After developing WinALDL with Jonas to help us TBI guys, John Wilson developed the simple Excel spreadsheet called "WINALDLVEFIXER.XLS" designed so that you could copy the numbers from a WinALDL saved table into it, along with your current TunerCat main fuel table, and it would give you a "correct" table. That's the idea, at least.

Obviously, you need to set your BPW match your injectors as close as you can. The formula is in TunerCat, I believe. If you haven't changed injectors, it might be okay to leave this as they are.

I discovered that the main fuel table #2 (at least for the '7747) is ADDED during all non-PE times. (I verified by reading the hack, repeatedly.) I noticed where John implements an adder of 39.1, which is apparently a stock value for another BIN - that fills the entire main fuel table #2 - but doesn't match what I have in mine. So, I made another sheet within the workbook and added *my* values in, and used those to add for correction. (E-mail me if you'd like to try my version.)

WINALDLVEFIXER is pretty good at getting you close, but if your BLM's are at 108 like mine were - it didn't really help a whole lot at first. Instead, I bumped my minimum BLM down to 50, which allowed the ECM to correct a rich mixture much further. Once I did this, after about 5 burns I had all my values above 108. I had started out with BLM's of 60-70. When I got the values in the #1 table too low (in the single digits) I lowered the values in the #2 table, and added the difference into the #1 table across the RPM spectrum. Eventually I just "levelled the field" and made all the values the same in the #2 table, so the #1 table would be easier to look at visually. The idea however, is that if your #1 table starts to get too low and you still have a way to go, lower the #2 table values and add the difference back into the #1 table through the RPM spectrum you changed. This gives you more room to change. (You can't use negative numbers in tables.)

Now I'm on my 9th chip, and my BLM's are between 126 and 130. Considering some of the 1st chips were discovering features such as disabling EGR (via temperature) to avoid complications of those calculations and changing my minimum BLM value, etc. - 9 chips isn't too bad.

Non-PE mode - this means KEEP YOUR FOOT OUT OF THE GAS! PE mode is usually invoked by a percentage of TPS. There's probably a table in TunerCat for your application that shows this. You can leave the values alone and just take note of what they are, and keep your foot out of it. I decided to bump my 800 RPM value up to match the other values - it was originally at 25%, and I put it at %60 like the other RPM values. PE mode if not tuned correctly, can quickly reduce your motor to SCRAP. From what I understand (Grumpy? feel free to correct me) PE mode assumes that all the fuel table values are set to 14.7:1 A/F ratio, and merely adjusts by A/F ratio according to them. If you're running too lean, and the ECM corrects for it just fine in closed loop, PE mode is "open loop" and won't correct for it - it just goes by it's own calculation of the table number. This is why you want to get your BLM's as close to 128 as possible. Note that if you've got values much lower (or much higher) than 128 - across the board - and you suddenly discover a perfect 128.0 in a higher KPa cell - it's most likely you've gone out of closed loop and you're in PE mode. Ignore these values. (That's not to say you can't achieve a perfect 128 - I have in a few cells already.)

I'd like to re-iterate something that Grumpy told me a long time ago - GIVE THE ENGINE WHAT IT WANTS, not what you THINK it needs. I've been working on that ideology and it seems to work quite well. Tuning the TBI in non-PE mode is fairly painless with these two tools (WinALDL and WINALDLVEFIXER.XLS) available now. I could easily lock my BLM's and perfect the non-PE mode #1 table, but I know once I start delving into non-PE mode spark, that table will once again change and have to be re-visited.

The cool part is, using WinALDL makes tuning *idle* very easy. It's just part of the non-PE mode table. Set your idle where your engine will run best (if you have a lopey cam, you may need to bump your idle up, otherwise it can probably stick around 650-700RPM.) Let the ECM do the rest. Tune the cell that the car tends to idle in (mine happens to be 800RPM cell at 40KPa, with the A/C off.) Don't forget, A/C introduces load - and that will skew your results. Might be wise to tune with it OFF first, then with it on.

IAC COUNTS - many of you are probably wondering what your IAC counts need to be. Stop and think about what the IAC is - {I}dle {A}ir {C}ontroller. It can correct for an overly rich condition by introducing more air - which of course bumps up idle speed. However, it can't correct for a *lean* correction. If you add more air.. it leans it out even more. So you want to have a few IAC counts at idle - just so you know you can have some leeway for correction if fuel is a bit too high. I would say no less than 15 or 20 counts at idle would be wise. (Grumpy? Thoughts?) If it's too lean, it can stall the engine. (Obviously not good.) Try to get your idle KPa/RPM cell as close to 128 as possible when tuning.

I've written this in hopes that some of you who sit silent looking for wisdom on here to start with tuning a TBI car will find a little understanding and maybe not be so frightened to "jump in" and start out. Grumpy did it with a stopwatch, a 10-LED O2 meter, a vacuum gauge and a DMM, and now Jonas and I have developed more powerful tools that help ease and speed up this process. However, I'd like to also put in my own note that if you do decide to "jump in" that you need to research your APPLICATION. Don't pick a BIN from the library that's for a 305 with a manual tranny, and try to run it in a 350 with a 700R4 - and wonder why it runs like crap! It's not going to work worth a damn. See if you can find a BIN that's much closer to your app. (Make damn sure it's for your ECM, as well!) If you're here, it's most likely not because you've got a stock engine, so I know it's not as easy to find a BIN that's close. Just do your research. Not only will it pay off in time shaved off of tuning, it will be less likely to explode that nice motor you've built up.

BTW, I am by no means any kind of expert. I've been silently following discussions for some time myself and taking the advice given - and occasionally rejected others. Grumpy pioneered this area, and I'm trying to develop it even further. I too am still learning, but I wanted to post my lessons so that hopefully some of you will start to see the light. Next I'll probably post something about tuning spark advance in non-PE mode, as this is the next logical step. PE mode is based off of non-PE mode, so you need to get non-PE mode working first. After that, I will probably do something on tuning lean-cruise mode, which for me will be a patch in the '7747, and for most of the rest of you, is already inherent in the '8746.

For those of you who are wondering, I drive an '82 Corvette with the original CrossFire on it - I've upgraded to the '7747, since the original ECM isn't hacked. The motor is totally stock - I've done this on purpose so I can hand out a "stock" '7747 BIN for this very same upgrade. Once I have this tweaked and tuned, I've got a nice set of L98 heads, some custom headers, etc. etc. that will be going into the car. I also have a '73 Corvette (hence my name) that I eventually would like to "push the envelope" and shoot for 400hp with a 2bbl TBI setup. (But that's another story entirely.)

Ken

 

Thanks to you two being so open minded about WinALDL, I've been able to get an almost perfect idle using some things that JoBy added that I thought would be helpful.

If you look at my sig you'll see that what I drive is far from an F-Body. I was at the Chevy dealer the other day with WinALDL running on the laptop in the passenger seat. A couple of mechanics giggled as I drove by, but when I got close enuf for them to see what I had going on they became real interested. WinALDL and the whole interface impressed them, and I never let on that it was home built until they asked where I got it. Basically, WinALDL is an incredibly powerful tool and I would still be putting up with a crappy idle and crappy acceleration if I did not have it.

------------------
'92 Astro, GM crate 350, Holley Pro-Jection Intake, MSD 6AL, 3.42's, 2.5" exhaust, Flowmaster 40 2 chamber, B&M 2nd stage shift kit, 255 60 R15 tires on AR-727's, TBI Bored out to 48mm and Polished , Custom EPROM in progress

 

Good post ken.

From what I have read and observed the IAC does not compensate for a lean or rich idle fuel mixture. It does not change air fuel ratio. The IAC is used to maintain idle speed. The "IAC step versus temp" table tells the IAC at what rpm the engine is to maintain. If you have a rich or lean idle condition, and the engine changes rpm because of that the IAC will adjust accordingly to bring the RPM back to the desired speed. The lean/rich condition is not changed by the IAC, just the rpm. For idle mixture the engine looks to the main fuel table and the appropriate rpm/kpa cell.

Any other comments?


------------------
Dan


[This message has been edited by Lionsden (edited December 13, 2001).]

 

Great post ken.. TBI tuning is starting to blow up! Awesome to see all this interest now, seems to be getting easier and easier

As for IAC, you might want to check out Rob Rauschers article on GMECM concerning the IAC functionality with the 7747 ecm

The iacs main purpose is to control idle speed. There are even fuel tables to correct for the increased air delivered by the IAC like a mini pump shot for its opening and whatnot.
Since fuel is drawn past the edges of the throttle body on TBI its HUGELY important to keep IAC steps to an absolute bare minimum. This is not so much of a concern on a stock motor because it pulls some pretty good vacuum at idle. BUt when you get into something like what I run, its alot more of a problem being that i only pull around 14" at idle, if there is alot of air bypassing the throttle blades and going in through the IAC cavity, that means the fuel landing on the blades is not being sucked in past the edges of the blades. This is important because it helps atomize the fuel. If there is no suction it just drips off and you get into the things ive witnessed on my car which is the rear cyls showing rich plugs and the front cyls showing lean plugs from idle.

 

It would be helpful to throw out the address that needs to be changed and to what for disabling EGR. I forgot what it was but I know you cant just raise the enable temp

 

Thanks for the post Ken.

It is really appreciated by people like me that need more guidance.

------------------
91 RS 5.0 TBI...Vortec heads...Edel Performer Intake...LT4 cam...1.6 Crane golds...TES headers...3"Dynomax exhaust...5spd... 3.08...Ultimate tbi...afpr...ZR 255-50's...Koni's

 

Ken
Where do you get the WINALDLVEFIXER program? That sounds like a good program to go with Tunercat and Winaldl.

------------------
Dan

 

It's an Excel spreadsheet, actually. The first revision by John Wilson is on the DIY-EFI FTP site. I, however, added in the functionality of the second VE table, which is fairly important. If you don't plan on changing your 2nd VE table at all, you can probably use John's version and just manually plug your numbers in. (It's a pain though.) I opted to "fix" it where there's an extra spreadsheet that allows you to copy and paste the 2nd table in from TunerCat.

If anyone wants a copy of my version, feel free to e-mail me and I'll send it your way.

Ken

 

Not sure if this was mentioned correctly or I misunderstood what what he was trying to say, but Ken said that Main Table #2 is added in non-PE use. I believe that this is a mis-statement, ie the Main VE Table #1 and Main VE Table #2 are added to each other at all times and the totals thereof are used in the PE fuel calculations, not just #1 table data. To wit, I have my #2 table set to all "0" and I use only the Main #1 table for all VE fuel calculations. Makes it easier for me to figure out and more importantly, to COMPARE bin files easier because you only need to look at the #1 table and the values are already "totalled"...

 

With out speaking for Ken73 I think he was saying/meaning the same thing. That fuel calculations are the sum of both tables all the time.

My first guess was that the #2 table was for PE mode.(I'm new at this) By trial and error it just didn't seem to work that way. Changes in the #2 table made int/blm changes in the non-pe mode.

Ken and I have discussed what the thinking or purpose might have been by setting up the fuel tables this way in the first place. Anyone have thoughts on this?



------------------
Dan

 

Guys,

This is a topic that Ken and I have had considerable discussion about. I had asked Grumpy to clarify as I was trying to modify operation of my Xfire at WOT. Based on wideband O2 sensor, my motor was starting to lean out between 4000 and 5200rpm.

Here is my question and Bruce's reply:
I have gone back and re-read the section of your tuning tips regarding the
Main Fuel Tables. What isn't clear is the effect of Table 1 on Table 2 after 3200rpm or vice-versa.
What does the ECM use for the VE after that RPM level?

Is it a combination of 1 and 2 with the value for #1 being the VE at 3200
and 100kPa. Or is the ECM relying solely on the VE in Table 2? Also, am I
understanding correctly that Table 2 is invoked in PE mode only? I look
forward to your clarification, if you would.

BRUCE:
Table 2 is an adder for when in PE
the values from 3200 up just use the last entries (not in PE)

This seems to contradict Ken's undertanding of Table 2 or I am reading it wrong?

 

From what I can tell in the hack, it appears that it uses the 3200 RPM line in the main table #1, with the #2 adder. I guess because fuel delivery gets a little inaccurate above those levels, or at least you find yourself narrowing down the KPa levels, it's easier to tune with table #2 above 3200 RPM.

That's what I've read from the hack.

Ken

 

Ken,

Yes BUT, Bruce clearly states that Table #2 is an adder table invoked at PE. In a subsequent reply, he stated that he considers
Main Table #1 the VE Table. Table #2 is the Adder table through an RPM range.

Bruce:
Table one is the VE table (least in my universe) fuel percents referenced to
RPM and MAP
Table TWO is a series of adders at various rpm levels
Are we on the same page?
Bruce

That answer coupled with the previous one indicates to me that Table 2 is added to Table 1 but ONLY when in PE.
I get the impression from Bruce, in some of his responses, that he doesn't like adder tables as a rule. He would rather tune the Main Fuel and Spark Tables and use the Adder Tables sparingly and only when necessary.

 

I still think #1 and #2 are added at all times. If they were not, the percentage difference of only using one table for CL vs PE would not support engine operation. ie, table 2 values are a huge percentage of the #1 values, and a huge percentage of the (#1 + #2) values, for that matter.

I use one table, #1 ONLY and it works WONDERFULLY. I have also taken the info from a good #1 table, subtracted an OEM #2 table and run both tables and could tell no difference.

Not sure why tboth tables are there but I suppose there must be a reason.

 

Dom, I found it impossible to tune without making SOME changes to the #2 table. Since it *is* added at all times (and Dan has also done some testing, and found it to be true) I was able to take some out of it, and add it to the #1 table. I had to lower the values in the #1 table so low from the BIN I had, that it was getting into negative numbers (which obviously won't work) so it was either lower the BPW, or lower the #2 table values and add them to the #1 table. Doing the latter worked magic. Gave me a little extra "room" to tune with. I may still have to lower some of my values a bit in the #2 table, but hopefully not much.

Tunercat doesn't like:

A. Negative numbers in either of the tables

and

B. Numbers higher than 100 in either of the tables.

That being said, if your numbers are too high, (trying to go over 100) then you simply remove an amount (say 10 or so, to give you some room to tune up) from table #1 and add it back in to table #2. Vice versa, if your numbers are trying to be negative, take an amount out of the #2 table, and add that value into the #1 table to give you some tuning room. Worked like a champ for me. I actually levelled out my #2 table at 34.8 I think, and added the values I took out, back into the #1 table. Works great, as I mentioned above, in 9-10 chips, I was able to get pretty close to 128 across the board.

I really don't know what to tell you Dom, other than to read the hack and visually see for yourself that the #2 table is always added to the #1 table. It's location A9 in RAM, I believe. In fact, I think the #2 table value is put in that location first, then the value from the #1 table is added TO that value, even.

Ken

 

If I were you guys, I'd make #2 table all zeros and just use the #1 table. Makes life A LOT easier. Just try it. It makes PROM comparisons VERY easy to grasp.

The OEM PROM (ASDU 7747 pickup) I have totals its VE to more than 100 at several places and Tunercat read it just fine. I think the ECU only "sees" 100 when you do that, though... ie, more than 100 works.

 

Fastbroker/Ken,


I did all of my tuning using Table #1. Never touched Table #2 until
I was looking to affect WOT operation. BLMs' averaged 127 for overall operation. For modification of WOT, I used Table #2 and the AFR PE adder. Got my best result when I modified both. However, Intech had made changes to Table #2 so that the Total VE was over 100% and making certain that the injectors were wide open at WOT. But its pretty clear that I wasn't running over 100% when rpm was 2000 and MAP was 50kPa.
Fastbroker, I agree that the negative VE is not an issue with Tunercat. I think that is a design issue of the ECM and its programming. It states in the 7747 hack, that the ECM will truncate total VE values to 100%. I have read some saying to the contrary however.
I believe that in tuning for WOT, you will want to pay attention to the area of Table #1 immediately preceding the point of entering PE, since that will be the last non-PE value that will be added to the values in Table #2 for WOT operation. I am not certain if you want the BLM corresponding to the last non-PE cell in Table #1 to be slightly rich or lean. If it is on the rich side then the VE adder from Table#2 will add to that until it can't add anymore beyond 100%. I think?!

"Dom, I found it impossible to tune without making SOME changes to the #2 table. Since it *is* added at all times (and Dan has also done some testing, and found it to be true) I was able to take some out of it, and add it to the #1 table. I had to lower the values in the #1 table so low from the BIN I had, that it was getting into negative numbers (which obviously won't work) so it was either lower the BPW, or lower the #2 table values and add them to the #1 table. Doing the latter worked magic. Gave me a little extra "room" to tune with. I may still have to lower some of my values a bit in the #2 table, but hopefully not much."

If that was the case, then why not just leave it out of #2 and be done with it. Why add it back in? If the ECM doesn't distinguish the overall result, it shouldn't have made any difference which table you used to make the change. And since Table#2 isn't a 3d table, how did you know that a change in one rpm range was the right change for all the other rpm ranges?

I know somewhere out there Bruce is sitting laughing his a** off at this dialogue. Maybe he'll weigh in with a final response on this.

 

Well, I added the numbers back in, and ran my correction figures against the NEW value. *Then* I burned a new chip. I didn't just remove/add and burn the new chip, I tuned afterwards.

Setting everything to zeros doesn't quite make sense either, but if your VE values add up properly, I guess it doesn't mater! I'm not totally sure mine would add up properly or not, but that's okay. It's fine where it is. At some point though, I believe you might want to add a little more fuel in at the 3200+RPM region. The only way to do that is through the #2 table.

Ken

 

I understand you added and then tuned, but why modify Table #1 if the ECM doesn't distinguish how it arrives at the VE value it is using? You should have been able to tune just by making the modifications to Table #2 according to your methodology.

 

After adjusting the int/blm to 128 +or- 3 in the #1 fuel table I began adjusting PE mode. Thinking the #2 table was PE I started making adjustments to correct a rich PE. I lowered the numbers in Fuel table #2. After making a few small adjustments in the #2 fuel table PE mode wasn't improving.

Out of curiosity I returned to the #1 table. The int/blm in a lot of cells were now above 135 some closer to 140. After comparing notes, any rpm cell in the #2 table that I lowered were now showing high int/blm numbers in all kpa cell for that rpm in the #1 table. Seems #2 table made a global change in all #1 table kpa cells in the corresponding rpm

I restored the #2 table and the int/blm in the #1 table returned to 128. Sum of the tables, pe and non-pe.


Just my experience.

 

Wrong. There were some areas that were still rich, and others were lean. I still had to tune tables in #1, but my *lowest* values got into the negative numbers, which Tunercat doesn't like. (It can only put a 0 in the BIN, not a negative number.) So, you take some out of the #2 table and add it in to the #1 table, then tune. If a cell was too lean, you still added to it - if it was rich, you still took away, just like normal.

In other words, if I've got a 0 in the 800 RPM/30KPa cell, and it's STILL running rich..... I can't tell Tunercat to put a negative number there. It doesn't accept negative numbers. So, I take a value of 10 out of the 800 RPM cell in the #2 table, and add 10 into all the 800 RPM cells in the #1 table. Now I have 10 in the 800RPM/KPa cell, and I can take some fuel out of there without having a negative number. Follow? I may have a 25 in the 800 RPM/50KPa cell, and it will now be 35 since I added the 10. In reality, the *total* value has not changed. If I'm running lean, I can still ADD to that as long as the value doesn't go over 100 (in Tunercat.)

Does that make more sense?

Ken

 

Just take all the values in Table #2, add them to their appropriate place in the table #1 data and input the totals into table #1, which is what the ECU does, anyway, right???. Then make table #2 all Zeros.

If you need more fuel at higher rpm, yeah you ned table two, but I have not needed it all for ZZ4 cam, 1.6/1.5 GMPP roller rockers and Fastburn Heads. I suppose more radical combos could use more fuel up top?

Like to hear Grumpy's thoughts on this and the reason why there are #1 and #2 tables???

 

Well, *my* thoughts are that the #2 table exists because it's mostly an afterthought. Remember, these ECM's were in trucks, Suburbans, vans, etc. They probably put it in when they realized some of the applications might go over 3200 RPM. Basically, sloppy coding on GM's part. Actually, if you think about it, the KPa range that's used in the upper RPM levels is pretty narrow. At 2400 RPM, you can get just about all KPa ranges, but with 4800 - are you going to see higher load? Usually you're at that RPM because you're in a lower gear, and possibly towing (remember, this is a truck ECM we're talking about.) When you drop into the lower gear and go to the higher RPM's, it lessens the load. Even when you accelerate, the higher RPM's have a lower load compared to the same acceleration rate in a different gear and lower RPM's. Just the same as you'll never see 100KPa at 400RPM. It just doesn't happen. Still, you had to put a fuel modifier in there somewhere for those higher RPM's.

Ken

 

Check me if I'm wrong, but aren't all the higher rpm VE adders in table #2 the same, like (30) from 3200rpm up to 6000+rpm?, so it doesn't/didn't really change anything for GM Engineers above 3600rpm (cannot remember) Ie, the table #2 added numbers DON'T change the total VE number to a higer number than it is at 3600rpm total, ie the VE total at 3600rpm is the same as it would be at 6000rpm? Also, the number(s) basically just add up to 100 or so, anyway, right?

IMO, most street/HP motors don't have much different fuel requirements/characteristics after 3000-3500rpm at WOT anyway, ie, only rpm changes the fuel req' at WOT. In my case, it works just fine.

 

Ken,

I think I see what you are saying. Maybe through
our dialogue, some others have gotten a chance to
understand it more clearly. Excuse me if I didn't get it
right away. I am sure I'm not alone.
Maybe this will help the others as it helped me. Think of Table 2 as a Constants Table for VE at rpm levels from 0-6400.
Table 1 modifies those values by introducing the MAP
dimension. So , in fact, the Total VE is the sum of #2
and #1. The value in Tbl 2, at a particular RPM, is a
constant that is applied across all MAP values for that
RPM range in Tbl 1.
Now, what I am still fuzzy on is when the system goes into PE. Does it use the last VE number it had read from Tbl 1 and applies it to all the VE values in Tbl 2 from the rpm point that the system
entered PE? Therefore, if you enter PE at 2000rpm, and the Tbl 1
value at that point is 49, then the values in Tbl 2 will
be added to 49 as the rpm's increase. So if at 2800rpm,
the Tbl 2 value is 37, then the Total VE in PE at
2800rpm will be 86.

How's that?

Dominic

 

Nope. Doesn't matter where/when you enter PE. Once at 3600+rpm, my understanding is that the ECU will use the 100MAP number in the #1 table at 3600rpm and the appropriate adder in #2. ie, the table #1 value picked is based upon the RPM/MAP you are at, not where you enter PE. RPM/load dependant, like all the other stuff in the code.

My point is/was that since the adder in #2 is (suually) the same from 3600rpm+, you can just use one table and make programming MUCH easier.

your initial explanation fo the table relations did make sense to me, too. ok stuff.

 

Depends on the BIN you get. Most of the stock ones have a low setting, or something like 39.1 is what I've seen, and the BIN that I started out with had 34.8 - but then again, the stock ones are meant for trucks.

WOT is PE mode, and PE mode is based on non-PE mode. You'll still want to tune those upper RPM tables so you can just punch in an AFR for the PE modes, and have them pretty close.

Ken

 

They way mine was set up to make 320+hp on the engine dyno was with highest value in my Table #1 was like 88 and my entire table #2 value is "0" and the FP was cranked to like 20psi on 55pph truck injectors. Dyno work always has always told me that the fuel req's don't change much after 3000rpm and are truly based upon RPM, but this holds true for carbed motors as well. That is why the values in the #2 values are usually the same from 3000rpm+.


Make sense?

I think I'll wait to post again until Grumpy chimes in. He'll know the poop on this stuff. I am just using what I have learned over the last 14 months or so, which, indeed, may be incorrect.

 

Of course! It works, doesn't it? That's just it - it works fine for you. That's another way to do it. I could probably drop all my #2 values to 0 also, and bump up my #1 table by the amount I took out. It's the same thing. Would probably make tuning a little easier visually, I suppose. You could certainly see the *actual* VE number at once, rather than having to add the #2 table value in your head.

Ken

 

Fastbroker,

That means you assume the 3600rpm/100kPa for any VE numbers beyond 3600rpm to be added to the VE in the #2 table.
Or are you assuming that the 3600 number will continue on up the rpm range?
On your dyno runs, were you able to see what happened to the AFR using a wideband O2 sensor. Mine climbed from 12:1 up to 14:1 beginning at about 4000rpm. What were the peaks for your torque and horsepower? RPM? I was running 66# injectors on a Xfire with 10.5psi and made the same HP as you.

 

You made 320+ ENGINE dyno hp with 65pph injectors at 10.5 psi??? ??? I couldnt' make more than 235 or so with the 55pph at 11psi??? No way. That's when I learned how to modify the FPReg...

I don't have the dyno data handy for the XE250-10 camshaft, it's on my home laptop but I never went below 13.2 AFR or so, I believe. If you are getting lean up top, it is from lack of fuel, IMO. rank up the FP a bit and you should get more HP/torque if you were tryuly at 14+:1. That ain't good for WOT power. Crank the FP to 15psi or so and do another engine dyno run...

EDIT oops, I beleive that the last rpm table in my table #1 is 3600rpm. But, from what I understand, when you are in PE/WOT, take the rpm you are at, the VE from both tables added, and the ECU will adjust the VE (the #1 and #2 tables are ALWAYS supposed to add up to make the engine be stoich @ 14.7) to the OPEN LOOP fuel parameter (say, 12.5:1) you have set in the PE AFR Constant area.

 

Fastbroker,

It was on a Dynojet chassis dyno. Pulled 252rwhp@4850rpm and 315rwtq @ 3800rpm. That's with full emissions gear. I believe the injectors were full out which is why the AFR climbed. I had made some changes to the #2 and AFR/PE Adder tables. I tested to ee if the addition of an 85 TPI fuel pump would help matters. It did in the midrange by 6-7 hp and lbft. But the topend followed the AFR curve.
That's why I am now looking into 90# injectors.

 

Don't bother with biger injectors until you are SURE that you need them. Crank up the FP 1psi at a time and see whatcha get!!! I believe you'll be pleasantly surprised.

 

Fastbroker,

Based on the Brake Specific Fuel Consumption formula, I do.
Of course the BSFC says neither of us should be making 320hp with the injectors we have. But I do believe that I am not maximizing the power curve with this size injector.

 

The 55's I used should be flowing about 74pph at the 20psi I ran, enough for almost 330 or so hp, ish, about, etc... That's a lot of psi, though, for long-term use, I bet. Don't ned anything to break!!!


JUST bought another new ZZ4 cam. SWEET!!! Gonna use it and the same rockers I have with the FastBurn heads but on Vortec heads and same manifold with carb in my other just-purchase Blazer. I'll see how the two different heads compare with the same EXACT other stuff...

 

Fastbroker,

I think you want to take the duty cycle into account when "pushing it". That's why I am looking at the 90#.

 

 

D'oh can't delete!

 

When manufactures rate their injectors is there a standerized %duty cycle they use? Whats the highest % duty cycle that a injector can be operated and still have reliable flow? One on line calculator uses 80% to figure pph.

 

Dan,

You are correct on that. It is 80% in order to give you some headroom. That's why the 90# are really 75#. There's also the FP that they are rated at.

 

I run 55pph injectors at 20psi and they seem to work just fine. For how long, who knows???

 

after screwing with this (you learn alot when you do things with no kind of direction or instruction, literally screwing it up) for like 3 years now i pretty much know how this works

1 and2 are always added
for areas from 3200 rpm and up, its the 2nd table added to the last KPA cell that you are in

like say you are at 4000 rpm and at 90 kpa, the 3200 rpm cell at 90 kpa is added to whatever rpm

Ive also adjusted ve2 so that its all zeros up till 3000? rpm (forgot the last rpm cell before 3200) and then left 3200 rpm as it was.. this way you can still toy with the wot afr at high rpm. If you look at the OE chips they all have a changing fuel curve even at high rpm, namely, leaner

I think disabling ve2 with ALL 0's is a mistake, ive done this and you lose any advantage FI has over carb at the top end of the rpm spectrum since you are pretty much stuck with the same fuel delivery from 3200 rpm up to 6000 rpm. Not only are the AFRs for peak torque and peak HP different (peak hp is leaner) but the advantage of being able to tune for this (an advantage over carb.. as i understand it, the area beyond peak torque a carb runs overly rich). When you really want to get crazy with it you can taylor the timing curve to take advantage of this by adding more timing beyond peak torque to compensate for the reduced cylinder pressure.

 

I've been following this post for a while and that makes the most sence. I thought that was how it worked before but I was never really sure since Grumpy says make the adder (VE#2 board) something like all 10's. This is what most of us have been doing with TBI and then tuning the 1st table for light throttle. Then playing with the WOT AFR ratio's for performance.
I think I'm going to adjust my tables now that I think we're on the same page. Grumpy, this is definatly a good time to chime in if you would. It also might be really worthwhile to get this all verified on a test bench with some wacko eprom values in the VE#2 table.

 

I was also told by a guru that you might want to make the entire #2 table something other than ZERO and all the same. I guess ZERO can screw up the ECU sometimes and if all the numbers are the same in #2, still makes #1 comparisons easier...

Of course I did not do it.

FYI, the 50-state EO'd PROM for the Edelbrock TB Power Package (heads, cam, intake, exhaust) has the #2 table as all ZEROS, and if it's good enough for the Feds, it's good enough for me.

 

yep ive heard the same, did that too btw

 

Pablo/Fastbroker/JPrevost,

Forgive me for being a little slow on the uptake. I understand now the relationship between #1 and #2 Tables. I would like to understand fully how that works when in WOT and going into WOT.
JPrevost:
"1 and2 are always added
for areas from 3200 rpm and up, its the 2nd table added to the last KPA cell that you are in
like say you are at 4000 rpm and at 90 kpa, the 3200 rpm cell at 90 kpa is added to whatever rpm"

Does this mean that the #1 Tbl VE used for WOT iss not always the the VE value contained in the 3200/100kPa cell?
Are you saying that when the motor leaves the last rpm level in Table 1, i.e. 3200rpm, that it may not be at 100kPa at that point ?
So if it is at 3200rpm but at 80kPa, then will that be the value used in conjunction with the Tbl 2 values from that point on?Not the value at 3200/100kPa? OR, Jprevost - Is it dependent on whatever kPa the ECM for a given GT 3200rpm, then it uses the corresponding VE at that kPa for 3200rpm?
To use your example, if the ECM sees 4000rpm but at 70kPa,
does it then use the 4000rpm VE in Table 2 along with the VE from Tbl 1 corresponding to 3200rpm/70kPa?
Hope this makes some sense. Thanks.

 

My understanding is that when in PE/WOT, when you break out in rpm from the Main#1 table, the ECU uses the Main#1 maxrpm and MAP 100 VE value and adds it to the appropriate #2 value, should a #2 value exist. The VE of most engines does not change above this rpm at high-load/WOT, that is why the main #1 table only goes so far, or so I was told. (look at OEM bins, see how the higher MAP and higher RPM values are same/almost the same?) The #2 was added in case extra fuel MIGHT be necessary, but in reality, it never is. Now, because the VE calculations are SUPPSEd to be the ideal 14.7:1 air/fuel ratio, the AFR you teold the ECU to be in can easily be deliverd by mathematically calculating the amount of fuel vs rpm, again, based upon PROPER VE TABLE data.

My understanding is that is does not matter where/when you get to PE. The highest rpm/MAP100 value in #1 is used as you actually achieve MAP100 via the MAP sensor when in PE. So I am told.

Again, tables #1 and #2 are ALWAYS added together, not just above 3200rpm!!! There is no "value" in table #1 above 3200rpm SO the table2 value is added to the 3200rpm/MAP100 value above 3200rpm, which is typically the highest value in the #1 table!!! you asked if you leave CL at say 70MAP, is that value used in calcs? My understanding is NO, the 100MAP is used (because you are AT 100MAP in PE and the ECU knows it!?!), but this is just what I was told.

So, I don't have any value but ZEROs in #2, so my ECU always is using 3200rpm/100MAP VE value at or above 3200rpm whenever in PE/MAP100...

Sorry, tired. Need sleepy...

 

Fastbroker,

Thanks. Your explanation is very clear and I thought that's what you had said earlier. So in fact, the ONLY VE value in Table #1 that is added to Table 2 ABOVE the 3200rpm level is ALWAYS the value found in the 3200/100kPa cell. That seemed to be contradicted by what JPrevost had posted. Which is why I asked the question.
Based on JPrevosts response, it is conceivable that a lower than maximum Total VE would occur when in WOT depending upon
what kPa the ECU found itself with at an RPM above 3200.
Understandably, at WOT, the likelihood of being at any kPa BUT 100kPa is remote.

 

I agree, it would be an incorrect VE value for the rpm/load, as well as bad programming.

 

Play with a light car, loose converter, and excessive wheel spin.

You can play with the above to leave with just about 0 wheel spin with playing with the table 1 to table 2 stuff.

On my 3rd gen with the cross fire, leaving from an idle, on old hard BF 245/50s with big sway bars, stiff shocks, truely in full street mode could run 2.00 to 2.02 60' times all day long. Unless the track was really hot and greasy.

(car weighted 3160 with me in it)
EZ 325 HP.
700R4, 3.43s, Posi, and reese bar rear suspension

Also the % TPS PE comesin to play.

While you can't make any changes that add up to over 100, by playing with the table you can control when that happens.

Also can matter what BCC you start with.