HP Tuners discussion and other Tuning options.

I'll start by saying I'm not computer illiterate. I take care of the 4 interconnected PCs that keep my office running and seldom have problems with them. I'll also say that I'm not exactly a pro at it, but between Google and the ability to follow directions, I get the job done. 

I would like to adjust the AFM and transmission shift characteristics on the 2007 Silverado I recently bought. It has also been suggested that some tuning would help make the most out of the CAI. Additionally, my long term plans for the G35 include a LSx swap at some point in the future. 

So, GM tuning. What do I need to know to get started? HP Tuners seems to be the go to product. Dollars vs capability seems to be pretty decent. Any other programs/hardware I should also consider?

Thanks, Allen.

I just bought the SCT software, they do chevy stuff iirc. ill let you know how it goes

4 or 6 spd?

HPTuners has changed how they do things and it seems with each new revision they quit backdating a previous generation of controllers. I’m not a fan of the new wireless interface yet.

4 speed. 

While I've not done any of the direct flashing, the time I've used the HP Tuner, it seems pretty good.  The hard part is figuring out what things need to be calibrated to do what you want to do.  The interwebs seem to know something, but much of it isn't exactly correct- and that's coming from someone who isn't a GM calibrator.

Still, the older you go, the easier it gets.  And while Ranger makes a good point about the lack of updating the old controllers, I will point out that you really don't want to, or sometimes, you can't update the interface...  If I were to work on an old controller, I can't use modern tools.

I know nothing about SCT- but both are just hacking into the OEM controller via the OBD port.  

So here is what I would like to do. 

I would like AFM disabled below a certain RPM. Right now it is set to about 1200 or so. I would like it to be set to 1800 or more. I would also like the ability to turn it off if necessary. 

I would like to tweak the shift points. It is a little to quick to drop all the way to 1st on a down shift. 

I’d have to look to see if the afm turn on point can be changed. I have mine completely turned off and never really saw any gain or loss in mpg. Plus the failure rate on afm lifters is still way too high for my liking.

I know on my 6l80, I was able to raise and lower the upshift and downshift speeds plus shift pressures and speed. I don’t see why you can’t do the same with a 4l60.

AFM is air flow meter... Unless its not.  Sounds like you are talking about the variable cylinder management system.

??

Edit:  Active Fuel Management.  That doesn't really describe whats happening, though.

Toyman01 said:

So here is what I would like to do. 

I would like AFM disabled below a certain RPM. Right now it is set to about 1200 or so. I would like it to be set to 1800 or more. I would also like the ability to turn it off if necessary. 

I would like to tweak the shift points. It is a little to quick to drop all the way to 1st on a down shift. 

That’s all quick and easy to do in HPT. Literally a click of a button. 

I recommend you download the HPT software  from their website. You can play around with the software without actually buying it. What you pay for is the hardware, and the credits to download/upload to specific cars. 

Youtube has had a ton of “how-to’s” on all the basics. There’s a lot to take in at first but once you get used to the interface it’s pretty easy. 

In reply to Streetwiseguy :

Active Fuel Management aka DOD (Displacement on Demand). 4 cylinder mode on the Gen4 and up Small Block Chevy.

I am not aware if you have access to the AFM tables.  All I've ever played with is the shiny, candy-like "Disable" button.   (Which really IS a radio-button option, not a table that has to be zeroed out)

I have played with EFI Live and got an extreme headache.  HPT is a damned fine product for the money.  I note that they support a lot more than GM/Ford engine and trans computers.  You can play with various VWs, Audis, Nissans (!), Mopars, and some non-engine related stuff like the RDU in the Focus RS.

I looked at my ‘13 Avalanche file and afm/did is time and vehicle speed based.

The HP Tuners showed up yesterday. I plugged up to the truck this afternoon and solved 99% of the issues I had with it in 15 minutes. 

DOD minimum RPM was raised from 650 to 1250. 

DOD minimum speed was increased from 15 mph to 50 mph. 

Throttle deactivation was raised from 6% to 15%. 

The first two eliminated the DOD at city speeds. It was driving me batty having it shift from 4 cyl to 8 cyl constantly in traffic. 

The last adjustment stopped the constant shifting from 4 cyl to 8 cyl at highway speeds and actually leaves it in 4 cyl mode more than the original setting did. I may try increasing this to 20%. Apparently this helps with fuel efficiency. 

That's all the changing I will do until I know more than I do now.

This was well worth the dollars spent. It drives like and entirely different truck now. 

In reply to Toyman01 :

Feels good to make HAL your b... uh, I mean make HAL do your bidding, doesn't it?  

In reply to Knurled. :

Yes it does. 

I'm pretty sure it's also a spectacular way to seriously screw things up. My first step was to download the original tune and save it somewhere safe. It's looking like the best way to adjust things is one parameter at a time, and save the modified copy every time, so you can go back to the previous tune if you don't like the changes. 

It's going to take some fiddling and research to figure things out. 

In reply to Toyman01 :

Ask questions here, too.  I read some of the HPTuners answers, and not all are that great.

In reply to alfadriver :

There do seem to be some hack answers floating around. 

alfadriver said:

In reply to Toyman01 :

Ask questions here, too.  I read some of the HPTuners answers, and not all are that great.

Some of the official help is very deep into insufficiently-socialized-engineer land.  (Like me on a bad day, BEFORE I've had my coffee )  I usually get better answers from some very good online guides along with a BS filter.

Back to OP, you would do very well indeed to save files iteratively so you can revert to previously known good examples.  The real time tuning feature is clunky at best, anyway.  I like to put a note in the actual filename (like "Silverado_DODtweak.hpt") so I can keep track, since it doesn't take long to get a half dozen files per day of playing.

Fixing the MAF transfer table is one of the easiest things you can do, actually, and a good place to start with playing with tweaks since many things are based off of the MAF, so that is the foundation that everything else comes from.  If the MAF is reading high, for example, then the fuel will be compensated for with fuel trims, but ignition timing will be retarded because the assumption is that the airflow meter is correct.  Make sure it's clean, though, and the air filter is freshly cleaned, otherwise you'll be tuning with an error baked in.

One thing that I rarely see anybody mention is that if you are running E10 fuel in a non flex fuel vehicle, make sure that the stoich AFR is programmed to be 14.2.  A lot of GMs up until remarkably recently will assume that stoich is 14.7, which will make you create an incorrect MAF transfer table.  I know the early 00s still expected 14.7.  I don't have access to the tune repository at home, but I do have the generic stock tunes that they give you with the VCM Editor download, and the '14 Corvette tune assumes 14.1 for stoich, so you may be okay.  And if you have a alcohol composition sensor in a flex fuel vehicle then this is all moot.

Usually, once you fix that, you don't really HAVE to mess with much of anything on a stock engine.  99% of the tables, as you could imagine, are pretty esoteric.  You're probably not going to have to mess with A/C compressor torque per PSI, or oil drag coefficients.

In reply to Knurled. :

I would not say that the answers frightened me, but the direction threw away a LOT of work GM did, with no real plan to replace it.

If I were to do the work that I helped with, I would have taken a very different path than what was recommended.  Someone needs to realize that for HUGE portions of the calibration, the OEM can do a light years better job.

Anyway, given what I see, the value of what some of us can offer is some decent money.... 

In reply to alfadriver :

Oh, I agree.

The best description I've seen of what is going on with this level of engine control, is that the various tables are not "tuning" the engine, they are "modeling" everything.  So you tweak the MAF transfer table to get the model correct if you have altered the intake stream.  You tweak the VE tables to get the speed-density model correct if you have altered the cam or manifolding or exhaust (because GM runs both speed-density AND mass airflow, sort-of at the same time, weighting one over the other depending on the situation).  You alter the throttle body flow model if you have a different throttle body.  Once you have everything modeled correctly, it will work GREAT.

There seem to be a lot of people who are content with doing away with the "modeled engine" paradigm and going with the GIGO paradigm of making whatever gross change makes the engine run sort-of good, like MAF-only or MAP-only tunes.  Bleh.

I'm kinda confused on their credits model.

$400 for MPVI2 that comes with enough credits for 1 vehicle, right?

Strike_Zero said:

I'm kinda confused on their credits model.

$400 for MPVI2 that comes with enough credits for 1 vehicle, right?

Considering their products, you would think they would have the best website in the world. Instead, they have one of the most confusing. 

I ordered the MPVI2 for $299. I then ordered 2 credits for $98 and change. Sounds like the $400 kit should come with enough credits for one 2 credit vehicle, but they probably don't actually spell that out anywhere. Keep in mind, not all vehicles require 2 credits. Some take more. 

In reply to Toyman01 :

The old method was a $600 product that came with eight credits.  So this way is actually somewhat more beneficial if you only plan on tuning ONE car with your VCI.

The old website was actually a whole heck of a lot easier to navigate, even though some of it was admittedly poorly laid out.  Worst is that the old tune repository is gone.

Knurled. said:

In reply to alfadriver :

Oh, I agree.

 

The best description I've seen of what is going on with this level of engine control, is that the various tables are not "tuning" the engine, they are "modeling" everything.  So you tweak the MAF transfer table to get the model correct if you have altered the intake stream.  You tweak the VE tables to get the speed-density model correct if you have altered the cam or manifolding or exhaust (because GM runs both speed-density AND mass airflow, sort-of at the same time, weighting one over the other depending on the situation).  You alter the throttle body flow model if you have a different throttle body.  Once you have everything modeled correctly, it will work GREAT.

 

There seem to be a lot of people who are content with doing away with the "modeled engine" paradigm and going with the GIGO paradigm of making whatever gross change makes the engine run sort-of good, like MAF-only or MAP-only tunes.  Bleh.

That's a good description of how things work these days.  And it's much more important for speed-density calibrations, like what loosecannon has in his MG.  Without a very good dyno, it's almost impossible to tune the air calculation, when people are used to MAF systems.  Which becomes a real problem when other features are tuned off due to not knowing what they do....

OK, first question. 

I am experiencing some knocking under high load and low rpm. Notable, 1500 rpm in OD, just before the downshift. At a guess this could be caused by the CAI. This is accompanied by some slight surging. I can't tell if the surging due to spark retard due to the knock or possibly the torque converter slipping a little.

So, were to start. 

Could be this?

Knurled said:

One thing that I rarely see anybody mention is that if you are running E10 fuel in a non flex fuel vehicle, make sure that the stoich AFR is programmed to be 14.2.  A lot of GMs up until remarkably recently will assume that stoich is 14.7, which will make you create an incorrect MAF transfer table.  I know the early 00s still expected 14.7.  I don't have access to the tune repository at home, but I do have the generic stock tunes that they give you with the VCM Editor download, and the '14 Corvette tune assumes 14.1 for stoich, so you may be okay.  And if you have a alcohol composition sensor in a flex fuel vehicle then this is all moot.

The AFR tables show Stoich based on alcohol content, but from research the 6.0 Silverado didn't come as a Flex Fuel. I'm assuming there isn't a fuel sensor. So does that mean the ECU defaults to the 100% gas setting of 14.67822?

Edit to add: Premium fuel cures the knock.