wideband and external dump tube??

[robertseber]

Hey i have a 97 eclipse gst that i have a external dump elbow on it. I am getting ready to put in my eprom and link so i had my bung welded up for my wideband in the down pipe. So my question is do i need to get rid of the external dump to get it tuned, since some of the exhaust is going out the external dump or is it fine like that. Thanks for the help guys.

 

[StarFawkes]

In short, no, you can keep your external dump.

 

[northernawd]

some widebands say in the instructions to have a certain amount of distance from the turbo. further away the longer the sensor will last, but the readings will be inaccurate.

 

[Melbowski]

Your exhaust is basically pressurized when your waste-gate is open, so it's not likely you'll have back-flow to give you bad readings. You also don't have to have to worry about the exhaust that you're dumping. The exhaust you dump has the same general O2 content/density as what stays in the exhaust and flows over the wide-band sensor so you'll have the same AFR reading.

Really with a wide-band the only time you'll have any problems with incorrect readings is when fresh air is leaking into your exhaust via a bad gasket or hole. You shouldn't have any problems otherwise, short of wiring issues.

Also as stated, the manufacturers claim that mounting the sensor too close to the turbo shortens the sensor's life-span, though many members have mounted it fairly close without issues. Meanwhile, the further you move it down the exhaust, the more delay there will be in your AFR reading. Most opt to risk the shorter sensor life for improved response time, since even if you cut the sensor's life-span in half, that's still 2-3 years of use. Do what suits your ideals, and have fun tuning!

 

[robertseber]

Ok cool yeah i have read about closer = faster response time but shortened sensor life, farther away = more delay and longer sensor life. I have read that alot of people use the front bung in the turbo elbow and use narrowband simulation. I was mainly worried about the exhaust being dumped and not being measured at wot. But it sounds like im in good shape, once again thanks fellas for your help.