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COBB Access Tuner Subaru

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Hi all, I have two questions regarding COBB access tuner. I am running this on a 2003 WRX with an EJ205 non-AVCS car. Modifying the OTS "Stage 2" tune 91.

1: while rescaling my MAF sensor I found my self MAXING out at 300 g/s far before the MAX voltage in the sensor table. Do you COBB guys find yourselves needing to adjust MIN/MAX and resolution on the sensor scaling or this showing a possible mechanical issue?

2: I was looking at the Air Fuel Ratio targets and found them to be richer than one would think given what I have learned here at HPA but I can also admit when I do not have the experience to know for sure, as well. When tuning COBB do you guys often change the AFR targets to be more along the lines of what one might see when doing standalone ECU target tables and then adjust them to test AFR targets like you would with any standalone?

I have included two photos of the tables and areas I am talking about.

Thanks for all the great help guys!

Attached Files

Hi Tyler,

those AFR targets are pretty normal to see on stock tunes and OTS maps. The OTS maps are designed to be very very conservative. With this in mind however, Subaru’s to like being ran a bit richer in my experience. For pump gas I like to target 11.5, Richening up to 11.0 at redline. This could be easily done by putting 11.5 at just before peak torque, 11.0 at redline, and interpolating between the two numbers for a smooth curve.

As far as your MAF scaling goes, do you have an aftermarket intake or big turbo? Why are you scaling so much? I have not maxed out the stock maf, even on an FP Red big turbo wrx.

Ok thanks for the input on the AFR targets. I shall adjust my targets accordingly.

I am scaling my MAF as i have a COBB intake with the air box. If you have not maxed out a sensor like that i will look into possible intake leaks and potenially changing out the MAF sensor.

Thanks very much

Good idea to check for intake leaks. How far off are your fuel trims? If you are using the COBB SF intake, there should be an OTS map that already includes a MAF scaling for that intake. It would read something like " Stage 2 91 + SF "

That is the base map you would want to run for that intake. If your trims are still very widely off, I would suspect a vac/intake leak.

The stock AFR targets are that rich to protect the cat from prematurely aging from heat. The WRX has a catalytic converter in the up pipe which makes it even worse. Cats die two kinds of deaths: the death by a thousand paper cuts variety, where it is repeatedly cycled hot, and the blaze of glory death where they blow up from misfire or other issue.

Thanks void i will check for intake leaks next chance I get. I was running lean by 3 to 10 percent on the COBB stage 2 tune.

If i remove the up pipe cat then leaning these targets out to more normal values should alright then argh?

There are normally an g/s limit set on those ECUs, you can just lift that, it’s usually set around 300g/s, where the actual sensor many times can flow 500-600g/s at 5V, depending on AFM housing size.

I often change that limits when raising boost, etc.

We usually reply within 12hrs (often sooner)

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