Boost Referenced Fuel System

ctuinstra

Goblin Guru
The fuel pump is marked supply and return.
If someone wanted to use an external pressure regulator and needed a return line they could remove the internal regulator and hook to the return port on the top of the pump.
Thanks Lonny! That answered the question. I'm going to slowly move forward with this. I don't want the car to be down for a long time while it have to get all the right pieces and tune the car. Certainly don't want to miss the Spring Meet.

If I can figure out how to mount the regulator on the fuel rail and modify the lines to AN fittings, should be a piece of cake other than the tuning.
 

ctuinstra

Goblin Guru
Another random thought, if you're at 40% DC at WOT, and your trims/afr look great, you really have plenty of room to up the boost. I was reading somewhere that the ZZP people hung out, that you didn't really need 60# until you were passing 18lb of boost. That 40% DC just really sticks in my head haha. The good thing is you aren't running lean.
We are pushing 15-16 as it is. I agree, I'm on the fence about just putting smaller back in.
 

taz_va

Member
I'm using an MPVI2 and the puck is a horribly overpriced unit just to add one more signal line. I was able to use the serial data out of the AEM gauge and map that into the scanner. No cost since my donor already came with the AEM AFR gauge. Pretty sweet until you forget to unplug it from the always hot line. Battery was dead in one day.
That's awesome.
 

ctuinstra

Goblin Guru
This may be a silly question, where is the pressure reference port on the intake? Is there even one that I can tap in to or do I have to drill one in?
 

JSATX

Goblin Guru
I was under the impression that any port post throttle body will work for BRF regulator. Keep us updated on the progress I’ll be doing the same in a month or two.
 

George

Goblin Guru
If you use a SAAB 93 fuel rail that has built in regulator. Only mod needed if fuel lines.
Brad
 

ctuinstra

Goblin Guru
While starting to take apart the intake system to drill and tap a boost port, I come across this one on the intake. Any reason I cannot "T" into this one??? It goes to the bypass solenoid.

Intake.png
 

ctuinstra

Goblin Guru
Good article here.

"Boost Reference Fuel System: This is beneficial for people running 60# or larger fuel injectors. When hooked up for full boost reference fuel pressure it will make the injectors smaller at idle and larger under higher load. This will help with idle AFR (air fuel ratio) when the injector is having a hard time opening for a short enough time to keep the AFR at the commanded 14.7:1 during idle and light cruise. "

https://zzperformance.com/blogs/import1/engine-modifications-for-2-0l-cobalt-redline
 

ctuinstra

Goblin Guru
I never really finished this thread. It just kind of stopped.

They system is complete and tuned and working very well. What tripped me up along the way is very coincidental issue with year-old fuel pump. Read more about that here....

I no longer have the bypass solenoid connected to the vacuum port on the intake manifold. It's left open to atmosphere now. The fuel pressure regulator is the only vacuum line using that port on the intake manifold.

I changed the fuel filter out from OEM filter that has a return line to one that does not.

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Obviously I had to buy some new fittings and lines to make it all work. I could go back and see if I can dig up all that information but everyone reading this will probably do it differently anyways.

As far as tuning goes, there is some information on my build about the tuning you can read here.... I'm not going to go in to great details about the tuning because everyone's tuning will be different. One of the main differences is the injector flow rate for the manifold pressure will be a static amount across all pressures.

Instead of this for stock:

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I use this now:

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The rest of the tuning is done in the primary VE table and don't forget to do the MAF tuning.
 
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