I HAVE A 2000 2500 WITH THE 360 CI. HERE GOES! I BOUGHT MY TRUCK WITH ITS CURRENT LIFT OF 4", AND 315-75-16 TIRES. MY SPEEDO IS APPROX 5 MPH OFF. BY NOT RESETING THE COMPUTER IS THIS HURTING MY RIG IN ANY WAY..(SHIFTING, GASMILES,ODOMETER,. ETC). SECOND ? IM GETTING A CODE WITH THE KEY TRICK... P 1596. WHAT DOES IT MEAN AND HOW DO I FIX IT ??? THIRD ? HOW DO U KNOW WHEN TO REPLACE O2 SENSORS. IM AT 92K WHAT KIND TO U GUY RECOMEND. THANKS A BUNCH.........................

 

shifting ought to be ok, its mostly related to rpms, so i dont see where having different tires would have any adverse effects. if your speedo is off, your odo may go off a slight bit with it. both are controlled by cables with sensors to tell them how frequently the wheel passes a fixed point. as far as gas milage goes, who knows? who cares for that matter, as compares to most of the rest of the world, we have it pretty cheap.

i wouldnt replace th o2s unless they are giving you a check light, dragging down gas milage, or bringing up a code on your scanner. come to think of it, they may do that around 100k, so go ahead and check those out.

the rest of your questions, i have no speculation about.

good luck!

 

your mpg is kinda hurtin but kinda not... if you think about it.. your odometer is running off your speed.. so if your speed is knocked off a bit and no reprogramed.. then your not clicking on the miles you should be...or the other way around... cant remember.. either way...if you do your mpg by how many miles you got till E on a 26 gallon tank...then its not at all accurate... and could give you a false feeling of good or bad mpg...more then likley bad.. im bad with ratios..the wife is the math teacher.. anyway.. check that CEL means

P1596 Speed Control Switch Always High Speed control switch input above maximum acceptable
voltage.

(thanks steve )

anyay...no clue what the hell that means.. hope this helps!!!!!!

 

your speedo is not cable driven and it's probably more than 5 mph off... I had 3.55 gearing, 285 tires and was 8.7% off, then went to 295's and was 9.35% off. the best way to check is to follow another car that has a correct speedo and go at least 10 miles and see what the odometer difference is, then you can calculate the error. the farther you go, the more accurate it gets. My 9.35% number came from following the wifes dakota for 120 miles and dividing her miles by my miles.

Get your speedo recalibrated at the dealer... they will re-set your ABS system and your PCM. I gained mpg by doing this, I was calculating mpg by miles traveled x 1.087 or 1.093 / #gallons. It was consistently around ~13. after the re-cal by the dealer, it jumped to ~14.2

your o2's... replace the two front ones as soon as possible and use the NGK's (found at sparkplugs.com) the bosch's dont seem to last as long for some reason in the dodges...

your code?... not sure... call a tranny shop that works on the rams and see what they say.