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Discussion Starter · #1 ·
After installing the Cobb SF intake I've been having some weird fueling issues. My AFR during normal steady cruise spikes to as high as 17 and drops as low as 13 randomly. My AF correction 1 spikes as high as +25 during these events and my car can be felt jerking. All indications point toward an vacuum leak. Vac leak testing turned up with negative results. I have no leaks. I figured it must be MAF scaling and its time for a tune anyway so I threw my stock back on until tuning could begin and got in contact with a Tuner. Now in the tuning process, my impression is that he seems stumped by the issue himself. The car runs great with the stock, without stock it runs like utter ****e. I'll attach a datalog where I isolated the issue. Any idea what is happening? Like I said, Stock air box no problems, SF suddenly huge fueling problems. Yes I've tried reorienting the MAF. Issues persist.

I deleted rows up to where the issue is. After the issue there is some more rows of just normal driving.
https://docs.google.com/spreadsheets/d/1ZjatIs_JqyjIvozM65u0HRlyBYT5bEoQ_kWG4GRql60/edit?usp=sharing
 

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Well yeah the car has to be tuned for an intake. I'm surprised you didn't lean out the engine and damage something.

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Discussion Starter · #3 ·
Yes, which cobb states is covered by their OTS maps. So really the issue shouldn't have arose to begin with since I this is what I was running [probably should have mentioned this]. The intake is relatively close to the stock airbox in setup and many people have run the intake without a tune without issue. I didn't lean out per se, but had extreme lean spikes at cruise, when cobb offered basically no assistance is when I got in contact with a tuner and am working on a custom tune. Still, why would the issues be as extreme as they are?

To clear up any confusion..
ej205 stock long block, cobb ebcs, invidia up and down pipes, blitz catback, perrin turbo inlet, cobb sf, access port, issues occurring with both cobb OTS 91 stage II + EBCS (yes intake is covered under this tune) and current revisions with my tuner.
 

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Discussion Starter · #4 ·
After reading some fuel pump posts, sounds like it might be fuel pump related? I don't understand why this only occurs with the SF though. Higher demand for fuel with increased airflow, not being met by the pump?
 

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Yep, sorry you didn't mention any tune or what vehicle you had.

It could be fueling for sure. I don't know what point you start running out of juice, but my tuner tells me that my 2011 starts running out of fuel with intake and turbo back and should really have an upgraded fuel system to go further and get the most out of it.

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Discussion Starter · #6 ·
Would that make sense for just normal cruising though? Demand shouldn't be that high at all. Did he suggest upgraded pump or injectors?
 

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They recommended for my questioning pump and injectors but that's geared towards my long term goal of e85,

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I thought you could only go DP or Intake but not both unless you upgrade the fuel system as well..


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