PovGRide742
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« on: February 11, 2012, 09:16:29 AM »
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Hello everyone,
For those who are using Bosch EV14 52LB injectors with part number 0280158117 like myself, I have created an excel sheet on how to determine the theoretical values (see attached) using the Bosch injector data sheet (see attached) and 0280158117 calibration summary (see attached). I have also attached a modified M-Box file to reflect these values with checksums corrected (see attached).
Couple things to note:
* This excel sheet isn't plug and play. Replacing your values with the ones on the sheet may not reflect correctly in the calculations, as I didn't set it up this way.
* This modified M-Box file is for a car running a stock MAF and stock displacement.
* These values are theoretical, and only serve as a starting point. USE AT YOUR OWN RISK!
Attached M-Box file has the following modified maps (everything else is stock):
KVB - 615.47 (Calculated)
KRKTE - 0.05206 (Calculated)
TEMIN - 0.2614 (Scaled from stock)
TVUB - 4.5259, 1.7682, 1.2908, 0.9735, 0.5467 (Calculated)
Brett
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julex
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« Reply #1 on: February 11, 2012, 12:08:54 PM »
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Something I noticed a long time ago but never had a chance to post in any thread.. The calibration sheet is wrong in couple of spots as values don't make any sense. The multipliers don't make.
60psi appears less than 55psi value which is obviously wrong. 49 -> 50 raises way too fast. Somethins is off here but if you compare these values to other injector sheets on the site, you can probably deduct proper multipliers for our applications of 3 and 4 bar.
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PovGRide742
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« Reply #2 on: February 11, 2012, 12:15:10 PM »
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Something I noticed a long time ago but never had a chance to post in any thread.. The calibration sheet is wrong in couple of spots as values don't make any sense. The multipliers don't make.
60psi appears less than 55psi value which is obviously wrong. 49 -> 50 raises way too fast. Somethins is off here but if you compare these values to other injector sheets on the site, you can probably deduct proper multipliers for our applications of 3 and 4 bar.
Yes sir... it was actually your post, http://nefariousmotorsports.com/forum/index.php?topic=320.msg2661#msg2661, that I used for multiplier values for 30.02 and 60.04 BEFORE performing the interpolation, and that is reflected in the excel sheet. Brett |
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littco
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« Reply #3 on: February 11, 2012, 06:47:17 PM »
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Hello everyone,
For those who are using Bosch EV14 52LB injectors with part number 0280158117 like myself, I have created an excel sheet on how to determine the theoretical values (see attached) using the Bosch injector data sheet (see attached) and 0280158117 calibration summary (see attached). I have also attached a modified M-Box file to reflect these values with checksums corrected (see attached).
Couple things to note:
* This excel sheet isn't plug and play. Replacing your values with the ones on the sheet may not reflect correctly in the calculations, as I didn't set it up this way.
* This modified M-Box file is for a car running a stock MAF and stock displacement.
* These values are theoretical, and only serve as a starting point. USE AT YOUR OWN RISK!
Attached M-Box file has the following modified maps (everything else is stock):
KVB - 615.47 (Calculated)
KRKTE - 0.05206 (Calculated)
TEMIN - 0.2614 (Scaled from stock)
TVUB - 4.5259, 1.7682, 1.2908, 0.9735, 0.5467 (Calculated)
Brett
Thank you for this and you could have posted it 2 days earlier:-) Seriously though I spent most of friday at work, working out these exact figures albeit at 3 bar! For my s3. Good to have something to compare it to though. |
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PovGRide742
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« Reply #4 on: February 12, 2012, 07:32:57 AM »
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Thank you for this and you could have posted it 2 days earlier:-)
Seriously though I spent most of friday at work, working out these exact figures albeit at 3 bar! For my s3. Good to have something to compare it to though.
Haha, you're welcome... sorry it wasn't earlier. |
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julex
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« Reply #5 on: February 12, 2012, 06:10:20 PM »
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I looked at the spreadsheet and one thing appears to be off. KRKTE value you have in there is for ~900cc injector as it is indicating almost 3x larger injector than stock M-box.
Stock 320cc: 0.146960 / 0.52 = 2.826 larger, which would mean you've scaled it for 320cc * 2.826 = 904 cc/min injector...
I use 0.048430 for my 1000cc injectors for what's it worth
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PovGRide742
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« Reply #6 on: February 12, 2012, 06:44:57 PM »
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I looked at the spreadsheet and one thing appears to be off. KRKTE value you have in there is for ~900cc injector as it is indicating almost 3x larger injector than stock M-box.
Stock 320cc: 0.146960 / 0.52 = 2.826 larger, which would mean you've scaled it for 320cc * 2.826 = 904 cc/min injector...
I use 0.048430 for my 1000cc injectors for what's it worth
I didn't scale it based on stock. I calculated it based on Qstat and Bosch's formula. Of course it's only theoretical. I had it scale it up by about 20% due to the lean LTFTs. |
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julex
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« Reply #7 on: February 13, 2012, 07:15:39 AM »
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I don't know what you exactly calculated there but ME7.1's units for KRKTE is ms/% which is ms opened per % of load on the engine. The value will change if you MAF is not scaled 100% toreal value as most MAFs are not properly scaled. Common tuning technique is to use fixed MAF table and instead of changing it when adjusting global AFR for the car, they just change KRKTE. It is easier to change one variable than scale 512 value long table.
You value is far off from what the ECU would need for 52lb injectors with properly scaled MAF table.
Just offering a comment, nothing more.
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PovGRide742
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« Reply #8 on: February 13, 2012, 09:08:00 AM »
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I don't know what you exactly calculated there but ME7.1's units for KRKTE is ms/% which is ms opened per % of load on the engine. The value will change if you MAF is not scaled 100% toreal value as most MAFs are not properly scaled. Common tuning technique is to use fixed MAF table and instead of changing it when adjusting global AFR for the car, they just change KRKTE. It is easier to change one variable than scale 512 value long table.
You value is far off from what the ECU would need for 52lb injectors with properly scaled MAF table.
Just offering a comment, nothing more.
No worries, I know you are only trying to help. Here is what I did: Theoretically, KRKTE = 50.2624 x Vh / Qstat. We know Vh = 0.4452, and, according to Bosch's technical information, Qstat AT 270kPa = 353. Now normal operation is in 4bar, or 400kPa, so to convert Qstat from 270kPa to 400kPa, we do 353 x sqrt(4/2.7), which gives us a Qstat of 429.6579. Now we can complete the equation. KRKTE = 50.2624 x 0.4452 / 429.6579, which gives us a KRKTE of 0.0521. I understand this is not accurate, but theoretically it is, according to Bosch's formula. I personally have an 85mm MAF housing installed, and am using berTTos's MAF scaling maps, so I am basically adjusting fueling to his maps. My LTFTs were +20 based on theoretical values. I just wanted to provide an example of how to perform theoretical calculations to use as starting values. Brett |
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s5fourdoor
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« Reply #9 on: February 13, 2012, 09:18:47 AM »
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A good starting value for these injectors has been around .0550 for multiple people I've assisted including my own car.
Julex - as always - has a valid point on the trade-off between MLHFM and KRKTE.
The best thing would be if somebody had a stock MAF against which they 0'd out their LTFT's to determine the technically correct values of KRKTE and TVUB.
The obvious way to do the TVUB adjustment would be to start with the base values from that injector sheet and multiple by (1+x) where x is some percentage TBD.
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PovGRide742
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« Reply #10 on: February 13, 2012, 09:44:40 AM »
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A good starting value for these injectors has been around .0550 for multiple people I've assisted including my own car.
Julex - as always - has a valid point on the trade-off between MLHFM and KRKTE.
The best thing would be if somebody had a stock MAF against which they 0'd out their LTFT's to determine the technically correct values of KRKTE and TVUB.
The obvious way to do the TVUB adjustment would be to start with the base values from that injector sheet and multiple by (1+x) where x is some percentage TBD.
Last I checked with theoretical KRKTE plus 20% (around 0.62) on scaled TEMIN and calculated TVUB (same values in the excel sheet) I'm around -3 to -4 for partial and idle LTFTs, but I want to do some more driving before perform any adjustments. |
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s5fourdoor
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« Reply #11 on: February 13, 2012, 09:56:06 AM »
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Yes, exactly the right idea. I typically try to do 100 miles of varied driving over a few days before considering my LTFT's "statistically valid".
It can take a couple tunes before all your trims are within +/- 1% but its definitely worth the effort.
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PovGRide742
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« Reply #12 on: February 13, 2012, 12:21:57 PM »
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Yes, exactly the right idea. I typically try to do 100 miles of varied driving over a few days before considering my LTFT's "statistically valid".
It can take a couple tunes before all your trims are within +/- 1% but its definitely worth the effort.
I will eventually have, hopefully, EPL dyno-tune my car. So this is just temporary. I just went with berTTos's 85mm MAF scaled maps, but I am trying to get the LTFTs dialed in somewhere between 0 and -3%, closer to the -3% side. I started out with an incorrect TEMIN value (only realized I calculated it wrong when I made that excel sheet) so I basically started over Saturday. I had adjusted KRKTE around 5 times before realizing I calculated TEMIN wrong. Sucks going back to square one. |
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julex
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« Reply #13 on: February 13, 2012, 01:47:26 PM »
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TEMIN is almost never used so don't sweat it. The only use for the variable is to institute minimum injection time when injector is active. It's purpose might be to inject fuel at the threshold of maf accuracy at very light loads (sub idle) to prevent misfiring at the expense of going silly rich in that are... but... I can't imagine when would that value ever be used on stock injectors which need to squirt 3x as long even at idle - I have no idea why it is even in the programming.
Even at the lightest load when decelerating (just before going VE - no injection at all) I still register more than 0.5ms injection time on my 1000cc very rarely touching 0.5ms. And if I do, the car is going VE immediately.
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phila_dot
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« Reply #14 on: February 13, 2012, 02:09:11 PM »
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I will eventually have, hopefully, EPL dyno-tune my car. So this is just temporary. I just went with berTTos's 85mm MAF scaled maps, but I am trying to get the LTFTs dialed in somewhere between 0 and -3%, closer to the -3% side. I started out with an incorrect TEMIN value (only realized I calculated it wrong when I made that excel sheet) so I basically started over Saturday. I had adjusted KRKTE around 5 times before realizing I calculated TEMIN wrong. Sucks going back to square one.
EPL and the mainstream tuning industry generally frown on DIY tuning and will likely blacklist you if they find out you have been tinkering. |
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