many inclines I have to go up. On a straight road with good pavement and no wind my Tahoe gets about 18 mpg at 60 mph. The only thing we can do is to constantly check our tire pressure and keep it set right, keep the fluids changed on a regular basis and when the time comes change the plugs and wires, etc. It is almost time for me to change my Trans fluid. I use synthetic motor oil and will do the same for my Trans and differentials. This does help out some with the gas mileage and also help keep a lot of stress off the internal parts better than the normal non-synthetic oil and lubricants. If you know of any simple non-expensive other methods of getting better gas mileage please let me know. When the time comes to change the plugs I'm probably going to get the E3 which I heard burn hotter and thus save on mpg. Also the plug wires and coils I've been thinking about changing out to a higher performance which should also help out a little with the mpg. Other than that I don’t really want to mess around with the engine or Tahoe itself. I like it just the way it is and the beefy sound that it makes. I have changed the Air Intake and put on the K&N 57 series at a cost of $270.00. I thought this was a little bit to much, but the adds all say you get approximately 15 more horse power and about 3% more in mpg. I really haven't notice that much of a change. Also I've had to clean the filter more often since it's not enclosed and this take an entire day since you have to wait for the oil to dry.
  • arriearrie Posts: 312
    Johnny,

    Your gas mileage at 18 MPG at 60 MPH sounds low. I get 18+ MPG doing 77 MPH. If I drive 60 MPH I get about 22 MPG.

    I have posted about my experience with my '04 Tahoe LT on this forum a lot and obviously it would take you too much time to find and read it all but I must say my work paid off very well.

    My Tahoe for the first about 1500 miles gave me about 17 MPG fuel economy but then it dropped way down to 13 - 14 MPG. The Chevy dealer said there is nothing wrong with my vehicle but I knew something was wrong as I drive 90% highway and always calculate my fuel consumption. Also my tailpipe was as black as the vehicle would be burning a lot of oil, which was not the case though.

    My engine is the 5.3 liter Vortec as yours obviously is equipped with the plastic intake air manifold, correct? My engine also is the Z or the L59 engine, the flex fuel thing.

    Anyways, after extensive trouble shooting I came across with a GM site, where I found a service bulleting talking about the intake manifold seal material for L59 engines and how it needs to be green color gasket, not orange. So I go checking on this and find the gasket at correct color but I also found that all of the intake manifold bolts were loose. Every bolt I could tighten by more than one full turn with the 7.5 lbft torque that it calls for the bolts.

    I also found that at about halft of the bolt locations the plastic was so thin that the bolt would not compress the gasket at all.

    The intake manifolt bolt arrangement is very strange. The bolt actually goes thru a sleeve, which meets the cylinder head. On top of the bolt there is a thick rubber washer and when the bolt is tightened it tightenes against the sleeve. This is supposed to provide enough squeeze on the rubber and make manifold gasket to hold.

    In my case there was very little squeeze on some of the bolts and on about half of the bolts practically no squeeze at all. I have modified this construction by removing the sleeves and installing double rubber washers under each bolt. Now when I tighten the bolts they tighten against the manifold providing much better seal performance.

    One symptom from this poor bolt construction was a high pitch whistling sound that sounded similar to sound that radio makes sometimes when the alternator interferes with it. The sound was not coming from radio though. My GM dealer service could not figure out what it was but it went away after I tightened the manifold bolts.

    It is rather simple procedure to check intake manifold bolt tightness. If you are a hands on person you just need a clicking torque wrench set to 7.5 lbft and 8 mm socket with some extensions.

    First tightening and later modifying the manifold bolt arrangement totally changed my Tahoe's performance. Gear shifting and engine pull improved a bunch.

    I highly recommend checking on this as it very vell could be your problem.

    Leaking intake manifold gasket messes up with engine spark timing since it changes MAP sensor reading to something else than what it should be.

    Again, this issue is with engines equipped with the plastic intake manifold. If yours is not this kind then it probably does not apply to you.

    Arrie
  • arriearrie Posts: 312
    Yes, the fix is very simple.

    The kit comes with instructions but those are not correct, at least not for my '04 Tahoe. Instructions say to remove the intermediate shaft from the car but this would be very big job as the end of the shaft is bolted to the steering wheel. I guess some other Chevy trucks have the intermediate shaft completely in the engine compartment.

    Before starting this job I tied the steering wheel with a rope so that I don't accidentally turn it around while doing the job.

    Then what I did was that I disconnected the lower shaft from the intermediate shaft. There is only one bolt to be removed for this. After that I collapsed the intermediate shaft enough to get the lower shaft to disengage.

    Then I removed the U-shaped spacer from inside the end of the intermediate shaft and pulled the shaft all the way out as it says in the instructions.

    Then, using the syringe that came with the lube kit I inserted the syringe inside the end of the shaft and pressed the plunger very quickly to make grease flow as deep inside the shaft as possible.

    After that, keeping the shaft at its maximum length, I inserted the plug that comes with the kit.

    After that I compressed the intermediate shaft all the way in and held it there for a a moment. That is what the instructions tell to do. I removed the plug and pulled the shaft out again but to make sure grease went to where it is supposed to go I inserted the plug again and compressed the shaft once more.

    Then it was to insert the spacer inside the shaft (VERY IMPORTANT TO REMEMBER PUT SPACER BACK IN) and re-connect the lower shaft to intermediate shaft.

    No more clunking!

    Arrie
  • Ok all you winter drivers I have a question for all of you! I live in Northern Canada and we are driving on snow covered roads regularly. My 07 Tahoe handles just fine but can anybody tell me how to keep the rear window clean? On long trips the snow build up 4 to 5 inches and the rear tailgate does not function. This is definitely a design flaw in the 07.
  • Arrie Thanks for the info on the manifold bolts. I have seen this on an earlier message posted by you and did check my bolts. The one's that I could check were about a 1/4 of a turn loose. I couldn't check the bolts that required the deep socket. I don't hear any whistling sounds coming from anywhere on my engine.

    I also have the Tahoe Z71 which has the off road package and I noticed you said that you have the LT. There is a big difference in the weight, height etc. between the Z71 and the LT. This is more than likely the reason you get better fuel mpg than I do. I also have 305/70R16 tires that also create a larger load on the vehicle. When I purchased my Tahoe it already had these tires on it, but I did notice that on the drivers door sticker it states the tire sizes are 265/75R17. So I assume that the previous owner changed the tires and also the rims since they are centerline rims. The Z71 off road package that comes from the manufacture already built in is approximately a 4" to 6" lift with a lot of extra suspension built up in the bodies carriage. This obviously adds on a lot of extra weight.

    I have also kept a mileage chart since I purchased my Tahoe in Jan 06. On my chart I annotate the Date, Beginning Mileage, Ending Mileage, Total miles driven, Average Miles Per Gallon, Cost/Amount paid for the fuel and lastly Engine Hour Reading. I have done this every time I fill up. Needless to say it may sound a little over board. It has also shown me how many miles I have driven, how much I've paid for fuel, how many hours I sat in the drivers seat and of course what my average gas mileage is. I also keep the running totals on the bottom of the worksheet for each item.

    I live out in the Antelope Valley Desert area and it gets and stays very windy here quit often. With winds averaging 30 mph on a constant basis when it's blowing. So this also creates a large drag on the Tahoe and the mpg significantly drop down to 13 mpg.

    My engine is the T, regular fuel only. I do as previously mention in an earlier post use 91 octane when towing my trailer or 4 wheeling.

    I don't know what color my manifold gasket is, green, orange or what ever, but I don't hear any whistling coming from the intake so you know the saying, if it not broke don't fix it. It does make since what you said about the tightening of the loose manifold bolts, eliminating any vacuum leaks, which would also change your ignition timing and give you better mpg. I do have the plastic manifold and I'm pretty sure that all Tahoe after 2000 have the plastic manifolds. I have been wondering if changing this out to an aluminum or cast iron would be better than the plastic. But since it's not broke then you know, don't fix it.

    I will how ever change out the coils when I have an extra $600.00/$800.00 to waste. I'm going to change my spark plugs and wires when it's time too, to a better quality and hotter spark. But now a-days the OEM plugs and wires last up to 100,000 miles or more. So I've got a while before I do that. I have also thought about trying to find or have someone manufacture some sort of tail to put on the rear roof to give less wind drag.
  • arriearrie Posts: 312
    johnny,

    One simple thing you could do right now to see if it helps gas mileage is one thing that you already are planning to do; change the spark plug wires. But don't purchase regular wire set, buy a racing set that you can use without the aluminum heats shields that are mounted around the spark plug boots.

    The story behind this is that some spark is lost in engine ground thru the shields. It is hard to believe but true. You can verify this by removing the small coil springs in the ends of the shields and in dark you can actually see how it makes spark between the heat shields and engine parts that are closest to the shields. With the coil springs installed you can not see the spark as the coil spring grounds the shield to engine.

    I removed the heat shields first and ran my truck without them. Spark plug boots made some smell first ar they over heated a little bit but did not catch fire or anything. My Chevy dealer service said they will not do that. I noticed a small improvement in my gas mileage so I went and purchased a set of Taylor spark plug wires that do not require using the heat shields. This was all before I found the leaking intake manifold gasket.

    About the tightness of the manifold bolts it does not mean that your gasket is properly compressed even if the bolts are tight. This is because the bolt does not tighten against the manifold, it tightens against a steel sleeve that the bolt runs thru. Tightening against the sleeve is supposed to provide enough compression on the thick rubber washer that the sleeve presses against the plastic manifold. In my case there was not enough compression on the rubber washer, under some of the bolts not any.

    Loose intake manifold does not always make that high pitch noise when the gasket leaks either.

    Arrie
  • Thanks so much for the good information on lubricating the steering shaft. I asked the service manager after it was done if they put a grease fitting on it for future service and he said no. He said it had to be taken off. When it needs it again it will be out of warranty, and I will buy the kit and follow your directions.
  • I was hearing the same buzzing sound from the little grill above the driver's head in my 2001 Suburban. I too thought it was some kind of microphone or speaker noise, but later figured out that it was a little fan. I bought a new "aspirator" (less than 30 bucks at GM Parts Direct); I followed these instructions, and it was simple to access the area and replace the part.

    The little grill you see on the headliner above the driver's head is the exposed part of a cylindrical bushing that slips through a hole in the headliner. On the upper side of the bushing (the part you can't see when the bushing is installed) are four plastic prongs that pop into four corresponding slots on the flat bottom of the aspirator housing. Once you have the headliner pulled down on the driver side (e.g., just enough to get your hands in), you'll see the aspirator housing, with a wire harness plugged into it. Just use a little screwdriver to lift up the harness clip; pull out the wire harness, and then use maybe a larger, flat-head screwdriver, or a trim tool if you've got one, to pop the whole aspirator housing off the bushing. Then you can pull out the bushing and clean it off too.

    On pulling mine out, I found that it was just really choked with dirt. It probably would have worked fine if I just cleaned it out with some canned air and put it back, but since I had already gotten the new part, I put that one in and put the old one aside, in case I have any trouble with this part again in the future.

    Thanks for this post (No. 5605). I'm sure it saved me a small fortune in doing this repair!
  • I have a 2001 Tahoe with 115,000 highway miles on it. A few days back while shifting from Park to drive I heard something 'snap'. My shift lever / handle felt like it had less spring and tension in it, but it was still shifting, and the car was going into the appropriate gears without problem. I got an appointment at a local dealer. In the meantime, 2 days ago (the vehicle has been driving fine since that 'snapping' episode) while shifting from park my shift handle got stuck in reverse, and the car was in reverse. The handle eventually freed, and I then shifted freely into whatever gear I wanted. Acceleration, braking have all been normal. Have not had any 'slipping' of gears, or odd shifting. The car went in to the local dealer today and after the put it 'on the computer' to be 'diagnosed' I was told I need an entirely new transmission!! Any experts out there?? I'm feeling like I need a second opinion! Thanks :confuse:
  • Hello, I was just reading through some of the post and had to give my comment on this particular one. Your mpg driving in the city has many variables. Mainly how many times you have to stop and go. This will make a large difference.

    The city in which I live has 4 stop signs from one end of town to the other, about 15 miles or so. I set my cruise control on 45 mph and get approximately 25 mpg in this area. If you take notice to your instant mpg when you come to a stop and then pick up your speed to the limit your gas mileage really is hit hard. So the comment I have is, there are a lot of reasons why peoples gas mileage may differ. If you live in a city that has a lot of stop and goes, well then your mpg could be as low as 9 mpg. If you are fortunate enough to live in a city like mine then your gas mileage around town will be a lot better.

    I only wish that my highway mileage were better. The best I've ever got was while cruising at 60mph for almost 200 miles and that was only 17.8 mpg. I've put 20,000 miles on my Tahoe since Jan. 06 and have kept a mileage record every time I fill up. I average approximately 8 tanks per month.

    Instead of people complaining about other people's mpg, ask for any help that could improve the mpg. I've already received at least 2 very good suggestions here lately and I'm going to do both of them. Tighten the manifold bolts and check the heat-shield springs for any arching. I have tightened up most of my manifold bolts approximately a 1/4 turn. I haven't checked for any arching yet, but plan on doing that as soon as possible.

    I have also replaced my stock Air Intake with the K&N 57 Series. It isn't cheap, but has given me better mpg and a little more horsepower. This is guaranteed to work and has 100% money back by the manufacture if your vehicle doesn't improve as stated in their policy. I purchased mine through performance products and received a free K&N oil filter and oil cleaning kit with the Air Intake system. It's easy to install and doesn't require a lot of time or tools to do. Good luck with your gas mileage and if anyone has any other suggestion on how to improve the mileage on the 2004 Tahoe Z71 I'd would be happy to hear from you.
  • I have towed my 18' Prowler with my 04 Tahoe Z71. The trailer is a dual axle and is heavy but I have no problems towing it. I also have a lot of stuff loaded on it, like a rear carry all utility rack, generator, 2 propane tanks, tools, etc. probably totaling an additional 1000 pounds or more.

    I just went on a long road trip, approximately 320 miles one way. I kept the tranny in drive with the tow mode on and got about 11 mpg. This was with the cruise control set at 60mph.

    I don't have the brake control lever yet. But I did not have any problems with stopping or swerving during stops. Of course I did not have to slam on my brake at any time either. Just kept a good distance behind other vehicles and my eyes on the road. The braking power of the 2004 Tahoe Z71 is sufficient, also the tranny will help you slow down quit a bit if you need to by down shifting. I did not have to do this on this trip. I did however on another trip up to the Sequoia Mountains use 2nd gear while coming down the hillside. I wasn't sure about the brakes at that time and I didn't want to get them hot. The road is a dirt road about 3 miles down. I didn't have any problem then either and hardly even had to use my brakes with the tranny in 2nd gear. As soon as I can I'm going to have the brake controller put on. It is a good thing to have if you are going to be towing something heavy. I had one put on my Van at ACE hardware with the complete tow package and it only cost $300.00. So I don't think that it will cost too much to just have the controller put on my Tahoe.
  • I have a 2004 Tahoe Z71 with the same set up. Mine does the same thing as yours. I assumed that this is the only way to answer the call. I did not know this and it took a few times of trying to answer the phone before I figured it out. You would think that it could be answered by pushing the button on the steering wheel. I guess that would make too much since and so Chevy decided to not set it up that way it appears.

    Also remember that come January 2008 you have to have the new OnStar system to use your OnStar Phone. I have generation 5 hardware in my Tahoe according to OnStar. They also told me as of 06/14/06 that they were at generation 6. I was told that my hardware is analog/digital ready and has to be upgraded to the Digital system. I was also told by OnStar that they will pay to have this upgraded in your vehicle if you need it, but you have to purchase a 3-year service contract at $549.00. Which really isn't that bad. I pay $16.95 every month as it is right now. So it's costing me $610.20 for 3 years the way I have it now. I don't understand why we have to upgrade to digital, other than I was told that they are doing away with the analog service all together. Some new regulation or bill that passed is supposed to be the reason why. This doesn't seem fair or right. I feel for the people who only have the analog system in their vehicle. I was told that they can not be upgraded and won't be able to use their OnStar come Jan 2008.
  • For the brake controller, you should look into buying the Tekonsha Prodigy. It's the best one on the market and shouldn't cost you more than $129. The '04 Z71 has a plug for the Produgy harness to plug into, so you could install it yourself. I had the trailer dealer install mine as I negotiated that and the weight distribution/sway control hitch as part of the deal when I bough my trailer.
  • EPA alters test that determines fuel economy
    By John O'Dell

    Los Angeles Times

    That 55 mpg hybrid car you've been eyeing might end up being a 44 mpg car if you wait for the 2008 model.

    The federal Environmental Protection Agency announced a new system Monday for evaluating fuel economy that will lower mileage estimates for most vehicles.

    On average, vehicles rated under the 2008 method will post a 12 percent drop in city-driving mileage and an 8 percent decline in highway mileage, said Bill Wehrum, the EPA's acting assistant administrator for air and radiation.

    The new requirements are an effort by the EPA to come up with mileage estimates that more closely reflect the real-world mileage people can expect when they purchase a vehicle.

    Under the current system, which has been in effect since 1975 and was last changed in 1984, actual mileage is often far lower than the posted EPA mileage.

    Hybrids will be hit harder because the new test eliminates some of the all-electric driving that helped them post impressive results under the present system, Wehrum said.

    For the first time, the EPA also will require estimated mileage to be posted on medium-duty pickup trucks, vans and sport utility vehicles.
  • arriearrie Posts: 312
    lachenda,

    My opinion is that you do not need a new transmission. You probably had something broken loose or something in the shift linkage but as you say it drives ok you really do not need a complete new transmission.

    It sounds to me that your dealer is trying to do a serious rip-off with you.

    I would take your car to a non-dealer shop for a second opinion.

    I'm not a transmission specialist. This is my own opinion only but it really sounds like you are going to be 'hosed' quite bad if you go with your dealer's suggestion.

    Arrie
  • Hello aa555zz,

    Can you tell me what process you went through and how you recieved the credit from GM, because I have the exact same issue, please?

    THank you
  • dpagedpage Posts: 1
    Did you ever find a fix for this problem?
    I have a 96 Tahoe and it has 125K and this problem just became very pronounced on startup, and goes away after a 5 or so minutes...
    Thanx
  • Arrie,

    Thanks for your feedback. I went with my opinion also and took my car out of the shop and took it to my local mechanic. Interestingly, I told him the same story and he found the problem in my sterring column. One $215 part and I'm on the road again. The dealership was attempting a dispicable rip off!! Amazing, a new shifting mechanism and I'm like new! Too bad there are such dealerships!

    Lachenda
  • arriearrie Posts: 312
    It's so bad but true some car repair shops try to cheat their own customers this bad. You should go and give ear's full to their service manager.

    Think about the victims who do not know anything about cars and don't even know to ask for advice. In case like yours they would have paid perhaps $3000 for the $250 fix. And probably the dealer would have left the original transmission in and just fixed the shift linkage.

    Arrie
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