Boosted... Where do I start?

[53mercury]

Brand new to this and a little overwhelmed by the information I;m looking at? Anyway I have HPTuners and have installed a procharger on my 1972 chevy with a 2008 LY6 6.0L did some research pretty sure I got the MAF where it's optimal installed 60lb injectors now need a baseline to get goin here! Where do I start? I;ve been a auto tech for 13 years and do understand some of the info but if I was pointed in the right direction I think I could work off of that. Here's my tune file.

[53mercury]

pcm tune

[53mercury]

pcm tune file

[IDRIVEAG8GT]

Ermmmm........ Lets narrow this down a bit first.

Do you have good Injector Data for your 60Lb XXXXXXX's injectors?

What DTC's you throwing?

What MAP Sensor?

What MAF sensor?

What are your plans to tune it for? (Drivability, racing, etc.)

[53mercury]

Thanks for responding. I have codes only when I first fire it up that system to rich bank 1 and 2 but once o2's come on line it runs not to bad, I have only the stock injector data, using stock 1 bar MAP, using stock MAF located as close to the the throttle plate as possible....... was told to do so, and I want to use this as a daily driver/tow duties. I have a 255lph pump with a aeromotive fuel pressure regulator and 94 octane in the tank. I've also installed a boost gauge and a A/F gauge along with a fuel pressure gauge. I'm thinking I have to dial in the injectors first along with removing some timing? biggest thing is I'm not sure where to go to accomplish this I guess it's just a little more info in HPTuners than I was expecting! I'm not afraid to mess with it though the truck is a learning tool and I have enough sense not to melt it down. Again thanks for the reply I'm excited to get started.

[IDRIVEAG8GT]

OK well we have quite a bit of work to do then. Assuming this is a stock block LY6 with L76 heads, you can figure a safe line of timing for WOT to be about 8 degrees at the lowest to 14 or 15 at Peak Torgue. You can add more, but probably not a great idea until you get more comfortable with your setup. I recommend an AFR of 11.9 so you will want to set your PE Multipllier table to 1.230 across the board and then simply dial in the AFR's by using your MAF. MAKE SURE WHEN DOING WOT AFR TUNING YOU PUT THE VEHICLE IN PURE MAF MODE! Dynamic Airflow Enable=2RPM, Disable=1RPM. Figure your idle and cruise to be around stoich 14.7. I haven't even glanced at your tune yet, but to get rid of the startup codes you need to lean out the portion of MAF Hz cells that the truck uses so your LT's don't skew everything. (Set LTFT enable to 120* or something like that as an aide.) That should kinda get you on your way.

[53mercury]

Yep ok right on I'll start there..... this is awesome thank you IDRIVEAG8GT I'm going back to work tomorrow for 5 days then I'm gonna set it up like you said to start... I'll be in touch then thanks again.

[IDRIVEAG8GT]

Happy to be of service. The Sticky's and HPT Help file's are pretty much what I quoted from. Open you HPT hit F1 and start reading. Then your already 3/4's of the way to mastering tuning in retrospect. Cheers yo.

[pontisteve]

You mentioned you have a fuel pressure regulator. Is it vacuum/boost referenced? If so, you need to flatline the injector flow rate vs KPA table.

GM doesn't typically vacuum reference their pressure regulator. Instead, they use a mechanical returnless system that applies 55-58 psi all the time. Without a vacuum reference, the injector flow rate will increase as vacuum increases, and decrease as vacuum decreases/boost increases.

In order to compensate for this manifold vacuum, Fords and most others just vacuum reference the pressure regulator. GM does not, so they have to have a table that "changes" the injector flow rate based on the MAP sensor. If you switch to a return style system with a vacuum referenced regulator, you no longer have to "change" the flow rate on the fly. So you simply take the flow rate of the injector and apply that same number all the way across the flow rate vs kpa table.

Of course, the first thing to do would be to enter the correct injector specs in the 4 injector tables. Greg Banish's DVD covers this well, and includes the correct data for Siemens 60's. But you would still have to modify the flow rate table by flat-lining it if you vacuum reference the regulator.

Without entering this injector data, the computer will be injecting almost 3x as much fuel as stock, and you'll certainly end up with huge fuel trims and probably O2 rich codes. You MUST get the injector data right before even bothering to touch anything else in the tune.

If you want to understand that flow rate vs kpa table more, you have to understand the Bernoulli equation for pressure changes. Also know that most injectors are rated at 43.5 psi, Ford typically rates their injectors at 39.15 psi, and GM rates theirs at (I assume) 58 psi. Siemens 60's in a GM PCM will be more like 80 something's due to the higher fuel pressure GM runs.

Once the injector tables are right, then you can start modifying the airflow calibration to get the a/f right, but you'll never get anywhere until the injector specs are close or right.

I would also start with a very conservative amount of timing, maybe 12 degrees even. You can always add timing and power later, AFTER the air/fuel is in the ballpark. Your tuning should go in order like this: Injector specs, airflow calibration, then timing. And work from conservative (rich/low timing) towards aggressive (higher power, leaner, more timing). Work methodically, and you'll end up right where you want to be.

[53mercury]

Ok so I understand flatting the flow rate because I have the regulator which I needed since I'm running the stock 1972 chevys fuel tank with a framerail mounted pump ( no in tank return ) but where do I find the baseline for the 60's to start? I'm away from my tuning computer right now but is it in the help section of HPTuners editor or can I purchase this CD? I totally understand what your saying start with correct injector pulse width first, flatline flow rate vs kpa table and airflow cal also pull timing to something like 12 degrees. Sounds good I'll play with it tonight let you know how it goes thanks guys .

[pontisteve]

Setting up injector specs really begins with the knowledge of what each table you're modifying means. Then, it involves having access to good injector data. Since you're new, I'll explain what most on here already know. Greg Banish is an OEM calibrator who wrote a couple books and made a DVD called beginners guide to GM tuning. The DVD is the most helpful thing I think you'll find if you really want to learn to tune and are just starting out. His first book Engine Management: Advanced Tuning is a treasure trove, and for the money there is no reason not to buy that one for sure. The DVD is a bit pricey, but it's one of a kind. And so is the injector data.

You see, Ford is nice enough to supply really good injector data on their Ford Racing Parts website, for all their injectors. Since the GMs use basically the same injector style, and since the Ford injectors are usually cheap, most guys swap in Ford injectors. Ford also markets the Siemens Deka 60's and 80's as a Ford Racing part, so we get that injector data as well. :-)

Greg uses his engineering degree to convert the Ford data into data that the GM PCM's need. This includes flow rate vs kpa, injector battery voltage compensation table, short pulse adder table, and the minimum injector pulse. All 4 of these tables need to be populated correctly. Greg shows you on the DVD how to copy his data into HP Tuners, which is a process all by itself really. Lots of careful copying, pasting, and interpolating off his data cd.

The flow rate vs kpa data can (especially in your case) easily be calculated using the Bernoulli equation for pressure change. The min injector pulsewidth is an easy one too, both of which can be figured out by the data off the Ford site if you're skilled. Even that's slightly tricky, as you have to convert to the right GM pressure from the Ford pressure. But the short pulse adder and the injector voltage compensation tables are important, and that data cannot be solved for on the car, and must be supplied by the injector guy or Greg, in HPT format.

By the way, HP Tuners has a unit conversion tool in the menus that does the Bernoulli math for you, one cell at a time. It's based on this: New flow rate = old flow rate * the square root of (new pressure / old pressure).

In your case, you take the zero kpa (that's zero kpa of VACUUM, not manifold pressure from the MAP sensor) flow rate and use that in all the cells in the flow rate vs kpa table.

Welcome to the rabbit hole. If you're gonna tune, be prepared to take a crash course in mechanical engineering, physics, and learn to like the taste of humble pie. But once you wrap your head around this, you won't believe how much better it will make your technician skills with EFI.

[53mercury]

Ok I'll Definitely get the CD for sure I want to get into this....I have other projects that could benefit from this as well Thanks.

[07MontRedcp]

Ok I'll Definitely get the CD for sure I want to get into this....I have other projects that could benefit from this as well Thanks.

http://www.summitracing.com/parts/SME-DVD-1/

BJK

[pontisteve]

He's got 2 books. The first one explains OEM EFI very well, from a tuning perspective. The 2nd book is more about standalone EFI's, but it is pretty relevant to GM vehicles since GM uses VE tables. All I can say is buy them. I took Greg's advanced Ford class at SCT, and can tell you he's as skilled as they come. You'll see in the DVD, but trust me buy the books at amazon.

[53mercury]

Awesome stuff... CD on the way in the meantime I was doing a little research and found flow rate for siemens 60's and at 40 psi they rate them at 60 at 58 psi they are 72.98 lbs or 766.29 cc/min which I'm pretty sure I have so now with it being vac referenced I should in the flow vs kpa table go across the board with this flow rate! Just trying to wrap my head around this! Understanding what your talking about and looking at it makes perfect sense..... So this flow rate does make sense right?

[IDRIVEAG8GT]

Awesome stuff... CD on the way in the meantime I was doing a little research and found flow rate for siemens 60's and at 40 psi they rate them at 60 at 58 psi they are 72.98 lbs or 766.29 cc/min which I'm pretty sure I have so now with it being vac referenced I should in the flow vs kpa table go across the board with this flow rate! Just trying to wrap my head around this! Understanding what your talking about and looking at it makes perfect sense..... So this flow rate does make sense right?

I'm going to tell you a bunch of shit just to try and help, use the data from a Corvette Zr1 with it's 52 Lbers to get you close on fueling issues. This is a CHEATING way to get you close to where you want to be, and is not to be used for a permanent fix.

[pontisteve]

http://fordracingparts.com/parts/ics/m-9593-lu60.pdf

No need to cheat. Here's the Ford data. If you convert Ford's Hi slope (static flow rate in Ford speak) from lbs per second to lbs per minute (by multiplying the hi slope by 3600), you'll get 60.2676 # per minute. Bernoulli that from 39.15 to 58 psi, and you'll come up with 73.355 # per minute at 58 psi. You would populate the flow rate vs kpa table with this number across the board, since you're regulator is vacuum referenced.

This is a very close number, but you may want to try 72.9 for now. Ford has the minimum pulsewidth at 1.391. You'll need Gregs cd to get the injector voltage compensation table and short pulse added. But just getting the flow rate vs kpa table right will get you most of the way there, and make the car run.

The way GM does the injector flow rate with their mechanical returnless fuel system is pretty weird compared to most, in my opinion. They change the flow rate constantly, based on vacuum/MAP. In your case, this is going to be undone since you're vacuum referenced. Here's another tip: You don't have to run 58 psi. If a 60#/hr injector is large enough for your anticipated power level to maintain an 80 - 85% duty cycle or less (shoot for 80) at WOT, then why run the higher pressure to get it up to 73#/hr? Why not just enter 60 and run 40 psi if they're exactly 60 #/hr at 40 psi? Or run 45 or 50 psi and bernoulli it. Whatever... now that you know how to populate the flow rate table, you can choose.

Although Greg's data is based on 58 psi, and the other injector specs can be skewed slightly based on pressure. Notice the Ford sheet's pressure multiplier tables on the right side of the sheet. Each of the injector specs is changed by the amount in those tables based on the psi you actually run. Based on that, I would run 58 psi and not confuse the issue.

[53mercury]

Guys this is all great stuff after work I've been inputing data and messing with it a bit and did come up with a pretty close number I will start with 72.9 keep the fuel pressure at 58 psi for now to avoid confusion while I'm waiting for the CD to arrive!!! Thanks. By the way when I do get to the point of start up is there something else I should change besides timing... to get going that is?

[53mercury]

Thanks again guys this is great help I live in northern Canada where I'm 4hrs from the nearest tuner in Edmonton so I would like to be able to drive the truck there for a dyno (final) tune.... without having to many issues. Thanks again

[pontisteve]

I find it helpful when beginning a calibration to put together a list of things that I've done to the vehicle, and decide on each thing if it requires calibration. For stock EFI's, the BIG tune changers are injectors, air inlet tubing and/or MAF sensor changes, and to a somewhat lesser degree, heads, cams, intake, boost. I say lesser because you can start with a stock type file and recalibrate with the lessers. With the big changers, you may need to calibrate some before even firing up, and this is 100% true with injector swaps.

With each modification on your list, think about how it affects the EFI calibration and what changes you may need to make. For example, a cam change won't change your MAF xfer function if all inlet tubing is the same, but it will change the VE tables since you've changed the volumetric efficiency of the motor, and it will also change idle characteristics, probably requiring more idle airflow.

With boost, you have to decide how much boost, and if you're going to go speed density only, custom 2 bar Operating System, or maintain the MAF sensor. You also have to back off some timing as a starting point, and the type of boost changes how much. A roots blower and a turbo both hit full boost pretty all-at-once, so they require an almost instant reduction in timing. A centrifugal blower will build boost as it builds RPM linearly, so it won't require nearly as much timing backed off, possibly until higher rpms.

And keep your head clear when calibrating. First, enter all your known things, like injector size. Then, back out enough timing to be FOR SURE safe... don't worry about power for now. Next, calibrate the airflow (MAP and MAF). Then, calibrate the spark for max power. Last, you can fix idle and other little things and button up the tune.

There's a lot of things we do in tuning that are temporarily rigged up just for tuning, and later put back to stock. Like turning off the O2s by forcing open loop, commanding either a solid 14.7 air/fuel for part throttle tuning, or a solid 12.5 for full throttle tuning (NA motor) or 11.7 for full throttle tuning (boosted motor). After calibration, we will go back and smooth these tables out for the desired final outcome. But just during tuning, having all commanded air/fuel ratios be one number makes life much easier.