Going out of state this comming Fri. This will be a good test since I know what I usually get with this trip. I will post my findings then.

 

Have a safe trip! Take plenty of PS and MMO with you!!

MikeyB

 

Always do!

 

Somewhere on here or TDR someone mentioned that you could accomplish the same thing by rotating the tone ring that the crankshaft sensor picks up (instead of modifying the sensor). So I got curious yesterday and took off the crank pulley and sure enough its a piece of cake to "modify" this ring with a file. The ring is clamped in place by the crank pulley with 4 bolts, and located by a dowel pin (separate from the 4 bolts). With a round file - the slot for the dowel can be filed (only takes about 1/16" of removal) to allow the ring to rotate advanced. I filed the slot only in the "advance" direction so that I could return to the stock position easily.

NOTES:

- Make sure and put a mark on one of the teeth and a matching mark on the c/s pulley BEFORE taking it apart for a stock reference. Then when you get the parts back together with the bolts still loose you can easily see how much advance you want.
- The width of one of the teeth on the ring comes out to right about 2 degrees.
- There is enough oversize in the 4 mounting bolt holes to allow the 2 degree movement without modifying those, so you only need to modify the dowel slot.
- For ADVANCE, you want the ring to rotate clockwise when looking at the engine from the front. File accordingly.

I haven't driven enough to tell if there is much difference - seems like a little bit more knocking noise at low speeds is all I have noticed so far.

Anyway - for those of you looking for a cheap way to try this - it took less than an hour. Forgot to take any photos - I'll see about taking one of the difference in mark locations tonight.

Mathew

 

Sounds like a good alternative in general. Although, I'm surprised you didn't see the same low end response as other people. IMHO, the fact you also notice rattling taking place on top of that might suggest you have over-advanced your tone wheel? However, it sounds like you measured everything competently so ? Rokktech mentioned that anything more than 2 degrees advance dramatically decreased performance and cause the rattling you describe.

You're one day too late for me to try this as I just ordered my Rokktech sensor on Sunday. Oh well, that's life I guess!

 

Mathew,
Keep us informed on how the tone wheel mod works out.

MikeyB

 

As mentioned before, I recently purchased one of these modified crankshaft sensors from Rokktech. Unfortunately, my wife's windshield cracked yesterday so I had to cancel my order for this and use the money to get her windshield repaired. Rokktech was courteous and prompt with my request for the refund.

Just for yuks, I might try the tone wheel modification for now. If it doesn't work, I can set it back to stock and then buy the Rokktech sensor down the road.

Mathew, do you have the TDR link for the person who did this so I can have a bit more background info on this? Thanks!

 

Regarding where I saw the comments about moving the tone wheel, see the last post of this TDR thread http://www.turbodieselregister.com/...ad.php?t=133663.

Still haven't got around to taking a picture yet. It is definately a little more rattly when you accelerate just off of idle and in some situations when giving a very light load. Idle seems fine though. There might be a little better response in the lower rpm - but its not drastic. This weekend I am hoping to try driving some and then change back to stock and drive again for a better comparison. This is where the modified sensor would be nicer easier - I have to loosen the 4 crank bolts instead of just one small bolt on the sensor. As far as function - I can't see how there would be any difference between moving the tone wheel and moving the sensor.

Mathew

 

Mathew,
Please fill out your signature so we know type of truck you own. I don't know if a person can feel much of a gain with the auto but it's noticable with the manual tranny.
I also notice a little more injector knock at low rpms and the engine is slightly louder at idle. I hear that's normal when the timing is increased.

MikeyB

 

MikeyB - signature loaded - looks like we have similar setups except for mines a 4x4. Yep the injector knock at low rpm is what I have noticed. Hopefully I'll notice it this weekend when I get a chance to play driving back to back stock vs advanced. Unfortunately - the first drive I took was 100miles into a headwind so I don't have any worthwile mileage numbers yet.

Mathew

 

I did the tone wheel mod this morning and it was pretty easy and straightforward like Mathew stated. There are 60 teeth on the tone wheel but there is an area that is missing a tooth or two to give a reference point for the ECM. In other words don't just count the teeth and do your math based on that.

Here are my measurements for people who are interested:

-there is up to 1.0mm of rotational play in the stock tone wheel mounting configuration that could amount up to 0.5 degrees of timing difference going from truck to truck. I'm surprised the tone wheel has so much play considering its importance to the operation of the engine. This is maybe why some people who install the Rokktech sensor experience some knocking as they have a more advanced stock tone wheel mounting?

Radius of tone wheel = 105mm
Diameter of tone wheel = 210mm
Circumference of tone wheel = 660mm (using the formula 2x"pie"xR)

2degrees = about 3.7mm of circumference movement, I shot for 3.5mm so I wouldn't overdo it.
Each tone wheel tooth looks to be just over 4.0mm in width, possibly around 4.25mm. Mathew, maybe you're just over 2 degrees of advance by a 1/3rd of a degree if you used the tone wheel tooth as a reference point?

The dowel pin slot is 22.5mm from the center and I calculated I would need to remove 0.75mm from the counterclockwise side to get the adjustability I wanted.

I started the truck when I was done and there is a bit more rattle to it, more like how a standard older diesel engine would sound. I will test it after I'm done with this post.

MikeyB, I notice your post in where Rocktech said they remove 0.080" from the thickest part of the sensor to get the adjustability they want. Does that mean the sensor tip actually moves 0.080" over the tone wheel or does the sensor rotate and the tip moves more than that? The reason why I ask that is 0.080" of movement over the tone wheel would only account for an advance of a little over 1.0 degree. Thanks!

 

Good info - thanks for taking the measurements. I had noticed that "play" while stock too - but forgot to measure it before I already went to work with the file. I'll get the calipers out and see exactly where I am at tomorrow. I may have taken the approach alittle bit too crude - just eyeball measured with a tape the distance between teeth (which would be 6 degrees) and found that the tooth was pretty close to one third of that. So I moved about 1 tooth. Luckily I did make some nice marks for reference and adjustment. I am curious like you how far rokteck is moving the sensor - maybe less than 2 degrees.

Mathew

 

SoCal-305,
Good info! As for the Rokktech that 0.080 is a rough estimate with a set of calipers. Since it's not perfectly machined, more like a egg shape looking down the center. The sensor rotates in a arc with the bolt being the axis. So the sensor head doesn't stay centered to the tone wheel teeth. Maybe that's where the extra degree comes in?

MikeyB

 

Just got back from a test spin. The extra rattle went away once it was warm. The truck is slightly more spunkier off of the line but that is the only difference I see. Also, I can do a rolling burn-out now vs. just a bunch chirps before in 1st gear. I have an auto tranny and the rpms that this mod benefits the most are quickly passed thru once I goose the throttle. I'm sure the manual tranmission trucks would "feel" the benefits of this mod more readily.

I'll post in a couple of weeks about any MPG improvements I see with this. MikeyB, from just looking at the sensor and the information you mention in your last post, I believe the Rokktech sensor tip is moving at least 3.5-4.0mm for the full 2 degrees of timing advance.

BTW - Use the measurement information I provided in this thread at your own risk! I assume no liability for the correctness of this information. (You can't be too careful in this day and age!)

 

SoCal-305,
When you opened up the dowel pin hole was that to the left if facing the front the engine?
I have two friends that are interested in doing the tone wheel mod, one 555 and the other is a 600.

MikeyB