I own a 92 full size Bronco with about 102K miles. It has the 351 engine with a automatic transmission (over drive). I have owned the truck since it was new and except for the routine oil changes, tuneups, and part replacements (batteries, tires, starter, mufler, filters etc.) I have kept it fairly close to stock. Right now I am running 10.5 x 30 size tires and a K&N breather system. My mileage is an average of 10.5 MPG around town and about the same on the highway (it use to be a lot better). I feel that the gas/peddle response is not what it should be. I would really like to improve the gas mileage and acceleration response. After my last tuneup (New Bosch 4+ plugs, wires, distributer, rotor, pvc, fuel filter, K&N filter) there seemed to be no noticeable improvement in performance. There are a lot of ideas out there about computer chips, ignition systems, side gapping spark plugs, exhaust systems, fuel molecule aligners, and K&N filters. I am looking for specific improvement examples and suggestion.
Thanks,

JamesM

 

Do you have the electronic speedo? (The digital odometer?) If so you may need to reset your speed constant to correct your transmission shift points and your speedo. I changed from 235's to 31's and had a huge drop in performance before I changed the speedo constant for the larger tire size.

 

i have about every bolt on mod you mentioned. i feel the two biggest gains in performance were from the k&n/highflow catalytic converter/freeflow muffler and a gear reduction from 355 to 410. you mentioned a k&n but without opening your exhaust you won't see all the benefits of improving your intake. you also mentioned your tuneup, did you set your timing?

 

You have one of the best engines ever made. It takes very little to make a 351 make 400rwhp. You won't gain any hp by changing gears, just multiplying torque & running higher in your powerband.
It all depends how much more power you want.
Are you just wanting to play with odds and ends or really get into it??
The key to power in a sb Ford is thru it's heads. If you want low budget, go for a set of take of GT-40's or a set of P heads. If you want move go for a set of Aluminum ones.

Iy you just want a good tune up? Try opening your TB Butterfly and spraying cleaner down your intake to get rid of carbon build-up and get some new O2 sensors.

-wheelspin-
92' GT
94' Cobra
01' Ninja 500R
90' Bronco - Stang Puller

 

Maybe this is a stupid question but when was the last time you serviced your k/n filter and when was the last time you got it tuned up?

You know if your filter is dirty bad gas and less engine responce.....

 

Wheelspin do you have a site for those GT 40s P heads? Know of one?

 

>Do you have the electronic speedo?
> (The digital odometer?)
>If so you may need
>to reset your speed constant
>to correct your transmission shift
>points and your speedo.
>I changed from 235's to
>31's and had a huge
>drop in performance before I
>changed the speedo constant for
>the larger tire size.


Yes I do. How do I go about doing this? Is it something that I can do myself, or do I have to take it into a shop. If I do it myself, what do I need to buy in order to make the changes?

Thanks,

James Mayhew

 

>i have about every bolt on
>mod you mentioned. i feel
>the two biggest gains in
>performance were from the k&n/highflow
>catalytic converter/freeflow muffler and a
>gear reduction from 355 to
>410. you mentioned a k&n
>but without opening your exhaust
>you won't see all the
>benefits of improving your intake.
>you also mentioned your tuneup,
>did you set your timing?
>

What would be the best brand for the Highflow Catalytic Converter and FreeFlow muffler?
On the gear reduction, Is that just in the rear end? What effect would it have on the overall speed of the truck? Would the upper end crusing speed be affected.
Would you have an estimated cost for making these changes?

To anwser your question in regards to the timing, no. I did not set the timing. I was not sure if the bronco needed it. I have limit experience in this area and did not want to mess something up. Is this something that is fairly easy to do? What equipment do I need?

Thanks,

James Mayhew

 

It's pretty easy to do. First do you have 31x10.50 tires? If you do your calibration ratio needs to be 918. To check what your ratio is hold in your reset (left) button on the speedo and turn your ignition to on (not start). The speedo needle will sweep across the dial and then back to 0. you should see something like E 08 6 on your odometer now. That stands for english units (miles), 08 is the software edition, and 6 will be the number of times you have left to reset your speedo (you can only do it 6 times). Now push your reset button again, now the odometer should say something like 972 cal. This is your calibration ratio. Mine was 972 for 235/75r/15 tires and I changed it to 918 for 31's per the manual. If you need to change it, turn off your ignition and now what you need to do is ground out the PSOM connector, it's a one wire lead that on my 95 bronco is located directly below the glove box right under the dash and is labeled PSOM. Using an alligator clip or a female spade connector ground out the wire on a metal part of the chassis or dash. Now do the same proceedure as I described before, this time when you get to 972 cal screen punch your select button (the one on the right) until it gets to 918. Now to save the change push the reset button again. Now it's saved. Turn off your ignition and unplug the PSOM connector. Let me know if you have any questions. Remember you only get 6 changes so if you mess up just turn off the ignition and it won't save the changes.

 

Beratte -

Thanks for posting the PSOM recalibration instructions. Your numbers matching mine exactly - going to 31" tires from stock, and the base cal number had never been changed on my truck. The previous owner had 31" tires on it - no wonder he thought it was a dog (5.8L even).

The difference in performance is amazing, no more engine bog - it's as if there were a different motor in the Bronco.

Cheers,
Mike

'93 BB 5.8L

 

Glad to be of help! I was really pleased for what it did for my truck too. It's amazing they don't tell you these things in the owners manual or at the tire shop. Take care, Ben

 

does anyone know what the calibration ratio is for 32X11.50 tires from the stock size of p235's. if you don't know the exact calibration then maybe where could i find it out?
thanks.


Chris
94 bronco 5.8

 

I double checked the Ford manual for you and it only goes up to 31's. I remember reading a posting in the 92-96 Ford section from a guy who had his recalibrated to 32's. If you do a search I'm sure you can find it and if he doesn't list it maybe you can email him and get the info. Good luck

 

thanks alot for the help.




chris
94 bronco
5.8

 

Thanks a lot for the Speedometer Calibration Info. I made the changes as you had suggested and it worked great. My truck seems to have much better response. I called a speedo calibration shop to see how much they charge. Your instruction took me 10 minutes and saved me $85.00. Its to bad that I did not know about this earlier, I have been running with over sized tires for about 5 years now. I really appreciate your help.

James Mayhew