JB4 Map 8?

[LinkA8A0A]

I was going through the maps on my JB4 this weekend and noticed the tach would go to 8K RPMs in the map selection mode but looking at the JB4 tutorial on n54tech, it only lists up to map 7 (7K RPMs). Anyone know what this is about?

Thanks

[Venom]

Map 8 is no turbo / waste gates open

[e36addict]

That's my blown chargepipe map

[LinkA8A0A]

Originally Posted by e36addict

That's my blown chargepipe map

Do you mean since the wastegates are open and the car isn't making any boost that it feels like your chargepipe has popped off?

[LinkA8A0A]

Originally Posted by Venom

Map 8 is no turbo / waste gates open

Thanks btw

[Venom]

Originally Posted by LinkA8A0A

Thanks btw

no problem

[e36addict]

Originally Posted by LinkA8A0A

Do you mean since the wastegates are open and the car isn't making any boost that it feels like your chargepipe has popped off?

Well yes, but I also used this map when my chargepipe actually blew to pieces, so that the car wouldnt try to build boost and get all confused.

[LinkA8A0A]

Originally Posted by e36addict

Well yes, but I also used this map when my chargepipe actually blew to pieces, so that the car wouldnt try to build boost and get all confused.

Ahh...good thinking!

[edisapimp]

Originally Posted by e36addict

Well yes, but I also used this map when my chargepipe actually blew to pieces, so that the car wouldnt try to build boost and get all confused.

The map sensor would register 0atm if the chargepipe were blown to pieces or were not in place at all. The turbo side of the engine is going to spin or not spin based on the heat of the exhaust, if the air it's compressing goes into the universe and not the engine then there's no boost, regardless of the wastegate position. You could take your chargepipe off, your intercooler out, and the car would run fine - it would just be a 3 liter without boost.

[edisapimp]

Or if I read that you have an '11 I would know you had a MAF sensor and that would ruin your life.

[LinkA8A0A]

Originally Posted by edisapimp

The map sensor would register 0atm if the chargepipe were blown to pieces or were not in place at all. The turbo side of the engine is going to spin or not spin based on the heat of the exhaust, if the air it's compressing goes into the universe and not the engine then there's no boost, regardless of the wastegate position. You could take your chargepipe off, your intercooler out, and the car would run fine - it would just be a 3 liter without boost.

My understanding is that the wastegate controls how much the turbo spins and subsequently, produces boost (not exhaust temp). Therefore, if the wastegate was completely open, the exhaust gas would bypass the turbine wheel and not produce any boost.

[e36addict]

Originally Posted by LinkA8A0A

My understanding is that the wastegate controls how much the turbo spins and subsequently, produces boost (not exhaust temp). Therefore, if the wastegate was completely open, the exhaust gas would bypass the turbine wheel and not produce any boost.

And you win this round!

[edisapimp]

The wastegate lets the air out. It's a flap. So yes, if it is all the way open, then not much air will be travelling to the compressor side.

The heat (more precisely heated air) from the exhaust is what makes the turbine fins actually spin (not magic).

You have to think of this system as plumbing (which it is.) If you remove the charge pipe (or create any other vast opening in an otherwise closed system between the turbo compressor outlet and the intake), all that's happening is the intake is taking in uncompressed air into the throttle body. Nothing out of the ordinary is happening with combustion, except that there is now no additional air (boost) entering the combustion process. The air is now coming in (directly) through the throttle body, instead of making it's way through the compressor, intercooler, charge pipe, etc. Exhaust is still going where it's supposed to, it's just spinning turbos that are forcing air through a hole instead of into the engine.

Does this make sense? Sorry for all the parenthesis.

[edisapimp]

Let me add on to this concept because we are talking about two different things here.

All I'm saying is that in a turbo car, if the CP is not in place, or if any of what should be a leak free sealed plumbing system has a massive leak between compressor and TB, then it doesn't matter if the wastegates are completely open or completely closed, no boost is going to make its way to the throttle body or combustion, the boost is going to go along the path of least resistance (the leak).

If there's no boost, the car (with a MAP sensor) will just operate as if there is no boost. It really wouldn't run any differently than a low compression 3 liter.

[LinkA8A0A]

Originally Posted by edisapimp

Let me add on to this concept because we are talking about two different things here.

All I'm saying is that in a turbo car, if the CP is not in place, or if any of what should be a leak free sealed plumbing system has a massive leak between compressor and TB, then it doesn't matter if the wastegates are completely open or completely closed, no boost is going to make its way to the throttle body or combustion, the boost is going to go along the path of least resistance (the leak).

If there's no boost, the car (with a MAP sensor) will just operate as if there is no boost. It really wouldn't run any differently than a low compression 3 liter.

Haha, when I read your first response I was about to say the same thing that this post says. I think we're talking about 2 different things.

[edisapimp]

:hugs:

[135iam]

So if I had to run 600 highway miles in a day, would my best mileage be map 8? or just run map 5 like normal?

[LinkA8A0A]

Originally Posted by 135iam

So if I had to run 600 highway miles in a day, would my best mileage be map 8? or just run map 5 like normal?

My gut would tell me to just run whatever map you have been running like normal. The only time I could see myself using map 8 is in a situation where I didn't want the car building boost for a specific reason (maybe I gave my keys to a valet and am worried about them beating on it).

[Venom]

Originally Posted by 135iam

So if I had to run 600 highway miles in a day, would my best mileage be map 8? or just run map 5 like normal?

I got 32 MPG on map 8 while cruising 70 mph. I got 25 MPG on map 5 while cruising 70mph. Same distance, different days. ymmv

[135iam]

Originally Posted by Venom

I got 32 MPG on map 8 while cruising 70 mph. I got 25 MPG on map 5 while cruising 70mph. Same distance, different days. ymmv

wow, wasnt expecting that good of a increase. I was thinking the same as LinkA8A0A that it wouldnt do much and I should stick with map 5

[BGR]

Originally Posted by edisapimp

Let me add on to this concept because we are talking about two different things here.

All I'm saying is that in a turbo car, if the CP is not in place, or if any of what should be a leak free sealed plumbing system has a massive leak between compressor and TB, then it doesn't matter if the wastegates are completely open or completely closed, no boost is going to make its way to the throttle body or combustion, the boost is going to go along the path of least resistance (the leak).

If there's no boost, the car (with a MAP sensor) will just operate as if there is no boost. It really wouldn't run any differently than a low compression 3 liter.

I just got confused, thought I figured it out, then got confused again.

If you are bleeding boost accidentally, wouldn't it keep everything closed thinking it is trying to build boost? The MAF sensor wouldn't be reading any boost making its way into the engine so wouldn't dump more fuel in, right?

[Venom]

Originally Posted by 135iam

wow, wasnt expecting that good of a increase. I was thinking the same as LinkA8A0A that it wouldnt do much and I should stick with map 5

Yeah neither did I. Could be a lot of reasons. That's why I said ymmv. Try it and let us know what you find.