I'm trying to get my injector flow rate constant right. They're 60lb injectors and I've progressively adjusted the constant from 60lb up to 63lb but my hot idle long term BLM has only progressed from 118 to 120. How far off can the constant be?
or am I missing something?
many things will change at that large of a jump.. what is your base fuel pressure set at? the battery voltage tables may also play a part.. the higher the voltage the better injectors respond especially highZ units. may try changing this table some as well.
I've got a stock regulator so it should be 43psi??
I've been running Mohawk 94octane with 10% Ethanol. I've heard that this might have something to do with it, and am going to try changing the stoichiomatic (sp?) ratio from 14.7 to 14.6.. It's getting cold here so the car will be parked for the winter soon.
results later
Decreasing your "minimum injector pulse width". Try 1.0-1.1 msec. This should help the idle.
Also, to make global changes in the BLM's you can raise or lower the injector constant. A higher constant will increase the blms and a lower number will decrease them.
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2001 White/Black/Black Vert M6/Z51. LPE 650TT 580rwhp/540rwtq
1994 White/Red M6 LT1 Corvette(US MUSL) 374rwhp/345rwtq,12.37@119: Heads/Cam/4.10's
2001 Ford Lightning(BLWN 01)425rwhp/503rwtq,12.85@108
2006 Cobalt LS (DD)
Question - what are you using for a conversion number to get from Pounds per hour to Gallons per hour?
CATS tuner wants a Gallons per hour number for the injector constant, right? The files I use for my '85 do at least. Maybe the '94 ECM does the conversion for you and wants a pounds per hour number, which would be simpler. But scary.
Because - that conversion constant can be fuzzy. It varies a Lot depending on many things. There really isn't any accurate way to know what you are running in the car other than to measure out a gallon and Weigh it. Temperature will change the density by a significant amount, too..
Gasoline will have a specific density in the range of about .71-.77, compared to water. Water weighs (standard temp and pressure) 8.288 lb/gal. That means the range for Gas ought to be about 5.9-6.4 lb/gal. It's a pretty big spread, when you are trying to dial in an exact A/F ratio.
For what it's worth I find that knowing the exact density of the gas doesn't really help me much. I have to give a value to TunerCat that doesn't make sense anyhow. For example, with 24#/hour injectors I end up using a gallons/hour number of about 4.3. That converts "backwards" to a density of 5.6 lb/gal, which is rather outside the range of densities that would/should be applicable to gasoline.
This Might make sense with the 10% alcohol in all the gas these days, I haven't dug into that to see..
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'85 automatic coupe. 260K and counting, 330hp Crate Vortec heads, SDPP base manifold, BBK TB, true duals w/3 muffler setup (that's right - 3), driven daily year round - snow tires a Must!
The display injector flow rate is used for the instant/average miles per gallon in the DIC. When using a larger injector than stock, I divide the new injectors flow rate by 5.85 to correct the fuel mileage display. I doesn't affect the engine's tune.
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2001 White/Black/Black Vert M6/Z51. LPE 650TT 580rwhp/540rwtq
1994 White/Red M6 LT1 Corvette(US MUSL) 374rwhp/345rwtq,12.37@119: Heads/Cam/4.10's
2001 Ford Lightning(BLWN 01)425rwhp/503rwtq,12.85@108
2006 Cobalt LS (DD)
The display injector flow rate is used for the instant/average miles per gallon in the DIC. When using a larger injector than stock, I divide the new injectors flow rate by 5.85 to correct the fuel mileage display. I doesn't affect the engine's tune.
My display injector flow rate is set at 4.09 with Ford 30#'s. Weird, so I should take the 30# divided by 5.85?
Steve, that's what I use. Seems to get it pretty close. Is your injector flow rate set at 30#, or the ~32# most use?
Thats right Ford Injectors flow more at GMs fuel pressure. So I should put 32/5.85=5.4 as mine in the constant for display injector flow rate?
My tuner set my injector flow rate at 29.1, due to FOrds being higher than GM. Tuners are all different.
There is nothing wrong with going up or down on the injector flow rates, that is the easy way to make global changes.
If you look at the stock bin file, take the "Injector flow rate" and divide it by 5.85 you will get the stock "Display injector flow rate" number. That's how I got the 5.85.
If your fuel pressure is at the stock setting and your injector flow rate is set at 29.1, I would divide that number by 5.85. If your fuel pressure is higher that will change the numbers.
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2001 White/Black/Black Vert M6/Z51. LPE 650TT 580rwhp/540rwtq
1994 White/Red M6 LT1 Corvette(US MUSL) 374rwhp/345rwtq,12.37@119: Heads/Cam/4.10's
2001 Ford Lightning(BLWN 01)425rwhp/503rwtq,12.85@108
2006 Cobalt LS (DD)
Why can't i adjust injector flow rate for BLM closed loop idle?
I know this question is old but you can still revisit the program and make changes. The injector flow rate should be set at the actual injector size that you have. You then adjust your MAS (mass air flow tables) to adjust for incorrect BLM's. If you make changes with the injector flow rates you are giving incorrect information to the computer that fakes it out and may correct the problem but can cause little tuning issues. In other words the idle BLM's may be correct after you make the change but now the WOT AFT may not be what you commanded because the engine believes you are running the wrong size injectors.
I do my tuning on a chassis dyno and I set my injector constants to the actual flow rates of the injectors and then I adjust the MAS tables to get my commanded AFR. If I want a 12.5 at WOT and am commanding a 12.5 but end up with 13.0 I will increase my entire MAS table by 4% until the commanded AFR and actual AFR match. I then go back and check my BLM's at various throttle positions to to check for errors and if I find a large error (+- 5%) I will then fine tune the MAS table in the effected areas to eliminate the error. This ensures that you are not tricking the computer in to giving you the AFR that you want and it makes it easy to make additional tuning changes while being confidant that you are asking for is actually happening. In other words if I decide that I want a WOT AFR of 12.0 I will get 12.0 with confidance by asking for a power enrichment factor of 1.225. If you have the incorrect injector constant added the 1.225 power enrichment factor will not give you an AFR of 12.0.
PE factor is power enrichment. To figure out what AFR ratio you are commanding take 14.7 and divide it by the PE factor and that will be your commanded AFR. 14.7 / 1.15 = 12.78 commanded AFR. If you have the computer set-up correctly for your car that is the AFR you will get.
If you haven't also properly adjusted the offset and adder tables for these injectors, you are going to have a VERY difficult time really getting that tune dialed in.
Just last night I sorted out the method for scaling all of Greg Banish's data automatically via Scilab and will be working on a full scale writeup in the near future.
bjankuski, this is starting to make a little more sense now, thank you both for your input. I'm basically trying to get my tune as close as possible with the stock O2 sensors before I eventually take it for a Dyno tune. Am I dreaming or is this possible with novice skills, TC and Datamaster?
Scott....I think they are Bosch 60's, but I'm not sure. I read your write up and my head is now spinning in confusion. Thank you though.
Can someone please explain the connection between battery voltage tables and injector performance?
Corvette Store
Tunercat injector flow rate
Haha, I think that's the way I was trying to dial in my injector size. No wonder it wasn't doing anything...Jeeesh
