Reduced performance after dealer re-programming

[Jim Rokon]

Our 2001 Chev. Silverado 4wd 3500 Crewcab had a 2-second automatic transmission slippage trying to pull a 12500 lb. 5th wheel trailer out of dirt (trailer wheels sunk in soft soil 3" deep). I neglected to put it into 4WD-Lo. That triggered 3 malfunction codes which put truck into "Limp Mode" where only 4wd Lo would work until we saw a Chevy dealer. The dealer upgraded the control software and we were left with a dramatically reduced power output. This was felt immediately when we left the dealer and confirmed on a 3 mile long Interstate grade where a previous climb pulling identical gross weight dropped 9 mph top speed near the top of the hill.

The Chevy dealer said he did the latest GM software and there is no going backwards to the old OEM software that we enjoyed with the truck for the first 2800 miles before this problem. While previously marginally satisfied with the truck's trailer pulling performance, I am now really disappointed with it. I am really angry with GM for this sleight of hand with hp/torque in reprogramming the controller, and suspect they did it to protect against future warranty claims. Basically they castrated the truck and it no longer has 300 hp and 520 ft. lbs. of torque as advertised by GM.

Can anyone express any similar experience and what is the ultimate way to deal with theis GM approach to performance. I suspect the snap solution from most of you would be: "Just buy "the Juice". I'd prefer to know more. Ultimately if I install the Juice box, have a failure of some sort, pull off the Juice box, bring it to a dealer, will there be any hidden indicators buried in some computer that will get me in a compromising position with respect to warranty?

I don't want to put on a larger diameter exhaust system since that will be very time consuming to remove if I have any warranty problems that must be addressed by a Chevrolet dealer. If I leave it on, I might have to fight with the dealer that could conceivably claim that putting on the larger diameter exhaust allows more engine performance which then had the ability to cook the transmission. A logical position, in my view.

Can I get substantial improvement with ONLY putting on the Juice box?

Also, if any of you have had this kind of performance loss or lack of performance loss, or improvement in performance following the upgrade in computer programming from the dealer, I'd like to hear about it. Obviously if some of you report that there are no downsides or even some improvements in performance after the dealer reprograms, then my dealer is screwing around with my truck!! (Perhaps because I didn't buy the truck originally from him???)

Are there things a dealer could do that would compromise performance, or is this not likely?

Jim Rokon

Thank you.

[mackin]

Jim,

This is what I did not want to here or glad I did here ......I was just about ready to truck on in to local dealer and get them oh so famous you won't be sorry your truck will be "SMARTER" upgrades.......Looking like it is back on the I aint doing it list till I here more from you, if you get it corrected.....I would think they checked the entire truck out , so other factors must not come into play .. For instance a dirty partially clogged fuel filter, or some sort of air cleaner blockage......

The mods you mention the JUICE is easily installed and removed prior to a dealer visit and is not traceable.... So no finger pointing if you went in with a bum caliper and the said it was a performance box issue.....Yes it can be done alone,but gauges are recommended for towing,and only max setting of level two is recommended.....As reported here it is a excellent enhancement to performance....


The exhaust mod I would certainly assume wouldn't be a problem ...Hypothetically,what if you went four wheeling ripped off stock exhaust would you be forced to buy OEM exhaust at an enormous price???Nah.....Can't possible see an incident where they can claim exhaust was part of the problem unless it was installed improperly.....

Now tires have been a different story,unreal.....There are a lot of dealer inconsistencies on this, some do some don't deny certain warranty repair unless returned to stock.....

Have you tried addressing your dealer on these subjects??You never know, get names.....Keep the JUICE box out of conversation, stick with exhaust, gauges.....

Best of luck and OH by the way Welcome to the best BB on the Duramax around......Keep us informed.....

MAC

[ 09-30-2002: Message edited by: mackin ]</p>

[Jim Rokon]

My truck which suffered at the hands of the dealer was box stock, no modifications at all. It has 2800 miles on it at the time of the incident. THe decrease in power was immediately felt as I drove onto the interstate leaving the dealer. It wasn't until we pulled our usual 5th wheel trailer onto our hillclimb test where we could document just how much it was hurt. It dropped 9 mph with the same at bottom speed and similar cool air temperatures, with AC off.

I had a long talk with the dealer's service manager today who convinced me that he did not know that the reflash would compromise performance and he seemed sincerely sympathetic, but said he had no ability to reflash it back to the old configuration. He explained that when GM gave him the new reflash configuration for the dealership, they took away the old reflash configuration that had dated back to the earlier times.

He agreed that the GM bulletin said nothing about decreasing performance while you get the upgrade.

If you experience the DTCs that relate to transmission malfunctions, you might want to consider not permitting the reflash. I am still anxious to hear from other owners who have experienced similar reflash abuse.

The service manager told me that if I bought a larger diameter exhaust to try and get some of the lost power back, that if I had ANY powertrain warranty issue that I could be denied based on the unauthorized change. He said the greater exhaust flow would allow the engine to produce more power, which put more than GM had intended into the Allison transmission, therefore warranty is worthless at their whim.

I asked him if I located an unaltered ECM like from a junkyard if installing that would create any problems and he said that would void my powertrain warranty because I tampered with the systems in the truck. There is an ID number in each ECM that is electronic, and when they study the ID code they can find the mismatch between the ID code not matching the trucks VIN, and then you have a problem with warranty. He said the only way around the problems with GM is having a very friendly relationship with the individual Chevy dealership's service manager and he admitted he cared too much for his job and preventing the dealership from losing it's franchise to help out customers, even if he was sympathetic. It is a very lousy deal, a very unfair one in my opinion. What do others think about this kind of treatment at the dealer level?

[Jim Rokon]

More to say on the topic of dealer lowering your power output. This particular dealer was not the selling dealer, and I have strongly resisted having any thoughts of suspicion that they might have deliberately compromised my truck's performance with any monkey-business, as it is just un-thinkable, and so risky for the dealer. BUt I admit I have not pulled out the fuel filter and checked for any tampering with anything, basically because beyond looking at the fuel filter and the air intake indicators, I don't know what to look for. Basically I have no knowledge of how to do an independent diagnosis and must trust the dealer. Are there any other things to check for, and wouldn't they cause a "check engine" light or other ECM warning light to come on in the dash display?

[mdrag]

Jim Rokon,

Sorry to hear that your truck's performance has apparently suffered from the updates. Others posted of decreased performance after software upgrades - but this was earlier in the '01 model year, and appears to have been addressed in subsequent software upgrades.

The overwhelming majority of those with recent software upgrades have noticed IMPROVED performance - including me. I'd check a few items before blaming the software upgrades (no particular order to this list):

1) Check/change your air filter. The later 2001's came with redesigned intake plumbing. There is foil tape covering the fender opening between the air filter box and the fender, and the snorkel between the air box and fender was removed. More than one forum member has experienced this foil tape coming loose and being sucked into the air filter housing - causing decreased performance.

2) Check the Allison ATF level. There have been scattered reports of overfill/under fill when delivered.

3) Change the Allison spin on filter before 5K miles. Although not a part of the GM recommended maintenance, the early 5K filter change is advised by Allison. Only the filter needs to be changed, not the tranny fluid - the filter can become clogged from debris during break in. Add enough Dexron III or Transynd to make up for the fluid lost in the filter change. Replacement Allison filters can be had for about $8 from an Allison dealer. Here is a link for the Allison dealer locator, the Sales/Service link is along the top:

www.allisontransmission.com

4) Change the fuel filter. Racor fuel filters are available for about $17.00 each - you'll pay much more at GM dealerships. Racor is supposed to be the maker of the OEM fuel filter:

www.dieselpage.com/racredu.htm

5) There are both ECM AND TCM updates, and they are performed in separate steps. It may be that the dealer updated only one and not the other. Take the truck back to the dealer (or another dealer) and have them confirm that ALL the updates were installed and scan for codes.


5) You state "While previously marginally satisfied with the truck's trailer pulling performance..." Can you explain what you feel is marginal?

Maverick recently posted that he was over 30K gross (100K miles on his truck); Maverick tows daily and makes a living with his hotshot service. BROKER recently retired an '01 DMAX with over 400K, and replaced it with an '03 - since he makes a living hauling, I doubt he would have bought another if it was a marginal performer...

Good luck.

[ 09-30-2002: Message edited by: mdrag ]</p>

[mackin]

Jim,

Not necessary would you get a SES on poor performance with a fuel filter issue or partially blocked air cleaner...This was just a suggestion a may not relate to you problem ......Prolly what your experience is the FIX for shift business and it is just getting into 5Th and not down shifting......

The Juice would resolve this and as I said no larger exhaust is needed.....Gauges are recommended.....

You must have one of them tuff dealers as a few guys/gals have brought there trucks in with larger free flow exhaust and never got any negative feed back.....Just goes to show the lack of a standard policy at dealers.....

This is just MY OPINION, I'd go gauges, try a JUICE box and see your results ........I'd find a friendlier dealer too.....
Good luck...

MAC

If your in southern NH there are some good dealers in southern VT......Brandy (A DP poster) could give you an insight on them........

[Jim Rokon]

Thanks for making those suggestions. It helps to know that others have had the upgrade on the software and felt improved performance. There is hope without taking on GM then. What really bothered me is that taking the truck home from the dealer felt like driving home my old 1994 Ford F250, it was a gelding, not a stallion and I felt the change over point in time was that day.

1. My 2001 was delivered to me in July, so I assume it doesn't have the later 2001 intake plumbing. Air filter restriction indicator shows no sign of a problem, and the truck now has only 3,100 miles on it.

2. The ATF fluid level gives inconsistent readings. When I follow the manual's proceedure, allow the temperature to cool for an hour or so, then it seems to be overfilled. But if I wait overnight, and then warm it up and check it, the level is perfect at idle, so I concluded that it was fine.
3. I'll change the spin on trans. filter, thanks for the tip since the manual doesn't mention it.
4. I'll locate a Racor fuel filter and change it. I have drained it once looking for any signs of water, and found no water.
5. I wasn't aware there were ECM and TCM updates and don't know if just the TCM update was done. I'll find out with the dealer and ask that the ECM be updated too and report on it once it is done. I won't leave my comments uncorrected once I learn the truth.
6. "Marginally satisfied" comment that I made meant that after all the internet raving over power that the Duramax/Allison had and having owned a Ford F250 Navistar from 1994 with 5 speed, I wasn't overly excited by the Duramax performance when pulling the 12500 5th wheel trailer. It was better than the Ford F250 Navistar, but not by a huge amount, and so that is what led to the disappointment.

Thanks again for the tips.

[mdrag]

If your '01 was delievered in July '01 (and was not sitting on the lot for a few months) - it would have been produced near the end of the '01 model run - and should have the modified airbox.

My '01 had a TPW of 05/28/01 and I took delivery on 06/12/01 - it has the modified airbox without the snorkel, and the foil tape covering the opening previoulsy occupied by the snorkel.

mdrag

[EIS01]

I had the updates done several times over the life of my truck. Most recently about a month ago. Some of the early ones where a real disappointment. To put it mildly! The last one in my opinion is the best yet, and I have no complaints with it. It resolved all of the issues with the transmission and engine that I was dissatisfied with. I pull up to 12,500 pounds almost every day. This truck is a stock 2001 D\A Ext. Short bed. It has the 1775 engine produced by Duramax in Oct or Nov. I think something else is wrong, or they came out with a update since the one I got. If your truck is running the way it should, I don't think you would have any complaints about stock power. I am dreaming of the day I can join the rest of the power hungry, speeding (Mackin) drivers....Until then I will enjoy my truck the way it is. Good luck with your truck, Kevin

[ 09-30-2002: Message edited by: EIS01 ]</p>

[Jim Rokon]

I spoke to the dealer today in person, while buying the spin on Allison trans. filter so I could replace it and inspect the original one for debris. I asked if I could have them do the ECM upgrade and was told "not unless GM authorizes it, and we can only get it from them, it isn't here in our shop". I asked him if GM wouldn't authorize it if I could pay for it and what would the cost be, and the response was: "That would void your warranty, since it wasn't authorized by GM".

Do I have an A$$hole of a dealer or what? OK, all that is left is to find out what the GM bulletin is that discusses the ECM upgrade. I subscribe to AllData and there is nothing on it there, though I am aware they don't have 100% of all bulletins.

Can anyone help out here? (Mdrag the moderator: I hope you read this and can comment more on what you wrote earlier which was:
"5) There are both ECM AND TCM updates, and they are performed in separate steps. It may be that the dealer updated only one and not the other. Take the truck back to the dealer (or another dealer) and have them confirm that ALL the updates were installed and scan for codes."

Please offer some advice, I am getting really frustrated and fantasizing about what would need to be done to...

[Joe.G]

I was charged $25 bucks for all the upgades at Carl White Chev. and mine is out of warranty, maybe you need to find another dealer.

2001 2500HD Dmax/All w/66000 miles

[mdrag]

Jim Rokon,

Mackin had a good point in his post - if the updates were installed correctly and fixed the 4/5 shift busyness (one of the complaints addressed by these updates), it may be that your truck did not downshift to 4th as early on the hill and you lost more speed than before - and the OD lockout switch should help.

If you still have problems after checking the items I suggested above, and you are not getting satisfaction from the dealer, switch dealers. If still no satisfaction, there is a description of how to follow through with complaints in the back of your owner's manual. Hopefully it won't come to that. Good luck.

mdrag

[Maverick]

Jim,
I had my truck reflashed in Sept of 01'. I too was not impressed with the seat of the pants performance after the fact. But after pulling a few passes with a load I felt the climbing ability was still there but still didn't feel as quick on flat ground as it once was. Just recently I has them update both ECM and TCM and feel it is still about the same. Granted I lost about 2 mph with the 19.5 conversion on the same passes but it still pulls real good. My 2500HD on the other hand is a real dog on the mountain pulls. I never had a chance to pull with this truck prior to getting it reflashed but my BIG DUALLY can pull the same mountains with the same loads about 6-8 mph faster than the 2500HD. The 2500HD feels faster on flat ground though. The 2500HD and the 3500 had both been reflashed within a month of each other so I would assume the have the same program. I know my 3500 weighs more than my 2500HD also, so its a mystery why my 3500 pulls better. Maybe its a GMC thing....just kidding. I guess some trucks just pull better than others. My stock 3500 did pull some impressive numbers on the dyno for a stock truck at 258rwhp and 477lbft.

As far as the allison holding up to the juice. No problems so far. Did slip 5th gear twice but thats it.

[ 10-01-2002: Message edited by: Maverick ]</p>

[GMC-2002-Dmax]

Jim,

I can't tell you if my truck stock was a problem. The most I ever towed stock with it was 6500-7000 lbs. NO PROBLEM AT ALL.

I did have the 5/4 shift reflash done with great success. IMHO it made a big difference. I have a mid year '02, built on 01/27/2002 and besides that update the "JUICE" will really wake the truck up!!! I run the L4 program in normal and T/H mode unless towing, then T/H L2 ONLY!!!!!

Try the "Juice" and I think for the money it's the best you will find. I am in the process of updating to 4.30 SUPER JUICE&gt;

GMC :D

[Jim Rokon]

I happen to have a G-Tech Pro meter, which is supposed to calculate fairly accurate 0-60 mph and 1/4 mile runs. At first I was skeptical, and finally when I spent the time to understand the instructions and really used tonight, I am now equipped with some documentation on my performance. Apparently the unit's processor takes the constantnly changing g-force and calculates it with the elapsed time, and can know when you have reached 60 mph or 1/4 mile and the speed at 1/4 mile along with elapsed time too.

I found a very flat area where it would bother no one, and made 21 runs in 90 minutes, removed the slowest and fastest and the average for the remaining 19 runs was 12.87 seconds 0-60 mph. I found one of the hosts of the show called "Shade Tree Garage" (SpeedVision TV on satellite) and it turns out he has the identical truck that I have, same everything, and he used the G-Tech pro meter to gather performance information and reported it on his website on his truck. His times were all in the mid 9's.

Do any of you out there have experience with the G-Tech Pro test meter? It seems like 3+ seconds on 0-60 mph runs is really a significant deficit on power for the truck. Can this kind of data be used to insist the dealer fix the truck? The dealer said that their $5000. computerized diagnostic machine has the ability for them to send the data from my truck in real time to GM's service techs, and that they can go through some tests to determine if it is up to specs. Is there any truth to that dealer claim?

[SoCalDMAX]

Jim,

Yes, I would say 12sec 0-60 is pretty slow. It's not your imagination. 8.4 to 9sec should be stock 0-60 times, 6sec if Juiced/modded.

I've been following this thread and trying to figure out what happened. I honestly don't think there was any foul play involved. Perhaps the ECM did not get properly reflashed, or the ECM was damaged during reflash. I've heard of some brands of programmers having very specific instructions to ensure the doors do not get opened, cable disturbed, etc during the reflash process due to adverse affects. This tells me that it's a critical time for the ECM and things can go wrong if not done properly. You may have had a concurrent failure unrelated to the reflash.

Just because somebody works at a dealership and physically touches a Tech II doesn't mean he's competent or should be touching the Tech II, to put it politely.

I would suggest going to the dealer and politely, calmly explain the G Tech data you have indicates a severe performance loss. If they seem unwilling/incapable of understanding/correcting the situation, I'd go to another dealer. The Tech II seems to be a very powerful tool and could tell them what's wrong, but it's only a tool and in the hands of the less than capable... as useful as a banana.

Good luck, Steve

[txguppy]

Rokon, check out this thread on transmission dipstick level problems. Hope you get your get-up-and-go problems fixed.

http://forum.62-65-dieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=003552&p=

txguppy

[Jim Rokon]

I just got a big break this morning from the Chevy Dealer's service department. The principal owner of the dealership, and who owns most of the dealerships in this area regardless of brand, happens to have his own personal Duramax Diesel and he is not satisfied with his truck's performance either, and the service department has been unable to get his running to his satisfaction. I told them about the G-Tech Pro unit but they were a bit skeptical of "how could it tell you are going 60 mph through a cigarette lighter?" I admit I was previously very skeptical too, but when I really carefully studied the way in which the unit's processor keeps a running track of G force versus time I can see how it could work fairly accurately. The theory behind it is pretty heavy stuff you'd perhaps get into in a University PHD (doctorate level study) but I believe it is valid. In any case they passed on borrowing it for the boss's truck, maybe another time they will.

The service department now is interested in solving the problem for me, and I believe them.

I carefully opened up the original red spin-on trans. filter in our shop lathe, using a very slow speed I was able to open it without any contamination (no chips, just long slivers removed) and the inside of the filter was perfectly clean, just a slight bit of blackness to the filtration pleating. The body had no debris in it at all. So that isn't the culprit, no flow restriction there.

The dealer said he went to the GM Dealer World site, and found that there were 6 reflash codes that they could try. (No we're getting somewhere.)

The air intake box opens to the right front fender inside wall, and the foil is well stuck on the fender, no obstruction of air there, and air filter pleating looks like new, only 3100 miles.

By the way, the best technique I could come up with ( I didn't want to be abusive to the truck on the 0-60 mph tests.) was to of course find my level straight road with no traffic at night. I'd reset the G-Tech Pro unit, zero it out, wait for the "go" signal, then hold brake, rev to 2000 rpm, and then to the floor in 2 WD Hi until just past 65 mph, and wait for the unit to analyze the run. I also tried a few in and out of Tow/Haul mode, and 1 in the 4WD Hi mode. The most I'd ever get of audible signs of performance was about a tenth of second of rear wheel spin on a smnall portion of the tests. I did no 1/4 mile tests.

I have an appointment on Monday and will share what happens.

[Jim Rokon]

Just a thought, on the air intake. If more air is always good, then wouldn't removing that foil on the inner right front fender wall and allowing it to take air inside from the wheel-well provide more power? If out of GM warranty of course, and if you don't care about problems in rain, snow, slush, etc. You could seal it back up for bad weather with an aluminum plate and aircraft dzus fasteners really quickly. I heard that GM did change from that design due to problems of water and slush intake. But why not a sensor that sensed moisture and closed a door, providing a dry alternate path? It would be ugly without doubt to have a ram air in the front of the right fender, but it seems you could force a lot of cold air into that box with the right bodywork mods. I hope this doesn't affect my credability as a forum contributor, since this is just a thought, but does anyone want to experiment with a fender ram air scoop?

[c5dura]

Hi Jim, just wanted to confirm what SoCal stated about G-tech times. With 1000 miles on my 3500, I consistently get 8.4 sec 0-60 runs and I'm running 32" tires (235-85-16's).

Also, I went ahead and removed that foil from the fender as I also believe that more cold air is always better. Have had no problems with water or mud or anything like that. Btw, I'm running an K&N filter which is even more exposed than the stock air box.

[mackin]

Jim,

On the ram air, credibility is secure......I want Mike {Micheal Tomac check out his PICS} to send me part numbers on his setup .....Nice...... There is another guy here who has Home Depot stock and manufactured a gutter setup, no really stop laughing......So don't you worry ......if you design something let us know...

MAC

[Jim Rokon]

Latest information is as follows: The Juice $799. was installed, and 0-60 mph times definately improved, averaging now 9.85 seconds(previously in the 12.8 second area) This seems merely what the stock truck reportedly will do. With this in mind, what other factors could be affecting my truck's performance. 3100 miles on the truck. Am I correct that 9.85 with setting #4 on the Juice box is not particularly good?

Question: Since the power levels we can select with the Juice is 0,1,2,3,4: will the setting of "0" mean the entire Juice box is bypassed and the engine is run off the default of the particualar truck's ECU and TCU, or is "0" actually what the Juice's manufacture have programmed into the box as what they perceive to be stock ECU and TCU settings?

[hoot]

Does the Juice come with spec's and directions? Only reason I ask is there seem to be an aweful lot of basic questions on how to set it up.

[Jim Rokon]

It has two sheets of instructions, somewhat incompmlete, and doesn't answer the questions I've had. I am still unclear if you can for example have #4 programmed for Normal mode and #2 programmed for Tow/Haul mode at the same time. And then it doesn't make it clear what happens if you only program Normal mode at #4, and you move to Tow/Haul mode and had not programmed that to anything, then will you get stock General MOtors ECU and TCM configuration, or will you get the Juice's manufacturers's interpretation of what the stock configuration is.

Anyone out there know the answers?

[mackin]

Jim,

The box retains "LAST" current settings plugged in or not....My SUPER juice was set out of BOX Level 1 T/H level 2 REG.....

It easy enough to tell what your current out of box setting is by,ideling truck,applying brake, select T/H do the P,R,N,R,P.....Count the revs......

Setting ZERO should be Zero or factory power .... I'm not really sure or should I say it's not for me as I never tried it....... ;)

Your truck still appears to be on the weak side with your 0 to 60 times.....Have you checked air box and dumped the fuel filter for a new one?
How does your truck coast??Just wondering if your experiencing some drivetrain drag or something.....

MAC

[ 10-04-2002: Message edited by: mackin ]</p>

[SoCalDMAX]

The Juice can be set for any of the 4 levels in normal mode. It can also be set for any of the 4 levels in tow/haul mode. They are completely independent of each other. The "R" or default setting is when the Juice adds timing only, and I don't know how much power that is. The Juice is always working when plugged in, so if you want to go back to stock, you must disconnect the Juice from the harness.

The confirmation is doen by shifting from P to N and back to P, listen closely because the first idle flare occurs as soon as the shifter hits P.

Your 0-60 times are still off, there is something wrong. I'd expect 0-60 in the range of 6.5sec or so.

Are there any other symptoms? Clattering? Smoke? Whistling? Low boost? High EGTs? Is it that the engine isn't pulling or the tranny won't shift?

I would think with a Tech II and a little common sense, the tech should be able to troubleshoot/diagnose/repair something as simple as a diesel engine.

Keep us posted and good luck! Steve

[RonCM]

Jim,

I just took my 2001 3500 in today and they did a complete update on both Transmission and Engine and even though the truck was running fine before,it is awesome now! The 1/2 shift is a lot more firm because of one of the many updates had a fix for it and the performance has really improved over what I thought was great. I asked the tech if he heard of any problems with loss of power after a update and he said no and in fact assured me I would have noticable performance gain. He downloaded the tech II on to the computer while I was there to show me how many updates there are for the 2001 early production, the list was long with many of the updates being revised more than once. All I went in for was the cruise control would shut off every once in awhile when you hit the resume so the tech told me that would most likely be a problem with the programing since the switch would have given a error code. I think you need to find another dealer to do the update over again. Hope this will help. Ron

[Jim Rokon]

Ron,
Can you possibly identify the updates by when they were created or by update number so my dealer can know what worked so well for you? (I don't know if you are on that kind of relationship where they would share that, but I am really frustrated.)

SInce my Chevy dealer's principal; owner has a similar complaint as mine on his Duramax, I believe the technician just doesn't know what to do to help either truck.

After putting on the Juice and actually getting to feel what 0-60 in 9.8 seconds is, I realize that I've never had that kind of "normal stock OEM power" since the truck was first delivered. I can only imagine what the mid 6's would be like. I can't wait to eventually experience it.

Today we leave on a 300 mile trip at 21000 gross towing weight where we can do more tests opn setting 2 and see how we do up hills, will report on Monday. Haven't had time to do the boost and EGT work, hope setting #2 won't damage anything without the ability to monitor EGT.

Jim

[RonCM]

Jim,

The tech just showed me the list of updates and he highlighted some of them,the 1/2 shift and several for false codes and on and on. He didn't go through all of them and he was showing me because I asked if there was one for the busy shifting. He then explained that there are so many updates for the many diferent chevrolets that he can't keep up with them. The Tech II is pluged into your vehicle and the information of the vehicle is downloaded into it then they unplug it from the vehicle and hook it up to a computer and the computer tells the tech II what needs to be updated, a program then is downloaded into the tech II and then is downloaded into the vehicle at least that's the way I understand it. In other words the tech doesn't put just one update in He puts what ever the GM program tells him to put in. Since our trucks are both 2001 3500's then I'm guessing you had the same work done on yours. I know one of the guys earlier in this thread suggested a fuel filter, if you haven't done that do it first before you go back to chevrolet. That's the first thing my tech asked me was if I had changed the fuel filter and my truck was running fine. All it takes is one fill up of dirty fuel and your filter will be wasted. I suspect since one dealer has two screwed up trucks that there is something wrong in that shop and it might not even be the techs fault. Try another dealer. I would like to hear how that trip went with the juice hooked up.

Ron

[Maverick]

Jim,
On level 2 I could run my truck's EGT to over 1400 on the right hill. I always had to back out of the throttle. I ran with my 4.30 on Friday on level one and was just as impressed with the power as in level 2. The best part is that EGT's never ran above 1250. I wouldn't push it to far on a steep grade without an EGT gauge.

[Jim Rokon]

Ron, thanks for the explanation on the Tech 2. Your reasoning that the only 2 Duramax trucks in the shop (The owner's and mine) have the same problem therefore Chevy dealerhisp may have a problem seems logical. I will try another dealer in a town 25 miles away.
The 20240 lb. gross combined weight trip for 300 miles: I ran only in the #2 position on the Juice, and the same long hill produced 72 mph near the top (versus 53 prior to installing the Juice). And the last 1/2 mile while still climbing but starting to decrease in steepness the truck went up to 78 mph. Transmission temps never got above 195 F and the truck definately felt better on all hills. I did have a strange recurring problem of the "Check engine soon" light coming on going up most hills, and then it would shut off 1/4 past the top while driving down the other side of the interstate hills. I happen to own a Actron OBD-II code reader (from Autozone stores $150.) so had it hooked up during the trip, and whenever those "Check Engine soon" messages came on the dash, I would do a check of all the parameters available on the Actron unit, and it never showed anything(no DTC, no M/L, no I/M problems) so I am puzzled by that. Will running the Juice result in this kind of dash warning? I did not have time to install the EGT and boost prior to the trip. Will do it this week. Will put my respirator mask on while drilling and tapping the 1/4"-NPT threads in the exhaust manifold while the engine is running. Hope that keeps the metal chips out of the Turbocharger!!!! Found the near-matching vinyl gray paint to spray the black guage A-frame holder at Walmart auto department.

Will report any significant developments.

[Jim Rokon]

FIXED GREAT by the Chevy dealer. The same dealer that I felt did me a bad deed with the latest TCM gave me the latest PCM upgrade and now the same truck stock runs 9.15 0-60 mph (versus the prev. 12.8 seconds). He could only explain that he gave it to the Technician, they put it on the Tech 2 machine, and GM recommended a certain upgrade, and 2 hours later I was out testing it on the same stretch of Interstate road with the G-Tech Pro. Two runs, both in 4WD hi so save on tire rubber, and average 9.15 seconds. Now I suppose the Juice will give me a real thrill, do I dare try it?

[Jim Rokon]

Service Manager explained how they did such a good job. The Chevrolet Technician hooks up the Tech 2 and takes a "snapshot of the TCM and PCM parameters" and communicates it to GM and they analyze it, and then they send back their revised parameters truck's PCM. That sounds almost like a custom configuration is created for each truck. Now he knows how to fix the dealer's owner's Duramax, which also did not run well.