Has anybody here with serious power(700-800) used the Pro-m maf to over come the limits in the pcm?
Chris B, Harlan, anybody?

Pro-M say they can calibrate the their mass air flow sensor to read what ever cfm we want at 12000 HZ. But what do you do on the tunning side of it?
Do you have to modify every table that relates to maf readings?
Do you have to double your Injector flow rate table(assuming the cfm of the meter was exactly double)?

Any help would be greatly appreciated.

Thanks in advance

 

Yep, but to do what you wanna do you would get a meter that flows alot at 12kHz. Say 800 g/s, but scale the MAF table to half the real flow of the meter.

then you would need to carry that factor of 1/2 to the injector flow tables, the VE tables, etc. Also, all your load axes will be half of what they use to be, since you're reporting half the air to the PCM. So your spark tables will shift down, etc etc.

it can be done, sure. Is it the best way, no. Is it for the faint of heart, no.

 

Like Harlan said its not exactly the best way to do it, but it is a possible solution. The only problem is the resolution is half as good, so you would have to pay good attention to the part throttle behavior.

Jose

 

Thanks for the input guys.
Would you divide the ifr table in half, or double it?

Will this result in horrible part throttle driveability?
Do I really need the Pro-m maf to achieve this?
How much air flow will the stock maf read(not the pcm limit)?
Harlan, are you using a stand alone system or are you doing something similar to what I'm talking about?
__________________

 

Harlan,
What do you use on your car? If you have the dual maf setup then arent you splitting all your signals, and doing the same thing basically?
thanks
ed

 

I am currently using the stock MAF and making 771RWHP and 716RWTQ. The MAF is maxing out in the table at 4200RPM so we are making adjustments to the Fuel using a W/B. The car currently has passed inspection and I want to keep the stock computer and maintain the great driveablity that I have right now. So what is the solution to this problem on a blown application

My fear is that come winter if I want to drive the car, the cold air will go into the engine, and the computer because it is maxed will not be able to adjust for it, so I will have a lean condition.
Thanks
Bryan
lunapark@perigee.net

 

I don't think anybody is maxing out the MAF unless they're in PE mode. The A/F adjustment in PE mode is fairly straightfoward. It seems to work fine. Are we making more out of this than needs to be?

 

OK maybe I didn't explain the problem properly. Let me re-explain.

When the MAF goes into clipping at WOT, or in my case WOT at 4200 RPM. Your settings in the computer are maxed out at 12000 HTZ or in my case well before that. The maximum setting that you can put in is 511 G/PS. When you are tuning your car in the summer months, or winter months, (makes no difference), If you are tuning in summer, and run out of MAF adjustability you have to make your adjustments to the fuel table. Those adjustments in the fuel table are fixed based on the amount of air coming into the system. On a stock Engine, when you do stuff like air lid, or blower of 5#'s or less, the stock ECM is capable of making fuel adjustments to compensate for the extra air up to 511 G/ps. If you are putting more air in the system that 511G/PS then you have maxed out the system and it can no longer compensate for the extra air. So, tuning in summer the air is not as dense, (air expands when it gets hot), you manually adjust the fuel table and the car drives great no problem, now come winter. The air is colder, and with a supercharger or turbo for that matter you are moving a lot more air, (a lot more colder air), now the air is much denser because we have outside temps well below the 90 degress that we had in summer. The MAF will see more air, this is why your car drives and accellerates better on a cold morning. With the MAF clipping in summer at WOT 4200 RPM, now in the winter, the MAF had already maxed out, is now worse because of the colder air. Now you will show an extreme lean condition.

If you did the reverse, and tuned in winter, come summer and the outside temp reached 90 degrees you would show an extreme rich condition, because the ECM can no longer compensate.

Any car that is moving more than 511 G/PS of air is not making more than they need to out of this situation. This seems to be based on my calculation 675-700 hp.

For all of us that want to keep their stock ECM, and not do a piggy back setup, this is a problem. For a car to be considered a true street car, IMO you have to meet certain criteria.

Stock ECM,
Catalytic Converters(not hollowed out)
No o2 simulators
Be able to pass state inspection.
All Emission controls and sensors
If you do not meet these qualifiactions, IMO, you should not be considered a true street car.

I need an intelligent person, hopefully Harlan, to offer a suggestion on how to properly address this issue. I am willing to pay him for his time, if he will respond. If I can find a way for the stock ECM to react to more air, my engine is more than capable of hitting the 1000hp mark. It is all about being able to measure the amount of incoming air, and right now I am moving so much air that I cannot do that above 4200rpm, so there is no point in changing pulleys.

I hope this helps to clairify this for you.
Thanks

 

Maybe you didn't understand what I was saying. I don't think even your car maxes out the MAF unless your deep into the throttle and go into PE mode. When in PE mode it goes to an Air/fuel vs. rpm setting. People are just plugging in whatever # they need to achieve the desired A/F for the rpm range after the MAF has maxed out (my case 4600rpm). It seems to be working for most people (your car included). What is the MAF's roll in PE mode? Maybe you do need to tweak it during seasonal changes. My point is that people seem to be making most of the power they desire still using the stock MAF by simply making changes in the PE vs rpm table. I know you would like to see MAF data all the way up but do you really need to? What about the pure size limitation of the MAF? Can it flow enough for 1000hp? It doesn't look large enough for me (no calculations, just eyeballing).

 

"Maybe you didn't understand what I was saying. I don't think even your car maxes out the MAF unless your deep into the throttle and go into PE mode."
I thought this was WOT. Is it not?


ok, lets go with what your saying, help me to understand then when I make adjustments in the PE table as you are saying, Am I telling the PE table what I want the A/F to be at a certain RPM. Right? If this is the case, Riddle me this Batman, becuase I really want to understand this and you seem to have great knowledge of how the stock ECM works, how would an o2 sensor capable of reading either lean or rich either high or low of 14.7 be able to set anything based on what that A/F table(P/E) has in it. So that there is no confusion, lets say I want an A/F reading of say 11.0 at 5500 RPM WOT. How would the stock o2 sensor know what 11.0 A/F reading was. It only has two readings to the PCM. 0 volts or 1 volt. Rich or lean from 14.7. If the stock ECM was using a wide band 02 sensor, this would make since, but I have completely missed the boat and perhaps you are the intelligent one that I have been seaking. Please enlighten me.

If this is all we need to fix the mysterious A/F problem and maxing out a ECM and maxing out the MAF, then Pro-M can go ahead and close their doors, and FAST, Accel, and Big Stuff can go ahead and stop making computers.

Sorry, I thought I was done, one more thing,
If I am forcing air into the engine, what difference does it make if the hole is 78MM or 85MM or 90mm other than velocity and low RPM driveability. I am willing to go out on a limb and say that the stock MAF and stock Throttle Body is more than capable of supporting 1000HP provided the computer will allow me to make adjustments for the amount of air coming in, and the MAF will read the amount of air coming in. The stock one doesn't do it, because it GM did build anything with that much power. However, GM did build a 1000 HP 16 Cylinder Engine and they did build a 700HP Northstar. So they were reading air from somewhere. Though the Northstar probably was not moving enough to max out the MAF.


I am patiently awaiting the answer.
Thanks for your help
Bryan

 

Brian, the PE adjustments everyone is making is like a mechanical fmu through the ecm. Your analogy is correct. You need a "summer time" tune since you're using PE and a richer "winter time" tune as you will go lean in the cooler air unless your summertime tune is very rich (which a lot of FI folks do to run one tune). The only current answer is Lingenfelter. They have changed the hex programming in the ecm to use an adjustable boost controller at different levels of boost with one tune....doesn't get any better than that...Jason Haines is the man. For $$$ LPE might hook you up.

 

Thank you very much sir, I will give them a call on Monday, my guess is that they will be stuck up as always and tell me they are not interested in helping.

Thanks again
Bryan
lunapark@perigee.net

 

Bryan, ask for Ed Potter at LPE....he is your best chance.

 

I met Ed at the Charlotte Auto Fair one time when Lingenfelter came to show off their cars. I will try him, he was very helpful the day I talked to him.

Thanks for reminding me
Bryan
lunapark@perigee.net

 

I don't know why you've gotten so condescending towards me. Anyway, I am no expert but I do tune my own car. With a wideband and trial and error you can dial in your PE table for perfect A/F ratio throughout the powerband. It works fine for me. Even though I max out my MAF it doesn't seem to be much of a problem. Like I said maybe it does need to be tweaked as seasons change (I don't know). Probably every car here over 600rwhp is maxing out and everybody seems to be working around it.

 

I got condesending, because of the comments you made. Like I said, I can tune my car right now to be perfect too, but when it gets cold, the tune will be off and very off in mine and yours if you are maxing out at 4600. Everyone with a stock computer who is maxing out their MAF is having this problem. They just dont know it, or they do know it and readjust. Who wants to drive their car careful when the weather changes. What then would be the point of having all of the power on tap. The whole point of using an aftermarket computer and making adjustments based on MAP not MAF, or using a recalibrated MAF is so that you dont have to readjust it every season. Who in the world wants to worry or screw with their settings everytime the weather changes. If you have an all out race car and that is your thing to tune everytime the weather changes, great, but don't dish on the people who want to do it right and by right I mean let the computer make the adjustments for you year round. It is more than capable provided it is getting the right information. The GM ECM is the fastest, best comptuer ever designed in the world of automobiles. Any ECM engineer from any car company will back me up. It is revered as the best. Period. I want to be able to drive my car to work, the track, or to the Silver State Classic in Nevada in Jan - Dec. I Live in NC. They have inspections here. Maybe they don't where you live and it doesn't matter to you. But with an ODBII inspection, you have to have the stock comptuer and you can't be switching them in and out because of the milage that has to be on the computer.

Your original commet was aren't we over reacting to this problem, and I would say that you answered your own question with this response. "Like I said maybe it does need to be tweaked as seasons change (I don't know)" I knew when you made the original comment you didn't know, because if you had known you would not have made the comment in the first place.

I am patiently awaiting Harlan's response and the other gentleman pointed me to Lingenfelter. Thank you very much for your assistance.

 

Sorry to dig up an old thread, but I was just curious if LPE was able to modify your PCM operating system? Did you ever find away around the MAF limit or are you going a different route now?

 

anyways have you guys been following the HPT 3 bar MAP sensor threads, should be able to ditch the MAF tuning soon as they release it and increase the resolution.

was thinking about going with the ProM, but this looks like a better solution

 

I am testing the HPT 2 Bar setup now. That should help me eliminate the MAF.

I will keep you posted, PM me your email address.
Bryan
lunapark@perigee.net

 

sweet i want this info two as i hope to convert mine to a 3 bar MAp when it comes out.
what version of HPT do you have now, am i able to read your flash with my 1.6? if so could you send it to jd_harder@yahoo.com

thanks.