PSA: 4G Tacoma TRD Pro / Trail Hunter Airbox Intake System Retrofit is NOT plug-and-play on standard models

[HarryDaHamster]

The Stillen intake uses a MAF housing diameter that's very close to that of the Pro/Trail Hunter. If you fit the Stillen intake onto a Pro/TH, no special scaling is required. Our Stage 1 calibration will get you sorted out just fine.

When fitting the intake to a non-Pro/Trail Hunter (gas or hybrid), the specific scaling option we offer will prevent CELs and is required if using our tuning.

I should've posted i have a Trailhunter. Not sure if that changes your response at all.

I heard the Trailhunter intake flows significantly worse than all other models due to the snorkel. With the Stillen intake tied into the snorkel, intake entry at the front of the truck and thru the snorkel, there's no additional calibration needed? I was told by another tuner there needs to be a recalibration due to the increased flow.

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[JustDSM]

I should've posted i have a Trailhunter. Not sure if that changes your response at all.

I heard the Trailhunter intake flows significantly worse than all other models due to the snorkel. With the Stillen intake tied into the snorkel, intake entry at the front of the truck and thru the snorkel, there's no additional calibration needed? I was told by another tuner there needs to be a recalibration due to the increased flow.

I understood you had a Trail Hunter.

Having the Trailhunter with the snorkel doesn’t change the MAF calibration itself. The way Toyota (and we) handle airflow is based on the housing the MAF sensor sits in, not what’s in front of it. The MAF measures the actual airmass that enters the engine, so even if the snorkel is more restrictive than a standard airbox, the MAF sensor is still reporting accurately. The only difference is that the restriction up front means the engine has less potential airflow available compared to, say, an open element intake; so you may lose some headroom, but you don’t lose accuracy.

Where recalibration does come into play is if you change the MAF housing diameter. For example, if you go to an intake where the MAF sits in a larger (or smaller) tube than what it was originally calibrated with, then the airflow speed across the sensor changes, and the ECU would misread airflow without correction. That’s when tuning or rescaling is required.

So, in your case, with the Trailhunter snorkel and a Stillen intake behind it, if the MAF housing is roughly the same size as stock, there’s no additional calibration needed. The snorkel may flow worse overall, but the ECU is still metering airmass correctly. The only time you’d need recalibration is if the MAF housing itself has been changed.

It’s also worth noting the difference between airflow and airmass. A snorkel can restrict overall airflow, meaning the engine just can’t pull in as much air as it could otherwise. But the airmass that actually makes it through is still measured accurately by the MAF. That’s why you don’t need a recalibration for a snorkel alone — the ECU is still getting the right information, just with a lower ceiling on how much air the engine can breathe.

 

[HarryDaHamster]

I understood you had a Trail Hunter.

Having the Trailhunter with the snorkel doesn’t change the MAF calibration itself. The way Toyota (and we) handle airflow is based on the housing the MAF sensor sits in, not what’s in front of it. The MAF measures the actual airmass that enters the engine, so even if the snorkel is more restrictive than a standard airbox, the MAF sensor is still reporting accurately. The only difference is that the restriction up front means the engine has less potential airflow available compared to, say, an open element intake; so you may lose some headroom, but you don’t lose accuracy.

Where recalibration does come into play is if you change the MAF housing diameter. For example, if you go to an intake where the MAF sits in a larger (or smaller) tube than what it was originally calibrated with, then the airflow speed across the sensor changes, and the ECU would misread airflow without correction. That’s when tuning or rescaling is required.

So, in your case, with the Trailhunter snorkel and a Stillen intake behind it, if the MAF housing is roughly the same size as stock, there’s no additional calibration needed. The snorkel may flow worse overall, but the ECU is still metering airmass correctly. The only time you’d need recalibration is if the MAF housing itself has been changed.

It’s also worth noting the difference between airflow and airmass. A snorkel can restrict overall airflow, meaning the engine just can’t pull in as much air as it could otherwise. But the airmass that actually makes it through is still measured accurately by the MAF. That’s why you don’t need a recalibration for a snorkel alone — the ECU is still getting the right information, just with a lower ceiling on how much air the engine can breathe.

Wow thanks for that clarification. Can’t wait to run OTT!

 

[tipsyjam]

If anyone is curious, I got my hands on a TRD Performance Intake (still waiting for the filter) and took some measurements of the inner diameter of the MAF sensor housing tubing compared to the stock Air Cleaner Assembly. Looks like the pro intake tube has about a 3-inch diameter and the stock tube sits at around 2.6-inches in diameter.

Some quick math shows that this seemingly small difference significantly changes the Reynolds number between the two intake tubes at the same mass flow rate. This means the heat transfer from the MAF would also be significantly changed, which would mean the MAF sensor should be giving incorrect voltage readings for that mass flow rate in a pro intake if it is still calibrated to the stock intake MAF tube size. It makes sense that a recalibration would be needed for the MAF. It would be interesting to know what the limits are for MAF housing size before a CEL appears for these trucks.

Stock Air Cleaner assembly: 17700-AK010
Pro intake parts: PTR03-35241-AA through -AE

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