03 1500HD Cam and Wideband Tune problems

Taylor Jones · July 30, 2019

So I have a 2003 Silverado 1500HD. I put the Brian Tooley Racing NSR cam in. Otherwise the whole truck Is stock. Mechanically in good working order besides the issue I"m about to explain. I got a Wideband tune done by a tuner about an hour away from me that is very reputable. The truck seemed to run pretty good right after the tune was done, but now that summer is in full force it's almost undriveable. I can't tell if it's actually the problem with the tune or if I'm missing something. I've taken several videos that explain and show the problem first hand. The first video I'll link has live data of a brake stand followed by a short acceleration burst. The truck just seems lethargic when taking off, absolutely can't spin tires from a dead stop the most I ever get is a little chirp, but if I shut it down the truck can't find idle and dies most of the time as shown in the video as well. Adding to that, occasionally I will get either detonation, or backfire through the intake. I can't tell which it is but it sounds like someone is hitting the firewall with a hammer followed by completely no power for about 5 seconds.

My next question would be does it seem like torque management is still in full force on this truck? This thing is a slug from a stand still. I can't hardly spin tires from a stop even on damp pavement. Even if I brake stand on slick pavement it struggles and seems to dip in RPM's shortly after tires start spinning This video below has a before and after cam 0-60. When I took this it was the day after the tune. That's honestly the most wheelspin I've ever gotten from a stab. I know the truck has it in it because at 60 when it shifts to 2nd it will chirp the tires most of the time. I know big cams tend to lose low end power, but this is excessive. Plus I've seen plenty of trucks with this same cam perform way better off the line.

I hope these videos help explain my problem. My main question is should I blame the tune, Was something not done right? If you can think of another problem I'm overlooking I'm all ears

Things I've checked so far... Vacuum leak (none found), Fuel pressure 55PSI with 3 psi dip at startup quickly recovering to 55, Plugs and wires only have about 15k miles on them, MAF is clean, Air filter is clean, O2 sensors are good, The only thing I'm going to check soon that I haven't is catalytic converters. They do make some noise, but I felt that if they were clogged top end power would suffer more than it does.

greatmizzou · July 31, 2019

God I love the sound of the exhaust from those cams!

What if you put your truck on a Dyno at a shop? Tire spin has maybe as much to do with the pavement type and condition which you can never control. I dont think your tests are completey scientific because your base test, tire and road conditions, climate environment, will all vary real world performance.

There is also the placebo effect. Sort of like how your vehicle "feels" great after a good wash, or a new big screen tv feels huge for the first few days....you probably felt that rush of energy from the initial performance boost and now you are simply used to it

Taylor Jones · July 31, 2019

The truck does sound good at higher revs! Especially for the stock exhaust.

I’ve definitely considered that, but something is for sure wrong. Once in a blue moon I will feel it pull like it’s supposed to and it’s night and day difference. I’ve been researching hptuners and think I might have figured out the problem, but no way of knowing without visiting my tuner.

when I watch live data, I can see the truck pulling timing doing a brake stand. So much so that it dies when I get off the throttle.

greatmizzou · July 31, 2019

http://www.masterenginetuner.com/ls-big-cam-idle.html

maybe this will be relevant?

Jglew82 · July 31, 2019

You'll definitely need to go revisit the tuner and have them record a scan. If timing is being pulled, you'll need to find out what is pulling it. There's no telling without seeing a file what changes the tuner made. I also noticed your short term fuel trims in the negatives, which indicates a slightly rich condition. I'm wondering if they messed with any IAT modifiers, ECT modifiers, etc. I don't see why they would, but I noticed your IAT's are pretty high as well (hello summer in TX) so if they changed something in those tables, that would explain the summer heat correlation with your issues.

Again, I'm just spitballing here since I don't have much to go on, but I've seen some wonky tune files cause all kinds of weirdness.

CamGTP · July 31, 2019

Just from being around the GEN 3 6.0 engines, there is a high possibility this thing can't even support the power it makes on the stock injectors too. The factory 25lb/hr injectors barely support the stock engine, now with a cam I bet it's touching 95-100%+ on the duty cycle. Surprised the tuner didn't say something or they didn't bother checking. That's my 2 cents on one thing without seeing a data log or tune file to see what's really going on.

Taylor Jones · August 1, 2019

16 hours ago, greatmizzou said:

http://www.masterenginetuner.com/ls-big-cam-idle.html

maybe this will be relevant?

Seems pretty spot on to me. Thank you so much for that resource

Jglew82...I'll be revisiting the tuner in a couple of weekends. I wish it wasn't an endeavor to get to him, but he's over an hour away and through a chunk of Houston. Not really where I want to drive with a truck that throws a fit, but I also want to bring it to him hot and experience the fix after he's fixed his business in the tune. So we'll see how it goes

I appreciate all of your responses. I'll take a look at injectors too. Past research no one has mentioned injectors with a mild to mid cam, but searching specifically for duty cycle like you mentioned leads to stock engines reaching 90% which means yes they are most likely tapped out by the time I get up in the rpm range. That thing has to be sucking some fuel through there. That will likely be a project for down the road though as it would require a re=tune and not just a free patch up like this time will be. I plan to purchase hptuners and the MIVP2 and start toying with it myself later this year. When I went in there I strictly asked him to make the truck run the best it could with the upgrades it had which is only the cam.

SierraHD17 · August 4, 2019

Looks like how they pull totally stock lol. I would not doubt duty cycle is maxed but I think you have a lot more problems there than that. The stock exhaust on those trucks is trash.. that muffler is tiny inside if you cut it open. I have to say my tune and exhaust but internally stock 05 1500HD would walk this truck bad..... and that's not right lol.

Taylor Jones · August 5, 2019

There's definitely improvement to be made if I were to do full exhaust and headers, but that's not in the budget. I have no doubt though that this truck should make good power on the stock exhaust. The one thing that I do think could be a possibility is my catalytic converters could be either clogged or broken inside causing them to not flow correctly. They do make noise. Kinda like gravel being shook around in a tin can to the tune of the idle of the truck. I'm torn between cutting them off altogether or cutting them off and replacing with an aftermarket Cat. I don't really want it smelly all the time, and I do live in an emissions inspected county, though that portion of the ECM is tuned out it appears on my last inspection report. The upside would be I don't have to spend the money on the new converters, and potentially more power to be had without them.

As far as it being slow, I definitely know what you mean. I've watched videos of this year model a lot though and the consensus is that my stock pulls look the same, but the pulls after the tune and cam should definitely be better.

SierraHD17 · August 5, 2019

I don't have headers on the 05 I am comparing you too.. just a muffler and a tailpipe swap. I still have my original 220000 miles cats on mine as well. The head pipes are 2.75" pipe and LS manifolds flow well. Yes long tubes are better ( did them on my 04 light duty 2500's 6 liter) but honestly a muffler swap with a 4" tailpipe woke up my truck in a big way.

If you cats are clogged you could always cut them out and reinstall them gutted... or aftermarket cats. A pair of 3" high flows won't be cheap either lol.

Like I said that stock muffler is a piece of junk.. it's dual 2.75" in, single 2.75" out and is close to 2" inside. Not something ideal for any kind of performance application.

Taylor Jones · August 5, 2019

I'll definitely keep that in mind. I'm an old man when it comes to loudness. It's not a muscle car, it's my daily so I want it quiet. Gonna look around for something that flows good has a good tone to it and is quiet in the cab. If you have a suggestion please let me know!

All of this will be after I get the tuner to look at it. If I take it to him with modifications he'll charge me for a new tune. I just want him to make it run properly. I plan on purchasing HPTuners this fall and starting to toy with it here and there.