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Re: If you have maf read this
quote:
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Originally posted by kvu
First off I'm not implying sd folks not to read,thank you.I would like you to post your rpm redline.Then post your gr/sec @ redline.Finally post the 1/4 mile time and/or dyno results for your car.Info like weight and mods would be nice.Just gr/sec and redline rpm if no dyno or timeslip.Thanks for any info.
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I can understand your enthusiasm.
I really can.
But, you're really to the stage of needing to build an ecm bench to really see what's going on. So far you've just been looking at one end of the equation, and drawing results from one car. Which while they may be true, they are only true for one car.
If you were to look at things on a bench and make slow deliberate changes, some answers might just pop out at you.
This is kinda a single reply to a few of your postings, and just my opinion, no flaming meant.
The MAF is a wonderful devise, and GM spent a bunch of money getting the calibration right on it. The reason I started off suggesting the ARAP, was that the fuel lined up pretty well with it.
Now, the ecm is doing almost all the fuel cals based on the MAF. If you somehow change the flow thru the MAF then you'll need to recalibrate it, ie if you remove the screens, cut the heat sinks out etc.. Those mechanical changes to the MAF will mean changing the MAF scaler tables. Since they influence the actual way the MAF senses things. Changing the injector size, engine displacement, etc, have no effect on the MAF, the mechanical changes done to the engine, won't make a mechanical change to the MAF. If you change the injectors then it's injector characteristics that need changed. The new injector will in all likely hood have different rates of response for it's pintle/disc/ball movement so the battery voltage correction would need changed as a result.
On the issue of battery correction, it's primarily noticed at idle. At idle the injector has a duty cycle of 2-3%. The 10% change that a battery volatge correction might make is then .1 msec.. That same .1 sec at a pulse width of 20 msec isn't hardly noticeable.
If you want to continue changing the scaler values, fine, but, please realise you not making the corrects the best way possible.
There is a difference.
To answer your guestions,
with a stock MAF, I pegged it at 3,400 RPM, and by 3,600 was into MAF drop out. Stock turbo
With a rescaled MAF, ie late LS1 MAF, I can draw about 400 gms/sec.. Stock looking turbo.
With some tiny injectors I ran a string of low 13s using part throttle until 3rd gear.
Now, if you want to get a second MAF, do some data logging, and build an ecm bench I can probably help ya get some more resolution out of a stock MAF. The real trick is that the output is no where near linear (at least in my application).
But, you still have the restriction of drawing thru a MAF.
Undoubtably someone will take issue with the above. To that all I can say is, Oh Well.
Thanks Grumpy, I did'nt think it was a flame.One thing that made me realize things,about maf was looking at the code..There seems to be "tables" that converts the sensors from vdc to useable terms,like coolant temp.Now I understand the maf tables are converting vdc to gr/sec,thanks Greg!.Not a "tuning" table,plain and simple.
Yes changing the maf table will work to richen and lean.I'm sure I could "trick the ecm" other ways to cure a lean idle.Your method, batt correct table(explained well now) does seem to have the less negitive effects.
I did'nt go around changing alot with the maf tables though.Just tweeks here and there.There seemed to be no ill effects from changing a point or two for idle though.Your right,that worked for MY engine.But I have realized my maf is 17 years old.
The only way to acurately recalibrate the maf tables would be to flow bench it,or measure actual gr/sec vs vdc before and after the mods.I guess it could be done with a ecm test bench w/ two mafs,right?
So from this point on I will do as you suggest,Grumpy.I have looked at my post as a newbee under a different user name.You have always gave me solid advice.I was just to un-aware to use your advice.It's kind of like telling sombody something and they dont listen.But without UNDERSTANDING why they can't compute the advice.I think thats why things get rehashed.It takes awhile for it all to sink in.So Grumpy,do I have it right,now?
quote:
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Originally posted by kvu
First off I'm not implying sd folks not to read,thank you.I would like you to post your rpm redline.Then post your gr/sec @ redline.Finally post the 1/4 mile time and/or dyno results for your car.Info like weight and mods would be nice.Just gr/sec and redline rpm if no dyno or timeslip.Thanks for any info.
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I can understand your enthusiasm.
I really can.
But, you're really to the stage of needing to build an ecm bench to really see what's going on. So far you've just been looking at one end of the equation, and drawing results from one car. Which while they may be true, they are only true for one car.
If you were to look at things on a bench and make slow deliberate changes, some answers might just pop out at you.
This is kinda a single reply to a few of your postings, and just my opinion, no flaming meant.
The MAF is a wonderful devise, and GM spent a bunch of money getting the calibration right on it. The reason I started off suggesting the ARAP, was that the fuel lined up pretty well with it.
Now, the ecm is doing almost all the fuel cals based on the MAF. If you somehow change the flow thru the MAF then you'll need to recalibrate it, ie if you remove the screens, cut the heat sinks out etc.. Those mechanical changes to the MAF will mean changing the MAF scaler tables. Since they influence the actual way the MAF senses things. Changing the injector size, engine displacement, etc, have no effect on the MAF, the mechanical changes done to the engine, won't make a mechanical change to the MAF. If you change the injectors then it's injector characteristics that need changed. The new injector will in all likely hood have different rates of response for it's pintle/disc/ball movement so the battery voltage correction would need changed as a result.
On the issue of battery correction, it's primarily noticed at idle. At idle the injector has a duty cycle of 2-3%. The 10% change that a battery volatge correction might make is then .1 msec.. That same .1 sec at a pulse width of 20 msec isn't hardly noticeable.
If you want to continue changing the scaler values, fine, but, please realise you not making the corrects the best way possible.
There is a difference.
To answer your guestions,
with a stock MAF, I pegged it at 3,400 RPM, and by 3,600 was into MAF drop out. Stock turbo
With a rescaled MAF, ie late LS1 MAF, I can draw about 400 gms/sec.. Stock looking turbo.
With some tiny injectors I ran a string of low 13s using part throttle until 3rd gear.
Now, if you want to get a second MAF, do some data logging, and build an ecm bench I can probably help ya get some more resolution out of a stock MAF. The real trick is that the output is no where near linear (at least in my application).
But, you still have the restriction of drawing thru a MAF.
Undoubtably someone will take issue with the above. To that all I can say is, Oh Well.
Thanks Grumpy, I did'nt think it was a flame.One thing that made me realize things,about maf was looking at the code..There seems to be "tables" that converts the sensors from vdc to useable terms,like coolant temp.Now I understand the maf tables are converting vdc to gr/sec,thanks Greg!.Not a "tuning" table,plain and simple.
Yes changing the maf table will work to richen and lean.I'm sure I could "trick the ecm" other ways to cure a lean idle.Your method, batt correct table(explained well now) does seem to have the less negitive effects.
I did'nt go around changing alot with the maf tables though.Just tweeks here and there.There seemed to be no ill effects from changing a point or two for idle though.Your right,that worked for MY engine.But I have realized my maf is 17 years old.
The only way to acurately recalibrate the maf tables would be to flow bench it,or measure actual gr/sec vs vdc before and after the mods.I guess it could be done with a ecm test bench w/ two mafs,right?
So from this point on I will do as you suggest,Grumpy.I have looked at my post as a newbee under a different user name.You have always gave me solid advice.I was just to un-aware to use your advice.It's kind of like telling sombody something and they dont listen.But without UNDERSTANDING why they can't compute the advice.I think thats why things get rehashed.It takes awhile for it all to sink in.So Grumpy,do I have it right,now?
Last edited by kvu; Jun 11, 2002 at 10:19 AM.
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Re: -
[i].It takes awhile for it all to sink in.So Grumpy,do I have it right,now? [/B]
You got it,
Now if someone really was serious about some MAF R+D, we're way past critical mass, and I think a joint effort could net some real results. Two channel data logging, and a ecm bench is needed. Might work, maybe not, but without some experimentation we'll never know.
ANYBODY (ies), serious about spending a bunch of time in a thankless job, just wanting to attempt to push the envelope, write me off list. Might be a waste of time, but might a good thing.
I'll be gone late tonight til late Fri, or maybe longer (biopsy time).
