GMC Yukon / Yukon Denali

willardh3 · January 2003

Thanks for the reply, it sounds like a reasonable explanation. Now I just have to quite down the wife, kids and radio to hear the fuel pump. Quieting two of those three should not be too much problem....

circutmann · January 2003

I won't ask which 2 you can quiet. You're doing pretty good to quiet two. At my house, I probably could only be sure of one, unless I waited for the other 2 to all go to bed. That's why the 15-20 seconds should be plenty of time.
Some fuel pumps are much louder than others. Good luck, both on the test, & on the quieting. Let us know how you make out. Dave

denali856 · January 2003

I've assumed that the loud whirring noise emanating from ther rear of our Denali at startup was the fuel pump, since it's done it from day one, and only does it at startup, but it's nice to have it confirmed.

Does anyone know whether most or all moder fuel-injected gasoline engines run such high pressure to the fuel rail? I don't think they did back in the 70's, which was the last time I was paying much attention to such details.

circutmann · January 2003

Unless my wife & kids are in the back, I think the whirring noise that you are referring to is the AutoRide compressor that runs at startup, & whenever the automatic leveling requires more lift at the rear of the vehicle. It is located behind the left rear wheel.
   The electric fuel pump is, (should be) much quieter, but still audible if you listen closely. It runs whenever necessary to maintain approximately 50 psi fuel pressure, which is continuously, when the engine is running.
   The older GM TBI (throttle body injection) systems of the 80's that you refer to, run at about 11 psi. Tighter emissions & fuel economy regulations led to the higher pressure MPFI, CPI, & SFI systems of newer engines. The higher pressure allows for better atomization & control of the air/fuel ratios.
   Hope this helps! Dave

boco420 · January 2003

Has anyone else had any problems with their Denali/DXL pulling left? I've noticed that my DXL pulls left especially under acceleration. Tire pressure is identical (36psi) in both front tires and it displayed the same pull both before and after tire rotation. I took it in to the local dealer (15K miles) and had them look at it. They claimed it was the alignment. $59.95 later, the problem is slightly better, but during acceleration you still have to crank the wheel right to keep the truck going straight. When the power is off, the steering tracks fairly well though I still have to hold it right of center in general. The problem is more severe (obviously) when driving on the left side of the crown of the road.

Any suggestions? Anybody else experienced this? I'm about to go back to the dealer again so I can use all the information I can get!

Thanks!

--B

orwoody · January 2003

My 2001 Denali was drifting/pulling slightly left. It wasn't too severe but was consistent across a number of different roads. I had them check it when I went in for an oil change - they did a realignment and it was fine. There was no charge for the realignment - under warranty even though the rig had almost 30k at that time.

boco420 · January 2003

Funny, the dealer (royal moore in hillsboro, or) insisted that alignment was only covered under warranty for the first 7k miles ... Sounds like you found a more "sympathetic" dealer than I did

On another note, the transmission started slipping today. I was stopped at a light idling for a few minutes. Hit the gas and all I got was engine RPM's but no go ... finally the transmission clunked and I was off to the races. Looks like I've more than just the alignment to discuss with the dealer now ...

--B

willardh3 · January 2003

Thanks for your input, as you suspected, fuel pressure issue. Entirely covered under warranty. The explanation I got was the ethanol they add up hear (MN) eats away at the bladder, thus allowing leakage.....who knows.
Interestingly, I found a slip in the truck from another shop advising me to immediately add fuel (not more than 20 gallons) and then drive all the way down to an empty tank. 1) They must have farmed out the job. 2) I assume the fill-up then down to empty allows the new components to get themselves worked out properly.

larry91 · January 2003

I believe the noise u hear from the rear is the suspension pumping up the rear end to level it.
Larry

orwoody · January 2003

I have never dealt with Royal Moore - their sales force has always turned me off. I used to deal with John Link(now a Thomason dealership) but became unimpressed with their service and Mr. Link(saw his interaction with employees). I started dealing with Weston(Gresham) several vehicles ago and have been quite happy. Maybe I'm lucky, but their service department has treated me very well from day 1. Maybe they just go a bit extra for customers - but service folks at Weston told me 36k/36 months was "bumper to bumper".

avolvofan · January 2003

The first thing that I would do is to replace the transmission fluid. By replace, I mean a complete swap of the fluid, not merely drain and refill.

donahues · January 2003

My 02 Denali with 5k miles shows 10.4 +/- volts in the morning (it is below 20 degrees at night). The battery seems strains to crank. Is this normal? I am worried about killing the battery if I were to leave it unstarted it for a handful of days.

lobsenza · January 2003

Your battery may be leaking. Mine was and was replaced under warranty.

mjwills · January 2003

I live in Michigan, it has been pretty cold here these last coulple weeks. When I start it in the moring after sitting in the garage it starts fine. After getting to work and sitting all day or sitting outside for a long period on time (enough to get cold) when you start it, it will turn over and start then give a noise like you stepped on a duck (waaaaah, use imagination). Any thought as to what this is?

Also I took this into the dealer and they could not reproduce it. When the car is warm and the climate control fan is blowing from 1000-1500 rpm there is a sound that sounds like the fan blade is out of balance. I hear it all 80% of the time. If you shut the fan off it is not there. I have read past posts about plastic in the vents, I will check. My wife in the passenger seat says she cannot hear it (selecetive hearing). Any thoughts?

This is my 2nd DXL, 2001, 2002. Do you feel that a lot of noises are just because of all teh plastic? I understand that it is cold and that plays a part. Could anyone tell me what is normal creeks and rattles? I have taken everything out and drove it for a few days like that - all sounds still there, so it is not anyhting I have in the vehical.

Sorry for the long post. Please let me know your thoughts. Thanks again.

rolandfarrar · January 2003

Are they any other Denali enthusiast sites out there?

stever · January 2003

Try a search engine (we frown on promoting competing forums here). And don't forget the GMC Yukon Owners Club! linked at the top.

Steve, Host

forzaroma · January 2003

forgive me i didn't have the time to read the 1731 messages before this one but i would like to offer my opinion on the yukon xl Denali that i test-drove

i thought it was one of the worst (new) cars i have ever driven

there is about 6 inches of play in the steering wheel before anything happens
the suspension is so soft that the car wallows from side to side like a dinghy in a storm and that is at 10 miles per hour, if you ever had to swerve to avoid anything you would surerly lose control
the interior looks like a time warp from the early 80s even the most basic mod cons like sat nav are not even an option
but worst of all was that 6 litre engine it was as rough sounding as a tractor probably has a 0-60 time of 20 seconds and probably consumes more than just about any passenger vehicle on the road

i am not right that this car is a dinasour and that surely its life is limited, as soon as bmw or merc produce a decent 7 seater for $50k this car will be dead

how can all you guys buy such a piece of cr** have you never driven an x5 ?

stever · January 2003

Yeah, but we're afraid one will burn our garage down. Bada boom bada bing.

Too bad Ferrari doesn't make a SUV eh?

Steve, Host

lobsenza · January 2003

Does not have the room that these vehicle have. Having to carry 7 passengers in a carpool, tow a boat, and take a family of 4 (and occasionally a set of grandparents) on a trip would not be possible with an X5. Yes, an X5 handles much better than any of these large vehicles. H have a sports sedan and it handles much better than these large SUVs. But, it can't do many of the things that these SUVs can. It is all a tradeoff.

denali856 · January 2003

You are certainly entitled to your opinion.

As for me, I haven't driven a DXL--I have an '02 Denali--but:

(1) I happen to like the relatively large neutral center on a vehicle of this size. I would not like the steering on such a large vehicle to be as tight as a sports car or sports sedan. It would be tiring on long drives.

(2) I also think that the suspension is well-tuned, soft enough to give a good ride, but firm enough to handle well. My truck does not wallow. If you read trade reviews of the Denali/Escalade duo, I think you'll find that the general consensus has been surprise at how well the truck handles, given its size.

(3) I don't know about the DXL, but I believe I've seen 0-60 times right around and in some cases under 10.0 for Denali/Escalade (better for the Escalade--tuned to put out about 25 more hp), which is certainly respectable for a car this size, and not that much off the times I've seen for an X5 (~8-8.5), given the weight difference.

There is no other vehicle in the class with an engine anywhere near the Denali/Escalade's Vortec 6.0 in power or torque. In fact, one reason I preferred and ultimately bought the Denali rather than a Navigator or a Sequoia was the superior performance.

Lastly, I don't understand the perspective of this post to begin with. No one shopping for a vehicle the size of a Denali or especially a DXL would reasonably be cross-shopping an X5. To compare the two vehicles is just silly, in my opinion, or shows that you are more concerned with owning a certain marque than with getting a vehicle with a certain set of attributes.

What do you drive now, if I might ask?

hrhauser · January 2003

Can one tune the Denali '03' to the same horse power rating as the Esclade? or did they use a different cam?
If it is only a software change anybody know what it is?

avolvofan · January 2003

Hypertech makes a "re-programmer" that re-programs the engine control computer to change the timing (and probably some other aspects) to increase the hp and torque output of the 6.0 liter engine to the same level as the Escalade. The downside to the re-programming is that you need to burn premium fuel. I do not know if the black box in the 2003 Denali can sense whether the engine settings have been re-programmed; if it can, you will have warranty coverage problems as well.

obyone · January 2003

will get you the same HP/torque rating as the Escalade. You will notice the difference if you're changed your tire size from stock, increased the shift firmness, and calibrated for premium fuel. How much difference to be felt is subjective to the user.

The programming may also be removed if taking the truck to the dealer for software updates or warranty work. In fact it is recommended since a reprogramming by the dealer will render your HPIII unit useless and require that you send it back to Hypertech.

denali856 · January 2003

I believe I saw this somewhere. It isn't possible to change the compression ratio of a normally aspirated pushrod engine without changing the cam, head, or exhaust manifold, is it? Don't know enough about engines to answer this question with confidence, would appreciate a reply by someone more knowledgeable. Thanks.

forzaroma · January 2003

hi denali856
you are quite right to compare an x5 and an xld is very silly. i am encouraged by what you said in your review.
lobsenza is also quite right that it is a trade off. what i am craving is an x7 the size of the xld if they every made one. the problem is that i own a 4.4 x5 now (and an 03 911 c2 cab) and i am starting to need more room. i like cars that handle well. i think i drove to xld tet drive in the 911 so that probably made the contrast worse.
i quite like those caneepa deanlis but a fully loaded one costs 130k. i fell off my chair laughing when they told me that.

avolvofan · January 2003

Hypertech claims a 20 point increase for both hp and torque. Presumably, they have the documentation to back it up.

Personally, if I were looking for increased hp and torque, I would go the supercharger route - a twenty point increase is probably worth only one tenth second reduction in 0-60 time. And you must run premium fuel all of the time.... The supercharger route would yeild 0-60 reductions of around 2 to 3 seconds. (On a 5,500 to 6,000 lb. truck, 2 to 3 seconds is significant.)

The more compelling reason to go with a Hypertech re-programmer is to remove the 95 mph speed limiter. HR rated tires are capable of 130 mph; the Denali can do at least 105 before wind resistance becomes a factor.

ahesq · January 2003

I have 1700 miles on this new truck and I am starting to hear (very slightly) the howling noise in the front differential at low speed, as some others have. There also is a slight whine between 40-50 mph. Both noises go away after 65 mph. I'm afraid if the dealer puts in a new diff, the sound will just come back after 1000 more miles on the new diff. or the sound could get worse (it's not that bad now). I had the same problem with my 2000 jeep GC and replacing diffs did not fix the problem (imperfect gear set up at factory). Jeep finally fixed the noise by replacing the front drive shaft with a simpler design using u-joints as couplings which would not transmit the front diff noise as much as the original drive shaft. Does anyone have any clues? Also, if anyone had their front diff replaced, did the noise ever come back after the new gears had some miles put on them? Many thanks.

obyone · January 2003

Hypertech doesn't require running 93 octane ALL THE TIME as you state. It allows you the option of tuning for 87 or 93 octane.

If you're thinking of a SC, then forget the HPIII as that would be throwing money away since the SC has its own tuning package.

I'd take any dyno results posted by Hypertech on their website with a grain of salt. TByrne Motorsports did an independent test and didn't even bother to post any difference after the Hypertech tuning....

http://www.tbyrne.com/99silverado.html

Course they sell the Hypertech unit so I can understand why.

lobsenza · January 2003

I think it handles well for its size and bulk. Compare it to an Excursion and I think you will see a difference. Obviously, the smaller more nimble vehicles will handle better. Ideally I would use the DXL only when I need the extra room or towing. But the cost of owning an extra vehicle is too great for that....

orwoody · January 2003

Reliability - I have nearly 34k on my 2001 Denali and pretty much zippo issues; burned out taillight bulb and a realignment besides regular maintenance. I haven't heard of any rigs locally loosing the differentials or drive train problems.
(I always pry on my favorite mechanic when I go in)

Handling - Compared to previous generation(and even std Yukon), the Expeditions and Navigators I've driven the Denali is winner hands down. I haven't driven a DXL. I will give the X5 top kudos but it is a different class than the Denali or DXL, so not sure that is too fair a comparison.

Top Speed - Don't tell my dealer but I've cruised at 100mph for a few stretches with no notice of drift, lift or other issues. (Didn't know there was supposed to be a governor on the top speed.)

Power - I'm pretty happy with the 325 ponies; I'd vote for the supercharger package(Lingenfelter also offers a package for the Denali/XL) I don't think going with the Hypertech for only 20hp/20ft-lbs gain is worth the effort. With these big rigs it's the amount of torque that really counts when it comes to making them quicken - that's where the supercharger will really help.

lobsenza · January 2003

Can you tow with a supercharger or would it put too much strain on the engine?

larry91 · January 2003

What does Lingenfelter offer for the Denali and how much?

John did two engines for me about 8 years ago. He did a great job, but my Vette was at his shop for two years. I haven't talked to him in a long time and didn't know he had a performance modification for the Suburbans.
Thanks,
Larry

orwoody · January 2003

I haven't dealt with Lingenfelter directly and did most research via their site and reviews. It's been a while since I visited their site. It's changed quite a bit and doesn't have as much info as before. They are listing the superchargers for the 4.8L, 5.3L and 6.0L at $5150. It doesn't say if the package is installed or just the supercharger kits:

http://www.lingenfelter.com/lingenfelter/product.asp?dept%5Fid=12- - 5&pf%5Fid=544

I was looking into them as they offered a conversion for the Sierra C3(now Sierra Denali) and they were going to offer packages for the Denali/XL. Back then the prices for the supercharger and some other treatments were in the $9k to $10k range. I decided to go with the Denali, am quite happy with it and didn't pursue supercharging.
My dealer had a Supercharger that they were/are offering but I can't remember the mfr off the top of my head - I recall it was also in the $5k-$6k range.

For lobsenza - supercharging is okay for towing - some race guys will supercharge their trucks used to tow their race vehicles and supplies to gain the power and avoid having to buy another rig. With proper installation(the kits will sometimes have upgraded parts for the engine) and aintenance there should be no problems.

obyone · January 2003

is the HP rating of the trans. You wouldn't believe the addtional strain placed on the trans with the increased HP.

orwoody · January 2003

Good Point, the transmission and some other driveline, suspension parts could be affected which is why it is good to work with someone who has experience converting and gives a guarantee. May also need or desire an upgrade to brakes.

erinsquared · January 2003

Take a look at this link to see the torque and gear ratings of the transmission in the Denali (and other products).

http://www.gm.com/automotive/gmpowertrain/transmissions/hydra/app- s/4l60.htm

Not sure if adding a supercharger would exceed the max torque ratings since I have not found any dyno graphs. Anyone have dyno data?

obyone · January 2003

a mechanic shop owner friend of mine just told me this story when playing a round of golf on Tuesday. They had installed a SC on a 01 Yukon with the 5.3, rear locker and 4L-60E trans. The had completed the work on Friday evening. Saturday afternoon he gets a call from the owner of the Yukon who said he thinks he blew the trans while doing a burnout. Upon inspection on Monday, they found that the torque converter was shot and the rear locker shattered into thousands of pieces.

If I were to add a SC to either the Denali or the Silverado that I own, I'd seriously consider one of these to go along with it.

http://www.transmissioncenter.net/4L80E.htm

Course you'd have to upgrade the rear end too.

stever · January 2003

More GM incentives announced.

Steve, Host

jammon1 · February 2003

The Lingenfelter kit installed kit is about $15k. That includes a magnacharger, headers, exhaust, hypertech programer, and transmission kit.
I put a magnacharger SC on my 01 DXL. $4300 installed by by my local GMC dealer. I too was a little concerned about the transmission, considering the problems some have encountered. So far I have not had any problems. During the summer I tow a boat. With the SC it feels like the boat is not even there.
As for speed, average 0-60 is about 7 seconds. Top speed is unknown but I have had it to 123MPH (w/ proper speed rated tires). Where I live I have not been able to find a dyno that can accomodate the all-wheel drive. I guess about 100 HP increase as magnacharger indicates.

gswenson · February 2003

What kind of mileage do owners of Denalis report? I have a 'burb (w. the 5.3 liter) and get around 17. Between the bigger engine, and AWD, what kind of mileage penalty is there?

Also, with all the incentives out there, how much off sticker would constitute a good deal?

lobsenza · February 2003

We get about 13.7 around town in a DXL.

orwoody · February 2003

Lately with winter gas(10% ethanol) my around town mileage dropped to 13-14mpg from 14-15mpg. My highway trips have yielded from 16-20mpg. Since my freeway driving is rarely less than 65mph I believe that if stuck doing 50-60mph I would get near 20(or more) consistently.

orwoody · February 2003

here is link to Lingenfelter web page refer to 1755
http://www.lingenfelter.com/pac6ltmagsc.asp
per the kit they do quite a bit of modifying to the engine, new camshaft, pistons, HD rod and bearings, and also replace the torque converter. Tranny rebuild is extra. It does come with 2yr/24k warranty.
at $15700 it's almost double what they advertised when I first looked at them about 2 years ago. (but you do get the Lingenfelter name)

jtbuff · February 2003

Get 14.5 around town on my DXL. On the one trip we took around 16 mpg. Only have 4000 miles on it.

hut2 · February 2003

Around town I'm getting 14.9 - 15.2 consistently. Of course, my 'around town' is very flat (Delaware) and rural (few traffic lights). Highway yeilds 16.8 - 17. All of this is on an '02 DXL with 19k since June and regular oil changes with synthetic oil.

ahesq · February 2003

Follow up to my post regarding front differential whir/whine:
It turns out that the front differential unit was low on gear oil (about 1 pint), but showed no signs of any leak. How could it come out of the factory like this? In any event, the noise is now 90% gone with 2100 miles and a topping off of gear oil.
I only wonder if any damage was done to the gears.

I don't know the front diff capacity in order to evaluate. Is one pint a lot??? Your thoughts would be welcome.

Thanks

obyone · February 2003

I'd be more concerned on how the vehicle left the dealership low on fluid than the factory. Afterall, they are suppose to check the fluid levels as part of the prep that they charge for.

Being lazy myself, I didn't bother to check the quantity of fluid required for the front differential. It is included in your owner's manual if you really wanted to check. I'd keep the receipt of what the dealership did as far as adding the fluid in case there was any long term damage done. There must have been some amount of additional wear as the sound or whining would indicate. How much additional wear would be impossible to predict.

I would recommend that you have the differential unit drained and replaced with fresh gear oil as whatever extra contaminants that was created during this whine is still in the fluid acting as additional abrasives....something which you don't need.

donahues · February 2003

Just hit 6k (Denali) and did a 250 mile all highway trip this weekend (flat roads). Got 15.2 mpg with cruise set to 76. Why such a low mileage? Was burning 87 with proper inflation (just had the car aligned that day) and burning a winter blend. It was about 10 degrees outside.

jgmilberg · February 2003

Not sure but I think there was a TSB on this and they were supposed to change the front diff. lube to a thicker one. A number of things could have cause it to be one pint low from the factory, but like it was posted before the dealer should have caught it during the prep process. A pint is 1/4 of 1 quart or 8oz.

tidester · February 2003

A pint is 1/4 of 1 quart or 8oz.

I'm sure that's a typo - there are two pints in a quart.

tidester, host

GMC Yukon / Yukon Denali

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