cp-e XCel intake fuel trim information

Yesterday we finally got the chance to get one of our intakes on our SPEED3 to record some fuel trim data for everyone. The point of this information is to show that our intake keeps the fuel trims as close to stock as possible as to avoid issues with exceeding the adjustment window the ECU is allowed to operate in. If you exceed this adjustment window, you'll probably experience a fuel cut. This is our justification for the extra time and effort spent machining our MAF housings and airflow straighteners. We try to keep the fuel trims as close to stock as possible. Yes, making the car run leaner by scaling the MAF voltage does make more power, but we contend that it causes problems down the road as you install more performance parts.

We started with the stock airbox. We disconnected the battery while we installed the stock airbox, and that gave the computer enough time to clear its memory. We then took the vehicle out for a drive to warm it up and brought it back to the shop to record some fuel trim data. Because the fuel trims are always changing, we took some data, took the car out for a spin, and then checked the numbers again. We did this about a dozen times, and the long term fuel trims settled at about -4.7%.

Stock airbox long term fuel trim (at idle): -4.7%

We performed the same procedure on our XCel cold air intakes with the machined MAF housing and the airflow straightener. After several runs we got a long term fuel trim of -7.1%, which deviates from stock by -2.4%.

cp-e XCel intake long term fuel trim (at idle): -7.1%

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Another forum member was kind enough to check the fuel trims on his Mazdaspeed intake, but I could not find information on his testing procedure. Previously posted:

GT1 said:
Long term fuel trim with stock airbox: -4 (average)
Long term fuel trim with MS CAI: +5 (average)

The ECU seems to be a bit confused by the MS CAI. I'm waiting to see if it will settle down in a couple of days.


In summation:

Stock long term fuel trim: -4.7%
XCel long term fuel trim: -7.1%
Mazdaspeed long term fuel trim: +5%



Consider that GT1's fuel trims deviated from stock by about 10% with the Mazdaspeed intake, whereas our XCel intake was off by about 2.4%. The computer only has so much adjustability when it makes changes to fueling, and when you exceed this adjustment window, the ECU simply cuts fuel to the engine in an effort to save it. Adding performance parts to your car inevitably changes the fuel trims, so you should consider this if you plan on modding your car beyond cold air intakes. I promise we don't make the machined MAF housing and airflow straightener just for fun! ;)

If you're curious about checking your fuel trims, you can perform this check with any OBD-II scanner that has the ability to log sensor data in real time. We used the AutoXRay EZ-Scan 6000 for all of our tests.

Please understand that we aren't trying to discredit the Mazdaspeed intake!!! People have been asking for validation of our MAF housing design and we used the only other intake on the market for comparison purposes. We are just trying to demonstrate the effectiveness of our design.

If you have any questions, please feel free to post them up and I'll do my best to answer them.


Jordan
 
good read interesting stuff.... wish you guys had a mspeed intake on hand to use as thats going to be the only way to do this reliably same car all 3 intakes in the same day...
 
tsunami said:
good read interesting stuff.... wish you guys had a mspeed intake on hand to use as thats going to be the only way to do this reliably same car all 3 intakes in the same day...


Yea, you're right. Ideally, we would have liked to have tested all at once, but I'm hoping more MS intake owners will measure and post their own fuel trim information. I guess we'll see!


Jordan
 
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