Will a magnaflow hurt my 2.7?

Hey everyone. I recently got a magnaflow muffler installed on my 08 Tacoma. With the less back pressure of this muffler will it cause my engine to run lean and hurt it? Or hurt it in any other way? I like the sound it's making and seems to run great but can't shake the paranoia. Just wanted to check with you guys. Thanks.

 

I wouldn't be too concerned as most of the time, your truck is running in closed loop mode where the ECU and O2 sensors are constantly adjusting the air/fuel ratio.

Mine runs lean on the dyno in open loop mode (wide open throttle) because of my Injen intake.




And no matter which muffler I ran (stock, Magnaflow, or Flowmaster) the engine consistently ran lean in open loop. So changing your muffler from stock to Magnaflow won't alter your A/F ratio enough to matter.

Greg

 

Thanks! So my engine will switch into open loop when I floor it? Is that correct? But stays in closed loop at any other time? Thanks.

 

Fwiw, the backpressure thing is a myth that should have died a few centuries ago. I think jesus said in the book of mathew, "backpressure? What a croc."

 

Closed loop means that the ecu uses sensors to adjust a/f ratio to keep ideal mixture with respect to environmental conditions. Open loop means that it defaults to a fixed a/f ratio programmed into the ecu. The ecu will switch to open loop at cold startup, and/or if you have a trouble code due to a sensor value that is out of range. Usually open loop is a little rich because it is safest for the engine, but it hinders power and fuel economy. Tooter's is running in open loop because his intake is messing up the MAF/intake temp sensor values, and he's running lean because the less restricted intake is allowing more air into the engine but the amount of fuel that the ecu is injecting is the same as if he were running the stock intake.

 

Just a slight correction...
My truck is not running in open loop all the time. The OBDII scanner confirms that both the long and short term fuel trims are operating properly with no codes either triggered or pending. It's only running lean at wide open throttle when the ECU reverts to its factory stock preprogrammed fuel map. Normal driving is all closed loop.

Greg