So i spent part of the day researching EGR deletes, cant find anything on someone who has done it and had a failure or amazing success. Everything i find they claim better mpg at the cost of more emissions. Reprogramming to adjust the fuel and timing is said to be done so the engine doesnt knock or ping. What are peoples experiences and or opinions on deleting emissions, if you are in an area where you can do so.
Dave, when I got the '90 f150 original stock EFI, it needed a cam and head to get back on the road. Not knowing the nature of the EFI 300 I installed a Crower cam with only 252* of duration and a refurbished EFI junkyard head. (Both still in service now, 10 years/ 100K miles later). I deleted everything except PCV, including cat, nearly filled a big trashcan with vacuum lines and parts. No mods to the ECM, 100% stock. It required premium gas mostly because of the short cam raising compression. It was the best running 6 I've ever owned. (That's a bunch.) I am not exaggerating these numbers: on a bi-monthly 175 mile round trip it consistently got 24+ mpg with AC and 26mpg otherwise. Flat road, sea level elevation, 60mph cruise (1600rpm), E4 automatic, 3.08 gear. In town average 15+.
Like TrickSix I've always deleted EGR. In my opinion- and while some disagree, this opinion will not change- it's even more advantageous to remove it from first-gen EFI engines because the intake is dry, there's no fuel moving thru it to clean the exhaust crud and carry it to the cylinder. The two EFI 300's I've disassembled, the intake manifold was severely carboned-up, just incredible. The moist crankcase vapors combine with the dry soot of the EGR and make a carbon glue that fouls the intake runners beyond belief.
I'll go on record and predict, if you delete EGR you will see improved economy and possibly mid-throttle power/response. I removed the valve completely and cut a thin steel plate as a block-off.
(NOTE- the reason I used past tense is because this is the engine I converted to carb a few years later. A big mistake. The factory EFI WITH emissions deleted was the economy ticket.)