My MPG went down after install...WHAT, WHY?!?!?!

[JSAP123]

Well I installed a AEM CAI and a Magnaflow 2.25' Exhaust on my 2.3L and now I've never been able to get better than 29 MPG!!!
I put the CAI on a month before the exhaust and I was getting 34 MPG and that was combined city/hyw!!! Then when I had the exhaust installed and my mileage plumited...has this happened to everyone else or is something wrong with mine? I was under the impression that both the mods should increase my gas mileage.
PEACE>>>

 

[keleko]

you have more power and you're USING it

i.e. leadfoot

 

[thebeansoldier]

you have more power and you're USING it

i.e. leadfoot

not exactly.

CAI gave more mileage because the engine ran leaner.

CAT-BACK decreased the exhaust velocity due to the wider piping over stock. So if you do more city driving, your mileage will drop cause you'll be subconsciously pressing on the throttle a tad harder to get the car moving quicker from a stop. Your mpg would increase if you drive on the freeway a lot tho.

Aren't you glad you didn't go with a 2.5" exhaust and a test pipe?

 

[keleko]

not exactly.

CAI gave more mileage because the engine ran leaner.

CAT-BACK decreased the exhaust velocity due to the wider piping over stock. So if you do more city driving, your mileage will drop cause you'll be subconsciously pressing on the throttle a tad harder to get the car moving quicker from a stop. Your mpg would increase if you drive on the freeway a lot tho.

Aren't you glad you didn't go with a 2.5" exhaust and a test pipe?

that's what i said






sorta

 

[eurotuner]

on my 97 VR6 i went from 23 to 32 city MPG with SRI and straight line 2.7 exhaust!

 

[CTGrey02]

Your putting more air into the engine and the ecu is compensating by adding more fuel to the mixture to even it out. Take the CAI off, reset the computer and see if it changes.

 

[mzdalvr]

Doesn't CAI make the engine run richer cause the ECU tries to compensate for the extra air being pumped into the engine?

 

[boostdog]

yes it can which is why if you look around at the subie forums they do not recommend installing an aftermarket cai since it leans the car out to much making it unsafe.

 

[mzdalvr]

yes it can which is why if you look around at the subie forums they do not recommend installing an aftermarket cai since it leans the car out to much making it unsafe.

Just to clarify...Its richer not leaner? The way your reply sounds is that the car leans out - which means that gas is less and more air. CAI makes the ECU mix more gas to compensate for more air. Just trying to make it less confusing.

 

[thebeansoldier]

An aftermarket CAI on any car will run leaner. The ECU's fuel trim has set parameters based on the amount of air coming in from the stock intake. It can handle very lean mixtures and if the amount of air coming in detected by the MAF sensor exceeds the set parameters (say 5th gear @ 80mph is normally getting 5lbs/min of air at 40% throttle, now is getting 16lbs/min air at the same throttle position) the ECU thinks it's one of the sensors or there could be a leak somewhere, then will throw a CEL to notify the driver and protect itself by getting limp mode values so the driver can safely get home and take it to the dealership.