Topic: 4Banger Jeep Speed (Ha! :)

[TrailsLessTaken]

I think mine tops about about 65 with 4.10's and 35's, it might be able to hit 70 if the wind is with it

[sharpxmen]

I think mine tops about about 65 with 4.10's and 35's, it might be able to hit 70 if the wind is with it

is it 65 what your speedo shows or based on gps or adjusted speedo reading?

[Torch_Ind]

I'm talking gps. my speedo reads faster then your actually going now with the 4.88s not much out but still go by my gps.

[sharpxmen]

I'm talking gps. my speedo reads faster then your actually going now with the 4.88s not much out but still go by my gps.

yeah, gps is good - i thought you said 35s and 4.10 (actually that was TrailLessTaken), that's why i was asking - but from what i know even with 4.88 and 35s should still show less than what your real speed is (unless you changed your speedo gear) - my understanding was that 33s and 4.88 is close to stock speedo reading

[Jeffy]

Not correcting your speedometer will have an effect on performance as the PCM uses the vehicles speed to adjust the timing and I believe the fuel curve.  Not to mention its a cheap fix.

[chrisfranklin]

Not correcting your speedometer will have an effect on performance as the PCM uses the vehicles speed to adjust the timing and I believe the fuel curve.  Not to mention its a cheap fix.

Ah, very interesting.  Didn't think of that. 

[chrisfranklin]

Not correcting your speedometer will have an effect on performance as the PCM uses the vehicles speed to adjust the timing and I believe the fuel curve.  Not to mention its a cheap fix.

Is the PCM adjustment to the timing/fuel curve pegged to the speed as shown on the speedometer or to the actual vehicle speed?  My speedometer reads about 5mph slow vs GPS readings.  I'm figuring the PCM adjustment to the timing/fuel curve is pegged to the speed shown on the speedometer.  I'' have to get this adjusted

[Jeffy]

The PCM reads speed by way of the VSS which is tied into the speedometer.

http://4bangerjp.com/forums/index.php/topic,731.0.html

[Jesse-James]

It's a 15 min job and is dirt cheap, mine's been corrected 3 times now for the tires I've run. Hard to believe anyone would deal with the wrong speedo gear as cheap and simple as the fix is.

[sharpxmen]

It's a 15 min job and is dirt cheap, mine's been corrected 3 times now for the tires I've run. Hard to believe anyone would deal with the wrong speedo gear as cheap and simple as the fix is.

who carries the gears? i am fine now but i want to get a 39T in case i ever go to 35s. and how much is one if you remember.

[Jeffy]

who carries the gears? i am fine now but i want to get a 39T in case i ever go to 35s. and how much is one if you remember.

Try the Dealer.  They are usually under $30.

[Jesse-James]

Dealer for sure, my last one was $22-23 IIRC

[Torch_Ind]

mine isn't far off. maybe 5-7km's with the 33's with 4.88's.

don't think it would do much to my timing on my old YJ lol being stationary distributor. the tj's with coil over plug would prod adjust for speed and various other conditions.

[Jeffy]

mine isn't far off. maybe 5-7km's with the 33's with 4.88's.

don't think it would do much to my timing on my old YJ lol being stationary distributor. the tj's with coil over plug would prod adjust for speed and various other conditions.

Timing isn't controlled by the distributor.

[pioneer4x4]

hate to butt in, but if i follow you guys correctly the ecu adjusts from vss inputs so in my 86 xj with no vss, just regular old cable driven type, it wouldnt matter (to ecu) if my speedo gear is wrong tooth count.