[Vettezuki]

Reading one of Ron's posts about potential trouble with MAF size on his Cobra, I realized I might have a similar problem. So, how do yo know when your MAF isn't big enough?

[BRUTAL64]

Originally Posted by Vettezuki

Reading one of Ron's posts about potential trouble with MAF size on his Cobra, I realized I might have a similar problem. So, how do yo know when your MAF isn't big enough?

When she points at it and laughs.


Sorry that is uncalled for.

I'll ask a couple of guys here for ya.


That is a really good question, it stumped a couple of the smarter FI guys here. They could not agree on how to tell if it is too small.

But they both agreed testing is the only sure way to tell. Hopefully some FI guy will chime in here.

[Vettezuki]

Well, maybe it's as simple as if the MAF is pegged at 100% during WOT it's not big enough because it's impossible to know if more than what the MAF can read is coming through. Thus causing a lean condition at WOT.

[BRUTAL64]

Originally Posted by Vettezuki

Well, maybe it's as simple as if the MAF is pegged at 100% during WOT it's not big enough because it's impossible to know if more than what the MAF can read is coming through. Thus causing a lean condition at WOT.

One of the guys here said just that.

[Vettezuki]

Originally Posted by BRUTAL64

One of the guys here said just that.

Not bad for an 87 IQ huh?

[BRUTAL64]

Originally Posted by Vettezuki

Not bad for an 87 IQ huh?

So you're right up there with Ex Pres Bush (jr).

[94cobra69ss396]

The job of the MAF is to keep the A/F at a given ratio according to what is programmed in the ECM. Let's just say the ratio is 12:1. It does this by heating the resistor inside it. As air flows over the resistor it cools it and the MAF has to increase voltage to keep it at the set temp. The voltage range is .5v - 5.0v. If the MAF isn't large enough it will peg at 5.0v and 12:1 A/F before the redline is reach and thus can not increase fuel to match the incoming air cause the ratio to go above 12:1.

On my Cobra the MAF was pegged at 6000rpms when we first tuned it a few years ago. DiabloSport makes a device called Mafia that allows your to control the voltage of the MAF so you can tune the MAF. This will allow me to still use my 80mm Lightning MAF without the engine running lean.

[BRUTAL64]

Originally Posted by 94cobra69ss396

The job of the MAF is to keep the A/F at a given ratio according to what is programmed in the ECM. Let's just say the ratio is 12:1. It does this by heating the resistor inside it. As air flows over the resistor it cools it and the MAF has to increase voltage to keep it at the set temp. The voltage range is .5v - 5.0v. If the MAF isn't large enough it will peg at 5.0v and 12:1 A/F before the redline is reach and thus can not increase fuel to match the incoming air cause the ratio to go above 12:1.

One of the guys here said something similar. So.........now we do what to figure if it is too small or not?

Something like;
Just check the voltage as you run up the rpm range?

[94cobra69ss396]

When we tuned the Cobra it showed what the voltage of the MAF was during the pull. So that's how we knew. I'm sure a good tuner could tell you what size you need before you even get to that point. When I was building the the engine for the Cobra I spoke to Steve first to find out what size MAF and injectors to buy. He likes the factory Ford pieces over aftermarket ones so he had me get the 80mm Lightning MAF and their 30mm injectors which he modified.