Page 17 - Spring 2018 GMC Vintage RVing

For additional technical presentations, papers, manuals, and other information go to gmcmi.comfilter or a lower profile air cleaner. Another option is a thinner adapter plate. Manny, of Manny Transmission fame, sells an adapter plate9for FiTech installations that usually allows the OEM air cleaner to be used with a minor modification to remove the registering tabs on the mounting ring.O2 sensor installation needs some forethought.The best option here is to go to a muffler shop and have an O2 bung welded into the exhaust pipe at the proper location and orientation (see manufacture’s instructions10). FiTech does provide an optionto install a bung yourself with the supplied clamp-on components. Basically, you drill the proper sized hole in the recommended position and using clamps install the supplied bung. This does work without leaking but I would recommend to eventually have this bung welded to be more reliable. Getting the bung work done can be completed ahead of the FiTech install but plug the bung – do not install the O2 sensor until ready to fire up the engine with FiTech installed.Tuning can take some time.But you say the system is self-learning, why do I have to do tuning? There are some initial parameters11 the system needs to know such as what size engine you have, idle speed, rev limiter, etc. Also, disablethe fan control unless you have the new fan system12 currently being talked about which can be controlled by most EFI systems. By default, the FiTech is set up to run really rich. Keep in mind that most of these aftermarket self learning systems are designed for hot rodders – they like their engines to run rich. Fuel economy will suffer with the default values so I recommend going into the Air Fuel Ratio (AFR) tuning section and changing the cruise parameters. There are 3 with the first being 45 map at 1100 rpms. I usually set this to around 14.2 to 14.4. The next is 45 map at 3000 rpms. I usually set this to around 14.6to 14.9. Then the last is 45 map at 6000 rpms. I usually set this to around 14.4 to 14.6. The system extrapolates between these values. Now, learning will attempt to “tune” the system to these extrapolated values. Depending on the final drive ratio you have, you might want to play with these numbers some. You want the leanest possible settings when you are at your normal cruise speed. I would be careful about going much above 15 on any of these settings without a good understanding of how the engine can heat up under loads. I run 16.5 to 1 AFR in cruise on my coach, but the EBL has more sophisticated fuel management with safeguards that protect the engine. I generally leave the next set of AFR numbers (engine under load) at the defaults. If you do a lot of mountain driving, I would consider lowering the numbers some as an added protection for the engine.The remaining tasks are fairly straightforward. One task is routing fuel lines. If you decide to use the FCC, then FiTech supplies a high pressure hose from the FCC to the throttle body. You will need a vent line running from the FCC to where ever you tie into the OEM venting system (two popular choices are either the vent hose going up into the filler neck or into the filler pipe accessible from the hatch).This hose is not provided in the kit. If you are installing two pumps either in the tanks or externally close to the tanks then either hard lines or high pressure fuel injection hose needs to be purchased and installed. Most pumps have good internal check valves but many owners use an additional check valve to keep one pump from pumping fuel back into the other tank. Other tasks include such things as wiring (some crimping and soldering skills), basic mechanical skill (removing carburetor, installing FiTech throttle body, etc.), some fabrication skill is helpful, and ability to read and follow technical instructions. If you are not comfortable with any of the tasks described in this article, then having a trusted mechanic do the install might be a wise decision.A well installed fuel injection system will perform reliably for many years with the following benefits:1. Good start-up and shut-down characteristics.2. Better driveability.3. Automatic compensation for altitude changes.4. In most cases, eliminates vapor lock concerns.5. Good support within the GMC community.6. Increased engine life (reduced raw gas washing downcylinder walls and diluting oil).With today’s EFI aftermarket systems with their new price points and resulting benefits, the decision to replace a carburetor has become much easier. Remember, you will smile each time you fire up the motorhome and go for a drive.References/Resources1. holley.com/products/fuel_systems/fuel_injection/sniper_efi/2. msdperformance.com/brands/atomic/3. fitechefi.com/4. gmcmi.com/vintagerving/2016-FallVintageRving/mobile/index.html#p=125. appliedgmc.com/prod.itml/icOid/1822 6. facebook.com/groups/GMCMHFiTech/gmc.mybirdfeeder.net/GMCforum/index.php?t=thread&frm_ id=1&rid=1215groups.google.com/forum/#!forum/gmcmh-efi chevelles.com/forums/89-efi/875969-fitech-efi-tuning-tips-info- sharing-ideas-settings-etc.html7. gmcmi.com/wp-content/uploads/2013/02/In_tank_Fuel_Pump_ Presentation.pdfappliedgmc.com/prod.itml/icOid/11308. amazon.com/Fast-304147-EZ-EFI-Cable-Mount/dp/B00BBOLWTM9. mannystransmission.biz/10. fitechefi.com/fitech-uploads/2016/07/30001.30002Instructionsm12.9.15.pdf11. fitechefi.com/tech-posts/fitech-efi-basic-setup-instructions/ 12. appliedgmc.com/prod.itml/icOid/1867SPRING 2018 GMC MOTORHOMES INTERNATIONAL 17