Why You Need wideband AFR When Getting An Email Tune

Posted this a while back over at WSC. Figured I should give it a home here as well.

Email tunes are sometimes necessary because there is no nearby shops that can provide the service. However, to maximize your chance of a successful tune, wideband AFR is a crucial piece of data that should be collected.

The following is an example of an Email tune that did not perform to what the parts were capable of. One of the contributing cause is the lack of AFR data.

Background info on the car:
-2L wrx
-16G turbo
-DW650 injectors
-Injen CAI
-Email tune for Accessport

Reference data before changing maps:
AFR is 9.x:1 (typical value is around 11:1)
Liam Ref AFR

Boost: 18, rising to 20psi
Liam Ref Boost

Road dyno result: For comparison, torque at 4000rpm (18psi) is roughly what a TD04 would do at 15psi
Ref HP

Fix the AFR…
Liam AFR compare

Run lower boost…
Liam Boost compare

Make more power…
Liam R107 dyno compare

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2 Responses to Why You Need wideband AFR When Getting An Email Tune

  1. Vally says:

    Hi Airboy,

    Website looks good, and is very informative.

    With regards to AFRs, if i placed the ‘sniffer’ in the tail pipe of my 2011 STi with decatted stock exhaust, how accurate would the readings be compared to placing the ‘sniffer’ in the downpipe?


    • Airboy says:

      If you have a quad tip exhaust, you’ll need to put the sniffer one the “oustside” pipes. Having it on the downpipe would be better.

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