COBB AccessPort Question

[rob-2]

I'm about to pull the trigger on the COBB AccessPort. I want to go stage 1 with one alteration. I'd like to ensure when cruising at 80mph, 3k rpm in the 5EAT I'm not in boost.

 

Does the COBB system allow you to program the system like this?

 

I realize, I'm going to get flack for 'wanting performance, while wanting MPG'. I want the balance of both. While in cruise control I dont feel the need to burn anything more. Thoughts?

 

Does the forum have a sponsor I should send my business to? In Nevada would love it by next week.

 

Thanks for the input.

 

Rob

[Haight 05LGT]

If you are looking for a custom tune then you should consider a pro tune or etune from forum tuners/vendors such as Infamous1 or Cryotune. Both of them would be able to answer your questions promptly. Both of them are also able to tune using the AP

[Max Capacity]

There is a Vendor forum on here, just look up top.

 

I don't believe AP can do what your asking. I tuner may be able to make some adjustments...?

 

I have found that my cars get better mpg on a tune rather than staying stock.

[lee07]

Sell the AP and use that $ to get a tune/stg2 parts

[iNVAR]

I'm not 100% sure but at 80MPH, your car is going up against a fair amount of wind resistance. The amount of power required to accelerate or even maintain speed goes up exponentially as you go faster.

 

Even with 0% WGDC dialed in, your car will still develop wastegate boost at that speed due to wind resistance and other things related to physics. It is impossible, without physical modification of the car, to make the turbo generate 0% boost under throttle at that speed because the load on the engine is high enough to cause the turbo to generate boost. And because it's a feedback system, it's not possible to open the wastegate to bypass the turbine until you're generating the required wastegate boost. Get it?

 

COBB does have an economy map that does kill off the boost as much as possible, but you'll hate yourself for running that map because it'll be slow as hell.

 

Control your foot, ease off the gas, you should be fine.

[Rester5350]

If you are looking for a custom tune then you should consider a pro tune or etune from forum tuners/vendors such as Infamous1 or Cryotune. Both of them would be able to answer your questions promptly. Both of them are also able to tune using the AP

 

 

Do not forget Tuning Alliance!

[rob-2]

I'm not 100% sure but at 80MPH, your car is going up against a fair amount of wind resistance. The amount of power required to accelerate or even maintain speed goes up exponentially as you go faster.

 

Even with 0% WGDC dialed in, your car will still develop wastegate boost at that speed due to wind resistance and other things related to physics. It is impossible, without physical modification of the car, to make the turbo generate 0% boost under throttle at that speed because the load on the engine is high enough to cause the turbo to generate boost. And because it's a feedback system, it's not possible to open the wastegate to bypass the turbine until you're generating the required wastegate boost. Get it?

 

COBB does have an economy map that does kill off the boost as much as possible, but you'll hate yourself for running that map because it'll be slow as hell.

 

Control your foot, ease off the gas, you should be fine.

 

This is great info. I really want the extra power for fun.

 

I saw last night they have the eco mode which could be great for the long trips I take.

 

I realize I am asking for a lot

[Berzerklo]

I

 

It is impossible, without physical modification of the car, to make the turbo generate 0% boost under throttle at that speed because the load on the engine is high enough to cause the turbo to generate boost. And because it's a feedback system, it's not possible to open the wastegate to bypass the turbine until you're generating the required wastegate boost. Get it?

 

 

^This. OP what you are asking for is impossible to accomplish with a simple tuning re-program. To do what you want would require a physical modification of your waste gate as well as a custom tune. Even then I don't think you will realize better fuel economy trying to keep your car moving at 80 MPH with no boost.

[rob-2]

^This. OP what you are asking for is impossible to accomplish with a simple tuning re-program. To do what you want would require a physical modification of your waste gate as well as a custom tune. Even then I don't think you will realize better fuel economy trying to keep your car moving at 80 MPH with no boost.

 

I believe you're right. I use cruise control for nearly all my freeway. Just thought the motor with low/no boost would burn leaner. I'm sure the eco map will pick a few MPG's up and that will offset my heavy footed fun

[Max Capacity]

I have never used the eco map, I had AP since they came out, never knew it was there. If you want mpg, don't drive these cars.

 

 

On Cobb stage 1 I would get 25+ on the highway, pretty much what I get now at 280whp, 21psi, on my Tuningalliance.com map.

 

My 09 Spec B got over 26mpg on the way back from NJ last Sunday.

 

You can contact Mike at tuningalliance from the vendor forum below.

[tDoug60]

Do not forget Tuning Alliance!

 

Is that who did your tune?

[iNVAR]

I believe you're right. I use cruise control for nearly all my freeway. Just thought the motor with low/no boost would burn leaner. I'm sure the eco map will pick a few MPG's up and that will offset my heavy footed fun

Your car stays in closed loop mode up to about 50-55 g/s on the MAF reading. In closed loop, your car will always target stoich so it will burn as ideal as possible.

 

I looked at my datalogs for you and in 5th gear at around 2800-2900 RPM, my WGDC is at 0% (I tuned it for this) and at 17-18% throttle I'm at -3.5 PSI vacuum, still closed loop at about 40g/s.

 

At 22% throttle, I'm in boost at about 2PSI, still 0% WGDC and I've just dipped into open loop at 63g/s.

 

So really, for fuel economy reasons, the question is... are you able to maintain 80MPH with less than 22% throttle? From looking at my logs, it appears that at 22% throttle I'm actually accelerating, very, very slightly, and at 17-18% throttle, I'm maintaining RPMs so I'm cruising.

 

But that's just to give you an idea of how thin of a line you'll be toeing between open/closed loop even with 0% WGDC dialed in.

[rob-2]

Your car stays in closed loop mode up to about 50-55 g/s on the MAF reading. In closed loop, your car will always target stoich so it will burn as ideal as possible.

 

I looked at my datalogs for you and in 5th gear at around 2800-2900 RPM, my WGDC is at 0% (I tuned it for this) and at 17-18% throttle I'm at -3.5 PSI vacuum, still closed loop at about 40g/s.

 

At 22% throttle, I'm in boost at about 2PSI, still 0% WGDC and I've just dipped into open loop at 63g/s.

 

So really, for fuel economy reasons, the question is... are you able to maintain 80MPH with less than 22% throttle? From looking at my logs, it appears that at 22% throttle I'm actually accelerating, very, very slightly, and at 17-18% throttle, I'm maintaining RPMs so I'm cruising.

 

But that's just to give you an idea of how thin of a line you'll be toeing between open/closed loop even with 0% WGDC dialed in.

 

Really interesting data. Since I don't have this data I'm not really certain.

 

There's a bit of mountain climbing I do on my treks, but in general it's basically flat driving. Of course I can slow down to 75mph, but than I'm 'in the traffic' and I find that more dangerous.

 

The AP will be in next week along with stoptech brake lines. So it should be a little more fun for myself. I'm getting the car in a divorce so this is a treat, distraction for me, not looking to make this into a track car - I have that. In case you were all wondering where I'm going with this modification.

[Max Capacity]

Is that who did your tune?

 

As far as both my cars, yes.

[rob-2]

Well it's been ordered. Got a great deal on it. I'll report back for all those interested

[iNVAR]

Really interesting data. Since I don't have this data I'm not really certain.

 

There's a bit of mountain climbing I do on my treks, but in general it's basically flat driving. Of course I can slow down to 75mph, but than I'm 'in the traffic' and I find that more dangerous.

 

The AP will be in next week along with stoptech brake lines. So it should be a little more fun for myself. I'm getting the car in a divorce so this is a treat, distraction for me, not looking to make this into a track car - I have that. In case you were all wondering where I'm going with this modification.

 

Well, I do run on a custom tune of my own, so I had WGDC dialed down to 0% at those low throttle areas. A stock map and I'm fairly certain even a COBB OTS Stage 2 won't have 0% dialed in... But it doesn't really matter because the WG actuator won't even respond until you've got sufficient boost pressure (7+ PSI) to force it open.

 

Also, at those RPM ranges on my 5MT, 2800-2900 RPM is about 68-70MPH only. At 80MPH, I'm doing 3300 RPM. I want to go back for a second and say that you actually require a little less throttle than 17% to maintain speed at 2800-2900 RPM (60-70MPH). But at 3300, you'll require more to maintain that speed/RPM.

[Haight 05LGT]

Well, I do run on a custom tune of my own, so I had WGDC dialed down to 0% at those low throttle areas. A stock map and I'm fairly certain even a COBB OTS Stage 2 won't have 0% dialed in... But it doesn't really matter because the WG actuator won't even respond until you've got sufficient boost pressure (7+ PSI) to force it open.

 

Also, at those RPM ranges on my 5MT, 2800-2900 RPM is about 68-70MPH only. At 80MPH, I'm doing 3300 RPM. I want to go back for a second and say that you actually require a little less throttle than 17% to maintain speed at 2800-2900 RPM (60-70MPH). But at 3300, you'll require more to maintain that speed/RPM.

 

It seems that the optimal speed/rpm range for freeway cruising is 72-75 mph. That is where I usually stay at and can achieve 26-30 mpg depending on weather conditions and the route that I am traveling. I have tried to stay at 80mph for a little over 60 miles and I averaged 23-24mpg. On the other side of that, oddly enough, if I try and stay around 60mph I also average 23-24mpg.

[Rester5350]

Is that who did your tune?

 

Yes Sir, and I am extremely happy with it. Mike was able to get my Revisions back to me just as fast as I could send him my data.

[bigjweb]

Even with 0% WGDC dialed in, your car will still develop wastegate boost at that speed due to wind resistance and other things related to physics. It is impossible, without physical modification of the car, to make the turbo generate 0% boost under throttle at that speed because the load on the engine is high enough to cause the turbo to generate boost. And because it's a feedback system, it's not possible to open the wastegate to bypass the turbine until you're generating the required wastegate boost. Get it?

 

You do not make any boost when cruising (maintaining a steady speed) on the highway. The engine will be under vacuum until you begin to accelerate

[Flipapotimus]

Well it's been ordered. Got a great deal on it. I'll report back for all those interested

 

How good of a great deal and from where? If I may ask . I'm trying to find a "great deal" so I can appease my wife.

[iNVAR]

You do not make any boost when cruising (maintaining a steady speed) on the highway. The engine will be under vacuum until you begin to accelerate

Your engine develops boost based on the load placed on it. The faster you are going, the more power it requires to maintain speed because of many factors (friction, wind resistance, etc.)

 

Most cars are designed to operate ideally around the 50-70 MPH speed range. Once you exceed that 70MPH, your fuel economy begins going down and you begin driving in open loop and possibly boost.

 

Have you ever driven at 90-100 on a very long straight stretch of highway before and tried to maintain your speed? Watch your boost gauge and watch how easily you slip into boost, just trying to maintain your speed. Watch what happens if you're at those higher speeds and you hit an uphill climb.

 

edit:

Look, I'll reiterate: the faster you go, the harder your engine has to work to maintain speed. What happens when your engine works harder? More exhaust. More exhaust means your turbine will spin faster because it's impossible to have all exhaust bypass the turbo, short of physically disconnecting the WG actuator and allow the WG to swing freely for exhaust gas to bypass. The design of a turbo is such that it relies on boost that it develops to force open the WG. It's a feedback system. And WG pressure for our cars is around 7 PSI. Therefore, even if you were to 0 out all of the WGDC across the board, you would still be developing boost because the WG can not open until there is boost. And therefore, if your car is going faster than about 70-80MPH, you may start generating boost as a result because you're going to have to step on the throttle more to maintani speed, regardless of your tune.

 

And to be frank, I believe I may have overestimated the throttle required to maintain speed at 80. (It's hard finding this in my hundreds of datalogs.) At 80, you should still be able to keep out of boost and stay in closed loop but like I said, you'd be toeing a thin line. If you are looking to maximize fuel economy, the ideal cruising speed would be around 55-65.

[bigjweb]

Thanks for the lesson in turbo 101. You pretty much repeated what I said. But with more words

[iNVAR]

I didn't but if that's how you want to interpret it, go right ahead.

 

edit: And don't forget, just because your gauge reads vacuum doesn't mean your turbo isn't producing boost.

[Haight 05LGT]

Thanks for the lesson in turbo 101. You pretty much repeated what I said. But with more words

 

You are wrong sir. He said nothing along the lines of what you are trying to say. Where is Bac when we need him? Bac! Calling Bac to the stage!

[thefultonhow]

You are wrong sir. He said nothing along the lines of what you are trying to say. Where is Bac when we need him? Bac! Calling Bac to the stage!

 

This doesn't require BAC5.2 levels of knowledge to straighten out. bigjweb, you're confusing cruising and coasting. You are not in boost when coasting (foot off the accelerator pedal). If you are cruising, you may be in boost depending on speed and incline.