A few questions

SilentBob · August 13, 2002

Yesterday I was speaking with a friend of mine who has the same truck as I do, 2500hd duramax, after he had returned from 1400 mile trip over into California. He was rather concerned that he had only gotten about 8 miles to the gallon hauling a 12,000lb toy hauler and he also seemed to think he wasnt making as much power as he should as he spent alot of his time in 4th gear.

His first thought was to do some mods to try and rectify the situation and after the research I had done I thought the Edge computer or one of its clones sounded like a good cheap solution to the problem and I passed the information along to him.

After speaking to me, he went down to one of the larger speed shops here in Phoenix and spoke with a friend of his who is a PSD guy about what he should do. The friend basically said skip the computer and do the following:

1 Exhaust

2 K&N Intake

3 Calibrate the injectors

4 Tighten the turbo

Now the first two seem pretty obvious to me and even with the computer I would assume that you would want to do those. The third I am not clear on and the fourth completely eludes me as to what the #### he is talking about..

I guess my questions break down about like this.. #1 I imagine the "Calibrate the injectors" means to flowbench them to determine flow rates? Am I close on this one? #2 What the #### does tighten the turbo mean? #3 Since this stuff will cost at least double what the computer does, is it worth it? #4 Should he even be stressing to begin with about 8mpg and driving in 4th pulling 12k?

SB

bluenote · August 13, 2002

It sounds like he's getting lower mileage and having more downshifting problems than he should with a stock truck. So, before he does any of those things, he needs to have the dealer check for ecm/tcm updates for his truck. All of the 2001's and some of the 2002's have software upgrades which will help his truck's towing performance, particularly the excessive downshifting. Also, if he's running cruise control through a lot of decent grades, he's going to have some downshifting regardless. Cruise control just doesn't have the touch that one can get when when running the accelerator on their own.

Your buddy could do all of the things that the guy at the shop suggested, but chipping is the cheapest way to get the large performance gains. Many people who are running the Edge "Juice" box, or it's equivalent, the BD EZamp, are also running different air filters/boxes (Amsoil is used by many, instead of K&N) and larger exhausts. It's also recommended to install boost and egt gauges when running these chips. If he's happy with the performance with the truck running empty, then the computer updates to his truck would likely be enough to make him happy when towing. If he really wants the top performance, the quickest way is to chip the truck.

SilentBob · August 21, 2002

Good info, Ill tell him to go check for updates.

I still dont understand those last two mod options though, anyone got a clue?

SB

dmaxdiva · August 22, 2002

I echo Bluenote's sentiments exactly. I have the Juice box on my truck, as well as a K&N, Banks Monster exhaust, pyro & boost gauges, etc. The Juice is definately the way to go for cheap, relatively safe HP gains.

As far as injector calibration and "turbo tightening" go, that's the first I've ever heard of such, with the DMAX anyway(although I'm by no means an authority). Frankly, a Juiced DMAX will beat the pants off a PSD, even one that has been heavily modified...and I know that from personal experience! :;):

SilentBob · August 22, 2002

Well 2 for 2 on the computer. I still wish I knew what that other crap was.. Thanks for the info folks.

SB

bummed-n-Md · August 23, 2002

As to 'turbo tightening' I believe he is probably referring to making sure all "hoses, pipes or tubes" are sealed tight so as to prevent any preasure or vacuum leaks. When I lived in W.Va a number of years ago, I had a friend who used to be a heavy equipment mech in the W.Va coal mines. One of the first things he would check when operators complained about 'power' was the turbo 'system'. Half the time, after a preventative maintenance cycle, intake or exhaust work, everything needed re-tightening about a month later. After a while, as part of his 'daily service checks', he started checking all the tubo system fittings and would tighten anything loose. It stopped most of the power loss complaints.

bummed...

MarkD · August 23, 2002

I am not a diesel owner, but have had some experience in the area.

Calibrating the injectors is never a bad idea. You are correct in assuming that this means matching flow rates on the injectors. I always figured this was done by the factory...surprise, surprise, surprise!

Bummed's comments don't sound like a bad idea regarding tightening.

I also spoke with my father (diesel mechanic for 30 yrs in Savannah,Ga). He said that if you can't install the gauges with the "juice" boxes, then don't do the boxes. He does not consider them an option. A good comparison is a scattershield bellhousing on a 7 second dragster, not a good idea to drive without one.

Colorado Kid · August 23, 2002

The bosch common rail injection system used in the Duramax balances it's own injectors for one thing, and they are harder than **** to get at for another, so calibrating the injectors has not happened on any Duramax that I'm aware of.

A lot of folks swear by their intake mods, but at least one outfit has tried removing the entire assembly ahead of the MAF sensor and found no difference on the Dynamometer, so there's not much to be gained there in terms of power. The 3.5" mandrel bent exhaust that comes stock on the D-max would have been considerred a high performance system on any earlier truck, there are small gains to be had by going larger, but not big ones.

Tightening the Turbo may mean screwing up the tension on the wastegate, to achieve higher boost. This again may be relevant to PSDs, but stock an near stock D-maxes do not suffer from inadequate boost or intake airflow in general.

ECM/TCM reflash at the dealer is a good idea. Juice is not a bad idea. On of the issues addressed it too uch downshifting when towing. As for Juice without guages, I would only run in Level 1 when towing without guages, but I don't think you can hurt it solo.

How fast was he going? I haven't dragged anything quite that heavy, but my 5th wheel is probably not a whole lot more aerodynamic than his toybox. I tow at 65-68 MPH (old 5'er, old bearings and tires that are not speed rated--the higest speed limit was 55 mph when it was built) and so far have gotten 14 MPG or better. Of course I don't have any problem with it shifting when I don't want it too :;): (see signature).