| Re: Caddy 500 Fuel Injection / Ignition Systems [message #369803 is a reply to message #369795] |
Thu, 26 May 2022 07:10   |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma:
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Senior Member |
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Rob,
For a number of years GMCer's were having excellent results with the Howell EFI kits which they built for the GMC Motorhome. Around 2009 (the time I purchased my kit) Holley changed the injectors from 80 pound per hour (PPH) fuel rate to ~63pph. Howell seemed unaware of this and the change threw the fuel calibrations out of kilter. The fix was to increase the fuel pressure so the smaller injectors would flow 80PPH. However the pressure regulator in the Holley throttle body (TB) could not regulate at the desired pressure so there was still fueling problems. While trying to fix issues with the smaller injectors, I came across the EBL system. It made fixing the fueling tables a snap. Ken Henderson also installed the EBL and soon a number of people with the smaller injector problem were installing EBLs.
Since the Holley could not regulate to the desired pressure and was unstable, many of us have changed to Rochester TB's from a 454 which had the higher flow injectors. I don't know if Holley brought back the higher flow injectors, or if Howell is using an external pressure regulator to make the smaller injectors flow at 80PPH. Maybe Randy Van Winkle would know. We do know the Rochester TB from a 454 does flow at the desired rate and works well.
As far as parts, the GM TB EFI system was used on millions of vehicles over many years. The sensors are readily available from many aftermarket sources. They are analogue output sensors (0-5 volt) mostly variable resistance so I would think other manufacturers sensors might also work. Did Holden use GM engines?
The sensors are:
-Coolant Temperature: thermistor
-O2 sensor: common part to many manufacturers
-MAP sensor: aka vacuum sensor. This might be harder to get down under, but is a common GM part.
-Throttle Position sensor: part of the TB, it's just a variable resistor, so more of a wear part.
-Ignition module for spark control: Common part, but good to have a spare.
I have never had a sensor failure (touch wood). Fuel pumps being mechanical, seem to be the main failure. I changed to dual pumps and kept my original EFI for a spare (10 years old and was still working). With dual pumps, I have redundancy.
As Jon said, the aftermarket kits use proprietary parts and require you to return it for any repairs. That pretty much forces you to carry a whole spare system with you. My biggest issue with them was they had the electronics housed in the TB. Heat is a big enemy of electronics and caused issues. I now see some aftermarket systems have moved the electronics to a separate box to install inside the coach.
I carry my original ECM from Howell as a backup, but have never needed it. Except for my original issues with Holley's smaller injectors, I haven't had any real issues with the GM based EFI system.
This document has all the common GM sensor part numbers. You could see if they are available either OEM or aftermarket down-under.
http://www.gmceast.com/technical/Swartzendruber_Generic_TBI_SlidesNotes.pdf
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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