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ECMlink Boost Control for 3rd - 5th Gear

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doubleclutch

10+ Year Contributor
830
175
Jun 26, 2009
Canton, Michigan
Hey guys,
I am in the process of turning up the boost to ~20lbs. I am using the factory boost solenoid and ECMlink and it is working awesome and I am really happy with it. 1st is currently at about 20 lbs spike followed by 17 lbs, 2nd hits 20lbs and holds at about 19, and then my issue...

If I do a third gear pull, I spike to 20lbs then drop to 14. However, in fifth gear it will hit 20lbs and hold at 20. Now I know that the rate of boost building and decay varying from gear to gear so this somewhat makes sense. My problem is I would like to get 3rd gear to 20lbs without having fifth be at higher boost levels. Is this possible with link or do I have to never WOT 5th gear? To that point 4th would also be higher boost levels than 3rd.

Thanks.
 
Two things:

Do you have a .025" restrictor between your positive boost source and the line to the wastegate?

Do you have/and are logging a MAP sensor?
 
I have a restrictor. I do not have a MAP sensor and I am not using the "Enable Error Correction"

This log doesn't have any WOTS in it, but it will at least show my settings. It is all I have on this computer.
 

Attachments

  • log.2016.07.29-01.elg
    1.6 MB · Views: 112
3rd gear pull and fifth gear pull attached. These were taken a day apart, but no settings have changed.

Fifth gear 21-19 PSI, 3rd Gear 20-14 PSI
 

Attachments

  • log.2016.08.03-02 - 5th Gear Pull.elg
    23.8 KB · Views: 70
  • log.2016.08.02-04 - 3rd Gear Pull.elg
    42.1 KB · Views: 78
There doesn't appear to be anything wrong with your setup. I would guess you're able to achieve a higher boost level in a higher gear due to increased load, and other external factors.

I believe you're simply experiencing one of the issues with running the ECMlink boost control without the error correction feature enabled. Ideally, you want to run the BCS in conjunction with a MAP sensor so that the ECU can reference that signal, and automatically adjust the BCS duty cycle to achieve your target boost level.

In the way you're BCS is currently configured (and this is also how mine is configured as well), the ECU just references the base duty cycle table and picks a cell based on speed and RPM, then modulates the BCS accordingly. In essence, you've got the BCS configured to work like an electronically adjusted manual boost controller. The problem with this is, you may see different boost levels under different conditions, even with the same duty cycle value in multiple cells...Just as you would with a MBC. Again, enabling the error correction feature and tuning the target boost table is designed to eliminate this since the ECU can make real time adjustments to the duty cycle based on your target boost level.

So, what can you do to fix this? You've got a couple options:

The first and easiest is to just play with your base duty cycle table, and tune the table to get the boost curve you want. However, you're probably going to have a hard time doing so without a MAP sensor. I would strongly recommend adding a MAP sensor to your car. There's no possible way to fine tune and make accurate adjustments to the duty cycle and really see how the car and turbo are responding unless you can log the boost curve and reference it later. Looking at the gauge during a pull just isn't going to cut it when you're trying to do boost by gear, and use some of the other advanced ECMlink boost control features.

The other option would be to add a MAP sensor, and enable error correction, allowing the ECU to adjust for your desired target boost level.

Here are a few pointers I've learned playing with ECMlink's boost control feature:

-You want to adjust the DC (duty cycle) to 100% below your turbo's boost threshold. You obviously don't want to wastegate blowing open prior to achieving your desired boost level, so ensure the BCS is not allowing the WG to see boost pressure until you are getting boost. On a 16G, you'll probably be at 100% DC below 3,500 RPM or so. If you get a large boost spike during spool up, you'll need to dial this back closer to the 3k mark.

-On a 16G car, as you approach redline, you'll more than likely see boost taper off. Again, to combat this issue, you'll want the DC to be set at 100% when you see boost begin to taper off. This will probably be right around 5,500 RPM on a 16G.

-You should only need to use boost control by gear in 1st. I don't really see any reason to use this in other gears on your car unless it's to prevent traction loss on some monster turbo setup. I would say it's a safe assumption that you don't have this problem. You should be able to achieve a consistent boost level in all gears with little variation in the cells for each gear. If you can't, I suspect there's a mechanical issue at play that's affecting boost under various conditions.

-Lastly, get a MAP sensor. If you're reading my suggestions above, you have surely come to the conclusion that there is a lot of data to ingest and review before you can effectively dial in this system...And that simply cannot be done by staring at the boost gauge during a pull.

Here's a screenshot of the BCS table I just set up on my brother's car. He's running a B16G, and this got him in the 17-20PSI range. Feel free to plug in these values on your setup and see what happens:
You must be logged in to view this image or video.


If you have any other specific questions, let me know.
 
Last edited:
Thank you for the great response. This is basically what I suspected as each gear builds boost differently. Without error correction, it makes sense to have boost by gear, I just would need 2 more gears to get it dialed in correctly.

No I do not have traction problems, AWD FTW. My base duty cycles are similar to your brothers set-up so that is good. I can't see how he doesn't hit over 20lbs in fifth though.

Looks like I will be installing a MAP sensor soon.
 
My base duty cycles are similar to your brothers set-up so that is good. I can't see how he doesn't hit over 20lbs in fifth though.

Well, it's perfect example of how a different setup and different conditions will net you 2 completely different boost curves with the same DC values.

I actually dialed in his setup without a MAP sensor. However, you can see how much more simple the DC values look compared to what is in your table. If you plotted his DC, it's a simple curve. By contrast, your DC values are all over the place. If you're going to get crazy and attempt to fine tune the setup to that degree, you'll absolutely need a MAP sensor.

Just think of adjusting this as you would a MBC. With a MBC, you'd do a pull, see if boost is where you want it, and if not crank the controller in or out. Do the same thing with the DC table until you've got the ability to log boost and really fine tune things.
 
I am looking into sensors now. Any thoughts on what is best and how to wire it? it doesn't seem like there is a consensus from the searching I did.

I wouldn't say my DC values are "all over the place" I basically control the spike and then set it for a flat rate per gear as they build boost differently.
 
Wiring is straight forward, it just depends what ECU inputs you have open currently.

MAP sensors are typically 3 wires:

1) Pick an ECU input, and wire the MAP sensor output to the corresponding ECU input pin.

2) Most MAP sensors will use a 5V source for power. So, find one under the hood and T into it. For example, the TPS and MAF sensors both have a 5V reference line available.

3) The other line will be ground. That's pretty self explanatory.

Once the sensor is wired in, assign the pin in ECMlink just as you did the WBO2. Done.
 
Are there any negative effects to replacing the mdp sensor with a map sensor? I was looking at ecmlinks oem style 4bar.
 
I'm not sure. I don't know the 2G well enough to say whether you can do without the MDP sensor or not.

@luv2rallye or @gofer can probably answer that.
 
Are there any negative effects to replacing the mdp sensor with a map sensor? I was looking at ecmlinks oem style 4bar.
The MDP is an EGR emissions related sensor, there's no problem replacing it with a MAP sensor as long as you have no problems with emissions in your area.
 
The MDP is an EGR emissions related sensor, there's no problem replacing it with a MAP sensor as long as you have no problems with emissions in your area.
So there should be no driveability issues or CEL associated with it? Just want to make sure. Seems like every project I do on this car one thing just leads to another.
 
Without the MDP sensor, you have to check the box for lock the MDP in ECMlink. This will prevent the CEL from coming on and the car will run normal with no problems.
 
So there should be no driveability issues or CEL associated with it? Just want to make sure. Seems like every project I do on this car one thing just leads to another.
What Joe said, just check the "lock MDP" box and it's business as usual...

If you'd like to keep the MDP functioning, I did being in SoCal on my stock IM, I used a AEM MAP and wired it into the SD harness. Then taped into the back of the plenum and threaded in the sensor. If you're interested shoot me a PM...
 
What Joe said, just check the "lock MDP" box and it's business as usual...

If you'd like to keep the MDP functioning, I did being in SoCal on my stock IM, I used a AEM MAP and wired it into the SD harness. Then taped into the back of the plenum and threaded in the sensor. If you're interested shoot me a PM...

I should be fine. No emissions testing in Michigan. I am most likely going to get the OEM style MAP since it will probably be a long time before I decide to go to a SMIM. Itwill look stock, no extra wires, installs in minutes, all sound good to me. Makes me wonder if I should just go to SD though if I only will be 1 sensor away.
 
Also, Thank you for all of the help, all of you guys are freaking awesome!
 
Go Speed density if you can. Get a MAP sensor, that will help us look at your boost curve and see where its going south. I would also recommend switching out that stock Boost controller for a 3 port Mac boost solenoid. They're like 30 bucks on ebay and fool proof install.
 
Go Speed density if you can. Get a MAP sensor, that will help us look at your boost curve and see where its going south. I would also recommend switching out that stock Boost controller for a 3 port Mac boost solenoid. They're like 30 bucks on ebay and fool proof install.

I imagine I will go to SD after a little bit of research to help the switch go smoothly.

So far the stock BCS has done well and been very responsive for my boost levels. I will probably be staying with the stock unless it doesn't quite cut it for error correction. If it ain't broke don't fix it, right?
 
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