7pane

Hello everyone! I have been lurking the fourm for around 6 months now reading and building and have my first ls build completed, and it runs like ****

Not a huge amount of change from stock. It is an lq4 but smaller cc heads and a mild cam. I assume the issue is computer related. I have ordered HP tuners and a wideband o2. I can see there is a load of info on the forum and I have no doubt I am capable of learning but I wonder if the Hp tuners book and cd is a valuable purchase. $500 for a book is pretty steep and after the parts, machine work, hp tuners and wide band, my cash situation is not the best. What do you guys think? Any recommendations?

gametech

iTrader: (1)

I would recommend looking at repository tunes of similar engine combos. Do a "compare" with HPT and see what changes have been made. If you are not well versed in the general theory of EFI, there will be a steep learning curve involved. If you have a good grasp of the basics of EFI, a lot of the GM factory tables still won't make a lot of sense at first, but you should be able to figure them out eventually. Remember that there are dozens of tables you will literally never have any reason to touch, and a small number of key tables that will make huge differences.

JakeFusion

iTrader: (7)

Read read read. Here and on HPT forum. HPT used to come up on Google searches... and honestly, that's the best way to look up info and find it. With HPT taking itself off the Google listing, it's harder now. So just hit me up if you need some pointers.

kingtal0n

iTrader: (1)

IMO if you are new, the best thing you can do is start with a stock engine, not a "built engine". This way, with all the stock parts, you can use a stock tune file, which will start and run the engine normally. This way you can rule out common problems if it does not run normally, and you can always try the stock ECU to make sure the engine itself is good. Then, gradually modify the stock tune file, see how the engine reacts.

7pane

I think I have a pretty good rough idea of efi, Please correct me if I am wrong, but I think the computer runs two basic functions, one with fuel/air. Determining the amount of incoming air(calculated based on maf sensor or intake pressure relative to rpm ) and operating the fuel injectors to dispense an appropriate amount of fuel relative to the air, then using the o2 sensor as a feedback loop that the previous process went correctly. The second function is the degree setting of timing. This system i dont know much about, other that it is using premade tables and then adjusting if it detects knock in some fashion.

The part I dont have any understanding of is how different components change these functions. I would think changes I have made that improve airflow (bigger valves, better heads, more lift and duration on camshaft) would result in more airflow and the computer could just calculate the new fuel value, not much change required. I assume stock timing advance is probably conservative for a better safe than sorry approach (likely a good idea for an average consumer) and maybe some more power could be gained by adjusting the timing curves.

Please anyone fill me in on anything I am missing, I have a feeling that a great core understanding is going to make this alot easier on me.

7pane

I am and continue to, are you saying the book is not worth the money and I should just keep reading the fourms? I appreciate the offer for help, I will likely need it.

7pane

I am pretty new to this, so excuse me if I am way out in left field but I think this may be a little bit of an over reaction. The camshaft I pulled out of this block was toasted, I would never put it back in and buying another stock cam as a testing point seems a bit much. I dont need to try the stock ecu, It has the same ecu that was on it before i tore it apart, with the same stock flash.

I am not sure what common problems I could be having that would effect operation that wouldn't be super obvious, can you throw me some ideas what I should look at?

Are you saying that even with the engine modifications it should run at least as good as a stock engine without modifying the computer?

kingtal0n

iTrader: (1)

Since your learning ill indulge

If you assemble an engine or do anything to it, a myriad part can fail or be un-true. quick examples
wrong size injectors, one clogged injector, improper gap/ring shape/location, wrong maf/map, bad maf/map, air leaks/vacuum leaks/pressure leaks, improper oil seal/retainer/low oil pressure, bad rocker geometry, broken springs/improper guide/seat, leaky injector Oring, bad wiring/relay/ecu, improper calibration for unexpected sensor (wasn't the sensor you thought it was), improper crankcase breathing route/check valve location, bad fuel pump/wiring/regulator, do you see the list is endless? That ANY and ALL of these items may befall an initial, new, untested installation, and cause any number of "strange" engine behavior ranging from misfire to poor performance/economy. If you have no previous proof that the engine was running fine a minute before you plugged in your laptop, diagnosis will be tedious because you will have to figure out if it is the tune calibration or the engine itself or something involved with the air/fuel/spark between the two.

If you have a known good stock engine, you can listen to it run with stock parts. Then, you can plug on the laptop knowing full well the engine was perfectly fine a minute ago. That way, when it starts to run like ****, you already know it was something you did.

7pane

I understand where you are coming from, and although effective singling out each change. I am very skeptical this process is necessary or widely used. I feel like there should be an easier way.

Could you please answer my other question

7pane

I should also clarify, I am not new to engines, just fuel injection and computer controlled timing.

Old Geezer

iTrader: (3)

For starters.....
Learn the HPT basics.
Post the tune that you are currently using.
Post some data logs.

LLLosingit

iTrader: (4)

Just look at EFI as a digital carb and ignition. It's not really any different other than adjustments are made via computer (easier physically) instead of mechanical means. The biggest learning curve is going to be figuring out where adjustments are made in the software and how much of a change equals what you would have made mechanically in the past. So instead of changing jets you command more fuel, Instead of adjusting accelerator pump rate/volume you also command it. Timing is no different except EFI gives you a much more precise control at all rpms and loads. Basically as someone posted above, Read read read (HPT and other forums are a good source) and don't get to aggressive with timing or leaning out the fuel until you feel confident in making changes and understand what the results will be.

gofastwclass

iTrader: (2)

No, I don't believe that is what was being said at all by kingtal0n.

Simply put, the stock PCM has a certain percent of adjustment built in that will allow the engine to run if something breaks or changes. Early on you mentioned modifying the heads and changing the cam - those are big changes. In essence, you raised the compression and changed the cam to an (I assume) more aggressive variant. In theory you are moving more air than the engine used to which makes all the PCM calculations off. From prior experience I'm not surprised the engine doesn't run well without a major calibration update. Depending on what changed and how far off it is, you could be running very rich, terribly lean or both depending on RPM and load.

Compared to a carburetor, tuning a fuel injected engine is similar to learning a new language. It doesn't matter how well you know how to tune a carburetor you need to learn the language of fuel injection and how to translate physical changes (jets, air bleeds, idle screws, etc.) into numbers and where to place them. It is absolutely amazing how many things interact with and affect each other that you don't think about until you start to tune an EFI engine.

7pane

Thank you, This is more along the lines of what I was looking for, While some hard part related failures cant be ruled out, I assumed the computer was the issue. I understand that things work before they dont, but all of the sensors worked fine before the engine was pulled(except the knock sensors, the old ones worked, but i figured I should get new ones because of the location) and I have no check engine light, no noticeable miss and almost nothing on the ecm miss counters, just significantly less power even with the upgrades and rebuild. And yes higher compression ratio larger valves and runners and a slightly more aggressive cam profile. I knew the computer could only do so much, and assumed that was my issue. HPTuners and the wide band showed up in the mail today, I havent unboxed them yet. I was really on the fence about the book and didn't really get a straight answer if it was worth the money. I decided to go ahead and get it, I will probably read it first and then dive in.

gofastwclass

iTrader: (2)

I can't say anything about the book because I either missed or you never mentioned which book you were referring to. I have literally read everything I could find that was free, purchased a few books plus asked questions and experimented with my own cars for years to get where I am. I have not personally done this, but I highly suggest a professional book or course if you have the means - you will learn multitudes quicker than on your own.

If you can't afford a professional book or course, read, play and understand the scanner. Start with monitoring a good running factory car. Learn what it does and understand why, then apply that logic to your calibration. If you don't understand the scanner, you are missing out on using a very powerful tool.

By the way - always make a backup copy of the original file and make each successive change it's own file. That way you'll never be stranded in a random parking lot with a self-inflicted non-running vehicle as you can always go back to the previous working calibration.

I.E:
MyCaroriginal.hpt - Never overwrite or change this file
MyCaroriginalbak.hpt - Never overwrite or change this file
mycarchange1.hpt - incremental change 1
mycarchange2,hpt - incremental change 2
etc...

Hope this helps.

7pane

The book wont be here until Tuesday, so I am twiddling my thumbs until then. I don't want to start the engine anymore until I have more of an idea of what I am doing. To clarify my issues, the engine idles ok, but doesn't seem to have very much power throughout the rpm range and when I accelerate rapidly to wot then let off it just dies.

7pane

The hptuners book, Tuning school: Tuning the right way

7pane

I have been expanding my scanner experience quite a bit, I had a cheap 20 code reader from ebay and it served me well for a long time, but I was constantly finding more and more things I couldn't do, so about a year ago I bought a tech 2. I am by no means a pro, there are so many functions, but I am learning as the need comes along/and just messing around with it. Hopefully it will translate in to some meaningful gains when I start tuning, or reading the book about tuning.

rpturbo

iTrader: (47)

Those 2 are great, and also Ed Mowton, ERM performance has some great help too, and he is much more reasonably priced for his services/training/help.

joecar

With your mods ("smaller cc heads and a mild cam.") the stock the engine should run fairly ok (not "runs like ****")...

maybe there's some physical problem somewhere (air/fuel/spark leak...?).