MSX turbo conversion

I am assuming here you have only done a turbo conversion but are still running the factory MXS ECM.
First thing to do is ditch any sort of fooling devices/resistors/whatever so all you have controlling fueling is the ECM (with the bullydog tune in it).
Have you checked fuel pressure under load? it should be at least 100PSI measured were it goes into the head.
A C18 boost sensor will not work with the Acert ECM period, you need the stock correct part numbered sensor fitted.
43PSI is pretty low boost even for a stock MXS, the ECM wont be derating on high boost.
Does it have logged faults/events or not? you say it doesnt then furthur on you mention "Boost lockout" (not sure what you're refering to with this) and then you say it is flashing 92. Post everything listed in the "Logged Event" and "Logged Faults" pages.
Also consider the possibility of mechanical issues, I have once seen a truck that would suck part of the intake system flat at a certain boost pressure cuttign off the power like a derate, it would not unflatten until the engine was switched off, not likely but possible.

 

I've done some calling and thinking the past couple of days about your problem and I still think you have a issue that isn't related to the BD tuner. I'm trying to figure out why you are pushing 43 PSI of boost on a single turbo setup...that is way to high for some reason. I have a few questions again and I hope you asnwer them so we can help.

1. What sensors were you running resistors on? Also what all have you done to this motor since it was stock till right before the BD conversion?

2. Why were the stock compound turbos failing? My sources tell me that you have lost 2 sets (4 turbos all together) on this engine...is that correct? Debris, oil starvation, or something else?

3. I have a feeling there is a electrical issue with your engine harness. Have the harnesses been checked and tested with a ohm meter?

4. BD has duplicated this problem on a stock ACERT at their shop by unhooking the diverter valve and you know about this. Have you replaced that valve yet?

Yes these are a lot of questions, but we need the answers to help you figure this problem out.

 

Let me get this straight in my mind.........you have a single turbo on the truck and it is the turbo Bully Dog sells as a BW. Bully Dog calls it s BFT-1 and it has a BD part number of 56200..........is this correct? Here is a link to BD website showing the turbo I'm asking about.

http://bigrig.bullydog.com/product.php?ID=15

This turbo if it is built using BorgWarner parts is maxed out at 45 psi of boost at 725 Hp on a 14.6 L engine, not a 15.2L engine. The 15.2 L engine at 725 Hp will be over spooling this turbo, so I'd drop the max power down to 650 Hp this turbo is safely capable of handling on your engine. If it is the Chinese imitation that I've seen sold, it will still achieve the 45 PSI of boost, but it may not live much longer than a year doing it at these power levels.

Unless BD writes a special program for the tuner to use this turbo conversion with an Acert tune and ECM, you'll never get full power from this engine and turbo combination. If you do achieve the 55-60 PSI of boost to get the the max rack travel in the ECM......the turbo will not survive for long at the boost conditions.

The boost output of this combination will not survive at 55-60 psi for more than a month or so in my opinion. You need to stop looking at the boost gauge and find out if the engine is achieving the maximum rack travel in MM in the ECM for max power output at 45 psi of boost and 650 Hp at the same time. The truck needs to go on a dyno to figure this out.

 

Looking at your avatar and location.......you haul very heavy. My opinion is that the turbo will not survive long at all at 55-60 psi of boost you want to achieve for max rack travel in the ECM.

The fuel tables have to be altered in the BD tuner file to deal with the lower boost pressure this turbo will produce. If they can't alter this area of the file to match the turbo correctly, you'll never achieve max Hp output.

 

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The turbo you bought is the turbo I'm asking about.

You have to understand the fuel tables in the ECM programming are designed for the twin turbo system. BD has to have a modified file to lower the boost pressure in the fuel tables in relationship to rack travel to achieve max power.

For hypothetical sake lets say at 60 psi of boost the rack is open 12mm in the original Acert programming at it's maximum amount of travel. At 45 psi of boost the rack is open 9.5 mm for the same RPM and throttle position. You'll never achieve max fuel flow from the ECM if you can't open the rack to it's fullest setting in the fuel tables at 45 psi of boost. You've lost fuel flow into the engine at this point and can't regain it without a flash file designed to allow 12 mm of rack travel at 45 psi of boost. You have to maintain the same fuel flow into the engine, otherwise power will decrease.

Now again hypothetically you've decreased the Exhaust Gas Back Pressure by removing one turbocharger. This would allow you to produce more Hp with less fuel being injected. My next question would be in doing this modification, did you gain enough Hp by removing the one turbo to make up for the lack of rack travel in the fuel tables?.........in my mind, I doubt it, but without a dyno test you don't know.

Actually the fuel tables need to be modified to go to full rack travel at 25 psi. You have to be able to have the same fuel curve as a standard single turbo file. Otherwise you could have times at low boost and RPM when you step on the throttle the engine doesn't respond well until the turbo starts to spool up. You have to remember the turbo needs energy from burnt exhaust gases to spool. The ECM needs to see the turbo building boost to supply the fuel to create that energy. This is why you truck seems to lay down. The ECM isn't releasing fuel to the engine because boost is low in it's mind. With no fuel the turbo won't spin.

Do a search on YouTube about home made jet engines using turbochargers. You'll get an idea very quickly that a turbo is a perpetual motion device if the fuel is there to turn it.

 

[ame]http://www.youtube.com/watch?v=l-spt7y1v6Y[/ame]