Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

Injector Constant Question

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Old Jan 3, 2004 | 11:18 PM
  #16  
Alvin@pcmforless.com's Avatar
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Originally posted by Dan K
Then how do you find an acceptable injector constant for a car that you don't have a "perfect" tune for when someone comes to you for a program?


I've got probally 150 different combinations for 93 F cars alone. many of them same cam but with differnet injector types.

Why? Figuring injector constant based on an injectors rated flow and the fuel pressure that you are using works fine and just seems a bit easier for most to understand.
Do you feel there is an advantage doing it the way you described? Or is it just the way you do it?
Listen to my method of finding correct injector constant and you should realize that it is the closest method. When nothing is changed between injector swaps then nothing should be changed other than injector constants (93's do not have offset tables like other MAF earlier and later).

This method is especially important when doing EEC IV Ford, GM TBI especially w/ larger or smaller factory injectors, and cars with low impedance drivers.

Tuning is 60% math and 40% of giving the car what it wants. no if ands or butts. math gets you in the right direction and playing around finishes it.

Every injector I've tested with the 93's I've done this way and some like lucas and accel are pretty close to what they are advertised and others and especially ford are different.

I've done some pretty radical experimenting with 93's. Hell I think i'm the only one ever to get fueling right on a 93 F car with 2 bar map sensor. (correct me if I'm wrong, I know quite a few have tried but failed) and alot of the values that i use would honestly shock and surpize you. But hell if it works it works.

Hell a car I tuned with a injector constant 5 pounds off what its "supposed to be" ran a 10.79 about two months ago.

I just challenge you guys to experiment and work. Theres way more to tuning than doing a x/x calculation and a prime example of that would be your average run of the mill PE table. Any reason why you think it should ocsollate, have a negative slope, or be flat?


but then again what would i know.

excuse the spelling.
Old Jan 3, 2004 | 11:22 PM
  #17  
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Originally posted by TriPinTaZ
I agree that using the wrong injector constant may work, but any corrections your PCM does to fueling will be incorrect due to the wrong constant.

I do not see why you should have to use a incorrect injector constant.

In my car I used 42.4 injector constant for my 42.5 lb lucas injectors. and any BLM problems were corrected via the VE table. Also altering your spark advance will change your BLMs. Maybe the tune needs more timing ?
Did anyone read where I said his BLM's where within 97-98% of being perfect the last time I went over his tune?

Prehaps I should run a VEcrapmaster on it and post the log.
Old Jan 4, 2004 | 12:52 AM
  #18  
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Originally posted by ROOSTER93V8
Did anyone read where I said his BLM's where within 97-98% of being perfect the last time I went over his tune?

Prehaps I should run a VEcrapmaster on it and post the log.
I was talking to the started of the thread. Tuning is not as difficult as you try and make it sound. They dont teach LT1/LS1 edit classes at your local university now do they?

And I never even used VE master, MY VE table changes were all made on a mustang dyno

Last edited by TriPinTaZ; Jan 4, 2004 at 12:56 AM.
Old Jan 4, 2004 | 03:48 AM
  #19  
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Originally posted by TriPinTaZ
I agree that using the wrong injector constant may work, but any corrections your PCM does to fueling will be incorrect due to the wrong constant.

I do not see why you should have to use a incorrect injector constant.

In my car I used 42.4 injector constant for my 42.5 lb lucas injectors. and any BLM problems were corrected via the VE table. Also altering your spark advance will change your BLMs. Maybe the tune needs more timing ?
So are you running speed density then?
Old Jan 4, 2004 | 04:32 AM
  #20  
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Trying to get a perfect tune can be very difficult. Anyone who has much experience will confirm that. My injector constants are so far from "reality" that it might surprise you. More than 50% off, in fact when you consider my elevated base fuel pressure. I agree with rooster that you should give it what it wants, not what you think it needs.

Rich Krause
Old Jan 4, 2004 | 12:08 PM
  #21  
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Originally posted by InjectedSS
So are you running speed density then?
Nope Im still using my MAF

Ask Joe Overton his opinion on tuning with VE tables on MAF cars. He seems to be the only other person that has had gains in HP by just tuning with VE and timing tables.

VE TABLES work in my car and Joe Overtons tunes he makes for OBD2. We are the only 2 with the magic touch so dont go trying to figure out why my MAF car responds to VE changes.
Old Jan 4, 2004 | 02:53 PM
  #22  
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Originally posted by TriPinTaZ
Nope Im still using my MAF

Ask Joe Overton his opinion on tuning with VE tables on MAF cars. He seems to be the only other person that has had gains in HP by just tuning with VE and timing tables.

VE TABLES work in my car and Joe Overtons tunes he makes for OBD2. We are the only 2 with the magic touch so dont go trying to figure out why my MAF car responds to VE changes.
So your telling me that VE TAbles WORK in your car, where's the rest of the entire F-Body MAF Tuning world THEY DON'T I think NOT...

Maybe you have your MAF unplugged and you DON'T know it Dude it's been proven a thousand time's. VE TABLES DO NOT CHANGE NETHING ON MAF CARS. Unless the MAF is unplugged or the car is in speed density mode.
Old Jan 4, 2004 | 05:57 PM
  #23  
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Injected SS , what credentials do you have to prove you are right or even qualified to say I am wrong ? YOu probably read someones post about MAF this and that and took it as rock solid words that you dont even have any experience in. Then you all share your mindless chatter here on the board and everyone believes the 1st Idoits post. Assinine...

I TUNED my car in VE, I GAINED 40 rwhp, I HAVE a VE tune. Like it or not, VE tables work in my LT1. So I am the only LT1 like I said in the previous post. I am magic, thats all there is to it.

I could give two ***** what you think
Old Jan 5, 2004 | 04:49 AM
  #24  
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I just want to be clear on a couple of things after reading this and seeing the pot that I accidentally stirred.

I am NOT trying to doubt Rooster's tuning capability. I have the highest of faith in his ability to tune my car. At part throttle, the thing is perfect. He's got it nailed in. I was merely posting a question of "if my injector constants were to be changed to the 31.xx would it feasibly solve my problem?" I'm just trying to learn and figure out this persistent problem for myself.

I have Rooster's tuning in both of my cars, and I can attest to his abilities. The 93's are a bit different from the MAF 94+ also.

Rooster, if you're keeping tabs on this, I should be swapping some parts later this week and running my latest update. I'll give you a buzz and let you know what I find.

Sean
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