Quote:
Originally Posted by FlashStopFall
In my 2003 Jeep Grand Cherokee with the 4.0L, according to DashCommand, I’m using 1.2gph at idle with the A/C on (it’s about 0.9-1 with A/C and all accessories turned off). This just seems too high, meaning I would be able to idle for only 16 hours on a full tank. Does anyone have ideas to lower idle fuel consumption or find the culprits? (I run E85, but gph seems to be about the same on 87 octane).
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During my time with Aerocivic, that small Honda D15 idled around 0.10-0.12gph. Part of this was due to a very low idle speed - around 550rpm. E85 does have 30% less energy content per unit volume, so you an expect to use ~43% more fuel under the same conditions. I assume you have a proper E85 tune?
I've also found OBD-based fuel economy instrumentation to be notoriously unreliable. They make a lot of assumptions, giving you the GPH based on displacement, RPM, load, and predicted air fuel ratio. There's a very good chance it idles using less fuel than is being reported, because it doesn't take into account fuel trims, air fuel ratio, or any number of other factors. You simply won't know, unless you can pull data on the injector pulse length, or use instrumentation like an MPGuino.