Ben Brown wrote:Well i just finished getting my engine going... And it hauls ass, but im having a big problem getting it to richen up in the top end... From like 6000rpms and up my VE % is 120 and i cant get any higher. How do i get around this?? Im running 60lb injecters as well.

Have you also minimized the VE table?

I find the VE offset to be mostly BS.

If a good portion of your table (or none) is not at 20% on the low end, then change your Injector constant and retune.
In other words if your table ranges from 50% to 120% then the real isssue is that the IC is wrong and if it was correct then the table would be 30% to 100%.
VE offset is just a "crutch" way to fix that.

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THanks for the info guys. I removed the s/c belt and disconnected the charge pipe (with a filter on it of corse) so i wouldnt get vacum in high rpm (gets about 2psi of vacum if it has to suck through the supercharger when its not turning) And tuned the VE tables, got it all nice and smooth. So tomorrow im gunna put in my 2-bar sensor, and set it up to raise the pulsewidth with boost, then tune the spark accordingly. This way the VE table doesnt have to rely on the boost.

Should work right?


I think im also gunna do a dyno run without any boost and the tune im currently running when i get to the dyno... While tuning today i walked all over a RSX type S, and this is all motor mind you... So i am really curious to see what it puts down to the wheels


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Well i got it tuned perfectly, i went into the IPW vs. vac table and set the value at 0 to 1.15, then some ve tuning and the car runs great.

needs something to cool the charge though, in this hot weather im only running 11* advance and still getting like 6* or KR after a couple pulls... Im blaming this on heatsoak.

Cant wait to see what she will do tonight when its cooler outside


<img src="http://memimage.cardomain.net/member_images/3/web/831000-831999/831395_11_full.jpg">

Ben Brown wrote:THanks for the info guys. I removed the s/c belt and disconnected the charge pipe (with a filter on it of corse) so i wouldnt get vacum in high rpm (gets about 2psi of vacum if it has to suck through the supercharger when its not turning) And tuned the VE tables, got it all nice and smooth. So tomorrow im gunna put in my 2-bar sensor, and set it up to raise the pulsewidth with boost, then tune the spark accordingly. This way the VE table doesnt have to rely on the boost.

Should work right?


I think im also gunna do a dyno run without any boost and the tune im currently running when i get to the dyno... While tuning today i walked all over a RSX type S, and this is all motor mind you... So i am really curious to see what it puts down to the wheels

Are you running S/C reflash!?!


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Nah, just hptuners... If i was reflashed i would still have the 6500rpm redline and my cams would be worthless


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Update

Ive run into this problem also recently with a 97 Z24, I had to raise the offset to 30% to compensate for the boost at 4000rpm where it requires the most fuel but running 30 in the lower cells still makes the car idle far too rich

ANother problem is that it doesnt have the IPW vs. Vac table



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

protomec wrote:

Ben Brown wrote:Well i just finished getting my engine going... And it hauls ass, but im having a big problem getting it to richen up in the top end... From like 6000rpms and up my VE % is 120 and i cant get any higher. How do i get around this?? Im running 60lb injecters as well.

Have you also minimized the VE table?

I find the VE offset to be mostly BS.

If a good portion of your table (or none) is not at 20% on the low end, then change your Injector constant and retune.
In other words if your table ranges from 50% to 120% then the real isssue is that the IC is wrong and if it was correct then the table would be 30% to 100%.
VE offset is just a "crutch" way to fix that.

See I wish it was that easy, but if you do that then you need to adjust the idle and cruise tables so they are correct...



" To study and not think is a waste. To think and not study is dangerous. "

update on this since I may encounter it again in the future with other J's

SO the correction if you maxing out the VE would be to lower the injection constant to a lower number and use the IPW vs Vac table?



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

Rodimus Prime wrote:Update

Ive run into this problem also recently with a 97 Z24, I had to raise the offset to 30% to compensate for the boost at 4000rpm where it requires the most fuel but running 30 in the lower cells still makes the car idle far too rich

ANother problem is that it doesnt have the IPW vs. Vac table

that sounds like an error. I used the offset to my advantage and it does make a difference and it shouldn't destroy your idle since your narrowbands go to work to achieve close to your cmd afr.

so should the constant go up or down to provide a wider fueling range



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

Rodimus Prime wrote:so should the constant go up or down to provide a wider fueling range

You need to use the injector constant formula to calculate your constant at stock fuel pressure. You raise the VE Offset to be able to add more fuel in higher TPS cells. You do not want to raise it above what your lowest value in the VE tables is.

For example, if your lowest value in your VE tables is 40, do not raise the offset over 140, if you do it will automatically bump that value that was 40 up to what ever the new offset is and you have thus richened up that cell.

As mentioned above if you do, the car will run crappy because it will be to rich at idle if you raise offset beyond what your lowest VE values are. If you let your car warm up a minute into closed loop, this may not be an issue for some people. To me it is annoying since I drive my car daily and don't always have time to let it warm up like I should.


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Hahn Stage II - Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |

BlackEco wrote:

Rodimus Prime wrote:so should the constant go up or down to provide a wider fueling range

You need to use the injector constant formula to calculate your constant at stock fuel pressure. You raise the VE Offset to be able to add more fuel in higher TPS cells. You do not want to raise it above what your lowest value in the VE tables is.

For example, if your lowest value in your VE tables is 40, do not raise the offset over 140, if you do it will automatically bump that value that was 40 up to what ever the new offset is and you have thus richened up that cell.

As mentioned above if you do, the car will run crappy because it will be to rich at idle if you raise offset beyond what your lowest VE values are. If you let your car warm up a minute into closed loop, this may not be an issue for some people. To me it is annoying since I drive my car daily and don't always have time to let it warm up like I should.

x2 the constant isn't something to be altered but once. Also you can alter when closed loop starts.

Your just repeating what I've already stated, I'm well aware that making the offset higher makes your lowest VE value go up as well. The problem I have is that in order to fuel upper parts of the powerband I might need 160ish VE which means the lower cells are over by 20-30. I need a wider range, so should the constant be moved up or down from what I started with



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

My ve offset is 76%, like I said the narrowbands will go to work and take care of you when close loop starts unless you guys are running the car completely in open loop.

76%!? Your car must run like ass at low rpms?

Rodimus Prime wrote:Your just repeating what I've already stated, I'm well aware that making the offset higher makes your lowest VE value go up as well. The problem I have is that in order to fuel upper parts of the powerband I might need 160ish VE which means the lower cells are over by 20-30. I need a wider range, so should the constant be moved up or down from what I started with

The injector constant does not make the "fueling range wider" it is a constant

It doesn't matter if you raise the VE offset to the point where you richen out the lower VE cells, or if you increase your injector constant to add fuel up top, either way it is going to richen the lower cells.


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Hahn Stage II - Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |

Admiral Jedi wrote:76%!? Your car must run like ass at low rpms?

not at all, again if you get the complete workings of hpt you can make anything possible. I once got 37 mpgs on a trip and during that trip 3 wot pulls 3rd through 4th where made and various other types. your narrowbands ignore your ve table and go straight for their own calculations for best fueling like i said above.

K. Vega..Mr. M62 L61 himself. wrote:

Admiral Jedi wrote:76%!? Your car must run like ass at low rpms?

not at all, again if you get the complete workings of hpt you can make anything possible. I once got 37 mpgs on a trip and during that trip 3 wot pulls 3rd through 4th where made and various other types. your narrowbands ignore your ve table and go straight for their own calculations for best fueling like i said above.

Actually they do not... In closed loop, your still running off your VE tables... you just have the help of the narrowbands to help fix your mistakes. your narrow bands simply tell the computer what they are seeing at the tail pipe. The computer compares the NB reports to the commanded AFR. If the difference is say 5% too lean... it adds 5% richness to the Fuel Trims.

Your computer tells the injectors how much fuel it needs by doing some fancy math that combines your VE table, Injector constant, and the Long and Short term fuel trims.
We have no control over the trims... they are based entirely on the narrow bands.

if you increase your ve offset... you just move everything up. so you cant have low entries on the table. it just shifts everything in one direction.. leaner or richer... (remember everything about VE is a percent.. as is the offset.. so you are really just adding the offset to the entire table. if you had a 10% offset and you change it to a 30% you effectively just add 20 to every cell in the table. any cell that was a 50 now becomes a 70. anything that was a 10 is now a 30. 90 becomes 110... etc... wont help at all with increased range in both directions.

I had thought the computer had an issue with cells with 3 digits before the decimal... but i guess this isnt the case as the offset actually makes the number HIGHER and gives more 3 digits... It must just be that it cant handle much more than a 0-100 swing. so 50-150 is fine... but 10-120 is not. Just an assuption here... trying to figure this out myself.

if you increase your injector constant it changes the durration your injectors are firing for. (to shoot 10 units of fuel a 210cc injector might open for 40ms but to shoot the same 10 units of fuel a 750cc injector need only open for 11ms.) The computer doesnt know what injectors you have, so it expects you to tell it in the form of a constant. (where the number initially came from who knows... but use what you have and do the math to figure out the new number)
The constant will basically just trick your engine into changing the time the injectors are open for.... lower numbers are for larger injectors which means they will open and close faster... so if you keep the same injector, but lower the constant you will get LEANER. raise the constant to get richer. Just remember that this effects EVERYTHING... and not always evenly across the board since you are changing TIME not PERCENT of fuel now.

and you loose accuracy if you have the wrong constant. since the real world and the computers math world arent exactly jiving anymore. You can try and make up for this with VE tuning... but it isnt always so much fun.