The 82 to 86 258 and the YJ's with the 258 all have a poor Ford attempt
at an emissions computer in them running the carb and the spark timing.

This computer acts like an old fashioned governor and limits the rpm to
slightly over 3000 before it clamps down and the engine won't rev
higher.

By modifying any part of the ignition or carb, this emissions computer
either gets removed or put to sleep or you get really ****ty performance
because it goes into 'limp home' mode.

Adding FI kills the sucker and you get a FI computer with it's inherent
poor(er) gas mileage. The carb well tuned gets about 5 mpg better
mileage than the FI systems from what I have observed.

Mike

William Oliveri wrote:
>
> Mike, how would you kill the computer with MPFI and the jeep still runs and
> was this in your mind when you wrote that below?
>
> > New Fuel injection = kill computer = instant 25% power boost.
>
> bill
>
> "Mike Romain" > wrote in message
> ...
> > Well............
> >
> > I am running an 86 with an Accel SuperCoil for hot spark, the timing
> > advance 'ported', the stock Weber-Carter BBD carb unplugged and manually
> > set up, the 'Nutter Bypass' or no emissions computer working, stock
> > manifold with a straight 2" pipe back to a Dynomax 'Super turbo' high
> > flow muffler, 3.31 gears turning 33" mud tires. In Canada it is a
> > Utility vehicle and don't require a Cat.
> >
> > I get a sweet 23 US mpg running at 65 mpg and passed the last emissions
> > with 15 ppm HC and 0.16% CO.
> >
> > 1st gear will light up my 33's way too easy when turning onto a 40 mph
> > road so I have to watch the pedal, 2nd pulls 'fast' up to 50 mph turning
> > 4400 rpm, 3rd is the power gear and hauls hard up to 75 mph or so, 4th
> > buries the needle easy and no freakin' way do I want to find out how
> > fast 5th goes.
> >
> > My speedometer is exact according to many checks with a GPS.
> >
> > My total cost was about $45.00 for the Accel coil. The Nutter which
> > puts the computer to sleep cost a couple bucks for wire, solder and heat
> > shrink and gave me a sweet 25% seat of the pants power and mileage boost
> > with at least a 10 mph increase in each gear and the ability to actually
> > get the rpm up to the top at 4500 for the 'red line'.
> >
> > I think the biggest boost anyone gets from 'any' mod to the engine is
> > because the computer has to be put out of it's misery for 'any' mods.
> >
> > New carb = kill computer = instant 25% power boost.
> >
> > New Fuel injection = kill computer = instant 25% power boost.
> >
> > MSD Ignition = kill computer = instant 25% power boost.
> >
> > Or you can just stay stock and kill the computer = instant 25% power
> > boost!
> >
> > I wish you luck and will look forward to reading about the improvements
> > you hope for.
> >
> > If or when I modify anything I will pay close attention to performance
> > increases. I think my 2" exhaust could use a set of headers and a 390,
> > but my manifold isn't broke and my carb purrs so I have no urge to
> > upgrade it. It runs pretty sweet for me now..... :-)
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > CJ7 Casey wrote:
> > >
> > > I want to see how much emission legal power I can get out of my 258CI.
> > > Inline six with just bolt on parts. I will be doing that this last
> > > weekend in February 2005. Any one who has dealt with these
> > > modifications, any advice would be greatly appreciated, You can e mail
> > > me at
> > > Bolt on parts, Bolt on parts "They said it was easy, I'm hoping it
> > > is."
> > > I bought the Holley 390 cfm carburetor / the Offenhauser 4 bbl intake
> > > manifold / Holley fuel pump / Pace Setter headers / K&N filter /
> > > D.U.I. Distributor / Cintech wiring harness / 86 Wide track high
> > > strength axels and lockers / M.O.R.E. spring over, shackle reversal,
> > > lift kit...
> > > I will document these modifications to help any one it can, with
> > > problem foresight. Like I said any advice would be greatly appreciated.
> > > I will list all pros and cons I can find with these "bolt on
> > > parts". I will be doing all of this with no automotive experience, or
> > > back ground. Wish me luck, and If you know what problems to look out
> > > for, let me know.
> > > I will start documenting and posting full results and in the end it
> > > will be dino tested.
> > > With current stock engine problems I have created, and I've tried to
> > > fix, I'm getting 12 miles to the gallon and 84 horse power. I should
> > > be getting 17 miles to the gallon, and 115 horse power, if it ran
> > > properly. "they say to expect 250 horse power with all modifications
> > > and 10% better that stock fuel economy increase, They also said I might
> > > get 300 horse power out of it? They also said it's easy bolt on
> > > parts. I'll let you know.