Foxbody with a Vortec.

So I’m working with this 1992 Foxbody. Came in with a few issues. It currently is a 302 with a V1-SC. So he took it to a well known tuner here locally to get it tuned and was told the MAF was not responding to the changes he was making but did not have time to investigate why. The intake tube leading to the MAF was riddled with holes so I am going to hard pipe that section. I know that will cause issue. Looking at the MAF, it is a Pro-M MAF. How many people have had luck with tuning on this style MAF. I ran the part number and Pro-M states it’s calibrated to a N/A setup with 24lb injectors and a cold air fender Intake kit. The owner “thinks” the car has 30lb injectors. Can these MAFs be recalibrated by a tuner or is it better to use a larger non calibrated Ford MAF? Also I am used to running larger systems than this one and do not see many systems not running bypass valves anymore. This kit doesn’t seem to have a bypass which I have always considered a must with a draw thru MAF setup.

I know it's a completely different car but when i put the vortech on my 96 Cobra i had the exact same issue.

I deleted all the egr and secondary air injection stuff and there was one setting in the pcm that had to be turned off for that stuff then the maf started responding instantly.

Took 3 tuners to figure it out.

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I know guys that have run Lightning MAFs on their foxes and were able to tune for it. So I would imagine there is some adjustment of the transfer. I would say the holes before the MAF aren't as big of a deal as the air isn't metered at that point. After the MAF would be a different story. I can't say I've seen any blower set ups without a bypass of some sort. All that air has to go somewhere at idle. I would definitely install a BPV in the system. And I would change it over to a blow through set up if you can. I had way better luck with blow through over draw through.

slo984now said:

I know guys that have run Lightning MAFs on their foxes and were able to tune for it. So I would imagine there is some adjustment of the transfer. I would say the holes before the MAF aren't as big of a deal as the air isn't metered at that point. After the MAF would be a different story. I can't say I've seen any blower set ups without a bypass of some sort. All that air has to go somewhere at idle. I would definitely install a BPV in the system. And I would change it over to a blow through set up if you can. I had way better luck with blow through over draw through.

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The holes are after the MAF. Between the MAF and the blower. Anything special to switching to a blow thru other than relocation?

LT1Porsche said:

The holes are after the MAF. Between the MAF and the blower. Anything special to switching to a blow thru other than relocation?

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I misread it. My apologies. But yeah, holes after the MAF could be the issue that the tuner was having.

Not really. Just make sure the pipe the MAF is in is as straight for as long as possible. Then it's just a matter of tuning.

Ya those holes have to get fixed. How did that happen anyways?

I can't remember if with Pro-M you need a new maf or a new metering tube inside the Maf to calibrate for injectors. Been a long time since I've played with a fox 5.0

It’s an older Vortech kit I think. It used a double wall flexible tube. Just old I guess. Doesn’t have a bypass valve and it using a calibrated NA MAF with unknown Injectors

Whats being used for tuning (chip/software)?

Verify injectors. IF they are a 30lb injector, and for example they are an EV1 Ford/Bosch injector, they should have a "red top" and 280 150 945 stamped into the top part of the red body.

How much boost is the blower set up for? What pulley sizes do you see?
If I recall correct, Low boost Vortech kits back then (6-8psi) didnt come with a by pass valve. Although I'd recommend one, even the black plastic BOSCH valve.

They are greentop Injectors. I’ll have to check for some numbers. I think it’s set for 10psi but I’ll have to measure Pulley size tomorrow. Not sure exactly what’s being used for tuning.

I've had dozens of fox bodies with vortechs over the years. There's many ways to go about getting the car running right. I'll provide 2 recommendations...one without needing a chip, one with a chip....

No chip. Confirm the injectors are 42lb green tops. Send the air meter to pro-m and have it calibrated for the exact combo....I.e., fill out their data sheet. Set base timing at 10 degrees. Pulley the blower for ~10 psi (6.87 lower and 3.12 upper on a V1) Use an MSD boost timing master box or similar and set the dial to 1/2

Option 2- fix holes between air meter and throttle body. Confirm injector size and air meter calibration. Make adjustments via chip tune to compensate for mismatched injectors and air meter. Target ~18 degrees total timing at WOT, max boost.

Caveat: after fixing the holes between the meter and TB, see how it runs and make sure it's not already tuned with a chip....check the processor for the presence of a chip....

There is a chip in the processor. Not sure how its tuned. Another thing I am looking at is if the MAF is possibly too small. Its a Pro-M 75mm MAF. When checking the numbers it comes up as a 75mm MAF that's calibrated for 30lb injectors and CAI.

Just got done exchanging emails with Pro-M and they say the current MAF will not work with this setup. At 75mm the housing will be almost maxed and being calibrated for 30lb injectors makes it useless. Going to push for him to upgrade to a Lightning MAF or something similar. Has anyone else had luck running a lightning maf of a forced induction foxbody? Thanks