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06 self tuning question.


Blayzin212
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I am brand new to the forum environment so I apologize if this is threadhacking. It's just the closest subject topic I could find.

I have a heavily modified lgt 06'. From the dyno I was making 378whp and 350tq on 17psi boost. I eliminated a high flow cat and this seemed to alow me to make a few more horses at the same boost level. I monitor my afr on romraider, and it appears to stay at 11.1 in boost with a narrow band. I have a manual boost controler and was wondering how much I can safely up the boost for short periods?

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I am brand new to the forum environment so I apologize if this is threadhacking. It's just the closest subject topic I could find.

I have a heavily modified lgt 06'. From the dyno I was making 378whp and 350tq on 17psi boost. I eliminated a high flow cat and this seemed to alow me to make a few more horses at the same boost level. I monitor my afr on romraider, and it appears to stay at 11.1 in boost with a narrow band. I have a manual boost controler and was wondering how much I can safely up the boost for short periods?

 

If you are still on stock internals, you are already past the safe limits of the block. Any pull you make at the current power level puts you at risk of blowing the motor. Any more boost and it's almost a sure thing.

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I am brand new to the forum environment so I apologize if this is threadhacking. It's just the closest subject topic I could find.

I have a heavily modified lgt 06'. From the dyno I was making 378whp and 350tq on 17psi boost. I eliminated a high flow cat and this seemed to alow me to make a few more horses at the same boost level. I monitor my afr on romraider, and it appears to stay at 11.1 in boost with a narrow band. I have a manual boost controler and was wondering how much I can safely up the boost for short periods?

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I am brand new to the forum environment so I apologize if this is threadhacking. It's just the closest subject topic I could find.

I have a heavily modified lgt 06'. From the dyno I was making 378whp and 350tq on 17psi boost. I eliminated a high flow cat and this seemed to alow me to make a few more horses at the same boost level. I monitor my afr on romraider, and it appears to stay at 11.1 in boost with a narrow band. I have a manual boost controler and was wondering how much I can safely up the boost for short periods?

 

If you can't find a relevant thread, why not start a new one?

 

Completely unrelated to existing thread, thus asking mods to move this to new thread.

05 LGT 16G 14psi 290whp/30mpg

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

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Don't use the stock narrowband sensor. Once you're close to 11.4ish it goes to 11.1 and has no accuracy.

 

You have two options for afr:

1. Buy an aftermarket wideband afr controller.

 

2. Remove the rear oxygen sensor and replace it with the front oxygen sensor. The front sensor is actually a wideband sensor but won't read accurately in the stock location. This really only works with a catless downpipe (which you have).

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Don't use the stock narrowband sensor. Once you're close to 11.4ish it goes to 11.1 and has no accuracy.

 

You have two options for afr:

1. Buy an aftermarket wideband afr controller.

 

2. Remove the rear oxygen sensor and replace it with the front oxygen sensor. The front sensor is actually a wideband sensor but won't read accurately in the stock location. This really only works with a catless downpipe (which you have).

 

Why do you say it won't read properly there? Most aftermarket downpipes will have a widebang bung just inches from the turbo. Generally if the spot is good enough for OEM tuning, it's good for aftermarket tuning.

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Why do you say it won't read properly there? Most aftermarket downpipes will have a widebang bung just inches from the turbo. Generally if the spot is good enough for OEM tuning, it's good for aftermarket tuning.
You're correct; after turbo would be fine too. I should have been more clear.
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  • 1 month later...
Thanks for replying even though I used the wrong spot. I went to the introduce myself and started a new thread. I explain my setup and ask for advice because it doesn't fit here....learning already.

 

I hope im not chiming in too late but figured I would contribute my 2 cents.

 

You really should get a real wideband and not rely on the factory ECU to report AFR durring wide open throttle passes. Even if it is "a wideband from the factory", the ECU will only report a small range of AFR and its accuracy is questionable. The front o2 sensor is only in use by the ecu when its at idle or part throttle (this is called closed loop). It uses the front o2 sensor to analyze the exhaust gas to make sure the car is running the AFR the ecu is calling for and makes corrections. It is actually ignored once the car goes to wide open throttle (open loop). That is where a true wideband will come in handy; its gives true readings over a very large range (typically 10:1 up into the 20:1 ranges). If your shooting for accuracy in your measurements, use the right measuring tools :).

 

If your running a factory ECU you are likely to run into several issues trying to mechanically tune your car. I am assuming your car is already tuned by a professional due to the dyno numbers your reporting. Although that throws some variation in the mix, I just wanted to give you some insight into boost control on the stock ECU's. In your tune is several maps that help the ecu get to the boost you want.

The first map is target boost: this map directly tells the ECU how much PSI to shoot for. It listens to the MAP sensor on the car and directly monitors pressure in the manifold. Whatever you target in this table is what the ECU aims to achieve.

The next map is initial wastegate duty cycle: The is the "baseline" wastegate cycle the car starts with. Ideally, what duty cycle you enter here will achieve your target boost, no corrections needed.

The next map we are concerned with here is Max wastegate duty: This is where you tell the ECU "never exceed this limit". This is a MOST wastegate duty you will allow the car to target.

With that being said, heres generally how it works: lets say for an example, at 5000 rpm with full load, you have a target boost of 18 psi, a base wastegate of 50% and a max wastegate of 80%. The ecu will being by running 50% wastegate duty, and then check the MAP sensor. It checks to see if actual boost is equal to target boost. Lets say its not, its only hitting 12 PSI. So the ECU will creep in a bit more duty cycle , again lets say for example, bumps it up to 70% duty cycle. It then checks actual PSi again. Now its at 14PSI. Better, but not there yet... So it adds in a little more duty cycle, now its at 80%. It checks again and now we are at 16 psi. So, it goes to dial in more...but wait! we have hit our max wastegate duty cycle! The ecu will not add any more duty cycle due to this. You will end up with 16psi.

OK, so now you see how that system works. So what you are doing when you run a manual boost controller is essentially running a manual wastegate duty controller. So if your only looking to do small changes, you may BRIEFLY affect psi, but when the ecu is targeting whats in its tune, it will throttle back its own boost control system and essentially undo whatever you try to manually add in..... that is until it hits the base wastegate duty. it wont go lower than that (minus compensation tables......)

Also, one last thing to keep in mind! There is a safty feature in the ECU called "Boost Limit - Fuel Cut" which the original tuner likely set. If you exceed the boost that is set in this field, the car VIOLENTLY fuel cuts and usually in my experience, stalls. So lets say your tune is targeting 18, the tuner may have set a boost limit fuel cut of 20 or so. So, if you try to dial in more boost and what was set, the car will react in a way you will not like.

 

I hope this info was helpful!

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