Perrin 3" Intake MAF Scaling
 

I've installed two of these now and both cars show large and varying fuel trims. +/-20.
Looking at the provided MAF scale it varies from 9 to 43% from the stock. This seems odd to me. Has anyone had experience with this intake?

@PERRIN_Chris do you know what's up?

The MAF scale is much different from stock because the diameter of the MAF housing was increased from stock. There's also a bunch of talk about how the stock MAF scaling isn't very ideal either.

I've noticed from the several reflashes I've done that it takes several miles for the fuel trims to stabilize. That being said, the only time I've seen positive LTFT in the range of 20+ is when I had an exhaust leak at the header to head gasket interface.

Just to be clear this is after a tune?

Yeh. A tune is required because of the MAF size change.

My fuel trims were less than +/- 2 before the intake swap.

I've done a few. All scaled up nicely. Didn't use any provided scale, just did them from scratch.

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Sorry I didn't see this earlier guys. It's normal that the percent over stock isn't going to be the same the whole way, since the airflow is going to be different through the revband. The MAF curve is an open thing we provide and we would love feedback from custom tuners as to what they left with. The thing is we took a stock car with tune, dynoed it, then install the 3" intake and dynoed it, the recalibrated the MAF to have the same AFR everywhere. We then did tons of street driving on it to ensure LTFT's stay zeroed under full throttle and plus or minus 5% under cruise.

If customers are not seeing this same thing, we would like to know to see if its a hardware issue or if its a issue with the tune.

What other mods do you have on your car?

How do you do that? I know about calibrating sensors, but you typically need at least two "standards" to test them against.

How can you calibrate an airflow sensor? A wind tunnel?

Don't forget the stock airbox has straighteners. Without those, the vortex created around the MAF sensor will vary based on airflow. So at 1.5v you won't see the same scaling difference as 3v.

This is why I want a 3" maf tube with a machined step so i can securely fasten my 3" honeycomb. :thumbsup:

Although I do have access to equipment to calibrate MAF sensors on the bench, that isn't necessary.

If you take your car to be dyno tuned, scaling the MAF should be one of the first tasks undertaken. Any supplied MAF scale is really just a starting point.

Either 86Drift's customers tried to do it themselves or they went to incompetent tuners.

I'm doing the tunes myself. Turns out the provided MAF scale is a fair way out. Rather than +9-43% over stock. I'm now running around +17-19% and it's much better. Still more work to be done though. Once finished I'll feed the data back to @PERRIN_Chris.

I would be interested in seeing this data as well seeing as I have the intake sitting on my desk waiting to go on and would be happy to run some scales and report out.


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For sure send me what you have, maps@perrinperformance.com, thanks!