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Old 06-30-2019, 10:15 AM   #1 (permalink)
hat_man
Master EcoModder
 
Join Date: May 2010
Location: Illinois
Posts: 423

Oh Deer - '03 Ford Ranger XL
90 day: 33.16 mpg (US)
Thanks: 50
Thanked 66 Times in 53 Posts
Needing some insight on OBD-2

Hello again everyone.

I've posted on here a few times about a fuel injector swap for my Ranger. Finding a different injector like what I want is proving difficult. The flow rates are always higher than stock. I was hoping the ECU (by way of the O2 sensors) could make the proper adjustments to the pulse width (I think Ford calls it the duty-cycle ?) to bring the AFR back in line. I asked on a Ranger website and even though I believe the response I got, I'm looking for either a second opinion or confirmation. The OBD systems are a bit above my pay grade.

Long story short......stock 2003 Ranger injectors are 4 hole, 18# flow rate. I have found "plug and play" 12 hole injectors but they flow at 23#. Nearly a 20% increase. The info from the other site goes like this.......new injectors will run rich. Downstreram O2 will read rich and ECU will throw a CEL and then make adjustments. If the ECU has the room in it's stock programming to make the adjustments to bring the AFR back in line it will do so, but still throw the CEL because it knows it shouldn't have had to make the adjustment in the first place. AFR may be in line but the light stays on.

My questions are this......

1) If the ECU makes the adjustment and the downstream O2 sensor reads OK, wouldn't the CEL go off? The ECU is smart but it isn't AI. It's more of an if then statement isn't is? If O2 is bad then CEL. If O2 is good then no CEL. Right?

2) and maybe not answerable.....Is a 20% increase to much for the ECU to handle by itself without having to pay for a custom tuner.

The 12 hole injector may not lead to much if any MPG increase, but might lead to a cleaner burn, unless it runs to rich. Wouldn't that help with emissions (we don't have testing here) and smooth out the idle some? I can get the injectors for about $50 but the time involved in removing the intake to install them is daunting. If they were easily accessible, I'd just go for it and report back on how it all worked out.

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