Interesting Rokktech crank sensor results

[JSchutz]

I average ~5000 miles per month so any improvement in fuel economy is welcome. I tried out the Rokktech crank sensor with great expectations but had a somewhat different experience than most.



A little background: All comparisons were done using the overhead computer and a minimum of 1000 miles of driving per result. My truck is in my signature and has a 1300 pound vet box bolted in the bed. I drive back country roads in western NC: Plus: Most driving is 45-60 mph, transmission locked in 4th. Minus: Lots of curves and steep grades. Only mods are a “Swiss-cheesed” air box and a Donaldson/Aeroturbine exhaust.



Stock the overhead read 20. 9 mpg after 58 tanks since last reset.



With Rokktech added I ran 20. 2 mpg. More diesel clatter was noticeable on acceleration. Power seemed comparable.



Rokktech customer service is excellent. According to their recommendations I tried various thicknesses of electrical tape to adjust the advance (tape is added to the cut-out area of the sensor to decrease the depth of the cut). The best I could get was 20. 6 mpg with 8 layers of tape (each layer of tape reduces advance by ~0. 1 degree). Engine does sound different as you change the advance.



I recently put on new tires and as the weather is cooler I retested:



Rokktech sensor (unadjusted-no tape): 19. 8 mpg after ~1000 miles.



Stock sensor: 20. 7 mpg after ~1600 miles.



Looks like I’ll keep the stock sensor on!



Jeff



Anyone want to buy a Rokktech sensor (with instructions and original box)? Cheap.

 

[PGreenleaf]

How cheap? -- email address removed --

 

[OHale]

JSchutz,



Could winter blend be a factor? My mileage always drops this time of year as we get into the winter blend. I'm in a colder climate but I think there is some winterization in NC. Just a thought.

 

[JSchutz]

Nothing but #2 diesel here all winter. The change in temperature was why I retested the sensors. No amount of testing or adjustments were able to bring the Rokktech mpg up to my stock economy. Jeff

 

[Saccowboy]

just a thought here but why are you using the overhead computer?? almost 99% of the time they are not accurate! the only accurate readings will be the ones that are hand calculated so try doing the math and then see what you get, i'd be willing to bet the results are better than what your overhead displays

 

[GaryCarter]

There's no reason the trip computer would be fooled by the Rokktech.



Adjusting the timing by shimming with electrical tape!!! :--)



Gary

 

[PKitzman]

Just finished running my first full tank of fuel with the sensor installed. Before the install my best tank was 18. 1 mpg (all hand calcs) nursing my speed between 60 - 70 mph. If I drove it normal I would get between 14. 7 - 17 mpg with speeds up to 82 - 83 mph. I would typically get just up to 500 miles per tank before hitting empty ( don't have the tank mod and I fill up till it clicks off the first time).



Put the timing sensor on and got 20. 0 mpg would have made it close to 600 miles but I filled up with 1/8 tank left. That was with 1/2 hour stuck in a traffic jam and some high speed driving over 80 mph but with an average in the low 70's.



The overhead was pretty close to the hand calculated milage and always has been for my truck. The sensor has given me a good 2 mpg increase. Well worth the money.

 

[rbattelle]

Adjusting the timing by shimming with electrical tape!!! Gary

Yikes. I hate electrical tape.



-Ryan

 

[KBertetto]

I posted this little test of mine in the other thread, but theres now about 8 million pages. It's not much of a test but here's my results:



I installed the sensor tonight, but before I did I ran a 48 mile round trip on the highway going from my favorite fuel station and back. Cruise set at 60 mph, 19 degrees, winter blend fuel. I used the same pump to fill both times and to the same spot in the fill tube. After my first run I went home and installed the sensor and ran the exact same 48 mile round trip... here's my results.



Before Rokk Sensor:

Overhead Mileage-- 17. 6

Actual Hand Calc-- 15. 78 (48. 3 miles / 3. 06 gals)

EGT-- 550 degrees

After Rokk Sensor:

Overhead Mileage-- 17. 6 (I was surpised there was no change)

Actual Hand Calc-- 17. 18 (48. 3 miles / 2. 81 gals)

EGT-- 500 degrees



The truck started and ran with absolutely no difference that I could tell. Power seemed the same, idle seemed the same... I could not tell any difference at all. I'm very happy with the 1. 4 mpg increase, time will tell if it actually really increased that much. Even though it was only 48 miles, it was the exact same 48 miles under the exact same conditions. I'm keeping the sensor because at this rate it will eventually pay for itself and then some.



Bert

 

[CRUSH'EM]

Ok, finally got the dealer to flash my pinion factor....BUT

:{ Finally got the dealer to flash my eprom for the pinion factor for the 285's... . now, my overhead is showing the crappiest mileage I have seen..... was averaging 16, now in town it is showin 9-11 and on hiway, its only reading 14-15... ... ... ... haven't had a chance to GPS the speed and see if he flashed the right code either..... any other ideas? Checked the position of my ROKKTECH CS and it appears to still be mounted correctly... am out of ideas gents... ..... lemme know what y'all think. Do I need to advance or retard the timing?? Or just move the sensor around on the hexkey screw and see what spot works best?

 

[JSchutz]

I used the overhead for comparison purposes only. It may not be exact (although mine is pretty close to hand calc. ) but I'm hoping it's consistent. I figure it's at least as repeatable as I would be filling the tank, since there are some variables involved there.



One thing that was consistent was that with the Rokktech, whether out of the package or adjusted with various layers of electrical tape, fuel economy was always less than stock. Jeff

 

[Sled Dog]

I average ~5000 miles per month so any improvement in fuel economy is welcome. I tried out the Rokktech crank sensor with great expectations but had a somewhat different experience than most.



A little background: All comparisons were done using the overhead computer and a minimum of 1000 miles of driving per result. My truck is in my signature and has a 1300 pound vet box bolted in the bed. I drive back country roads in western NC: Plus: Most driving is 45-60 mph, transmission locked in 4th. Minus: Lots of curves and steep grades. Only mods are a “Swiss-cheesed” air box and a Donaldson/Aeroturbine exhaust.



Stock the overhead read 20. 9 mpg after 58 tanks since last reset.



With Rokktech added I ran 20. 2 mpg. More diesel clatter was noticeable on acceleration. Power seemed comparable.



Rokktech customer service is excellent. According to their recommendations I tried various thicknesses of electrical tape to adjust the advance (tape is added to the cut-out area of the sensor to decrease the depth of the cut). The best I could get was 20. 6 mpg with 8 layers of tape (each layer of tape reduces advance by ~0. 1 degree). Engine does sound different as you change the advance.



I recently put on new tires and as the weather is cooler I retested:



Rokktech sensor (unadjusted-no tape): 19. 8 mpg after ~1000 miles.



Stock sensor: 20. 7 mpg after ~1600 miles.



Looks like I’ll keep the stock sensor on!



Jeff



Anyone want to buy a Rokktech sensor (with instructions and original box)? Cheap.

The Rokktech appears to work well on newer trucks, 4. 5 600 HO and 05 610 HO. I have the same set up as you in an 05 LWB, and was getting maybe 15 mpg's before advancing the timing. I don't believe if I were getting your stock mpg's that I would change anything.

 

[RonsRig]

The only way I can get my computer to get close to hand calc is to reset the computer just after filling up BEFORE moving the truck. Otherwise, if you are close it is just by coincidence. My computer has been within . 3 unless I reset while driving down the road, or when I have the BDDL Extreme program in. I do have to Rokktek sensor and it does help with EGT, boost, and MPG.

 

[p-Bar]

A dealer told me that the reflash for the overhead/better mileage was due to recal overhead for accuracy and advance timing for mileage. Maybe with the added advance of the Rokktech we are getting out of the envelope. I never had my early build 04. 5 reflashed and I have nocticed considerable mileage gains

 

[RKerner]

A dealer told me that the reflash for the overhead/better mileage was due to recal overhead for accuracy and advance timing for mileage. Maybe with the added advance of the Rokktech we are getting out of the envelope. I never had my early build 04. 5 reflashed and I have nocticed considerable mileage gains

I have the reflash and am getting an honest . 6 -. 7mpg better for combined city/ highway mileage. I think the dealer stating it advanced the timing is more anecdotal info than factual. My engine pings a bit more at light throttle openings, turns over longer when cold and has a few second lope after a cold start. I need to get more miles to confirm the goodness of this mod so I'll report back in the spring.

 

[p-Bar]

I get no pinging out of mine ,it does run healthier at lower RPM's

 

[10-9jc]

Overhead computer

Haven't done Rokteck (yet), but -

Maybe there's a gremlin ["on-board hacker"?]

in these OH computers!

Mine would always be about 1 mpg Better than hand calc.



Then - last fill my hand calc read about 1 mpg better than

the OH. [OH was less than hand-calc, not better]

Checked my figures about 3 times - same result.

Always fill same [as much as possible].



I just figure the OH computer is "headliner dressing", with

"ballpark" mileage figures.