Fuel Control Syste and CAI Impact on Gas Mileage
11-30-2005, 02:56 PM
#1
Fuel Control System and CAI Impact on Gas Mileage
Sloppy has a Cattman CAI on the 1997 I30t. Unless its just my heavy foot (I like the growl), I think my mileage may have dropped 1-2 mpg (based on 3 fill-ups using the same 94 octane gasoline from Shell Oil.
Question: If a CAI rams colder, more dense air into the throttle body, doesn't the car's ECU compensate and add more fuel? How does the computer controlled fuel system work anyway? Please delete if this is a repost. Thanks. -Sloppy
Question: If a CAI rams colder, more dense air into the throttle body, doesn't the car's ECU compensate and add more fuel? How does the computer controlled fuel system work anyway? Please delete if this is a repost. Thanks. -Sloppy
11-30-2005, 03:16 PM
#2
Originally Posted by Sloppy Snood
Sloppy has a Cattman CAI on the 1997 I30t. Unless its just Sloppys heavy foot (I like the growl), I think my mileage may have dropped 1-2 mpg (based on 3 fill-ups using the same 94 octane gasoline from Shell Oil.
And it's normal.
Originally Posted by Sloppy Snood
Question: If a CAI rams colder, more dense air into the throttle body, doesn't the car's ECU compensate and add more fuel? How does the computer controlled fuel system work anyway? Please delete if this is a repost. Thanks. -Sloppy
11-30-2005, 08:18 PM
#4
Originally Posted by Sloppy Snood
Unless its just my heavy foot (I like the growl),
Originally Posted by 99grnmaxgxe
You're probably using more gas b/c you want to hear the intake more so you step on the throttle a lil' bit more.
12-01-2005, 07:07 AM
#6
Originally Posted by njmaxseltd
Is your I30t and auto or 5 speed? Auto's don't take well to aftermarket intakes.
12-01-2005, 07:11 AM
#7
Originally Posted by NmexMAX
At 50% (not sure but hi throttle setting) the ECU has a set map it uses, regardless of O2 sensor input, so that would negate the effects of the metered air(dense or not), since the map its running in is open loop (pre-set)
And the ECU does take cooler air into consideration since the two primary inputs at open-loop are the CPS (POS) for RPM and MAF voltage. Cooler air will remove more heat from the MAF heater element and the ECU will have to add more voltage to compensate. This translates into the ECU seeing more air coming in, and adding more fuel.
12-02-2005, 03:46 PM
#8
Originally Posted by njmaxseltd
Is your I30t and auto or 5 speed? Auto's don't take well to aftermarket intakes.
Originally Posted by nismology
They do if you keep the stock intake resonator. That's the key.
12-02-2005, 03:48 PM
#9
Originally Posted by nismology
Open-loop starts at 40% throttle and around 3k RPM.
And the ECU does take cooler air into consideration since the two primary inputs at open-loop are the CPS (POS) for RPM and MAF voltage. Cooler air will remove more heat from the MAF heater element and the ECU will have to add more voltage to compensate. This translates into the ECU seeing more air coming in, and adding more fuel.
And the ECU does take cooler air into consideration since the two primary inputs at open-loop are the CPS (POS) for RPM and MAF voltage. Cooler air will remove more heat from the MAF heater element and the ECU will have to add more voltage to compensate. This translates into the ECU seeing more air coming in, and adding more fuel.
12-02-2005, 08:18 PM
#10
Originally Posted by Sloppy Snood
Please excuse my ignorance but could you please tell me which part the stock resonator is? Description or picture would help. I am assuming it is the plastic, rectangular-shaped piece that I removed when installing the Cattman CAI. Can someone confirm? Thanks. -Sloppy
12-03-2005, 07:15 AM
#11
Originally Posted by nismology
That's the one. Reinstall it and you'll restore your throttle response and low-end punch to stock while still retaining the advantages of a true CAI. That's the best combination to me.
12-03-2005, 07:37 AM
#12
Originally Posted by Sloppy Snood
Not trying to be a complete doofus, should I install the stock resonator in the stock postion (post MAF sensor that is)? Imay need to shorten one or more of the Cattman CAI kits rubber hoses for a good fit. Sound like the right approach Nismo? _Sloppy
Throttle body->resonator->MAF->piping->filter
Sounds good to me.
12-03-2005, 07:47 AM
#13
Originally Posted by nismology
The stock location is before the MAF.
Throttle body->resonator->MAF->piping->filter
Sounds good to me.
Throttle body->resonator->MAF->piping->filter
Sounds good to me.
12-07-2005, 02:46 AM
#14
Questions: Hybrid OEM Resonator/MAF plus Cattman CAI Set-Up
Originally Posted by nismology
That's the one. Reinstall it and you'll restore your throttle response and low-end punch to stock while still retaining the advantages of a true CAI. That's the best combination to me.
My Cattman CAI has the port for the intake temperature sensor on the piece of tubing that I just removed (the piece that replaced the resonator in the first place). I can't find a good mounting location. Do I just tneed to extend the wiring 6-7 inches and drill an appropriately sized hole in the metal tubing that leads into the MAF?
It just doesn't look like the sensor can easily go into the flex tubing between the throttle body and resonator or between the resonator and the MAF. I guess one option might be to drill a hole in the OEM tube section where the MAF sensor resides but I do not want to disrupt the air flow with the temperature sensing element. Anyone have any advice? Thanks. Sloppy
12-07-2005, 07:09 AM
#17
Originally Posted by RedfoxXx
it can take the ECU up to 400 miles to fully adjust
also dose the stock intake resonator really make a big diff on autos?
I took mine out, what is the advantage
I took mine out, what is the advantage
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