1993 Cobra Mass Air Meter!!!

Maybe a small increase. If is cheap, get it & use it.

Edit: What are you asking??
Do you realize that Ford made the Mustang and Cobra for more than one year? YES, it's TRUE!

WHAT YEAR "Cobra" MAF????


My orig post assuming the question was about the 93 Cobra MAF:

Sorry, I can't resist. Yes, you can use a piece of bread for a piston. What I'm really saying is that you're asking about something that does not exist! There is no such thing as a Cobra 70mm Mass Air Meter calibrated for 19lb injectors. Edit: Make that 93 Cobra MAF.

The 93 Cobra MAF does NOT have the same MAF scale as the "Fox 5.0" MAFs. So, you can NOT use the 93 Cobra MAF on a stang unless you have a chip or (93 Cobra EEC & 24's). BTW: No OEM MAF is "calibrated" for injectors.

If you want to run a 70mm MAF, use the 94/95 Mustang MAF with a flange adapter (the 94/95 GTs and Cobras use the same MAF). If you want to run 24's, get the 70mm 93 Cobra MAF and the 93 Cobra EEC.

FYI:
http://www.veryuseful.com/mustang/tech/engine/93cobra-maf-vs-stock-gt-maf.html

The post by stang&2birds is correct, but I will try to expand as to why, as this seems to be confusing to many. Including myself up to about a month ago.

When dealing with stock Ford components there are 4 parts that need to match. If any one of these components is not aligned with the rest, then there will be fuel metering issues.
1. MAF Transfer - this is part of the computer program. It can be modified with the use of an aftermarket tuner.
2. MAS - this is the black electronics box on top of the MAF tube. These are different based on the MAF tube they were originally used on. The A9L 5.0 HO motors used a 55mm MAF tube and thus had a 55mm MAS. The 93 Cobra had a 70mm MAF tube and used a MAS specific to the 70mm MAF. So far as I know, all 70mm MAS sensors are the same.
3. MAF Tube - the major spec to be concerned with is the Inner Diameter of the tube.
4. Fuel Injectors - such as 19lb, 24lb, etc.

Air flowing through the MAF tube is sensed by the MAS.
The MAS converts that signal to a voltage, which is sent to the computer.
The computer converts the voltage signal back into an air flow, which is used for multiple calculations.

If the MAS does not match the MAF tube diameter, then the conversion of air flow to a voltage will not be accurate.

If the MAS/MAF tube do match each other, but don't match the MAF Transfer in the computer, then the conversion from voltage to air flow will not be accurate.

Notice that Injector sizes have not been mentioned to this point. Ford did not program the output of the MAF/MAS combo based on fuel injector sizes. Instead Ford made all of these changes in the computer.

If that left everyone completely confused try this FAQ I posted on my site.


The 93 Cobra 70mm MAS sensor is not interchangeable with the 5.0HO 55mm MAS sensor. Two issues exist.

• <The slope of the air flow increase (as related to voltage gain) may not be the same on each Sensor.
• Airflow at min/max voltage may not be the same between Sensors.

Some Numbers as an Example:
At idle both MAS sensors could be at say .5v and ~30 kg/hr mass air flow.
At higher rpms both sensors could be reading the same as well, say 4.5v and 1000 kg/hr.
This would is possible because both sensors are operating on the same 0-5v range. Both motors have similar air flow capacities, so similar amounts of air would be flowing at min and max levels.
However, the rate at which the voltage changes with respect to mass air flow can vary in the middle of the 0-5v range.
At ½ throttle the Cobra meter could read 2.5v and ~200kg/hr; while the 55mm sensor could read at 2.5v and ~180kg/hr.

Some Real MAF Transfers from C&L as an Example:
The following graph illustrates how these 2 different sensors will react in the same C&L meter, with the same Red calibration tube. What is important to note is the way the 55mm sensor line (top) climbs faster, and finishes higher than the 70mm line (bottom).


Long story short…
If you have an A9L, you must use the 55mm 5.0HO MAS sensor.
If you have an X3Z, you must use the 70mm Cobra MAS sensor.
The MAS must be matched to the ECU.

What if I Use an Aftermarket Tuner?
If you do use an aftermarket tuner, then it is possible to use the cobra MAS on an A9L, or a 5.0HO MAS on an X3Z. All you need to do is make sure that the MAF Transfer you enter into your tuner is correct for the MAS/MAF you are using.
Some more Info specific to the 93 Cobra and 5.0 HO can be found here... http://www.veryuseful.com/mustang/tech/engine/93cobra-maf-vs-stock-gt-maf.html

You have many things correct.
But, you're very wrong about what you're calling the "MAS". Here again, there is no such thing in OEM Ford terms. People get confused because of that F*$#@**## company called C&L. IMHO, buying a C&L is like playing the lottery. A SMALL percentage of the people get "lucky".

EVERY Ford MAF sensor is custom tuned to a specific MAF body.

Let me repeat that for people that use, like, or think that C&Ls aren't a joke:
EVERY Ford MAF sensor is custom tuned to a specific MAF body.


ProM/ProFlow does the same thing. Ford has always done laser trimming of the electronics. ProM did sand blasting. Pro Flow (the new ProM) does the better and more accurate laser trimming of the electronics.

This is REQUIRED for MANY REAL LIFE REASONS! The tolerance on mechanical parts is "a joke" when you're talking in fractional percentages. Plus, the tolerance on analog components is also "pathetic".

So, in real-life, some sort of calibration is required. For the TPS, the EEC "calibrates" the TPS for every start-up. For the MAFs, Ford calibrates every MAF sensors to a specific and unique MAF body.

You can NEVER EVER "reliably" swap MAF sensors among MAF bodies. Will it work? Well, does playing Russian Roulette "work"? You MAY get lucky most of the times. But, you also MAY have your engine go BOOM because you have an incorrectly calibrated MAF.


BTW: For those that don't know, I "do this stuff" for a living. I do the electronic/computer architecture, specs, and design of control/response systems. So, I know a lot of the theory and reasons for the designs. But, people like Joel have more of the "real life" experience with the symptoms of when things go bad. As an Engineer, I look at the correct and structured way to diagnose, verify and then fix a problem. But, that sometimes involves test equipment that some people don't have. Although, in most cases, just a code reader and a volt meter that can also read frequency will help diagnose ~95% of all EEC problems that are NOT do to someone hooking something up wrong. Sorry, when people start doing "random things" to their EEC system, all bets are off.

BTW#2: I finally finished my TPS FAQ. So, I guess it's time to also finish up on the MAF FAQ. It's "only" ?2? years past when I said that I'd have it done.

stang&2Birds said:

You have many things correct.
But, you're very wrong about what you're calling the "MAS". Here again, there is no such thing in OEM Ford terms.

.

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I am not sure I see what you disagree with me on.

I am calling the black electronics unit on top of the MAF tube the MAS (Mass Air Sensor).
I feel the MAF and the MAS are two different parts and deserve separate names.

I was trying to make the point that the MAS and MAF have to match each other and must match the MAF Transfer loaded in the EEC.
I think you agree with this.

jason

Some semantics about your grammartics is in order…

stang&2Birds said:

EVERY Ford MAF sensor is custom tuned to a specific MAF body.

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Do you mean a family of MAF bodies with the same design specifications or a unique, individual MAF body? My understanding is that there is a specific family of MAF sensors that mate with a specific family of MAF bodies. Beyond this, I can’t see custom matching a MAF sensor to a MAF body in a production environment. That would be very expensive & time consuming. It also defeats the concept of interchangeable parts.

Joe-- I think you've hit it on the head. I think what should have been said for the sake of clarity is"

EVERY Ford MAF sensor TYPE is custom tuned to a specific MAF body TYPE.

The sensors and housings are then mass produced for their intended applications. They don't go through and "hand tailor" each and every unit as they roll from the assembly line.

I think that the reason folks are used to saying things like "calibrated for 19s", and the like, are because of the similarities in the A9x family of EEC processors (aside from the 93 Cobra EEC).

There are a LOT of folks that do not understand the MAF transfer function in realtion to both the EEC and injectors. It does make for some confusing conversation when trying to explain why meter X doesn't work on application Y with EEC Z. The dawn usually lights when folks start working with a tuner that's capable of custom loading of a meter's trasfer function.

All of this being said, I have one of these so called 70mm Cobra meters [car runs fine for now] and am searching ebay for a 80MM PRo-M to replace it with after M.Yount had this same conversation with me

srothfuss said:

All of this being said, I have one of these so called 70mm Cobra meters [car runs fine for now] and am searching ebay for a 80MM PRo-M to replace it with after M.Yount had this same conversation with me

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get the WOT A/F checked with a wideband at stock fuel pressure with the stock and the 93 cobra MAF and post back , that might end alot of the guess work ........I have a wideband and a my friend has been wanting to do this to his since hes running the stock MAF but hes been short on cash to buy the thing to do some experimenting

I should schedule some dyno time at PHP and see what they say...

Edit: I don't have a wideband yet or a tuner so that is why it'll have to go into the shop to get it checked.

Edit #2: I've an appointment setup on Monday 6/12 in the afternoon to get the AFR checked out and a dyno to see my baseline before I change some things on the motor

Daggar said:

Joe-- I think you've hit it on the head.

There are a LOT of folks that do not understand the MAF transfer function in realtion to both the EEC and injectors. It does make for some confusing conversation when trying to explain why meter X doesn't work on application Y with EEC Z. The dawn usually lights when folks start working with a tuner that's capable of custom loading of a meter's trasfer function.

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I agree completely with that.

Just to make sure I do have a strong grasp on this...

I assumed that every 55mm MAS was the same, and any 70mm MAS could be interchanged as well.

Are there differences that I am not aware of?

jason

When development begins on anything, like the MAF + MAS, there were probably prototypes that used laser cutting and very exacting measurements. These expensive tools aid in the development of the transfer function and the computer. But as production begins all of those 'exact' preproduction tools are thrown away and the mass production begins. Now, in mass production there are build tolerances and some are smaller than others. I don't know what the specs were for the +/- voltages for the MAS itself because I don't have the drawing(s) in front of me. Either way, non of this really matters because I know I made an impulse purchase that was wrong (didn't do any homework) and now need to find a new meter anyways

Go figure I ran a 1993 Cobra 70mm MAF on 19 lb and 24 lb injectors for a decent amount of time and had zero issues. Car ran great, and although wasnt extremely fast at the time (didnt have anything to do with the MAF), didnt gain any power, or change characteristics when I later sold the MAF and injectors. Wish I kept the 24s, but 19s have been working for me!

srothfuss said:

When development begins on anything, like the MAF + MAS, there were probably prototypes that used laser cutting and very exacting measurements. These expensive tools aid in the development of the transfer function and the computer. But as production begins all of those 'exact' preproduction tools are thrown away and the mass production begins. Now, in mass production there are build tolerances and some are smaller than others. I don't know what the specs were for the +/- voltages for the MAS itself because I don't have the drawing(s) in front of me. Either way, non of this really matters because I know I made an impulse purchase that was wrong (didn't do any homework) and now need to find a new meter anyways

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I think you will be surprised to see what you can adjust with a simple fuel pressure regulator and flathead screwdriver once its on the dyno ........

25thmustang said:

Go figure I ran a 1993 Cobra 70mm MAF on 19 lb and 24 lb injectors for a decent amount of time and had zero issues. Car ran great, and although wasn't extremely fast at the time (didn't have anything to do with the MAF), didn't gain any power, or change characteristics when I later sold the MAF and injectors. Wish I kept the 24s, but 19s have been working for me!

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Perhaps, but it would have been cool to see the differences in the ratings of of you KAMRFs between the two injectors. The EEC's adaptive control can make up for a decent amount.... enough to clean up the differences between a stock Fox meter and a 93 Cobra meter. According to the verbiage in Vristangs post (using this as an example) the differences between:

2.5v and ~200kg/hr; while the 55mm sensor could read at 2.5v and ~180kg/hr.

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are well within the EEC 20% adaptive control ability to trim fuel.

In other words... though the facts posted so far are true, we're leaving out the built in ability of the EEC to allow for and adjust to variances. Once the variance gets outside of the EEC's ability to trim, then you'd begin to run into tuning issues. I don't see the curve represented above as being much outside of that 20%. Conceivably, you could get away with running that Cobra meter although you might be a bit richer up top.

Daggar said:

Perhaps, but it would have been cool to see the differences in the ratings of of you KAMRFs between the two injectors. The EEC's adaptive control can make up for a decent amount.... enough to clean up the differences between a stock Fox meter and a 93 Cobra meter. According to the verbiage in Vristangs post (using this as an example) the differences between:
are well within the EEC 20% adaptive control ability to trim fuel.

In other words... though the facts posted so far are true, we're leaving out the built in ability of the EEC to allow for and adjust to variances. Once the variance gets outside of the EEC's ability to trim, then you'd begin to run into tuning issues. I don't see the curve represented above as being much outside of that 20%. Conceivably, you could get away with running that Cobra meter although you might be a bit richer up top.

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When I wrote that I knew it would come back to haunt me. I pulled those numbers out of my... well just look at my avatar and you'll know where I come up with most of my thoughts.

From what I have seen and read in the forums there is a 12% maximum on the adaptive strategy for the A9L computers (A9L and X3Z for sure, but I am not sure on others).
Daggar - I don't know about other computers, but I would be interested in knowing if some have a 20% limit.

Yeah, maybe running the 70mm meter could be compensated for by the adaptive strats, but if anything was slightly off ideal, you would have issues. For example if the O2 output was skewed/shifted, you could quickly hit the max of 12%.

Another note - I drove the 408w in my sig for a year before getting the tweecer. I thought the motor was running fairly well, and just wanted to clean up the idle a little. When I hooked up the tweecer though I found that my KAMRFs were maxed at 1.12x under most load rpm conditions. The motor was lean and trying to richen the mixture.
Things were good, but they could have been much better (as they are now).

Good Thread

jason

Yeah... I gotcha. I wan't concentrating too hard onthe numbers either. Just using them to illustrate a point concerning adaptive control.

I do think that your 12% figure is a bit shy. I remember reading a paper on EEC-IV internals that suggested that 20% was the max towards fuel trimming at the bottom of the duty cycle and it skewed to a lower percentage towards the top of the duty cycle.

I have no real way to confirm which of our sources are correct though.

My car as it stands right now is rich @ idle and fine in the middle and upper RPM's. If it was lean at all I can not tell but I am not using any type of AFR meter or other devices other than my smell and touch. Other than the transfer function being off the car "seems" to run better than ever.

But like I said before, I'll know more about the AFR after Monday.

srothfuss said:

My car as it stands right now is rich @ idle and fine in the middle and upper RPM's. If it was lean at all I can not tell but I am not using any type of AFR meter or other devices other than my smell and touch. Other than the transfer function being off the car "seems" to run better than ever.

But like I said before, I'll know more about the AFR after Monday.

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I'd like to hear your results, if you don't mind coming back.