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Self-learning fuel injection systems-FiTech, Sniper, EZ-EFI


Paul Bell

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Thank you Paul,

 

I too have done alot of research and work on EFI and the engine controllers out there.  I cut my teeth on an Edelbrock MPFI conversion from a OBD1 TBI 454 in a truck.  I used the stock PCM and cut out the factory chip and replaced it with a E squared Prom.  The stock OBD1 system advantage at the time was the knock sensor retard capability that was not available on the ECM's a few years ago and transmission controlling of a 4l80E. 

 

knock sensing and retard during the initial tune and if you transition through limited Octane zones (California 91 max) can save your motor.  knock sensor counts versus RPM are a critical EFI tuning tool...  VERY CRITICAL if the motor is built.  Detonation is killer... been there... done that... paid the price! 

 

The single narrowband O2 sensor feedback method is a problem for dual exhaust, with or without a crossover, which side do I put the O2 sensor on?  It cant be both....  The single O2 sensor feedback method relies on all 8 cylinders running the same, each bank of 4 being identical.  So monitoring and deriving AFR feedback from one set of four cylinders means one bank of 4 cylinders is assumed to be the same as the O2 monitored set of 4 cylinders.  keep that in mind, it is OK as long as everything is OK...  

 

Megasquirt and Holly (Dominator) are the only PCM's that have knock sensing and dual (or more) wideband O2 sensing/feedback capability and transmission control capability.  Holley Dominator will control a 4L80E but not the 6L80E (Yet, I am waiting for it).  

 

Additional deficiencies of all but megasquirt and the Dominator is the VE tables near idle are to course to effect a good tune with a motor that has been modified.  Paul touched on the minimum vacuum issue above quite well.  I circumnavigated the issue by adding more rows of VE at smaller RPM ranges from 600 RPM's to 2000 RPM's increasing my resolution.  so instead of having 4 adjustment ranges of 500 RPM's each (ie. 1000 to 1500 RPM's), I created tables with 125 RPM ranges for "Near Idle"  VE lookup tables.  This was effective as witnessed by the variation in the VE tables below 2000 RPM's at each of the 125 RPM ranges, dramatic changes required to properly fuel the big block near idle.  Big difference in driveability with the up camming effects on vaccum and air flow in the heads...

 

I have gone through a lot learning on EFI systems and I fully embrace the EFI world.  Once I learned how to use the mouse, computer, EFI tuning software, chip programmer/burner, data logging software I was doing it.  The EFI gives us the capability to have different jetting/timing at any RPM by hitting enter...

 

Hotel Sierra

 

I could go on for hours on this subject... happy to respond to questions...

 

john

 

 

I am currently anticipating 

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It’s been a year and a half since I contributed to this thread so here’s my update:

The Fitech EFI stuff seems to have improved along the way. Many people are posting good results in various web sites with their systems. There’s still a few with issues but nothing that can’t be ironed out. Avoid their fuel pumps and systems.

I believe the Holley HP systems can now be bundled to save some money. This and their Dominator system can use crank & cam sensors and actually do sequential injection (you’d need a throttle body, port bungs, injectors & rails and 8 LS coils). These like the others are speed density. Holley offers an external 58x crank wheel & pickup for small & big block Chevy engines. EFI Connection offers crank and cam pickup solutions for small block Chevy and gen 6 big blocks, even harnesses and GM PCM support. Very clever people.

I’ve learned the best fuel system is non-return, like OEM’s are now using. BUT, you’d need a fuel controller like the OEM’s use. Rick’s Tanks offers tanks for our cars that’ll accept a GM style fuel module which solves fuel slosh starvation. VaporWorx offers PWM controllers for the pump that has a fuel pressure sensor. This reduces current to the pump unless pressure calls for more which greatly reduces fuel heating. This is all costly, but the best way to go.

Fitech EFI offers an LS system from harness & ECM to harness, ECM, manifold, throttle body, rails, injectors, etc. The system also controls 4L60e & 4L80e transmissions and dual cooling fans. The system uses stock LS sensors. It has dual wideband o2 sensors. If you’re doing an LS swap, this is the system you want.

I took this Fitech LS system one step further. On my mkIV big block, I created a crank pickup with a LS 58x reluctor wheel on it and a Vortec distributer with 1x cam sensor. This system (and also the Holley systems) will recognize any combination of crank & cam sensors. To get the side-to-side o2 sensors controlling the correct bank and coils, I had a custom cam with the LS firing order ground (firing order can NOT be changed in the Fitech software, I believe it can be changed in the Holley systems). I’ll be using the above Rick’s Tank, VaporWorx controller and a CTS-V pump, which is actually two pumps good to 950hp. I’m using a Edelbrock 1,000 CFM four barrel throttle body that has GM style IAC and TPS. I drilled a hole in it to position the air temp sensor just above a primary throttle blade. It’s all working pretty good. I don’t expect anybody to do this insanity but it shows what can be done with modern fuel injection. Turn the key, it starts, runs and learns along the way.

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  • 2 weeks later...

For those of you considering upgrading to fuel injection, here's why OEM style fuel systems are better than any aftermarket idea to convert stock fuel tanks with foam or pickup pads. Thanks to Carl at VaporWorx for this video:

 

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A lesson learned with fuel injection tuning...  If the motor is built and the vacuum is altered....   The PCV valve requires changing.  The stock "Tapered" PCV will oscillate open and closed and make tuning below 2000 RPM's a series of over compensation.  Straight wall PCV is required and meters correctly at lower vacuum...  

 

john

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On 8/5/2018 at 8:22 PM, NWmonte71 said:

I am curious if anyone is running a Holley Sniper EFI setup on their Monte. I am very interested in putting one on my 71. Looking for "real-world" feedback.

At 426 posts, this would be your best read: https://www.chevelles.com/forums/89-efi/938377-holley-sniper-efi-tuning-tips-info-sharing-ideas-settings-etc.html

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