firebirdjones

I am exhausted reading all the stickies and still can't find a cut and dry simple explaination of how these tuning graphs work exactly. All these abreviations for words are driving me nuts.
Could someone please explain how the graphs work when following them accross the board? What is added where and what some of this stuff stands for? Alot of this is taken for granted when explained and for the newbie it is nearly impossible to comprehend.
Timing for example,,,,I understand that kpa on the top has something to do with vacuum and I assume that at 100 kpa you are at wide open throttle, with that said, how do you compute total timing, is the base timing figured in already?
I am having the same problems with fuel graphs. A nice picture of a graph with a very simple explaination would help greatly. Is there a link to something like that, or maybe it's still hiding within these walls and I simply cannot find it. Any help is appreciated, many thanks, Larry.

firebirdjones

I am starting to tune on my 88 Iroc, and I am told a good baseline chip tune to start with is the ARAP bin. Problem is, it's for an 89 model that doesn't have the cold start injector. I am not interested in replacing engine components just to run a computer chip so my thoughts are,,,,and correct me if I am wrong,,,,can I just download an ARAP bin,,,and compare it to my stock 88 350 L98 Bin, start with my stock tune and change the fuel and timing curves to the ARAP bin and reach nearly the same benifits? This way I can keep the cold start injector feature on my car,,,,it works fine so I see no need to change it at this time. I can continue to tune from there I guess, I have read that the ARAP bin is a good place to start though. Any more thoughts, thanks, Larry.

michal_larson

100 Kpa (imo) isnt WOT, its the end of where vacuum was at your throttle blades, mine goes to 100 Kpa's at about 1/4th pedal while cruizing at any speed. mine has changed alittle because i swapped in a huge camshaft where a stock one was. so.......i measured my TPS voltage right after my vacuum gage goes to 0 @ part throttle (i.e. 2.76V) and that is where I set my PE to come in at. i dont know much, but i know a little and you didnt have any hits so i told you what i know from working with it. i work on my stuff 24/7 and love to talk about it. lata
----------
mass air flow is different though
----------
Im assuming your firebird is TPI right?

michal_larson

i found for my stock 87 350 IROC with an LT1 camshaft just using the whole bin file and just adding 6 degrees to the 400 and 600 rpm (where the engine idles) across the board, installing it, then set you Dist @ 0 degrees under your hood made mine run great

RednGold86Z

iTrader: (1)

88's are MAF, so using kPa terms are a bit useless. LV8 would be the right term. LV8 is a "load value" that relates to cylinder fill, similar to kPa*VE I guess you could say.

The 32B uses a LV8 vs RPM PW table. $6E just calculates the PW based on airflow.

To convert from 32B to $6E, just unplug the cold start injector.

If you're engine is iron headed, you'll want to start with AUJM, in my opinion. ARAP is a corvette bin, and has too aggressive spark, and requires other modifications to get the fans to be controlled correctly, and some other things.

Tuning MAF in a Nutshell:

Just try it stock at first (if you have stock injectors, or change just the injector constants (both) to match your injectors). Take a look at your BLMs after a lot of driving. See if it's bad (<115, or >140). If bad, get into MAF table calibration.

Take some datalogs and look for high knock counts, and knock retard. Retard is more important than counts. If it's retarding a lot, performance will suffer. If it only retards a little at a few points (like shifts - that's common, and likely ignorable), then work on the spark table at the LV8 & RPM points that had knock repeatedly.

If your throttle tip-in or snap-in response sucks, then your AE (Acceleration Enrichment) needs work. If your full throttle air fuel ratio is lean, your MAF table probably needs work. If your high RPM full throttle air fuel ratio is wrong, then the PE (Power Enrichment) needs work. Big power engines can max out a stock MAF's sensor at high RPMs, and this will usually require PE at high RPMs to be raised to compensate for the missing MAF flow.

AFR is Air fuel ratio. 12.5 is rich (good for full throttle). 10.9 is very rich. 14.7 is stoichiometric (equal air to fuel for cats and emissions). 15.5 is lean.

Spark advance is only correct if the "Base Timing" is set correctly, by adjusting the actual distributor location (with EST bypass line disconnected) to the same base timing that your chip uses. Most 5.7L TPI bins use 6 degrees advanced. Check for knock and reduce in the locations with it. Tune PE spark on a dyno, after you've made sure to get rid of most full throttle knock.

Closed loop fuel tries to achieve 14.7:1 AFR using the standard narrow band oxygnen sensor, except at high throttle, and in deceleration (where the throttle is closed, and the car is pushing the engine). At full throttle, the engine uses PE (Power Enrichment) + MAF Fuel. At closed throttle decel, the injectors are shut off.

Most problems come from Closed Loop being aggressive and causing unstable idle. Other problems are from MAF modifications that require re-calibrating the MAF tables. Acceleration is the next issue, where the car either bogs a little at tip it, or it backfires, or hesitates. PE is usually too rich from the factory, and leaning it out a little (bringing it from 11.7 to 12.7) will generally get more power. Spark advance should be kept conservative for a daily driver, and make sure the knock sensor is reading accurate knock.

Wideband Air Fuel Ratio meters will keep your hair in your head, thus they are worth it.

firebirdjones

Thanks guys, that helps clear some things up. I am a little confused about the ARAP bin, I read in here somewhere that is was used on 89 F-body press cars, I didn't realize it was a corvette bin. I didn't read anywhere about this AUJM bin. Is it more aggressive than the stock 88 L98 tune?
It almost just sounds like I may want to read my chip, download it and burn it into another chip, save the old one just in case, and start making small changes from the stock tune on another chip, if I get so far out of wack I can always reinstall the stock chip and start over.
I will have to check out the MAF tables, calibrating is another issue. I know there are math formulas to use on these graphs to figure how much you need to increase certain areas, certain percentages etc....multiply this by x amount and divide by x amount etc....is there a sticky on this somewhere that shows how to approach each graph on an MAF car? I find the biggest problem here is most guys are speed density and it kinda leaves the few MAF guys out in left field, and what I do find I can't make much sense of with all the abreviations. Don't get me wrong though, I am no dummy when it comes to tuning, been doing it for 25 years on my old cars, but when it comes to computerized tuning I am very green, learning all this computer lingo is going to take some time for me.
I understand timing curves and what they do, but looking at computer graph is a little odd, and some of the numbers I see are very low, which makes me think there is another number that should be added to the equation that is not there.
I also understand Air Fuel Ratios, and block learn, over 128 is lean and under 128 is rich etc....I can make sense of that stuff, but changing numbers in a graph and how it affects things is another story,,,,I am used to jetting carbs, drilling idle feed restrictors, air bleeds, and playing with pump squirters etc...but when it comes to a computer graph again, I am a little lost, especially when it is abreviated, PE, $6E, LV8, PW, once I understand what the graph is for and understand how changing the numbers up or down affects it, I think I will then feel more comfortable and possibly understand more of the info in the tuning threads here. I seem to remember some really good tuning info on MAF graphs several months back but since this site has been redone I can't find them anymore. I also seem to remember reading somewhere that playing with the MAF graph was somewhat of a no no,,,that it was lying to the MAF so to speak? I don't know.
I appreciate he help guys, hopefully I will figure this out,,,,I am sure I will have a ton of questions as I get deeper into this, changing things and wondering why it changed something somewhere else etc... Larry.

michal_larson

the corvette bins agressive sparkmap worked well in my L98 becuase i use large camshafts, just have the fuel getting to it.

Vortex91

Firebirdjones, I'm with you.
There should be some info like a Glossary of terms kind of thing.

Personally I was wondering if ppl on this board can recommend a good book one can buy and use it as a starting point.
I bought a book a while back but it's more of a generic nature, I'm thinking something geared toward Chevy engines/ECMs would be a better option.

If you find links to info us newbies can use please share it here.

D.

firebirdjones

Well Vortex,,,I may be able to help, another kind fellow on this board recommended a book to me called "How to tune and modify Chevrolet Fuel Injection" by Ben Watson,,,,it can be found at Motorbooks.com I have ordered mine but have not recieved it yet. I am hoping it has some tuning guide lines and all the math equations to figure it out.
It was only $17 or so,,,,if it helps me the least bit I think the money is well worth it because at this point I am in the dark.
I can't really figure out the discussions on this board and what really ticks me off is when you get into a good tech discussion that looks like it will give good info then someone has to chime in about how this or that is not a good idea blah blah blah and then you have to read through 30 posts about people arguing and everything gets off subject I am getting a little tired of that. Another problem is most people here are completely hung up on speed density and there isn't much info in here for the MAF people. And when you ask about that you mostly get comments about how speed density is better Fact is I really don't care,,,I just want to know how to tune what I have,,,period! Fact is,,,I wanted an Iroc Z,,,had to be an L98,,,and it had to be totally stock and unmolested with VERY low miles,,,,that kinda narrows the search down quite a bit,,,,know what I mean? So quite frankly I could not be picky about whether I found a car with MAF or speed density.
What I would like to see are some stickies totally dedicated to MAF tuning,,,,with pictures of graphs and what they mean, what they do,,,with all the math formulas needed to figure the numbers out. I am not asking for tuning secrets,,,,how much timing works where etc.....I will figure out what my car likes on my own,,,,every engine is different anyway,,,,I just want to know how the tuning tables work and what is added where for total timing,,,because as it stands right now,,,,I look at a timing graph and there is no way those are total timing numbers in the graph, there has to be something else added somewhere, either base timing or some math formula etc....What it is going to boil down to in the end is,,,,,I will probably have to find a tuning guru in my area that knows the ins and outs of how everything works that can spend an afternoon to sit down with me and go over all the graphs and what they do and how to change them etc......so I can get started. I hate for it to come to that but it's looking that way. Sorry I am done ranting now,,,,hope the book info helps you out,,,Larry.

MadDogginYa

Firebirdjones, I can understand your frustration belive me. I to am a newbie if you will but my first tune did pass california smog check. I am not a guru by no means but Homework is requirement of this community of tuners. TGO LOL! If you need help understanding basics you might try emailing me at pboyflyd@sbcglobal.net hope that is OK with TGO , it would save alot of space here on the forum. LOL! I too was buried in all the information available here but I now have a descent grasp on it. It comes with time believe me but right now you don't feel very patient I am sure. There is good help available here at TGO , you will grow to know this in time. When you can talk the lingo , the help will poor in. Maybe I can Help with Basics. I would post links but I don't have them saved because I copy everything I read for my own use. I can explain or get you too stuff that will help I believe.
I check my mail once a day!

michal_larson

i agree, it took me like 400 burns to get where im at now. My tunning is WAY off from stock, not even close, nor will my chip work in a stock tbi camaro. i installed a camshaft in my 305 TBI that was "way to big","absolutley WILL NOT WORK", " there is no way to get it to start". if i listened to all that BS, my engine would still be stock, and yet i have achieved over 2 seconds off my 1/4 mile time with a huge camshaft and alot of tuning. I would never believe anyone if they told me they could get this cam to run in their 305 TBI car, i still dont think anyone would even attempt it i go all out, off the wall, i take chances, if i have to jump, i take a running start, so yes, stick with it

RBob

iTrader: (1)

i agree, it took me like 400 burns to get where im at now. My tunning is WAY off from stock, not even close, nor will my chip work in a stock tbi camaro.
As the tune should be. The stock TBI stuff is tuned for a mild engine.

i installed a camshaft in my 305 TBI that was "way to big","absolutley WILL NOT WORK", " there is no way to get it to start". if i listened to all that BS, my engine would still be stock, and yet i have achieved over 2 seconds off my 1/4 mile time with a huge camshaft and alot of tuning.
Recall that it wasn't said here on the DIY_PROM board. Also note the entry you made to your thread. It had a lot do due with some of the responses you received. (Other responses were flat out incorrect as they didn't understand that you already installed that cam). On the other hand, this is the Internet.

I would never believe anyone if they told me they could get this cam to run in their 305 TBI car, i still dont think anyone would even attempt it i go all out, off the wall, i take chances, if i have to jump, i take a running start, so yes, stick with it

I could get that cam to run in a 305. I too jumped in with both feet. And learned a lot in the process. The reason you heard what you did on the other board is because folks don't understand TBI setups. They are willing to put out hundreds of $$$'s for larger injectors for their TPI setups. But why in the world would I need to do that for a TBI setup. Heck, it's just a carb with these things that spray fuel in it.

TBI is so misunderstood I've actually had people tell me that it isn't a 'real' fuel injection system.

Now that you have some additional fuel, the track times will either improve, or a lot of rubber will be deposited on the track

Either way keep an eye on the injector PW and the duty cycle.

RBob.

RednGold86Z

iTrader: (1)

Larry,
I've got a nice complicated, confusing MAF scalar spreadsheet on my other computer in Dong Guan (I'm in Chang Chun now). I'll be flying down to Hong Kong tonight, and probably spend my evening in Dong Guan, so I'll see if I can remember to find it.

It helps make the MAF scalar changes blend smoothly into the MAF tables. It's a lot of typing in numbers when you change scalars, but I suppose GM only had to do that once or twice.

MAF Spark is similar to MAP spark. There's a LOAD axis and a RPM axis. LOAD is basically %TORQUE (from available torque at that RPM). So, at low RPM, medium throttle can make big torque (from what's available), at high RPM - bigger throttle opening is needed to make bigger torque (LOAD). To READ a spark map, look at the RPM that you want and read across to the LOAD that you want to look at. That's the spark advance there - pretty simple.

At full throttle, you'll use the columns or rows that are in the HIGH LOAD, that goes from low RPM to high RPM. At near closed throttle, you use the columns or rows that are in LOW LOAD.

Which software are you using to tune? TunerPro RT? Which Mask ID? 32B or 6E? Which Bin? AUJM or ARAP or Other? Which .xdf or .ecu or what-have-you file are you using to view the BIN?

AUJM is a STOCK bin. Stock for your combination (i.e. Iron headed L98+700R4+F-Body) is always a good place to start. It's the newest bin for MAF (made in 91 IIRC, according to one site, strangely - perhaps an updated version).

Also, I've tried to find good books. Never found any that even touch ACTUAL tuning of GM ecu's. TGO is the best living book, but yeah - a little disorganized. The book you ordered will tell you lots about sensors and trouble codes, woohoo.

I think Jeff Hartman's books on "How to Tune and Modify Electronic Fuel Injection" are pretty good (there's an old version and a new one). (Name of book and author are just off the top of my head, maybe spelled wrong or mis-typed). There's also a Corvette Fuel Injection book that's pretty cool. It covers Crossfire, L98, LT1, and LS1. It talks a lot about what the code is doing and why. It doesn't cover actual tuning L98's though.

michal_larson

actually, i think 2 seconds is alot with just a camswap and tunning i cans see much of anything accept s/c,turbo or nitros that could beat that

michal_larson

by the way, the camshaft i use is the smallest one that a class in circle track uses. the induction for that class is a stock iron 2 bbl manifold and stock rochester carberator and that engine ran great, so i knew ahead of time that my camshaft would work in my TBI set up
----------
and, my engine turns 7 grand with NO valve float what so ever, the solid lifters really helped me out in that department




PS.----i still dont believe you

Fast355

iTrader: (2)

I have sucessfully tuned cams that large in a TBI 305.

Michal_Larson-
If you re-read the posts on the TBI board, it was stated that there were better cams to run. I said it could most likely be made to run well, but would never be a great cam choice for a L03 car. My statement was based on the nature of the torque converter, gearing, head flow, intake flow, TBI size, exhaust setup, etc. In a 305 with the potential to run from 2,500-7,000+ it would be a great cam. I ran the L82 cam with 1.6:1 rockers (224/224* @ .050, .480/.490" lift, 115 lobe seperation) in a TBI 305, that made peak HP at nearly 6,000 rpm and peak torque around 4,000 or so. The very modern Crane roller cam that I later went to, pushed peak HP to around 6,500 rpm and brought peak torque down to 3,600. It increased torque, increased HP, increased idle vacuum, gave better throttle response, and broadened the powerband greatly. The crane roller cam was 2x the cam of the stock L82 cam.

michal_larson

i think my engine peaks at 4800

michal_larson

i like the old blueprint cams crane has now, this is my third one and i just keep getting the bigger one every time. lol i was really debating on the 222/222 hydralic, but i thought id give a solid lifter cam a chance. man i am suprised. i may have my car dynoed this month.
----------
my Duntov 30/30 camshaft is a legend. i love it

RednGold86Z

iTrader: (1)

Larry,
have you had any more time to give this stuff a try? I switched to windows live mail a few weeks ago, but it works very inconsistently from China, dunno why. I saw your email, but haven't been able to open any hotmail stuff for a few days.
I looked for my spreadsheet, but couldn't find it. I know I didn't dream it, but maybe it was lost when that hard drive crashed (I paid some money - kinda cheap to do in China actually, to recover a lot of the data, but didn't get it all back).
BUT, it basically just does what you can now do in TunerPro RT. All you have to do is change the factors for the MAF tables to look at the MAF scalars, and then visually recorrect for MAF scalar changes. I'll see if my .xdf is correct for $6E (I think I posted it on Moates a long time ago, but I can't remember if it made it on there, cuz I was having some difficulties from here).

Acronyms are the fun part of learning EFI, hehe. I think JPrevost once tried to break an Acronym record in one post. I'll try to find it, you might get a kick out of it, or make you beat your head against a wall trying to understand it.

RednGold86Z

iTrader: (1)

https://www.thirdgen.org/forums/diy-...?highlight=TDC

Can't find the funny one yet.

MONZA355

this might help u guys that want a glossary out a little i acctually found this here in a round about. well anyway you can thank member JP88SS for this

http://www.diy-efi.org/gmecm/faq/biglist.txt