THE ISSUE: Maxed out MAF and tuning around it.
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From: DETROIT, (formerly Eaton County, Michigan)
THE ISSUE: Maxed out MAF and tuning around it.
MAF SENSOR BEING MAXED OUT:
I'm talking about the Stock Ford OEM 90mm MAF sensor.
Everyone knows changing from the 80mm to a 90mm severly leans out the a/f ratio and the PCM needs to be recalibrated to compensate for the change.
Even going to autozone and buying a remanufactured MAF sensor will not read the same a a stock OEM ford one
Now when you start adding mods to your truck and aftermarket pullies and porting and perhaps a s/c change, the MAF can be maxed out easily... everyone has read at least 10 threads regarding that.
So what are we to do? Buy a Pro-M model with matching injectors? make sure we get the flow chart for the MAF so the tuners can precisely tune the truck?
What are we to do?
Well I've heard there is/are tuner(s) that can tune around the maxed out MAF. But how? how do you calibrate the fuel tables to compensate for the air rushing in the engine, when you don't know how much air is going in becuase the MAF is maxed?
well they guess... educated guess at that.
when the MAF is maxed the sensor simply can't read the amount of air entering the engine, there is too much. so the engine is tuned to dump fuel into the combustion chamber. therefore a dreaded lean condition is not created. everyone knows a lean condition can cause a hole in the piston or melted plugs either way it is TOO HOT in the chamber.
How do they know how much fuel to dump in?
CAN'T USE THE maf b'cuz it's maxed. well using hte O2's you can see if it is running rich or lean (O2 bung or the less accurate Tailpipe sniffer) that will get you close. so if they have a lean reading on the dyno, they simply richen it up a little, or vice versa if rich.
Is that accurate?
I'd say NO. why? thinkof it like this, drive your lightning in the winter (cold and dry) and then drive it in the summer (hot and humid) there is a noticable difference in the power. in the summer it is much slower (common knowledge) SO if you are tuned on a Hot humid summer day, expect to be lean on a cool/cold dry winter day. That isn't accurate.. more like a shot in the dark... lets try this and see what happens, nope let me change this and try it again... getting closer...
Can the PCM take that into consideration?
Well yes and no...
it can to a certain extent, after that no. the PCM can make changes to the fuel tables up to a 33% divergence from the norm. so basically ifthe conditions create a situation that is more than 33%... the PCM cannot calibrate the Fuel tables to compensate (OK I admit that is a **** poor explanation) basically hte stock computer can correct it if it is a small hickup, big hickups start sending codes and SES lights. P1132, p1152 and a few others.
SO lets back up a little
why is dumping fuel into the combustion chamber a bad idea?
It saves the engine and prevents a damaging lean condition right? right... but there is a lot more going on in there isn't there?
flooding the chamber with fuel washes the oil and lubrication off the cylinder walls. Now that can't be a good thing when you are turning over 5000 RPM's, with little or no lubrication.
for every revolution the piston goes up and down once. so basically 5000 times a minute that little bugger is going up and down without lubrication. 83.3 times a second. OUCH...
Perhaps some of this is wrong, which I'm sure someone will correct it and that's fine. I just want to see what everyone thinks.
Do we have to use a MAF sensor? is there anything else we could use? How accurate are the O2 sensors.
From my understanding you can tune using the MAF and O2 sensors unti lthe MAF is maxed out, then you have to rely on the O2 sensors for the a/f ratio.
thoughts comments gripes...
I'm talking about the Stock Ford OEM 90mm MAF sensor.
Everyone knows changing from the 80mm to a 90mm severly leans out the a/f ratio and the PCM needs to be recalibrated to compensate for the change.
Even going to autozone and buying a remanufactured MAF sensor will not read the same a a stock OEM ford one
Now when you start adding mods to your truck and aftermarket pullies and porting and perhaps a s/c change, the MAF can be maxed out easily... everyone has read at least 10 threads regarding that.
So what are we to do? Buy a Pro-M model with matching injectors? make sure we get the flow chart for the MAF so the tuners can precisely tune the truck?
What are we to do?
Well I've heard there is/are tuner(s) that can tune around the maxed out MAF. But how? how do you calibrate the fuel tables to compensate for the air rushing in the engine, when you don't know how much air is going in becuase the MAF is maxed?
well they guess... educated guess at that.
when the MAF is maxed the sensor simply can't read the amount of air entering the engine, there is too much. so the engine is tuned to dump fuel into the combustion chamber. therefore a dreaded lean condition is not created. everyone knows a lean condition can cause a hole in the piston or melted plugs either way it is TOO HOT in the chamber.
How do they know how much fuel to dump in?
CAN'T USE THE maf b'cuz it's maxed. well using hte O2's you can see if it is running rich or lean (O2 bung or the less accurate Tailpipe sniffer) that will get you close. so if they have a lean reading on the dyno, they simply richen it up a little, or vice versa if rich.
Is that accurate?
I'd say NO. why? thinkof it like this, drive your lightning in the winter (cold and dry) and then drive it in the summer (hot and humid) there is a noticable difference in the power. in the summer it is much slower (common knowledge) SO if you are tuned on a Hot humid summer day, expect to be lean on a cool/cold dry winter day. That isn't accurate.. more like a shot in the dark... lets try this and see what happens, nope let me change this and try it again... getting closer...
Can the PCM take that into consideration?
Well yes and no...
it can to a certain extent, after that no. the PCM can make changes to the fuel tables up to a 33% divergence from the norm. so basically ifthe conditions create a situation that is more than 33%... the PCM cannot calibrate the Fuel tables to compensate (OK I admit that is a **** poor explanation) basically hte stock computer can correct it if it is a small hickup, big hickups start sending codes and SES lights. P1132, p1152 and a few others.
SO lets back up a little
why is dumping fuel into the combustion chamber a bad idea?
It saves the engine and prevents a damaging lean condition right? right... but there is a lot more going on in there isn't there?
flooding the chamber with fuel washes the oil and lubrication off the cylinder walls. Now that can't be a good thing when you are turning over 5000 RPM's, with little or no lubrication.
for every revolution the piston goes up and down once. so basically 5000 times a minute that little bugger is going up and down without lubrication. 83.3 times a second. OUCH...
Perhaps some of this is wrong, which I'm sure someone will correct it and that's fine. I just want to see what everyone thinks.
Do we have to use a MAF sensor? is there anything else we could use? How accurate are the O2 sensors.
From my understanding you can tune using the MAF and O2 sensors unti lthe MAF is maxed out, then you have to rely on the O2 sensors for the a/f ratio.
thoughts comments gripes...
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From: Selden NY
I believe it can ALWAYS be tuned around (if you want to)
But hey why not sell new Pumps, Injectors, Maf, and another 500 in Dyno Tuning.
I never asked Sal for my Maf Voltage during the Dyno pulls we made, BUT FUEL SURE THE FRUCK IS NOT A PROB FOR ME
(this is my first pull, 501/615)
(this is my second pull, 490/619)
But hey why not sell new Pumps, Injectors, Maf, and another 500 in Dyno Tuning.
I never asked Sal for my Maf Voltage during the Dyno pulls we made, BUT FUEL SURE THE FRUCK IS NOT A PROB FOR ME
(this is my first pull, 501/615)
(this is my second pull, 490/619)
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From: STL
Re: THE ISSUE: Maxed out MAF and tuning around it.
Originally posted by l-menace
Now that can't be a good thing when you are turning over 5000 RPM's, with little or no lubrication.
for every revolution the piston goes up and down once. so basically 5000 times a minute that little bugger is going up and down without lubrication. 83.3 times a second. OUCH...
Perhaps some of this is wrong, which I'm sure someone will correct it and that's fine.
Now that can't be a good thing when you are turning over 5000 RPM's, with little or no lubrication.
for every revolution the piston goes up and down once. so basically 5000 times a minute that little bugger is going up and down without lubrication. 83.3 times a second. OUCH...
Perhaps some of this is wrong, which I'm sure someone will correct it and that's fine.
Ya, that's wrong.5000 RPM is NOT the amount of times 1 rod end is spinning. It actually works out to 1/8 of your calc. Think about the firing order. You wouldnt want all 8 cylinders at TDC each revolution. One fires, then the next in succession, etc.
So it's more like ~600 strokes/min or 10 strokes a second... 10Hz per cylinder if you want to relate it to a speaker reproducing a 10Hz sine wave.
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From: Albuquerque, NM
No max power, L menace had it right. Each rod and piston is attached to the crankshaft and every revolution it makes they go up and down. Now if you want to talk about ignition pulses, divide that by half cause this is a 4 stroke engine, it fires once for every two revolutions.
L menace: Lots of cars are tuned without a MAF, GM and Ford went back and forth between Speed Density and MAF controlled engines. Emission controls finally did away with speed density type factory systems, the MAF does a better job of determining how much air is being pulled into the engine, speed density tries to calculate how much air is going in by measuring air pressure, rpm and air temp.
L menace: Lots of cars are tuned without a MAF, GM and Ford went back and forth between Speed Density and MAF controlled engines. Emission controls finally did away with speed density type factory systems, the MAF does a better job of determining how much air is being pulled into the engine, speed density tries to calculate how much air is going in by measuring air pressure, rpm and air temp.
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From: DETROIT, (formerly Eaton County, Michigan)
Originally posted by quiksilver
No max power, L menace had it right. Each rod and piston is attached to the crankshaft and every revolution it makes they go up and down. Now if you want to talk about ignition pulses, divide that by half cause this is a 4 stroke engine, it fires once for every two revolutions.
L menace: Lots of cars are tuned without a MAF, GM and Ford went back and forth between Speed Density and MAF controlled engines. Emission controls finally did away with speed density type factory systems, the MAF does a better job of determining how much air is being pulled into the engine, speed density tries to calculate how much air is going in by measuring air pressure, rpm and air temp.
No max power, L menace had it right. Each rod and piston is attached to the crankshaft and every revolution it makes they go up and down. Now if you want to talk about ignition pulses, divide that by half cause this is a 4 stroke engine, it fires once for every two revolutions.
L menace: Lots of cars are tuned without a MAF, GM and Ford went back and forth between Speed Density and MAF controlled engines. Emission controls finally did away with speed density type factory systems, the MAF does a better job of determining how much air is being pulled into the engine, speed density tries to calculate how much air is going in by measuring air pressure, rpm and air temp.
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From: Mi.
FYI,
http://www.modulardepot.com/?show=articlesdet&aid=37
http://forums.modulardepot.com/showt...threadid=14764
http://www.modulardepot.com/?show=articlesdet&aid=37
http://forums.modulardepot.com/showt...threadid=14764
Last edited by Thor01; Aug 8, 2004 at 12:24 AM.
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From: DETROIT, (formerly Eaton County, Michigan)
the only thing I don't agree is
Now, with a mass air system, it calculates volumetric efficiency. If you know the air flow going into the motor, the engine RPM and the engine displacement, you can calculate voleff very, very accurately. The Y-axis on the spark tables in the Ford software is voleff. In the above example you would see a higher voleff. If you set up the spark table correctly, you will now go in there and look up a spark value with a higher voleff, which is set up for less spark at this higher voleff. No need for boost reference, it¹s based on how much air is flowing into the motor at that RPM.
given our vehicles have a boost bypass, the air going past the MAF in doesn't necessarily go into the engine..
Also I've seen rubber boots on Lightnings COLLAPSE do to the suction of the S/C.
I still think it is a shot in the dark, but what do I know... once that MAF is maxed out and I think he agrees
So, as long as your mass air meter does not saturate (meaning the output of the meter exceeds the 5 volts that the EEC will acknowledge), and the transfer function within the ECU is correct (meaning at that given voltage the air flow that it thinks it has at that voltage is correct) the ECU will automatically calculate the correct amount of fuel to inject and deliver that fuel. So, if you run more boost, the EEC will automatically put in more fuel at any given RPM based on the air mass increase. Now, if the air meter saturates, you have a huge problem. Then means the ECU no longer knows how much air is flowing into the engine so it no longer knows how much fuel to inject. In this situation, the engine then starts to drift lean; pretty much any KenneBell car with a stock MAF does this. Yes, many people will "rape" the calibration and do things like command a richer and richer air-fuel ratio to maintain a constant air-fuel ratio. This is a failure waiting to happen. If you set up the table to give you 12:1 air-fuel ratio with the MAF pegged, and now you get a day with better air, the engine WILL run leaner.Five percent better air is 5% leaner than when it was on the dyno. Same thing applies if you try to use the volumetric efficiency table when the MAF pegs. This specific table gets heavily modified based on a bunch of things, most of which no longer apply correctly due to the mods on the vehicle, and the motor will NOT be right as air density and air temp change.
Last edited by l-menace; Aug 8, 2004 at 12:33 AM.
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From: Mi.
SCT has a way around it. It's not my place to say how they are doing it. I heard word of mouth that their SCT software and MAF combination will not max at 700+rwh.
It may not be a big secret....It may have already been mentioned by them on another thread or board. I know some here will not agree with what he said. I'm not hear to open that can of worms.
You can P.M. Jerry over on the other board and he might have time to explain the details on their MAF and software. Their MAF is reading and not pegging.
It may not be a big secret....It may have already been mentioned by them on another thread or board. I know some here will not agree with what he said. I'm not hear to open that can of worms.
You can P.M. Jerry over on the other board and he might have time to explain the details on their MAF and software. Their MAF is reading and not pegging.
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From: Northern, California
Two other alien ideas. Resistor the MAF voltage to read less voltage at said airflow...say 50%......and then adjust fuel tables. (This is actually a known and used method. Good solution? That I don't know). or...switch to a engine management system that uses speed density, and no MAF.
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Originally posted by Calightnin
Two other alien ideas. Resistor the MAF voltage to read less voltage at said airflow...say 50%......and then adjust fuel tables. (This is actually a known and used method. Good solution? That I don't know). or...switch to a engine management system that uses speed density, and no MAF.
Two other alien ideas. Resistor the MAF voltage to read less voltage at said airflow...say 50%......and then adjust fuel tables. (This is actually a known and used method. Good solution? That I don't know). or...switch to a engine management system that uses speed density, and no MAF.
Only other thing would be, how would it affect driveability.
Oh and someone did a seperate ignition system, but i never got any email notifies for updates and never saw a new thread, i dunno how that went.
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From: Auburn Wa
SCT will have us covered on the MAF very soon.
Something I just found out.....SCT is having Hitachi build a MAF sensor in 3 different horsepower levels. The meters are very accurate,easy to tune for and will bolt up to the stock location they look almost identical to the stock Ford meter. They will all come with preset tables that you just plug into your program......SCT program that is, I don't think the meter tranfer function info will be available for other tuners....just SCT.
Anyway thats all I know for now. Here's a thread on it.
http://www.modularfords.com/forums/s...ad.php?t=13454
Something I just found out.....SCT is having Hitachi build a MAF sensor in 3 different horsepower levels. The meters are very accurate,easy to tune for and will bolt up to the stock location they look almost identical to the stock Ford meter. They will all come with preset tables that you just plug into your program......SCT program that is, I don't think the meter tranfer function info will be available for other tuners....just SCT.
Anyway thats all I know for now. Here's a thread on it.
http://www.modularfords.com/forums/s...ad.php?t=13454
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From: Northern, California
Originally posted by grinomyte
see this is kinda what i was wondering for awhile now. Is the maf (when pegged) still sending appropriate voltage when it's considered pegged, or does it just stop at 5. In other words is this the pcms fault or the mafs fault. As i understand it the MAF basically works on the principle of measuring how much power it takes to make one wire stay the same temperature, so i'm guessing it would work past 5v just fine, and this idea will work.
Only other thing would be, how would it affect driveability.
Oh and someone did a seperate ignition system, but i never got any email notifies for updates and never saw a new thread, i dunno how that went.
see this is kinda what i was wondering for awhile now. Is the maf (when pegged) still sending appropriate voltage when it's considered pegged, or does it just stop at 5. In other words is this the pcms fault or the mafs fault. As i understand it the MAF basically works on the principle of measuring how much power it takes to make one wire stay the same temperature, so i'm guessing it would work past 5v just fine, and this idea will work.
Only other thing would be, how would it affect driveability.
Oh and someone did a seperate ignition system, but i never got any email notifies for updates and never saw a new thread, i dunno how that went.
Steve