Why do PRO-M meters have so many problems???

95.0Stang · Mar 19, 2004

Why is nearly every month in either MM&FF, or 5.0 we read about people installing Pro-M 75mm MAF and almost instantly having problems. It seems to carry over onto this site and corral also. Why do people say Pro-M is so much greater when it seems they have SO MANY more problems the say C&L???

zenboy99 · Mar 19, 2004

The Pro-M 75mm bullets had problems, especially with our cars from what I've heard. The Pro-M 77mm, 80mm and universal are all good meters. I haven't heard anyone having problems with those meters.

Eric94GTvert · Mar 19, 2004

Some people get by with the Pro-m 75, but for the most part it's junk and causes problems. Why? I am not really sure. Do a search for problems with Pro-m and the 75 is the one to avoid. Then do a search on the 77mm and the 80mm and you will see their track record is much better. In fact, I don't really recall anyone ever having problems with them.

mto502 · Mar 19, 2004

My 75 mm seems to work fine. Mine is the chrome sensor. I assume that's the bullit ?

Eric94GTvert · Mar 19, 2004

zenboy99 said:
The Pro-M 75mm bullets had problems, especially with our cars from what I've heard. The Pro-M 77mm, 80mm and universal are all good meters. I haven't heard anyone having problems with those meters.

beat me to it......

Killercanary · Mar 19, 2004

I've had ZERO problems with my Pro-M 75 bullitt.... ZERO

Rootus · Mar 19, 2004

Killercanary said:
I've had ZERO problems with my Pro-M 75 bullitt.... ZERO

Ditto.

VibrantRedGT · Mar 19, 2004

The Pro-M meters for a FOX body car is the way to go.

pleasehelp · Mar 19, 2004

Why is that?

VibrantRedGT · Mar 19, 2004

I wish I knew but I've owned three Fox body meters and two 94-95 meters. I had to return the 75MM bullet twice to Pro-M before I Ebayed it. My current meter is off a 91 LX.

pleasehelp · Mar 20, 2004

How did you know there was something wrong with it? And how did you know it was the meter? Just curious.

Zero Signal · Mar 20, 2004

It just sems wierd to me to be installing an aftermarket MAF sensor without actually changine the curve in the computer. Could it have something to do with that?

mto502 · Mar 20, 2004

Zero Signal said:
It just sems wierd to me to be installing an aftermarket MAF sensor without actually changine the curve in the computer. Could it have something to do with that?

Not really because the aftermarket MAF has to be precalibrated to match the size of the injectors.

Killercanary · Mar 20, 2004

Zero, the ideal way to do it is to tune the MAF function tables in the EEC instead of useing a cal'd meter. For those that don't know, "calibrated" meters compensate for larger injectors by tricking the EEC into thinking less air is actually coming into the car than really is. The EEC then uses a smaller pulsewidth than it normally would for the actual amount of air coming into the engine, but since there is an injector on the car that is larger than stock and flows more, this shorter pulse width actually flows more fuel than it did before. Some of the problems with the 94-95 processors is that they use LOAD for a lot more tables in the EEC than the A9L family of processors did. That being said, load is determined in our cars via the MAF, so when we go tricking the output voltage of the meter we end up messing with the LOAD as well inadvertently. I will say this, I had my MAF tranfer function tables re-done to read true voltage from the MAF so I wasn't relying on this "tricked voltage" this should have yielded a better running car and theoretically more power... it did neither. The car lost 1HP and gained 2ftlbs of torque, but it would stall all the time and ate fuel like it was candy, so I went back to the calibrated meter and factory EEC tables.

mto502 · Mar 20, 2004

That was a nice bit of info. I'm glad you found out the hard way instead of me Seriously though that was an interesting read. You've educated me but I'm glad I have what seems to be the best setup in those regards.

Slow5.0 · Mar 20, 2004

VibrantRedGT said:
The Pro-M meters for a FOX body car is the way to go.

Why

brentwoodboy · Mar 20, 2004

HairyCanary said:
Ditto.

Ditto.

VibrantRedGT · Mar 20, 2004

pleasehelp said:
How did you know there was something wrong with it? And how did you know it was the meter? Just curious.

Well when I installed the bullet meter over my 77MM standard it would stall and surge. Put the other meter on and it was fine again. Went back and forth a few times with the same result. I sent it in to Pro-M to get fixed. They told me they had issues with this meter and 24# injectors. They sent it back and it was only a tad better. Then I brang it back to Steeda and got another one. Well I had the same results. Put the 77MM back on and had zero issues. The bullet meter was flanged so I could bolt the air filter to it with my homemade cold air kit. The 77MM standard was too big for the fender. I sold both and bought a 77MM shorty. This will be my meter forever. Both 77's came off of Fox body cars. Whether it had anything to do with the way the car performed I don't know.

Zero Signal · Mar 20, 2004

I will say this, I had my MAF tranfer function tables re-done to read true voltage from the MAF so I wasn't relying on this "tricked voltage" this should have yielded a better running car and theoretically more power... it did neither. The car lost 1HP and gained 2ftlbs of torque, but it would stall all the time and ate fuel like it was candy, so I went back to the calibrated meter and factory EEC tables.

I wonder why that would happen. You don't suppose something else was looked over in there do you? DId you use the flow sheet that came with the sensor for the MAF function itself? I'm curious now!

I always thought it was all about how to set it up in their to get your max potential and streeability. But then again alot of cars respond in different ways to the same modification. Maybe it has something to do with your cam? That's one of those things where I'd say 'wait a minute that should work. . .' then drive myself insane trying to figure it out!

Someone wrote an article online about the aftermarket MAF sensors and he mentioned that he was able to tweak his curve & tables and run incredibly fast with the stock sensor. It went faster with the aftermarket only becuase of the better airflow through it.

final5-0 · Mar 20, 2004

Over the years I have seen many threads just like this one.

I called ProM and asked their tech guy about the 75mm and told him about threads like this one and made sure he understood I wanted no probs with the maf.

He said some don't have a prob one with the 75mm and some do.

I then told him I saw very few people say they had probs with the 77mm and asked about the differences between the two mafs.

He said that the electronics on the 77mm were better and the 80mm had the same electronics and due to the body being plastic could be had for less $$$.

I went for the 80mm.

I have used a Tweecer to dial in the maf & 30# inj's and everything seems to be working as it should.

Later
Grady

Why do PRO-M meters have so many problems???

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