Which Way Do I Go , Which Way Do I Go?

[logfarmer]

Hi You all,

I just picked up a new to me 2001 Silverado 2500 HD (see signature). I made the deal about a week and a half ago but the owner agreed to fix a few things before I took delivery so all that waiting time has been spent pouring over this forum looking at what I might do to the truck and just getting information about it. Ive only had it two days but what a pleasure to drive compared to my 83 ford diesel you talk about acceleration delay, that ford had acceleration delay I am not sure after only driveing it two days what the lag before acceleration exactly is but Im compareing to an old diesel so maybe that explains it.

When passing with the Silverado from about 50mph there was not as much pickup as I would have expected compared to a 70's Buick deuce and quarter I had with a 502 or something like that.

The Silverado jumps up and goes but just doesnt seem to go as much a I expected is that the tourque management I read abput here?

But really I could live with that it still has plenty of power at least compared to what Im used to.

I just retired to my place in Eastern Washington so most of my driving is rural and I dont want to hotrod the truck or beat anybody off the line. The closest large town, Colville is 35 miles away posted limit is 50 on winding country roads not much elevation gain or loss exept for some slight up and down. The next destination is Spokane 65 miles further at 60 mph limit again mostly flat a few hills maybe 300 ft higher, this 100 miles is where I will do the majority of my driving. I will be pulling a 7x14 cargo trailer loaded about 4k to 5k at times once a month or so. In addition I will go back an forth to Seattle 400 miles one way several times a year.

I have noticed that at indicated 60 mph (about 63 with the 265 tires) the tach shows 1900 rpm so most of my driving will be around 2000 rpm even at 70 indicated it was only at about 2300 rpm.

My question is about maximizing economy I have read here that the custom tune is probably the best way to get an increase in mileage and performance for the money. I really think I am happy with the performance as it is the truck has lots of power and should be able to do all that I want it to do. So what mods would be the most efective at increasing economy at around 2000 rpms?

I am willing to go back to the stock size tires of 245 its just that 265's is what the previous owner has on the truck.

I have read that the stock air intake is pretty good on these trucks but maybe the GMPP CAI would help, or just a new tube from the filter box to the intake. It does have a muffler shop dual exauhst installed presently with factory pipes back to glaspacks then about 2 1/4 back to the rear bumper. The glass packs are pretty loud so I will probably take them out and put in something new from the cats (there are two catalytic converters) back.

I dont expect to get good mileage Id just like to do the best resonably posssible for a 496ci.

So given the type of driving I'll be doing what would you all recomend?

Thanks in advance.

Martin

[bryanhunt]

The 50-70 thing is probably because it's not downshifting. You can specify to a tuner what you want the shift points to be like.

 

Torque management is associated mainly with off the line performance. Passing speed and downshifting is a fuel conservation thing. Often you mash the pedal and it just hums along up to whatever speed when most people would have downshifted if they had a manual.

 

To get more of an idea it would be useful to know what size tires you have and what your rearend ratio is.

 

Edit I noticed that you did mention it was running 265s instead of the stock. I'm wondering if the previous owner actually took it into the dealer to have the size changed. If its not right then correcting it will help.

[logfarmer]

Bryan,

I called the previous owner he did not have the tire size adjusted in the computer so it is still running 245's as far as the computer is concerned.

 

Martin

[Haulin' 8.1]

Logfarmer as far as power and mileage improvements it helps to keep it in tune. Due to low tension rings there is oil consumption and plugs don't stay clean for 100K no matter what the EPA mandates. If you pull a plug you'll see what I mean. A new set of plugs, air, and fuel filter will wake up any 8.1 at that mileage. Make sure that the basics are good before you decide you need performance upgrades as they usually reduce mileage. If the crank sensor has not been updated yet you should do that asap. The '01 sensor is problematic. Do a search and you'll see. Going back to 245 tires will help mileage. Your best bet for mileage is conservative driving speeds and not putting things on the body that will add wind drag. If you install a high flow filter be sure it's boxed for cooler air. A Magnaflow muffler sounds nice without being overly loud while matching the stock pipes well. The two things that hold the 8.1 back the most are the programming and the camshaft. Those are the two most cost effective things to modify for power. Comp makes a small cam that optimizes mileage with an increase in power. Most of the other bolt ons don't compare for the costs to benefit ratio. Torque management is just about gone half-way through second gear, do a tune up and you'll find your passing power there.

 

Don't overlook the GM Gassers forum at dieselplace.com there's a lot of 8.1 discussion there also.

 

Vernon

 

Vernon

[andreancic]

I have a very similar truck. I purchased the Hypertec Power Programmer III and it let me adjust for the change in tire size. I also like the fact that I can adjust the octane to run on 87 or 93, but I can;t change the shift points for the Allison. I am running 265 BFG TAs. I also have a magnaflow muffler with 2 1/4 to the rear with 2 1/2 dual tips. I also have a K&N FIPK. Have you thought about checking the mass air flow sensor? I have also switched to full synthetic in oil and tranny fluid. Hope this helps.

[logfarmer]

A tune up sounds so boring but that is probably good advice for a place to start I hadnt thought about the oil consuption ruining plugs faster and it does probably need to be done.

So an air filter, fuel filter and spark plugs and I assume just the standard issue for all these? I noticed in your signature that you have a special plug but it sounds like the timeing has to be modified in order to take advantage of the plugs you speak of.

 

Tomorrow I will call the dealer where all the privious maintainace was done and see if the crank sensor has been changed.

 

Going back to the 245 tires would be fine exept for now I got an allmost new set of four 265 snow tires and rims included with the truck and I hate to not use them up. The regular summer tires are close to worn out so they will have to be replaced soon anyway. Maybye I can find someone localy who wants to trade up a size or something.

The cam looks to be about 380.00 at jegs but I will wait and see what the tune up will do.

The 75,000 mile service recomends changing the allison trans oil, maybye this is a good time to go to synthetic?

Sounds like magnaflow is a good way to go with this rig.

I'll try the other forum.

 

Thanks,

 

Martin

[Haulin' 8.1]

On the tune up parts, standard issue is fine as long as you stick with proven brands. The new synthetic air filters are nice, Purolator Pure One or Fram Syn Wash. They are a nice upgrade in flow and capacity for a stock air box for the money. Maybe NAPA or Wix for the other filters. I wouldn't worry about the most expensive plugs as you should change them before 50K anyways, a good single platinum will do. Avoid Bosch platinum plugs altogether. My plugs work with increased timing like a progammer or tune will provide but due to being one step colder they may foul sooner on a stock tune. A good fuel injector cleaner is also good medicine. Remember these engines use about 3 times the fuel of a common car so fuel related maintainence should be done 3 times more often than those.

 

If you need a new crankshaft position sensor make sure that a "crankshaft variation relearn" procedure is done at the time. It helps in enough cases to warrent the small increase in price.

 

New tires are usually easily found as guys want the big look and take the stockers off almost before leaving the dealer. Try Craigslist or the net for sale/trade forums and you'll find some. In any case shifting and mileage, speedo, etc. will suffer without a correction in the PCM for the tire size. Handhelds aren't worth the money, buy a good tuner's services after you get settled on your set up.

 

The cams go for about $320 if you look in the right places, Tbyrnemotorsports,Comp direct, sdparts.com (Scoggin Dickie GM Parts) etc. Depending on which grind you go with you may spend $400 altogether for the adjustable rocker arms that are needed. Comps Tri-power series may work as is but ask them. SDPP can advise you on low cost factory parts you need.

 

The Allison holds a bunch of fluid so buy in bulk. Also when changing the spin on filter be sure not to loose the magnet that comes off with it, clean it and put it on the new filter.

 

Vernon

[Burbman]

Agree with previous recommendations. The plugs are supposed to last 100K, I changed mine at 75K and they were ready, I've talked to several other folks with similar experience. I have 265's on my Suburban, and never did any programming to compensate for tire size. The diameter of the 265 vs 245 is close enough that it shouldn't be a big issue with the computer. Although I have heard that the Ally transmission is more sensitive to tire size changes especially as it relates to shift points (I have the 4L80E in the Sub).

 

I would tow the trailer once or twice before you spend any $$ on mods. The interesting thing about the 8.1 is that it's drive-by-wire, meaning the gas pedal is only one input point to the PCM, there is no throttle cable. The engine is programmed with a lot of torque management, and it needs it. Otherwise, running without a load, you would light up the tires every time you stepped on the gas.

 

The 8.1 does not "feel" fast when driving it around, BUT, hook a load to it, and you'll feel the power. When under a load, the torque management really lets the motor open up when it has a job to do. Remember the engine is being controlled by the PCM, not by you.

 

Once you see/feel the performance of the engine while towing, that will give you a better sense of what mods, if any you need/want to make, inlcuding smaller tires.

 

Welcome to the single-digit MPG club!!!

[logfarmer]

Vernon,

The diesel place was a good tip there was a whole lot of good info over there took about 3-4 hours of reading and not even close to done yet.

I was thinking to replace the air and fuel filters with a stock ones from the dealer the plugs AC 41-932 with a gap of 45 thousandths, start using chevron 93 octane and put in some techron for a few tanks to get it cleaned out. It sounds as if the synthetic air filter would be better so I will do that.

Are the special pliars for removing the spark plug boot necessary? Sounds like it might be cheaper to get the pliars than to replace a boot or two.

The comp cam is tripower extreme optimized fuel milage and good torque horspower # 46-525-9. Called them and they said that that cam would require no changes to the valve train it is a straight replacement and it is the best one for milage gains.

On the trans fluid is it worth the extra $ to get synthetic? I read on another thread here that it took about 2 or 3 drain and refill cycles to get all the old fluid replaced and the new in, if that is the case it would be real expensive to go to synthetic.

 

Burbman, it is my sincere desire to avoid membership in the club you mentioned I dont even want to say the name of it, allthough my choice of vehicle may preclude my desire to avoid.

When I was driving home from picking up the Silverado there were several hills of modest grade maybye 2 or 3 % at 60mph and 1900 rpm I kept waiting for it to downshift but it woulndt. You could tell it was hunkering down a little more but it never did downshift.

That was kind of nice Im looking forward to hooking up the trailer to see how it does.

Then I will probably be in the club you mentioned.

Martin

 

PS Does anyone have an email adress for ABQFirefighter? I was reading on a post about a programer for an 8.1 and he said that he had a Westers tune PCM for a 2001 in his garage.

[logfarmer]

The crankshaft position sensor was replaced at the dealer in June of 06.

Martin

[Hulk1999]

Logfarmer,

 

I was reading about Wester's Tune and decided to email them the other day. They told me i could get a 100hp increase and 4-6 mpg on my rig. Has anyone gotten a Wester's tune? Are their claims creditable?

 

Hulk

[logfarmer]

Hulk,

That sounds unreasonable to me from what Ive read on these different truck sites. That is more like twice what people seem to be getting. But maybe westers is extremely good I dont really know for sure. Do a search on Westers and you will find all kinds of info.

Martin

[BigJayDogg3]

I read elsewhere on here that Wester's claims weren't accurate, but they do see a significant difference.

[lord-dogbert]

I have an 03 8.1l with the Allison, 96k miles. Stay with the Allsion Transynd and pick up your allison parts at a big truck dealer like freightliner, Kenworth or such. Go to Allison's sight for dealers near you.

 

I currently haul a 38' toy hauler scaled in at 14,900 pounds. My previous trailer was 30' and weighed in at 12,000 pounds. I've only had one hill tame me, Sherwin Grade on the i395 outside of Mamoth, I took this at 35 at 4200 RPM. I've hauled all the way to Wisconsin and back. Aside from mpg I wouldn't give up my 496.

 

I just picked up the wait4me tune, i'm still testing but this gives the same results as Westers for a whole lot less. You have to have patience as wait4me literally means wait4me.

[logfarmer]

Just for fun I floored it from a dead stop a couple of times today it chirped the tires or hopped a little each time, well maybe I tried it six times, or more. Anyway I sort of see the acelration lag but it dosnt seem that bad. This truck really moves out! Its going real fast real soon.

When I called the dealer he said that the trans fluid had been changed at 50k which would be 25k ago. He said just to remove the filter and drain it but dont take off the pan and get up inside and dont let enyone talk me into power flushing it, that GM had sent out a service advisory against that.

 

Im curious to see how the wait4me tune goes for you, did you send in your PCM, get a new one, or get the tune on the SCT excaibrator so you could get three different ones.

Speaking of three different ones I read somewhere that if you use the mileage tune you shouldnt go back and forth between tunes as the milage on requires consistent use of itself to learn how to save fuel and gets confused if you try to switch back and forth from one tune to another?

Martin