Jackson Racing Supercharger Owners Thread

[CSG Mike]

Originally Posted by mrg666

JR factory tune works with stock MAP sensor; it even throws a CEL if you upgrade the MAP sensor. If the tune is not factory, you need to ask this question to your tuner. They will tell you which sensor is required since tune needs to be calibrated for the specific sensor.

Yes, but only because it works on a set of assumptions. When every factory tuned car is running the exact same setup otherwise, you can do this.

This is also why even a header swap will make the Jackson Racing factory tune not work.

[Randoman5]

Originally Posted by CSG Mike

Yes, but only because it works on a set of assumptions. When every factory tuned car is running the exact same setup otherwise, you can do this.

This is also why even a header swap will make the Jackson Racing factory tune not work.

I’ve got a high flow second cat. If I want to run the carb tune I need to switch back to the stock pipe correct?

[CSG Mike]

Originally Posted by Randoman5

I’ve got a high flow second cat. If I want to run the carb tune I need to switch back to the stock pipe correct?

Yes.

[mrg666]

Originally Posted by Randoman5

I’ve got a high flow second cat. If I want to run the carb tune I need to switch back to the stock pipe correct?

FYI: CARB tune is running fine with my catless HKS dual resonated front pipe and 2017+ stock header since almost a year. More power at high rpm and more mpg with normal driving, and no CELs.

[Randoman5]

Originally Posted by mrg666

FYI: CARB tune is running fine with my catless HKS dual resonated front pipe and 2017+ stock header since almost a year. More power at high rpm and more mpg with normal driving, and no CELs.

I'd be interested to see what the actual effect is. I suspect the concern is that it would cause greater exhaust flow to a level that affects air/fuel ratio and causes many minor knock events. Conceivably the computer could be automatically pulling timing out to compensate... But it's also possible I have no idea how the ECU actually works.

It seems like an unnecessary risk with questionable reward.

[mrg666]

Originally Posted by Randoman5

I'd be interested to see what the actual effect is. I suspect the concern is that it would cause greater exhaust flow to a level that affects air/fuel ratio and causes many minor knock events. Conceivably the computer could be automatically pulling timing out to compensate... But it's also possible I have no idea how the ECU actually works.

It seems like an unnecessary risk with questionable reward.

Knock is less likely after reducing exhaust back pressure by removing the second cat which reduces the cylinder pressure. We are talking about the second cat which has no oxygen sensors. So, AFR is controlled by the oxygen sensors on the first cat which is still there. Second cat shouldn't have much of an effect on AFR. Again, my engine is fine. But you should of course do as you feel less risky. I am just someone on the internet after all.

[CSG Mike]

Originally Posted by mrg666

Knock is less likely after reducing exhaust back pressure by removing the second cat which reduces the cylinder pressure. We are talking about the second cat which has no oxygen sensors. So, AFR is controlled by the oxygen sensors on the first cat which is still there. Second cat shouldn't have much of an effect on AFR. Again, my engine is fine. But you should of course do as you feel less risky. I am just someone on the internet after all.

More flow = more intake air = leaner mix. Remember, the engine/ecu has no idea there's more air going in. The tune works on the assumption that every car has the same flow with the same factory exhaust setup.

[mrg666]

Originally Posted by CSG Mike

More flow = more intake air = leaner mix. Remember, the engine/ecu has no idea there's more air going in. The tune works on the assumption that every car has the same flow with the same factory exhaust setup.

There is a MAF sensor for that purpose. There is no such assumption.

[ybotspawn]

Originally Posted by mrg666

There is a MAF sensor for that purpose. There is no such assumption.

Correction map sensor, different principle entirely. I’m not going to attempt to debate you on what you’re doing and why it’s bad. Generally though I tend to believe guys like @ know more than I do. Good luck with the ticking time.... ummm motor


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[tomm.brz]

Originally Posted by CSG Mike

More flow = more intake air = leaner mix. Remember, the engine/ecu has no idea there's more air going in. The tune works on the assumption that every car has the same flow with the same factory exhaust setup.

your in-house tuner keeps CL fuel control active it won t run leaner or richer, maybe just transiently because of the integral/proportional corrections, but anyway afr is going to be quite spot on all the time

only bad things I would think of about upgrading to catless without returning, is the performance left on the table
ecu won t rise ign timing more than it is allowed to, and cam timings could be made more aggressive and with less overlap at higher rpm
also at lower rpm and loads it could need some fix

[mrg666]

Originally Posted by tomm.brz

your in-house tuner keeps CL fuel control active it won t run leaner or richer, maybe just transiently because of the integral/proportional corrections, but anyway afr is going to be quite spot on all the time

only bad things I would think of about upgrading to catless without returning, is the performance left on the table
ecu won t rise ign timing more than it is allowed to, and cam timings could be made more aggressive and with less overlap at higher rpm

By not retuning, I left that performance on the table on purpose. My main purpose was to increase engine reliability by reducing the exhaust back pressure.

[tomm.brz]

Originally Posted by mrg666

There is a MAF sensor for that purpose. There is no such assumption.

maf doesn t pick up all the airflow differences, specially if there are unexpected changes of volumetric efficiency
Also, it relies entirely to a pre-set scaling

Primary lambda is what catches AFR fluctuations
but the ecu must be in a closed loop mode (either stock logic, or ecutek CL fuel control) to take action and correct that AFR to follow the target

CSG Mike maybe forgot, but the master tuner of his company is already enabling closed loop mode all the time at all rpm

[tomm.brz]

Originally Posted by mrg666

I left that performance on the table on purpose. My main purpose was to increase engine reliability by reducing the exhaust back pressure.

yoy were right about knock relief when going catless, but to take effectively advantage of its scavenging potential, needs to be retuned again

[mrg666]

Originally Posted by tomm.brz

yoy were right about knock relief when going catless, but to take effectively advantage of its scavenging potential, needs to be retuned again

It is *really* fine. I will not retune.

Edit: I actually did. Worked with one of the most popular places. They sent me a tune which was garbage that I couldn't even drive. Second iteration was no better. I said keep the money and cut the chase, installed the stock MAP sensor and flashed back the JR factory tune which is working great.