How much tuning really?

[ImpalaSam]

Thank you for the confirmation. I read/listen to all replies I just give some more weight than others.
I know in the end it is up to me to do the research and find which method would work the best for
me. I said it before that I am not ready to do this now but it is something that I would love to
try but I know my limitations and don't want to get in so far over my head that I just give up.
I work only about 5 mi from DIY autotune and live just a little farther so that makes MS an
attractive option. I have stopped by there and they seem very eager to help (even when I
haven't spent any money with them). I started this thread for an education, thanks again
for the input. Amazing that without the web this exchange of information would be almost
impossible.

[dieselgeek]

Ahem. Refer to my post above about where you get advice Sam, guys like Alex can really steer you down the wrong path as they pretend to know this stuff.

HPT will let you easily run Speed Density by disabling the MAF in the software. Most GM MAFs have a built in air temp sensor so if you plan on removing it you need to wire one up, it's cheap (less than $20) and two wires to re attach.

In fact, the proper way to tune HPT is to first tune speed density so your VE tables, the basis of all fuel maps, are correct. Then the next step up is to tune for MAF usage (if you don't mind a little power loss with the airflow restriction, it's minor), and let the computer get back to closed loop self tuning. The car will run very nice if you go through all of this.

Also, one thing I *do* agree with Alex is using the Tuning School's instructions - I used them to get up to speed on the LS's I've tuned in the past month with HPT (lots of them, I tune for an LS crate engine manufacturer now). It's expensive though, you might be able to get by using online tutorials as well, there is lots of help and good reading at the HPT forum. The downer to HPT is that the software is a little bit unorganized and it's more complicated to TUNE than something like Megasquirt. HPT does NOT "replace" the software on the GM ECU, all it does is load a simple little module that allows "sorta realtime tuning" but this is not nearly as easy as the realtime tuning on any standalone - consider Holley HP or Dominator, I've used them and love them! - tuning is faster on the standalone and the standalone, whichever you choose, will have more features down the road.

You also won't be tampering with an EPA-certified ECU which, on a street car, is a hefty offense - FYI. The feds have been cracking down on OEM retuners in the diesel world and the gasser engines can't be far behind.

In reality, the best choice is probably to go with whatever your friends or local tuners are most comfortable with, doing EFI should almost require "getting help from a friend" - that way you won't end up giving up when you run into something you don't understand.

I can help you with either as I am pretty well up to speed on every standalone out there, plus HPT now.

[TC]

So the HPT works kind of like a firmware on the oem hardware? Am I understanding
that correctly? I guess I kind of viewed HPT as more of an advanced
hand held tuner like a hypertech/diablosport. I am the first to admit I don't
understand a lot about HPT, that is why I started this thread. I have a better
idea what a standalone is cabable of although I have no experience using one.

I guess the biggest advantage to HPT is that is doesn't require as much
set up time to get to the tuning due to the fact that the system as a
whole is oem.

Ya, I'm not an expert in anyway on how they program the ECM's, I just have HPT and it works for what I need to do.... I'm in the process of swapping the heads and cam on the white Camaro in my sig, though the Tuning School manuals cover the tuning for head and cam swaps I'm going to have a well known local Tuner tune it for me.... To me it's a win win situation, his fee is very reasonable, he will leave the tune unlocked so I can improve upon it, and I won't waste my money on dyno time tuning the car myself, and he'll explain to me what he's doing so I'll be more comfortable in the future making changes on my own.... Basically he'll give me a baseline to where I can improve upon....

And as for HPT being like a hand held, it's not like that at all, it's a computer program that runs on a laptop(I use a netbook) with an interface cable that plugs into the USB port on the laptop and the other end plugs into the OBD II diagnostic port under the dash.......... It also allows transmission tuning along with the ability to turn off DTC codes, like for the rear O2 sensors, EGR and the Air System, if you choose to delete those systems.............

And IMO if you can use the factory EFI system your way ahead of the game since the ECM is matched to he drivetrain that you install, so it makes engine swaps almost plug and play......

[ImpalaSam]

So the HPT works kind of like a firmware on the oem hardware? Am I understanding
that correctly? I guess I kind of viewed HPT as more of an advanced
hand held tuner like a hypertech/diablosport. I am the first to admit I don't
understand a lot about HPT, that is why I started this thread. I have a better
idea what a standalone is cabable of although I have no experience using one.

I guess the biggest advantage to HPT is that is doesn't require as much
set up time to get to the tuning due to the fact that the system as a
whole is oem.

[TC]

So it is possible to run the factory ecm, which uses a MAF, as speed density
using HPT?

Yes, HPT allows the use of Speed Density with the stock ECM..... Here is a screen shot off my laptop of the different Operating Systems(OS) that HPT has that you can install......

Realize that HPT doesn't really use the Stock software for the ECM, it replaces it with it's own version, you can also install Real Time Tuning, so you can make adjustments on the fly, which is something the Stock Programming didn't come with either....



Also realize even though DG is very informative about EFI tuning, he is the first to admit he doesn't work with stock ECM's, and that he doesn't use HPT, though if your looking for advise on a MegaSquirt he's the man to talk to.....

[ImpalaSam]

So it is possible to run the factory ecm, which uses a MAF, as speed density
using HPT? I was under the impression one would have to work within the
confines of the factory system with HPT. I understand that the standalones
allow that kind of customization but you are kind of starting with a blank slate.

[dieselgeek]

MAf has nothing to do with the "amount of boost" - it has a maximum measurable airflow regardless of the PSI of the incoming air charge. The "amount of boost" that TC is confused about, is how much MAP sensor you have available for tables that use MAP (manifold absolute pressure) as an axis for referencing load. So your spark table might be limited to 3 bars, but that's not really a limiting factor to your maximum allowable boost.

You can get MAF configurations nowadays to support relaly high HP - no problem there.

[TC]

I understand the difference between speed density and MAF. I remember the OEM's bouncing back
and forth with it back when. My experience with it is limited to to turbo Buick where it maxes
out pretty quickly. That being said are the oem mafs able to keep up with the massive increase
in airflow that a turbo provides? Is the MAF used with most LS turbo builds? Does HPT allow the
option of removing the MAF or is this an area where a standalone is required? Lots of questions
I know, thanks to you guys for sharing the knowledge.

It depends on the amount of boost, HPT will support 1 bar using a MAF sensor, that is an OS option, if you want to go higher than that they have a 2 bar and 3 bar OS that uses Speed Density which doesn't use a MAF...... So you can use one or not use one, they also have a 1 bar speed density option......

That's the thing about HPT it makes the factory ECM quite versatile........

[ImpalaSam]

I understand the difference between speed density and MAF. I remember the OEM's bouncing back
and forth with it back when. My experience with it is limited to to turbo Buick where it maxes
out pretty quickly. That being said are the oem mafs able to keep up with the massive increase
in airflow that a turbo provides? Is the MAF used with most LS turbo builds? Does HPT allow the
option of removing the MAF or is this an area where a standalone is required? Lots of questions
I know, thanks to you guys for sharing the knowledge.

[dieselgeek]

Megasquirt lets you run a MAF and has for nearly 10 years.

The issue with that is, nobody with any kind of performance skills or knowledge WANTS to run them.

They do work great for two stroke engines though, when there is no real manifold pressure signal worth using. Maybe TC can tell us all about how to do that.

[TheSilverBuick]

I leave the tune alone for several months at a time, I put 16,000 miles on my Skylark last year alone, how much of that mileage do you honestly believe I was fiddling with the tune? Most of what I'm doing is splitting hairs, but over the last couple years I've made an annual significant change to the car requiring some tweaking. Gear ratios, compression, cam swaps, heads, etc. Significant changes require tune changes. Glad I'm not forking out $500 each time. I usually break out the laptop when ever I make a road trip because they are great times to collect data on the highway and large changes in elevation and barometric pressure, but several thousand miles were traveled out of town with out the laptop hooked up.

[dieselgeek]

Only take EFI advice from those who have done it. not those who "are gonna do it some day"

[TC]

LOL. The MAF sensor is primarily an emissions sensor it back checks the speed density calc's.

Though your the prime example of the guy with Speed Density that is always fiddling with his tune........ You get that figured out yet??


And that's the thing I like about HPT and using a Factory ECM it gives you the ability to run either MAF or Speed Density programming, so he can pick either one.....

[TC]

Fair statement. It gets you going faster if doing it yourself, although make sure you understand that some basic tech skills will be required... TC tried both MS and HPT and couldn't figure either one out, and if you ask him he's a badass expert hotrodder so.... maybe EFI is super duper hard. It depends on your ability to learn IMO.

I have had no problems tuning my car with HPT with the use of the Tuning School, my main problem was reading internet forums about programming HPT where the "so called experts" were doing it all wrong and I didn't find that out until I joined the Tuning School and read their manuals..... They make it real easy and give you outlines to fallow so things are tuned in the proper manner.....

As for MegaSquirt, it is more complicated and at the time I didn't have the time to invest in learning how it works. It is not that I "couldn't figure it out" it's that I didn't have the time to invest into learning how to program it...... Though I haven't given up, I still mess with it from time to time, and still do plan on getting it running on the car I bought it for........

[TheSilverBuick]

LOL. The MAF sensor is primarily an emissions sensor it back checks the speed density calc's.