optical bump [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: optical bump


countrycoach
07-15-2005, 04:02 PM
OK I have done a search and tried to lear something but all I did was get confused. I don't know all the abreveations and timing mumbo jumbo. All I want to know is who can perform this for me, how much would it cost me, what kind of gains will I expect, fuel millage, and last but not least will it hurt my engine. I don't want this to start into another war of knowledge I just want to know the basics above.


oh yea and one more thing, what do I tell the dude at whatever shop I take it to do?

All the discription of my rig is in my sig.... :help:

Firefighter
07-15-2005, 04:10 PM
You are probably better off doing it yourself if you have any mechanical knowledge at all. It is really easy, and you can't really hurt your motor as long as you don't do something really silly to the bolts you have to turn on the Injection Pump. If I was near you I'd do it for you, it only takes about 15 minute to do now that I have played around with it a bit. I'm sure someone on here will give you a hand with it.:grd:

countrycoach
07-15-2005, 04:13 PM
Is there any way you can explain it to me over the web? I am pretty mechanical but I don't know all the abriviations and technical stuff. I just know how to take stuff off and put stuff on and things like that! lol

wild willy
07-15-2005, 05:09 PM
countrycoach I just had a dude do it for me and use his tech II to set the hole thing up and it cost me a buck sixty five. He had some special wrenches that look like an S curve and slightly offset. I wasn't there while he did the deed but just as he was cleaning up. It is set at -1.94 for TDC offset and it seems to run well. Started easier and hard to tell it seems to have less smoke on startup.

countrycoach
07-15-2005, 05:23 PM
So do you have to have the tech two? I would love to get this done tonight if I can do it my self cause tomm night is a dhra race at Rockingham Speedway and every little thing helps. Please someone let me know what to do.

Thanks John Kruckeberg

Firefighter
07-15-2005, 06:55 PM
You don't need a scanner to do it but I used a Snap-On Mt2500 to do mine. No special tools involved either. Just a socket to get the upper intake off, a screwdriver to take of the top of the pump, and a T40 or 45 socket to loosen the bolt holding the optic mount. Once you have the top off the pump, before you loosen the T40, take a scribe and put a light mark on the ring along the passenger side of the optic sensor to mark the original location. Now loosen the T40 and move the optic sensor to the passenger side about 1mm. Put it all back together (don't forget the ground wire on top of the pump cover) and see how she runs. You can repeat the steps above untill it either starts to idle rough or you get an SES light on the dash, then back it off 1mm at a time untill it runs smooth again and voila! You have now done the optic bump! If you know someone who has a scanner, it is even easier to get it bang on. You will be able to without one with a little more trial and error. Just go through the steps until you have no SES light, rough idle, or driveability issues like studders or such at various speeds. :grd:

countrycoach
07-15-2005, 07:43 PM
Thanks ff I will give it a try tomm. As far as the t40 or 45 that is a torx type bit isn't it?

quantum mechanic
07-15-2005, 08:50 PM
countrycoach I just had a dude do it for me and use his tech II to set the hole thing up and it cost me a buck sixty five. He had some special wrenches that look like an S curve and slightly offset. I wasn't there while he did the deed but just as he was cleaning up. It is set at -1.94 for TDC offset and it seems to run well. Started easier and hard to tell it seems to have less smoke on startup.

Setting the timing range (TDCO) and the "BUMP" are two different things.

Texas Diesel Guy
07-15-2005, 08:54 PM
Yes, Torx 40 for the Optic sensor hold down, and Torx25 for the top cover screws.

PM me with your # if you need help when you get at it.

countrycoach
07-16-2005, 02:02 AM
thanks tex will do. I think I can figure it out. Right now I am chasing a low fuel presure problem.

MDT
07-16-2005, 04:03 AM
Optic bump is a trial and error art. I had to move mine 8 times before I got it where I liked it. 5min. job, I don't have upper intake in the way.

countrycoach
07-16-2005, 05:46 PM
Hey guys,

Ok I did something now I can't get it back right. I don't understand what you are supposed to be moving. I losend the screw and used a screw driver to move the whole thing and then tightned it back down. But even with it tightend down you can still move the whole thing back and forth. Now it is runing extremely rich and has a very rough idle but no ses light. I loosend it too much one time and the whole thing came apart but I was able to get it back together. So now what do I do?

quantum mechanic
07-17-2005, 12:24 AM
Did you look at CR's pictures from his bump. You're setting the square part of the sensor relative to the lock plate.
http://www.dieselplace.com/forum/uploads/BZE_afterbump4.jpg
Don't worry if they both move you're not changing anything if the sensor is tight.
The rough idle sounds like you bumped it too far and you should move it back toward the right a hair.

countrycoach
07-17-2005, 01:49 PM
Yea I finally figured that out last night. I just sat there and stared at it till I figured out what had changed. So I got it runing again and just stoped messing with it. I have to go back and fine tune it to get it right. Thanks for the pics!