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Old 08-06-2018, 11:45 AM   #79
Scooby Newbie
Member#: 453963
Join Date: Sep 2016
Location: UpState NY
2017 WRX
WR Blue

Default Similar problems

Originally Posted by simpleJ View Post
Alright folks let's see if you are all having the same experience:

Installed the Cobb big SF and associated 93 octane map per the instructions exactly and have been having nothing but issues with the tune, which I believe is due to the scaling or turbulence in the intake.

-the filter was on the reccomended one inch, I then adjusted it to about 7/8 s of an inch which improved AF learning values to an acceptable range but not AFRs

-I put dielectric grease on the MAF cables

-I installed the coupler but fear it may be "backwards" although Cobb told me if it fit, it's on there correctly as it is not kinked or anything.

And onto the issue:

I was seeing wild AF learn values indicative of a leak, poor MAF scaling, or turbulence. This was ranging from +- 10 and spiking to about 15 in traffic. I adjusted the filter and saw a major improvement, values dropped to about +-6. However data logs on both show the car running lean as soon as soon as it hits open loop and pulls data from only the MAF.

AFRs spike at the open loop switch to about 12.3 then taper down to 11.3-12 when the car is targeting 11-11.6. In closed loop fueling is acceptable.

I played with the scales to no avail.

If I had a leak, in theory this should show more at idle where a 1 g/s leak should cause the ecu to add a significant amount more fuel than further up the rev range, instead the car is taking fueling out at idle, as much as -6% long term trim and a negative or near 0 short term trim. This tells me the metered air is less than the ecu is expecting, though my thought process could be erroneous here. If it was leaking it should be adding fuel to compensate at idle, one would think.

So, other owners and tuners, have you seen this issue?

Is it the coupler causing turbulence back to the MAF?

The Cobb map itself just not cleaned up enough?

A leak?

Or is the Cobb intake just a turbulent piece of junk?

Other mechanical issue?

Logs to follow

*Yes I know protune blah blah. I'm waiting for a GS TMIC. Also intake bro sounds, I'm aware. I know stock is suitable for power, but that's not as fun.
Iím getting similar problems if you by any chance read this can you reach out to me 5188481879
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