Pro-M MAF Calibration question

[ylw95gts]

Can any Pro-M MAF sensor be re-calibrated for larger injectors?

 

[Julian Moore]

I say yes. I had a 98 Cobra MAF, redone for a 95GT engine. They recalibrated and changed the connection for me.

 

[ylw95gts]

The reason I'm asking is there's a guy who has a 1 yr old Pro-M for 19lb injectors for $100. I really wanted to upgrade to 24lb injectors. Thanks Julian!

 

[Denunzio36]

I had a similar question: I had installed 24 lb injectors myself and have been experiencing some problems. I had changed the entire MAF, IAC, 02 sensors...the whole 9 yards..In the end my car still idles like crap. After speaking with a technician, he told me that I need to calibrate the on board computer as well. Has anyone heard of doing this? I imagine that this is done on a dyno?

 

[Stang D]

I'd be patient. You can get a good deal on a Pro-M already set up for 24s. I see several of them in the Corral classifieds each week. Generally around $150. It costs about $100 for a recalc, plus round trip shipping costs.

 

[Denunzio36]

What's the process for recalculating? I heard they have to burn a chip to fix the problem in the computer

 

[Stang D]

What's the process for recalculating? I heard they have to burn a chip to fix the problem in the computer

Short version. your PCM still thinks it has stock injectors in it. The MAF lies to the PCM, so your larger injectors send the appropriate amount of fuel. You could go from 19# to 30# to 42# injectors. Your GT PCM still thinks it has 19s. MAF calc needs to be different for all three scenarios. I'm hardly an expert tuner. Someone please correct me if I explained it wrong.

 

[ylw95gts]

So what happens if you're running 24lb injectors with a 19lb calibration? Does it "F" it up?

 

[Julian Moore]

I ran 30 pound injectors witha calibrated maf, car would run real rich until I got a tune. I then jumped to 50pound injectors witha maf calibrated for 42's. The chip thinks I was running 30's...man it ran pig rich, would stall and stutter. Once Kaufmans got done tuning and burning a chip..ran like a champ. I guess my point of this is..tunes are a vital part of a reliable street car. Do I think 24 pound injectors with a 19 pound calibrated maf will do anything..no, it's just a waste of bigger injectors. The next big question to ask yourself..how much injector is too much.

 

[Denunzio36]

No no...my MAF is calibrated to 24 pounders, I am running 24 punders. My car still runs like crap...Now, I hear that I need to have my computer calibrated / chip burned / tuned so that it runs right. I just don't wnat to go spend an "s" load of money on having a chip burned if it's not going to solve my problem. Has anyone run into this problem? There must be other pople that have 24 MAF and 24 injectors!! Did you need to have the computer calibrated?

 

[ylw95gts]

Well here's my dilemma. I purchased the Pro-M MAF (19lb calibration) off Ebay for $102. It should be here tomorrow. Today I made a deal on a set of 24lb polished injectors w/ 300 miles on them for $150 shipped. So do I turn around and sell the MAF and get the right calibrated one or send the one I have to Pro-M? Decisions! Decisions!

 

[Denunzio36]

I'd say, stay as close as possible to what it's supposed to be calibrated for....There's a reason why the MAF gets calibrated for 24 pounders, and if mine runs like crap with everything calibrated right, there's a chance yours might run worse...but it also could run better...who the eff knows

 

[Stang D]

Well here's my dilemma. I purchased the Pro-M MAF (19lb calibration) off Ebay for $102. It should be here tomorrow. Today I made a deal on a set of 24lb polished injectors w/ 300 miles on them for $150 shipped. So do I turn around and sell the MAF and get the right calibrated one or send the one I have to Pro-M? Decisions! Decisions!

If you really want to run the 24s, it would probably be a bit cheaper to sell your current MAF and buy the correct used one. Of course if you send in yours for recalc, you'll know with near certainty you have a properly working, good as new MAF.

 

[Julian Moore]

I'll take one more shot at this. If you run a stock computer, and install a maf with matching injectors, you will have no problems. If you run a maf with the wrong injectors, the maf reads airflow and if it's n ot matched with fuel flow, the car will run poorly. Denunzio36, I think you did a bunch of work, and I would do the standard check for vacuum leaks. My other question for you is, are you running a pro-m meter or C&L. If it is a C&L, you have to change the sample tube to match the injectors. The sample tubes, as usual with 94/95 models are different then pre 94's colors. Hope this helps guys. Driveability issues can really be frustrating. Good luck and keep us posted.