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How does the MAF compensate for the dry shot?

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Old 01-24-2005, 02:40 PM
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Originally Posted by 93LS1RX7
But what happens if your MAF sensor goes bad? BOOM BOOM

If the MAF goes bad you will most likely happen when you are not sprying. With a fuel noid you will not know untill you go to spray it......and you will be F#%$ed.
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Old 01-24-2005, 03:09 PM
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I have a lot more faith in dry kits anyway. I'm a firm believer in the KISS principle. You don't see much about stock MAF failures. However the more complicated you make a system, the increased likeyhood of a mishap. Going from:

Just a series of Nitrous solenoids,
to
A set of nitrous solenoids, a fuel solenoid, and a nozzle (2 jets),
to
Dual stage (2 n20 noids, 2 fuel noids, 2 nozzles (4 jets)),
to
Direct port (2 n20 noids, 2 fuel noids, 8 nozzles (16 jets)).

Just imagine the nightmare one little obstruction, or even a solenoid failure could cause in one of those setups.
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Old 01-24-2005, 03:54 PM
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Originally Posted by 5.8litrels1eater
I have a curiousity question. Since we have learned (or at least was stated in this thread) that the MAF tells the computer to add fuel as it get's colder, wouldn't that put the "freezing the MAF with nitrous and it goes lean" to rest????

How is it possible to "freeze" the MAF?? I have seen a couplepeople post about it, but myself, nor anyone I know that has run literally hundreds of bottles on a dry shot, has "frozen" the MAF.
WHen a MAF freeezes it maxes out the fueling and if your injectors cant keep it then boom!....Thats how I read it. So yes it can go lean if your injectors cant keep up or you max the MAF table itself out and it wont add anymore fuel. You can go in and scale your MAF table to add some more fuel in the higher loads that you wont see but on the giggle gas when this happens...But you can only do sooo much.

Mike


Mike
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Old 01-24-2005, 03:59 PM
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Originally Posted by V6 Bird
you max the MAF table itself out and it wont add anymore fuel. You can go in and scale your MAF table to add some more fuel in the higher loads that you wont see but on the giggle gas when this happens...But you can only do sooo much.

Mike


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This is what we are going to try so I can spray a biigger dry shot.

My MAF is pretty much maxed out at a 140 shot. Gonna play with the tables and hit it with the 200 shot
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Old 01-24-2005, 04:58 PM
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[QUOTE=93LS1RX7]Wrong wrong and wrong. The MAF reads nothing it senses. The MAF sensor gets hot as stated about and the amount that it cools lets it know the velocity then along with the IAT sensor and the TPS sensor it determines how much fuel to put in the motor. QUOTE]


In an LS1 when u go WOT you run off of the MAF alone. No IAT, that is used for timming maps.

There has been lots of discusion over this before. I did end up finding out I was wrong on the use of the IAT and MAF used in combination by the PCM to determin fueling, but not completely. I found that during startup the PCM will use the IAT, TPS, and MAP sensors in a speed density mode. If you have a MAF failure it will switch over to this mode also.

I found this searching with google and comming across the ECM for Holden(foreign LS series).
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Old 01-24-2005, 06:37 PM
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Really. Huh didnt realize it eliminated the IAT under WOT. That is actually suprising. I was actually talking about all conditions not just WOT but I do have to say I learned something today.
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Old 01-24-2005, 08:31 PM
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Yup, is perty cool. I figured you were talkin about all around driving, just figured I'd spread some good info. IAT is for timming tables only, thats why you can do the 750 resistor trick to pull up to 4 deg out.
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Old 01-24-2005, 09:28 PM
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We logged a run of mine and the IAT went from 75* down to 8*

Nice and cold
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Old 01-24-2005, 11:00 PM
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Originally Posted by 93LS1RX7
Wrong wrong and wrong. The MAF reads nothing it senses. The MAF sensor gets hot as stated about and the amount that it cools lets it know the velocity then along with the IAT sensor and the TPS sensor it determines how much fuel to put in the motor. The ECM couldnt care less about the bottle pressure or lb's left. It doesnt care when the bottle is empty either. All the computer cares about it how cool the MAF ends get over a given time. Nitrous causes them to get colder faster so the injectors add more fuel. When the nitrous runs out the ends dont cool as fast so it takes fuel away, so you were right saying it takes away fuel but your logic was all jacked up . Technically the MAF ends are supposed to stay the same temperature and the ECM just adds current to get the ends to the desired temp. That is what is read by the ecm is the current needed to make the MAF end stay the same temp.

Show me where on your car the ECM gets a signal from the nitrous bottle to measure the pressure and lbs remaining??
"The Maf reads nothing it senses".
Here's a qoute, HP Books "Chevy ls1/ls6 Performance" page 31, "This is done by injecting the nitrous before the mass airflow sensor, which reads it as extra airflow". Now, who will the readers believe, you or the experts at HP Books.

93ls1rx7, man are you a mountain of miss information. IAT sensor ?, you better go back to research.

You say all the computer cares about... what the hey, the computer is an inanimate object and unable to have feelings (hows that for technical correction).

"The ECM couldn't care less about bottle pressure or lb's left".
WTF, here's a quote from HP books "Chevy ls1/ls6 Performance" : Dry systems differ from their wet counterparts in that they inject nitrous oxide only, and rely on the PCM to supply supplemental fuel by increasing injector-pulse width. This is done by injecting the nitrous before the mass airflow sensor, which reads it as extra airflow. This increases the amount of fuel delivered by the injectors at the PCM's direction. "...the PCM is using information from the MAF to add the necessary fuel". ECM ? was never mentioned.
Also, velocity/tempurature equals density, right? So, another quote, from CARTECH by Joe Pettitt "How to install and use NITROUS OXIDE", "...the denser the air, the lower altitude ; the lower the humidity and temperature, the more power an engine can generate. air density changes with altitude and temperature (read n2o) and is a major factor in tuning... and, "Cooler air means a lower density altitude and thicker air. If the fuel remains the same, the mixture will get leaner". But this does'nt happen because the MAF sends electrical signal to PCM to make nessasary changes in a/f ratio.

Someone correct me if I'm wrong. The MAF wire reads resistance depending on the air temp (remember density) passing over the wire? And then, sends this electrical signal to the computer fuel table needed to maintain safe a/f ratio? I am not an expert on this.

"...your logic was all jacked up".
You might try some yourself. I think your doing a disservice to yourself and to the readers by putting together a bunch of half truths and partial facts.

"Show me where on your car the ECM gets a signal from the nitrous bottle to measure the pressure and remaining??"
I reread my post a half dozen times and can't find a reference to an ECM, or did i state that a signal was sent from the bottle to anywhere. What I said was "So on a dry shot the computer makes adjustments for a/f accroding to bottle press/lb's left, and ultimately adjusts fuel to when it is empty so as not to run pig rich" (wet does not). Now remember density, as the bottle press goes down (through temp or lb's) the maf reads air temp/velocity (or density) as less and less and the computer adjusts as needed to maintain correct a/f ratio.

One more thing to check out is barometric pressure.

Oh, do you have one of your n2o lines plumbed up your nose? Nothing personal really.
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Old 01-25-2005, 09:33 AM
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Default Look slim shady you are as screwed up as a football bat

The Maf reads nothing it senses".
Here's a qoute, HP Books "Chevy ls1/ls6 Performance" page 31, "This is done by injecting the nitrous before the mass airflow sensor, which reads it as extra airflow". Now, who will the readers believe, you or the experts at HP Books.

This shows your lack of being able to UNDERSTAND something not just READ it. The MAF sensor doesnt READ airflow it reads the current required to heat the element in the MAF sensor. If you want me to quote you a source here you go from Granetelli the guys that make some MAF sensors "How They Work: Mass air induction systems measure airflow with an electronic “hot-wire” type mass airflow sensor. The sensing element in the air intake provides an output voltage reading that is directly proportional to the amount of air that is entering the engine." So once again they measure the voltage and it is proportional to the airflow. To "read" airflow you need some sort of differential pressure sensor or a flow tube calculating the flow which isnt how a MAF sensor works.

93ls1rx7, man are you a mountain of miss information. IAT sensor ?, you better go back to research.

I dont understnad what you are confused about on this one. The IAT sensor is obvious let me SPELL it out for you and you lack of UNDERSTANDING. IAT is the commonly abbreviated reference for INTAKE AIR TEMPERATURE Sensor, once again put down the crack pipe just long enough to UNDERSTAND things not just recite them.

You say all the computer cares about... what the hey, the computer is an inanimate object and unable to have feelings (hows that for technical correction).

Funny...

"The ECM couldn't care less about bottle pressure or lb's left".
WTF, here's a quote from HP books "Chevy ls1/ls6 Performance" : Dry systems differ from their wet counterparts in that they inject nitrous oxide only, and rely on the PCM to supply supplemental fuel by increasing injector-pulse width. This is done by injecting the nitrous before the mass airflow sensor, which reads it as extra airflow. This increases the amount of fuel delivered by the injectors at the PCM's direction. "...the PCM is using information from the MAF to add the necessary fuel". ECM ? was never mentioned.

ECM/PCM same thing tomato, tomatoe again demonstrating your LACK of UNDERSTANDING. And I still hold to the fact that "The ECM couldn't care less about bottle pressure or lb's left." Show me in your "book" where the (as you like to call it) COMPUTER measures bottle pressure or lbs remaining.

Also, velocity/tempurature equals density, right? So, another quote, from CARTECH by Joe Pettitt "How to install and use NITROUS OXIDE", "...the denser the air, the lower altitude ; the lower the humidity and temperature, the more power an engine can generate. air density changes with altitude and temperature (read n2o) and is a major factor in tuning... and, "Cooler air means a lower density altitude and thicker air. If the fuel remains the same, the mixture will get leaner". But this does'nt happen because the MAF sends electrical signal to PCM to make nessasary changes in a/f ratio.

I agree completely with this statement. Where did I not agree with this?

Someone correct me if I'm wrong. The MAF wire reads resistance depending on the air temp (remember density) passing over the wire? And then, sends this electrical signal to the computer fuel table needed to maintain safe a/f ratio? I am not an expert on this.

Correct again and that is exactly what I said when I stated "the ECM just adds current to get the ends to the desired temp. That is what is read by the ecm is the current needed to make the MAF end stay the same temp." Current and resistance are essentially the same thing. Current is the amount of force required to overcome the resistance, so again I fail to see the flaw in my statements.

"...your logic was all jacked up".
You might try some yourself. I think your doing a disservice to yourself and to the readers by putting together a bunch of half truths and partial facts.

Nope not "half truths and partial facts" you on the other hand did not say ANYTHING correctly.

"Show me where on your car the ECM gets a signal from the nitrous bottle to measure the pressure and remaining??"
I reread my post a half dozen times and can't find a reference to an ECM, or did i state that a signal was sent from the bottle to anywhere.

And I quote from you previous post "So on a dry shot the computer makes adjustment for a/f mix according to bottle press/lb's left, and utimately adjusts fuel to when bottle is empty so as not to run pig rich", the computer you refer to is the ECM, thats the specific term for the "computer". So apparently you cant read real well either

What I said was "So on a dry shot the computer makes adjustments for a/f accroding to bottle press/lb's left, and ultimately adjusts fuel to when it is empty so as not to run pig rich" (wet does not). Now remember density, as the bottle press goes down (through temp or lb's) the maf reads air temp/velocity (or density) as less and less and the computer adjusts as needed to maintain correct a/f ratio.

I get it you think the lbs left in the bottle by itself effects bottle pressure. Wrong again. The temperature and volume effect the pressure. I can have 1 lb remaining as long as I get it warm enough the pressure will not change. YOur flaw in thinking is right here "(through temp or lb's)", it is actually both temp AND pounds.

One more thing to check out is barometric pressure.

I never said these were the ONLY factors into the equation.......

Oh, do you have one of your n2o lines plumbed up your nose? Nothing personal really.

Nope but once AGAIN proves your lack of UNDERSTANDING or you would realize commercial grade Nitrous has sulphur added to it so people wont "huff" it. Medical grade is what you are thinking about.

Oh and I dont take it personal.
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Old 01-25-2005, 01:38 PM
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Can't we all just get along?

Seriously, what I'd like to know is if it's just a coincidence that the MAF adds the proper amount of fuel for a given shot of nitrous. I'm on board with the fact that it's safer. The thing that made me go wet was my 26.6# injectors was a limiting factor in going over a 75-100 shot and converting to wet was cheaper.
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Old 01-25-2005, 02:50 PM
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Coincidence? Not really but sort of. The nitrous manufactuers do a lot of R&D to see how much nitrous it takes to get the MAF sensor to add X amount of fuel. Again the MAF sensor doesnt care that it is nitrous coming across it, it just cares that it is moving a "lot" of air according to the MAF.

Put it this way say the nitrous is -100°F when it crosses the MAF sensor (I dont know the actual temp it is I am just making up a number), that MAF sensor thinks that the amount of air that is coming in is enough to cool it the same as the -100°F nitrous spray. For example if you got compressed air (regular old stuff that we breath everyday) in a bottle and found a away to get that air to -100°F without freezing it then you shot it into the intake right at the MAF sensor the ECM would add the same about of fuel as it would if it was nitrous. It is gas INDEPENDANT.

Was that confusing?
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Old 01-25-2005, 05:28 PM
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I would contend that it is gas independent. Maybe I didn't phrase my question correctly.

Regardless of what jets you use and bottle pressure, a dry nirtous kit depends on the MAF to add enough fuel to keep the A/F @ ~12.5-1 (just a # I picked because it is a standard N2O A/F).

If you were to spray the same jet(s) and bottle pressure worth of compressed air, if it were gas independent, the A/F would still be 12.5-1 and I don't think that would be true with compressed air. The burn characteristics of compressed air would be different than the nitrous. Thats what I mean by coincidence. Its coincidence that the burn characteristics of the nitrous jive with the amount of fuel the MAF decides to add. Is is coincidence that the nitrous is the right temperature at that pressure for the MAF to add the correct amount of fuel?
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Old 01-25-2005, 07:36 PM
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Yes I said gas independant. The MAF would still be trying to add the same amount of fuel but it wouldnt combust right like you said.
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Old 01-25-2005, 08:37 PM
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93ls1rx7, forgive me for doubting your wisdom and ultimate truths. I realize that my 3-years of tech college, 4-years more to get Mech Engineering degree, and not to mention, my 40+ years in drag racing and 20+ years using N2O (most of those years where sulfur added free and I stuck the hose up my nose one to many times), couldn't compare to your accomplishments. Did I mention that I currently am the chief Mech on Vic Edelbrock's new $15 million dollar yacht under construction and engineer parts and systems that would put the vette to shame (like mounts, fuel sys, etc for dual 16 cyl Detroit Diesel engines and much more). With that said, now that you've pointed out how foolish I am, I wonder how my company (NordlundBoat.com to see the old Edelbrock boat which I was a mech on) hasn't noticed. However, I am going to give them your e-mail address so they can offer you a lucrative position (owners best boy). I would do this for you because I realize that if you were really putting your talents to work you would be driving a Vette or f-body and not the wantabe 1993 ls1Rx7.

OK, back to the tech stuff. Oh, did I say that most at work think I'm a smart azz, I don't know where they get it.

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Old 01-25-2005, 08:59 PM
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WOW....

So many confused people out there.

Here is the real world application of all this crap that has been spewed out in this thread. This is how you DO a dry setup through the MAF.

1) Do not leave the screens in and spray, you will ice them up and clog them, restricting flow.

2) 50 shot or 250 shot it cools the wire the same, ie. it fuels the same (or there abouts the same given a few tiny tiny variables). So your best bet given that your MAF will max anyway no matter what pill you use is to tune your nitrous delivery to the amount of fuel your car's system will put out when the MAF is maxed. The important thing to remember is that no matter what happens nitrous is allways the same temperature.

3) Run cold plugs

I am living proof that it is as I say. I run 200+ dry into a stock 98 LS1 with stock fuel.
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Old 01-25-2005, 09:08 PM
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Originally Posted by Homeslice (tm)
WOW....

So many confused people out there.

Here is the real world application of all this crap that has been spewed out...
Hey wait a minute, confused/spewed out, I resemble them there remarks.

Homeslice, I agree with what you say and your the kind of guy that's going to give the dry sys the respect that it deserves.
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Old 01-25-2005, 09:29 PM
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Originally Posted by Homeslice (tm)
WOW....

So many confused people out there.

Here is the real world application of all this crap that has been spewed out in this thread. This is how you DO a dry setup through the MAF.

1) Do not leave the screens in and spray, you will ice them up and clog them, restricting flow.

2) 50 shot or 250 shot it cools the wire the same, ie. it fuels the same (or there abouts the same given a few tiny tiny variables). So your best bet given that your MAF will max anyway no matter what pill you use is to tune your nitrous delivery to the amount of fuel your car's system will put out when the MAF is maxed. The important thing to remember is that no matter what happens nitrous is allways the same temperature.

3) Run cold plugs

I am living proof that it is as I say. I run 200+ dry into a stock 98 LS1 with stock fuel.

What does it run?
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Old 01-25-2005, 09:38 PM
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IMO there's nothing more beautiful than spewing information

Homeslice has a C5 vette. The rest of the car is very stock so it got a not so good 1.76 short time and 11.0 @127

It had headers and ported MAF & ran the plug on the left.
Oh yeah and a CTS tricker box.


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Old 01-25-2005, 09:39 PM
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Originally Posted by ATVracr
What does it run?
11.0 @ 127
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