Is it just me or has anyone noticed a difference in take off from a dead stop (not riding the brakes to spool the turbo) the lag on the LLY is more noticeable vs. the LB7? It seems to take longer to get that throw you back in the seat feeling...


Is this because of the new Variable vain turbo, it takes longer to spool up from a dead stop?

I would say its more because of the restricted exhaust flow with the cat.

Is what you detecting turbo lag or could be EGR probems?


See message below..


My brand new 2004 2500HD, Duramax (LLY) is at the dealer due to engine hesitation between 1600-2000 RPMs. The dealer states that the EGR valve must be replaced. The truck only has 1,000 miles on it. Has anyone else had this issue? Is this a wide spread problem?


I hope this is not a sign of more trouble yet to come. I tow a 11,000# fifth wheel and don't need these type of problems on the road.

I believe it is lag because it is only from a dead stop and only in first gear for a few seconds. Once it picks up a little speed I can hear the turbo spool up, then it's like a rocket. When I am rolling in that 1600 to 2000 range I don't notice any type of lag in any gear.

This all sounds backwards. My understanding of the VVT, is that the whole premise is to reduce/eliminate turbo lag. It is turbo lag in a normal turbocharged system that is causing a lot of the emissions problems because the air/fuel mixture before the turbo gets up to speed in a normal system is way rich.

That is what I thought also.


Maybe I am still remembering my 03 that I had a Quad 60/110 module and that truck took off! I should have took the module out and ran it stock for a while and maybe I wouldn't be noticing a difference.


Just a thought...

Don't forget about 1 and 5 gears are still at LB7 power levels.


They have to cut something to reduce the power, so that could be what u feel.

Having driven both vehicles right after another (2500 HD 4 x 4 CC Short box) there was a huge difference indeed - but the other way around! The LLY moved much quicker off the line comparable to the LB7. Why should GM also spend time and effort to built a variable charger if it doesnt work? The trick is to have a small charger from the start (w/o lag) and a big charger later on to make power, thats what the variable vains are for IMHO.
MK

the variable turbo has absolutely nothing to do with boosting performance, its used for emmisions mainly. The egr system on a gasser needs crankcase vacuum to suck the gasses into the engine, diesel dont make that.... so.... the turbo vanes are manipulated to put a negative pressure in the crankcase and thus suck in egr gasses...


its also used to load the engine during high idle to put some heat in it.....


again, nothing to do with performance

I do NOT completely agree with that!
True the VTG was probably mainly installed to reduce emissions buts thats not all. The VTG does have more advantages:
- higher torque (boost) at low engine speeds (you feel that in the LLY comparable to the LB7)
- better transient response (drivability)
- increase in braking power at low and high engine speeds
- drive EGR at part + full load to reduce emissions

MK

I have had both and i feel the LLY has more lag off the bottom than the LB7 but pulls harder on top. Just my opinion.

It is the turbo or the way the programming controls the turbo. It is really easy to notice on a 6 speed truck.

The LLY is a dog off the line. Even power braking I can't smoke the tires. Turbo lag is much worse than the LB7. I Hope Edge Products can fix it soon.

My LLY has less turbo lag but IMO the limited power available in 1st gear makes the truck feel very lethargic until after the 1-2 upshift. Get a clue GM, we want more power and we want it all the time! http://www.dieselplace.com/forum/smileys/Angry.gif

FASTOYS


That is exactly my opinion!


I am glad that I am not the only one seeing this.


RaceHemi


You are right, GM better get a clue!

Yep. Power braking the LB7 with chip was pretty easy !


Powerbraking the LLY with chip is alot harder but once it gets wound up, look out ! Maybe this will save my pocket book from buying tires. Urrrrrr notttttt! lol

I have severe turbo lag when cruising at about 50mph and the tranny drops it to fifth. I hold the pedel down to the sweet spot and it takes about 15 seconds to build anything over 5 psi.

I called Banks and they are not ready yet to offer the six gun diesel tuner. The reason is all the electronics involved to control the VTG turbo and other stuff (which keeps tires from spinning etc.) makes it so much more complicated to deal with. Fact is that the LLY produces more torque at a lower rpm than the LB7 which comes from the turbo and new cylinder heads since the block is still the same...If you need easy power upgrades you are better of with the LB7 and put on the biggest non VTG turbo you can fit along with the proper modules to support it. But I dont understand why you not drive a Corvette if you just want to smoke tires... the LLY is meant to pull a heavy load IMHO

You dont have to agree with it or not, it wasnt opinion, it was fact from Duramax Engineering...


Internal engine remains the same as before, cyl heads are only different in the aspect of injector mounting..

So WHERE come the +10 HP and +70 ftlbs. torque come from if the VTG turbo has NOTHING to do with it? Just from mounting the injectors in another way- if EVERYTHING else is the same?
Anyway the fact regarding the VTG remain the same, whatever goal GM had in designing it. BTW the duramax is NOT a GM but ISUZU product (with Bosch common rail injection), dont know who is responsible for the LLY changes, maybe you would know?

Same place it comes from when you add a box or a programmer. The GM/Isuzu engineers knew how to do it before, Edge, Quad, VanAaaken, Banks,etc, on the LB7. And they know how to on the LLY.


Power output level decisions are made by committee, taking in to consideration the various limiting factors throughout the vehicle's systems. They consider all factors before selecting the programming of the engine management computer.


It's a sometimes complex trade off between reliabilty vs. marketing bragging rights.


I'm not an automotive engineer, but I did stay at a Holiday Inn Express last night http://www.dieselplace.com/forum/smileys/Big Smile.gif!

Programming is responsible for a great deal of any power... Look at what those little boxes can do! I have seen many boxes easily put another 200 hp to the ground by themselves with out putting so much as a wrench on the truck


I dont know what they base numbers on but they have a fine line between emmisions, economy, cust wants/needs, insurance people, longevity, etc. etc. etc.


Dodge has that big 600 out...just cant get it in some states cause it dont meet emmisions....Big numbers mean 0 if ya cant buy it in CA or VT.http://www.dieselplace.com/forum/smileys/Disapprove.gif


I realize that the engine is mostly Isuzu/Bosch, but GM none-the-less. GM owns Isuzu and has deep ties in Bosch. And they own Allison as well...

Thanks for that good infos. I am realizing that the Duramax is getting less reliable and I dont like that move in the wrong direction. Just because people want / need more and more power (for what?). I am spoiled with utmost reliability (from driving Landcruisers for more than 10 years without any brakedown, most of that miles where diesel miles delivered by an inline six 4.2 ltr. turbodiesel). If the duramax cannot deliver that promise I can also keep my fun SUV/truck Avalanche, at least that one rides like a dream (in comparison the the LCs).

But I dont understand why you not drive a Corvette if you just want to smoke tires... the LLY is meant to pull a heavy load IMHO


I not drive a Corvette because it not pull RV!Edited by: CntrlCalDmax

Dodge has that big 600 out...just cant get it in some states cause it dont meet emmisions....Big numbers mean 0 if ya cant buy it in CA or VT.http://www.dieselplace.com/forum/smileys/Disapprove.gif





What are you talking about? Get your facts straight. The 600 is 50 state emmisions legal. the 2003 305 HP model was the one your thinking of.

mahalkita

What are you basing your reliability comments on?

Dodge has that big 600 out...just cant get it in some states cause it dont meet emmisions....Big numbers mean 0 if ya cant buy it in CA or VT.http://www.dieselplace.com/forum/smileys/Disapprove.gif





What are you talking about? Get your facts straight. The 600 is 50 state emmisions legal. the 2003 305 HP model was the one your thinking of.


my bad, didnt research it enough, just going on rumers... point is.. and you made it, that the 305(then) dont.

I believe that when Engineers design an engine there are many factors that are considered. Fuel mileage, emmisions, HP, torque, reliability, comfort, (ease to drive), marketing, price, durability and many other factors. It would be nice if we could have all the above. But the reality is that every thing's a trade off. When Isuzu and GM designed this engine JOINTLY! that they looked at all these issues and came up with a compromize. They tried to do the best they could given current technoligy. To compare it with the LB7 is unfair. It may share some common componants but thats it. I would not try to guess what the REAL driving force was in designing this motor. I would hope they saw some faults in the LB7 and tried to build and engine that was improved (next generation). IE; high idle and turbo exhaust back preasure for warm up. Engine braking through the turbo etc. The bottom line is the LLY is a diffrent engine than the LB7 and it is going to run and perform diffrently. We need to understand and except that. As far as reliabilty is concerned I think it is way to early to determine faults in this engine. A certin amount are going to have turbo failures, pump failures, glow plug controler failures, engine bearing failures, water pump failures and other failures of any nature. I don't think we have seen any real repeat patterns yet. Turbos and injectors can be a week link. Time and mileage will tell. For now lets just enjoy and drive and all agreee there is no going back to gas! We are all here because WE LOVE DIESELS!

RaceHemi,

after I have read all the comments (early failures...) of the new LLY engine I compared this with my own experience with the japanese made trucks (Toyota LC) I have driven for more than 10 years. Those trucks never had a problem of any kind. I am still waiting for my new truck (Duramax) to be build.

Some of the well known Japanese makes didn't make into the top 10 for quality according to JDpower results. Pretty neat that some American brands scored very high. Caddies are better than Nissans etc.... I had a Nissan truck by the way. It needed the transmission replaced at 28 miles. It needed a new wiring harness at 150 miles after it shorted out. Spent a month in the shop. Never buying anything but American again.


Jeff

Jeff,
I am just talking from my personal experience. The Nissan truck you had was probably made in the U.S. and is basically speaking an american car (made in America for American people).
If you compare the Landcruiser with the Sequoia you will notice the LC costs almost twice as much (the LC is made in Japan opposed to the Sequoia made here)- the LC is surely the much better build truck. There are many people with different experiences (good and bad). I personally love the Avalanche of my wife, never had a problem and rides like a dream, costs about half of a Landcruiser has more power and space....thats why I bought it. It presents a very good value for money. The LC is still better build with nicer materials used throughout though. I think the american made cars have improved a lot over the years, forced by strong competition - which is a good thing for all of us (Toyota will be no. 2 after GM within this year and there is little doubt they will overtake GM also in the near future...). So I will wait for my american made Silverado 2500HD Duramax to be build and I am sure I will be very happy with it!
Frank

I must admit I am somewhat surprised with the lag off the line on the LLY (no experience with LB7). I have 6k miles on mine and have to admit the power and torque are very impressive when it spools up and when towing an 8k TT. The lag reminds me of my 79 Ford Capri turbo http://www.dieselplace.com/forum/smileys/Ermm.gif. I didn't buy it for drag racing but would like a little more oomph off the line.

I must admit I am somewhat surprised with the lag off the line on the LLY (no experience with LB7). I have 6k miles on mine and have to admit the power and torque are very impressive when it spools up and when towing an 8k TT. The lag reminds me of my 79 Ford Capri turbo http://www.dieselplace.com/forum/smileys/Ermm.gif. I didn't buy it for drag racing but would like a little more oomph off the line.

Ditto.

I used to be pretty heavy into turbo cars (a few Omni GLH Turbos, Shelby Daytona, and an Eagle Talon), but over the last few years, I've been more into V8s ('00 WS6 T/A, '01 Z06) Not to mention, last two trucks were GM 5.3Ls... so I kinda forgot what turbo lag was all about. I've been used to that "instant" hit when I jam on the gas.

This truck definitely reminds me of what it's like to drive a turbo. Every time I need to leap out in traffic from a stop... or quickly jump over into the faster-moving left lane on the expressway. Floor it, and wait.. wait.. wait.. GO! Kind of frustrating. I hope when the Edge is released for the LLY that it takes care of this - I definitely didn't expect this much lag from a VGT-equipped truck. I've driven a car with a VGT turbo ('89 Shelby CSX), and the power was INSTANT. If it wasn't for the "LLY" printed on my glovebox sticker, I'd think I wound up with an LB7 truck.Edited by: OmniGLH

are you guys forgeting the 7K lbs it has to push around?

And the fact that it now has to push harder to get the exhaust through all the restrictions. My LLY definatly is much quicker than my LB7 was.

I ran mine in the quarter today with my G-Tech just for comparisons against my old LB7 and the LLY IS quicker and definetly faster !


LB7 with 120 edge = about 94mph


LLY with qaud 90 hp = about 98mph


It DEFINETLY takes much more boost to get it going out of the hole though. I dont have guages but could hold my LB7 for about 3seconds and get a good 4wd launch.


LLY takes at least 5 sec. to get much .


I know they are not race trucks and prolly not everyone will agree but this is just to back up what most are saying and what i have found !

Who makes the quad chip and how much are they?

QUADZILLA is the name brand .

There is a group buy going on the LLY Juice/attitude, reserve one at the best price before release. LB7 shipping now.


http://www.dieselplace.com/forum/forum_posts.asp?TID=5553&PN=1&TPN=3

I tried to look at the thread but it said I didn't have permission what the?