? about maf sensor & tb

[jimster502]

Greetings,
For my latest project, I'm going to add a custom made dual cai in my 97 xlt with the sohc engine. I already know how the whole setup is going to be but I have some questions. Since I'm already going to modify the intake setup, I was thinking of putting a bigger tb & maf sensor. I've heard that I can use the gt's,lightnings,& aerostar's maf sensor. My question is can I change the tb & maf sensor without having any problems? I read that there's problems with the a/f ratios if not tuned, but can I change any of these without having any problems and w/o having to tune it?

Thanks in advance,
Alex

 

[94Eddie]

As long as the MAF is calibrated for your injectors then there shouldn't be a problem. Changing the throttle body may not be worth the time and expense. When replacing a stock throttle body it is possible to go too big. If you do it will reduce the low to mid range torque output for the engine. Large diameter throttle bodies are intended for high RPM horsepower applications and this comes at the cost of low/mid RPM performance.

 

[jimster502]

Hmm so if I were to change the maf to mustangs maf, what kind of injectors would I have to buy?

 

[94Eddie]

You won't have to buy new injectors. The MAF needs to be calibrated to the size of injectors you currently have on the engine. Most Mustang GTs came with 19# injectors but Lightnings probably came with 24/30# or even 36/42# in the supercharged models. Another way to handle a discrepancy between the MAF and fuel injectors is to get a custom tune but even then you will have to know the calibration chart for the MAF to program it into the chip. To be sure, you can order a MAF from a manufacturer like Pro-M or C&L to be calibrated for your injector size.

 

[jimster502]

Ohh sweet! So I can order an maf sensor from c&l and I will not have to tune it? By any chance, would you happen to know which injectors a 1997 sohc would have?

 

[94Eddie]

I don't know the size. Search here and I am sure you will find it. Also, C&L might know the size.

 

[rocket 5979]

You won't have to buy new injectors. The MAF needs to be calibrated to the size of injectors you currently have on the engine. Most Mustang GTs came with 19# injectors but Lightnings probably came with 24/30# or even 36/42# in the supercharged models. Another way to handle a discrepancy between the MAF and fuel injectors is to get a custom tune but even then you will have to know the calibration chart for the MAF to program it into the chip. To be sure, you can order a MAF from a manufacturer like Pro-M or C&L to be calibrated for your injector size.

Eddie that may have been acceptable practice back about 10-15 years ago when custom tuning had not really advanced much. But now there just is no good reason to do that calibrated MAFS BS instead of a proper custom tune. Going that route nowadays would be like cooking a t-bone steak on a stick over a campfire when you have a gas or charcoal grill right next to you. It is a band-aid mod, and not a very good one, at best.

The benefits that a custom tune will net that a recalibrated MAFS cannot are:

-About 15-20rwhp more since spark timing can be advanced to take advantage of higher octane fuel.
-Properly recalibrated AFR's
-Proper load calculations in the tune due to proper recalibration of everything which means properly referenced spark timing and transmission shifting to name but a few.
-Better shifting transmission.
-Better gas mileage since your part throttle AFR's will be fully dialed in.
-You can pull and clear DTC's with the Xcal flash tuning device as well as datalog the engine and transmission if you bother learning to do so.

These are just a few of the benefits that a real custom tune offers that a recal'ed MAFS does not.

OP I suggest not even bothering to upgrade to a larger diameter MAFS or TB because the gains will be minimal unless you are really pulling some air through by means of forced induction. The performance gained to dollar spent ratio just isn't high enough to justify it at your current mod level. I also am curious of your meaning of "dual CAI"? My suggestion is that you do a CAI and some other bolt-on mods that have been proven to net power and performance such as exhaust, ASP Underdrive pulley, custom tune (Henson Performance can help with this one), etc. Of course this all depends on how much money you can invest into the project. Good luck with everything.

 

[94Eddie]

I have the tune option on the table for him. People do mods for all kinds of reasons. Some only care about performance gains and some only care about looks. I addressed the mild performance gains he woulds see and even spoke about how he could see a loss in performance at certain RPMs. If the OP is going for looks and some performance then it is better to have all the parts in place before getting a custom tune. Then buying a MAF with proper calibration allows him to drive the vehicle as long as he wants before paying a pretty stiff price for a proper tune.

 

[rocket 5979]

I have the tune option on the table for him. People do mods for all kinds of reasons. Some only care about performance gains and some only care about looks. I addressed the mild performance gains he woulds see and even spoke about how he could see a loss in performance at certain RPMs. If the OP is going for looks and some performance then it is better to have all the parts in place before getting a custom tune. Then buying a MAF with proper calibration allows him to drive the vehicle as long as he wants before paying a pretty stiff price for a proper tune.

You are correct in that people do all sort of mods for many different reasons. But if the OP's reason is to gain better horsepower/torque then the proper path is more defined than you may think. The issue is that the physically bigger MAFS is not going to gain much if any power unless he is moving allot more air into the engine with something such as forced induction. So unless the OP plans to go with forced induction then that is wasted money unless he mainly cares about appearance; and in that case then it is his prerogative. If he happens to get a MAFS that he has to send in to be recalibrated then you have those charges too. By the time you have spent the money on that it won't take much more to get either a chip tune or a flashed tune. Those will gain considerably more power in addition to having the other benefits I listed in my previous post without the disadvantages that a calibrated MAFS bring to the table. When you buy an SCT X3, for example, you will get 3 tunes. So what the OP could do is get a canned tune for whatever mods he has currently, then when he adds a few more mods later he can ask for another updated tune to get things fairly close again. Then when he has all his mods on it and wants a full tune he will already have the tuning hardware to be able to get one.

Spend money to gain almost nothing with a band-aid mod; or spend a little more and actually get safe and quantifiable results that really improves the all around performance of the vehicle. I know which one I would pick but then again I am not the OP so I will leave that decision to him now that he is a little more informed on a few of the technical aspects of things.

 

[94Eddie]

I have a '89 Mustang that has a Kenne Bell Blowzilla/Flowzilla on it (12-16 psi) with water injection, a J&S Safeguard, a TwEECer chip I have been programming since the mid 90s etc. and know all about the ins and outs of modding engines whether they be forced induction or not. The curve of any MAF has to be entered in the data set for any computer or chip. The tuners mess with the fuel curves to adjust AFR, not the MAF curves. A tuner just needs to insure the MAF curve is compatible with injector size it was programmed for then adjust fuel curves, load table etc.

The function of a MAF is to measure air flow and that is all. The companies that sell MAFs have the machines to measure air flow through the MAF and program it accordingly. The tuner needs to know the MAF's table of air flow data to input into the data set. The tuners I know, and my own experiences tuning my car, never create a MAF curve from reading AFR from dyno pulls or running the engine. If the OP buys a used MAF then he needs to make sure the calibration data comes with it so he won't have to pay to send it back to the manufacturer for calibration or flow testing. One of the main reason to have the specific flow data for a specific MAF from the manufacturer is to make tuning more accurate.

One other thing, going with a properly calibrated MAF gives the user control over his build. The parts can be installed and it isn't required to have anyone tune it in order to drive it. This doesn't eliminate the opportunity to have a custom tune done in the future. I wouldn't recommend getting it tuned until he has done all the mods he wants and/or planned. Doing multiple tunes is just throwing away money, IMO.

 

[rocket 5979]

I have a '89 Mustang that has a Kenne Bell Blowzilla/Flowzilla on it (12-16 psi) with water injection, a J&S Safeguard, a TwEECer chip I have been programming since the mid 90s etc. and know all about the ins and outs of modding engines whether they be forced induction or not. The curve of any MAF has to be entered in the data set for any computer or chip. The tuners mess with the fuel curves to adjust AFR, not the MAF curves. A tuner just needs to insure the MAF curve is compatible with injector size it was programmed for then adjust fuel curves, load table etc.

The function of a MAF is to measure air flow and that is all. The companies that sell MAFs have the machines to measure air flow through the MAF and program it accordingly. The tuner needs to know the MAF's table of air flow data to input into the data set. The tuners I know, and my own experiences tuning my car, never create a MAF curve from reading AFR from dyno pulls or running the engine. If the OP buys a used MAF then he needs to make sure the calibration data comes with it so he won't have to pay to send it back to the manufacturer for calibration or flow testing. One of the main reason to have the specific flow data for a specific MAF from the manufacturer is to make tuning more accurate.

One other thing, going with a properly calibrated MAF gives the user control over his build. The parts can be installed and it isn't required to have anyone tune it in order to drive it. This doesn't eliminate the opportunity to have a custom tune done in the future. I wouldn't recommend getting it tuned until he has done all the mods he wants and/or planned. Doing multiple tunes is just throwing away money, IMO.

I was ready to leave things be but I had to respond to the above post. Sorry OP. Okay you are starting to irritate me with your outdated information. I have been custom tuning for over 6 years and with the modern day stuff like SCT an HPTuners too, not that twEECer stuff that was only acceptable 10+ years ago. Who really cares if you have a Kenne Bell blown Mustang with 16 psi? Does that somehow establish that you know what you are talking about here? Well if that's the case then I MUST know more since I have a Kenne Bell blown built 4.6 V8 Explorer pushing 20 psi of boost and a Twin turbocharged 402ci stroker Pontiac G8 that will be pushing 700+rwhp here soon, both of which I tuned. Of course not. Just because you own a modded to hell car and just because you may have done a little tuning on it doesn't mean you are some sort of custom tuning expert. This holds especially true when I am speaking to a guy who references using twEECer tuning hardware/software which is very outdated. I am talking about using modern day professional grade custom tuning platforms such as SCT Advantage. That is the exact tuning system the OP is most likely to get his 97 Explorer tuned with if/when he decides to get a custom tune. So, being that I have tuned Ford Explorers, Ford F-150's, Ford Mustangs, Lincoln LS's and Lincoln Mark VIII's with it with great results I believe I speak from more experience here. Have you tuned any vehicles with SCT Advantage? Have you tuned any vehicles newer than 1995 and if so with what tuning platform?

You do adjust BOTH the fuel curve and the MAFS curve in the tune itself. The fuel curve is set in the base fuel table and the MAFS curve(read as incoming aircharge mass vs Voltage, MAF Ad Counts, or Hertz) is calibrated within the MAFS transfer table which is measured in #/min, #/mass tic, g/cyl. The reason for this is that you command what the AFR will be in the base fuel table and then tell the ECM the exact amount airmass entering the engine via calibrating the MAFS transfer function. You can rape the base fuel table to come up with whatever AFR's you want but then the load calculations will be off which will affect everything else load dependent such as spark timing and transmission shifts to name a few. You do not need to know the MAFS curve to be able to input into the tuning software either. The reason for this is because the way the ECM performs the calculation between the base fuel table and the MAFS transfer function. You set the base fuel table first and then through datalogging AFR's you adjust the MAFS transfer function calculated airmass column accordingly until actual AFR's match commanded. Since commanded equals actual you now know that the incoming aircharge is being properly calculated since the ECM understand the relativity of the ratio between how much fuel should be requested when a given airmass is entering the engine which means that calculated load is calibrated properly too. I can assure you that you don't just throw a MAFS curve into the tune and all of a sudden commanded AFR equals actual AFR without any need for finetuning. Any real custom tuner can take a MAFS and install it onto a vehicle and recalibrate everything back into PERFECT equilibrium within the tune itself without needing to know anything about the MAFS curve. Even if you buy a MAFS that has a sheet saying that x amount of voltage equals y amount of airmass you will still need to do a finetuned recalibration within the ECM tune itself because your AFR's will still probably be off by at least a few tenths here and there. I don't know about you but I prefer tabletop WOT AFR curves, not something that resembles Dolly Parton's chest. About the only thing that having the MAFS flow vs voltage sheet does is assists in speeding up the process for a starting baseline MAFS curve in the ECM tune. The MAFS curve will still need to be dialed in further from there to ensure that AFR's match commanded.

There is no such thing as a "properly calibrated MAFS for a given size of injector" anymore man. This is what I am trying to tell you. Us modern day custom EFI tuners don't send the MAFS in to be recalibrated by the manufacturer or other aftermarket company anymore unless we are working on a vehicle that is not able to be recalibrated via the ECM. We recalibrate EVERYTHING within the ECM tune itself. The main thing that people have to worry about when selecting a MAFS anymore is if it has enough electronic range that will allow the meter to accurately measure the amount of aircharge that will be coming into the engine without pegging and whether the physical size of the MAFS housing is large enough so as not to serve as an airflow restriction in a bigger power combo. Go ahead and give James Henson, Jerry Wroblewski, Tim Barth, Justin Starkey, or Bob Kurgan a call and ask them if they have bothered having a MAFS sent in to be recalibrated to a specific injector size within the last decade while tuning any Ford that is OBD-II or newer. Don't be offended if they have a laugh before explaining to you what I just did.

Attached below is an example of what the MAFS curve looks like in modern tuning software. The example is from HP Tuners for GM because I don't have SCT Advantage installed on this computer yet but their appearance is very similar. The Ford tune in SCT Advantage will use voltage (or Ad Counts) on the x axis rather than Hz though. As you can see, it is the MAFS curve itself, not a fuel curve since we see airflow measured in lb/min and not a targeted AFR which is in the base fuel table for Ford in SCT and the Power Enrichment table in HP Tuners for GM. When you adjust this table in the tune you are essentially telling the ECM how to interpret the hz (or in Fords case Volts/Ad Counts) into equating to a given incoming airmass. Then those changes work their way down the pipeline of data in the ECM and will change your actual AFR and also affect spark timing, etc.

Eddie it is obvious that you aren't a newby to custom tuning or probably making power with performance cars but it is also apparent that you are operating off of information that hasn't been updated in over 10 years too. If this were the late 90's then I am sure you would have schooled me but the plain fact is that times have changed and custom EFI tuning has drastically evolved with the times too. The way we tune cars now, and the level of access and detail we have when creating a custom tune, is very different and much more advanced now. Sorry man but you are dead wrong and completely outmatched when it comes to having the technical knowledge for discussing the finer points of modern day EFI tuning. I am not going to argue this with you anymore because the OP's thread has gone far enough on a tangent as is.

OP if you really want some up to date and accurate technical information on which steps would be best taken to gain the best performance per dollar spent then feel free to PM me. Eddie if you would like to PM me with further discussion on the finer points of modern EFI tuning that is fine as well.

 

[jah81592]

As long as the MAF is calibrated for your injectors then there shouldn't be a problem. Changing the throttle body may not be worth the time and expense. When replacing a stock throttle body it is possible to go too big. If you do it will reduce the low to mid range torque output for the engine. Large diameter throttle bodies are intended for high RPM horsepower applications and this comes at the cost of low/mid RPM performance.

Even if you do run a calibrated maf you still have to change the injector slopes and adjust the transfer function accordingly. Unfortunately the misconception is that a calibrated maf doesn't necessitate tuning. I also do a ton of EEC-iv tuning-matter of fact had a boosted car on my dyno yesterday. I use a Sneec datalogger for those cars and SCT or Diablo chip. This is the area where the misconception of calibrated meters come in were with the Fox body cars. Just to throw it out there when I tune any 1996 or newer Explorer I don't chip them. The simple reason is because typically the jumpers weren't soldered onto the circuit board unlike the Mustang until 2004. I am not trying to be a rear end just clear up some stuff regarding this.

I run big throttle bodies on most of my projects in the shop and on my dyno the torque losses are negligible.

 

[94Eddie]

Even if you do run a calibrated maf you still have to change the injector slopes and adjust the transfer function accordingly.

You don't have to change any programming data if the MAF is calibrated for the injectors. I have personally seen many aftermarket MAFs installed with no programming changes and the engine ran like it did with the stock MAF.

Unfortunately the misconception is that a calibrated maf doesn't necessitate tuning. I also do a ton of EEC-iv tuning-matter of fact had a boosted car on my dyno yesterday. I use a Sneec datalogger for those cars and SCT or Diablo chip. This is the area where the misconception of calibrated meters come in were with the Fox body cars. Just to throw it out there when I tune any 1996 or newer Explorer I don't chip them. The simple reason is because typically the jumpers weren't soldered onto the circuit board unlike the Mustang until 2004. I am not trying to be a rear end just clear up some stuff regarding this.

The OP is installing an aftermarket MAF and some intake tubing on an otherwise stock engine. He doesn't NEED a tune to make the engine run close to as it did with a stock MAF if the MAF is set for his injector size. Are you saying he does NEED a tune for the engine to run?

I run big throttle bodies on most of my projects in the shop and on my dyno the torque losses are negligible.

Intake runners, throttle bodies etc. all play a part in tuning for low/mid range torque. It is why many engines are designed with variable length runners that switch from long narrower flow paths to short, more open ones as RPMs increase. A good example is the 3.0L Duratech engine has variable length runners. A larger throttle body will likely cost low end torque and for a heavy brick like the Explorer it isn't something I would want. On stock 5.0L engines anything greater than a 65mm TB/EGR plate will cost low end torque and the larger the TB the more torque it will lose.

How much torque will be lost is up for debate but an appreciably larger throttle body will very likely cause a loss of low end torque that will be noticed.

As a response to you and rocket, the OP specifically asked if he could change the MAF without having to o custom tuning. Are you two saying that he HAS to do custom tuning if he swaps in a MAF calibrated for his injectors or is it your suggestion that he get the tune done. Also, what is the going price for an SCT tune nowadays including any hardware required along with tuner and dyno time?

 

[ssp.interceptor]

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[ssp.interceptor]

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[rocket 5979]

Also, making a super custom intake will not gain you any more ponies than opening up your stock airbox and putting a quality filter in. May actually hurt you by throwing off your MAM if not done right.

I know that's not what anyone wants to hear when they get an itch and a bright idea, but that's the truth.

I disagree with the home fabricated CAI not gaining anymore than a stock intake with a replaced higher quality filter. Most aftermarket conical filters have more filter surface area which equates to less restriction to airflow coming into the engine than a panel filter of similar build. This restriction usually isn't anything large but couple the gains of that with the other items I will mention below and you have some gain. Also allot of stock intake tubes are designed in a way that usually has some sort of sound dampening affect. Baffles, ribs, and a few other structures will hinder maximum flow while allowing for a quieter engine in a decent amount of engines. Since most people that are wanting more horsepower also don't mind a little additional noise then it is not a bad thing to allow for max flow while also adding a little intake growl. Lastly I will end that if you are taking the time to make your own CAI there are some do's and dont's. First off is making a heatshield that allows the conical filter to draw the coldest air possible outside of the engine bay. Ensure that you minimize the amount of size transitions and don't step up to a needlessly large intake tube if your TB will just neck the diameter back down.

I sort of agree with you and I don't at the same time. I think that allot of peoples attempts at making their own CAI perhaps does not yield what it should, due to the way they made it. But if made properly then most aftermarket style CAI's will gain a bit of horsepower on allot of vehicles. Some do not because their stock intake flowed more than normal, but that is more an exception than the rule.

 

[ssp.interceptor]

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[rocket 5979]

I have yet to see a dyno where a 4.0 or 5.0 explorer has picked up more than 5hp (peak) out of any retail or custom intake. Considering you can spend anywhere from $100-$400+ buying or making one, and considering if you were only looking at it from a hp-to-dollar standpoint, the money is not worth it.

The problem I see is that the focus is only on peak numbers which only tell a fraction of the story for a mod. I have personally seen mods that gained "nothing" at peak when dynoed back to back, but picked up 20+rwhp and similar rwtq under the curve. People would take one look at the peak numbers comparo's and totally write the mod off, even when it had displayed significant gains at non-peak RPM's. I would rather gain 20hp for the duration of 2,000 rpms under the curve than 35hp for only a few hundred rpms at peak. It would be different if our engines only operated at peak RPM when the vehicle is accelerating but they don't.

It would be nice if some of the vendors on here who have a dyno and who sell these kits all day would actually do a back to back test with one. But the problem in that is (and this is what erks me) that they usually tune it at the same time so you do know how much came from the custom tune and how much was from intake.

The issue with installing the CAI and not tuning it to see the gains alone is that CAI's will sometimes throw the AFR's off in a vehicle so much that it will go dangerously lean at WOT. So you have to retune it so that actual AFR's match commanded once again. Another reason why is that sometimes doing one mod such as a CAI allows you to unlock more power with the tune due to it pulling colder air so you can advance spark timing a bit more. While technically the tune gained the power through additional spark timing advance, the gains never would have been realized without the CAI being in the picture.

On top of that, if the intake did make a big difference, than it might take a little while for the computer (stock with no tuning)to readjust to the changes and coming back and dynoing the truck after a week or more of driving will not suffice since air temp, baro, and everything else will be different. But i guess that's what DA correction is for. Sure would be nice to see some hard data, otherwise it's all on faith.

However far the CAI throws the AFR's off there is only so much the ECM can do to get the part throttle closed-loop AFR's back into equilibrium at stoich. Usually the factory spec is tuned within +/-3% fuel for part throttle before adaptive learned long term fuel trims try to get even closer to stoich. However, adaptive learning does not learn any values for open-loop fueling/WOT fueling so even if you drive for a month after installing the CAI your ECM will never learn the proper WOT AFR's because it is not designed to. This in turn means you would still have a lean condition at WOT. This leads back again to the reason why allot of vehicles are better served with a custom tune to recalibrate the part throttle and WOT AFR's back to commanded as well as add any additional spark timing that you may be able to run.

 

[ssp.interceptor]

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[rocket 5979]

Rocket,

If you can show me one back-to-back dyno (with or without custom tune, but tuned for same octane) that shows a stock 4.0 or 5.0 Explorer gaining more than 5hp peak or anywhere else on the curve with a retail or custom CAI when compared to just an aftermarket filter and airbox mod, then I will eat my words and run out tomorrow and get one.


Nick

You can do whatever you want to do man. I am not here to convince you or anyone else that they need a CAI. I am posting on the technical facts and data that are out there if you bother looking in the right places or perform your own tests and data analysis. Do your own homework.