i know the first thing i'll get it did you search and yes i did. i'm curious as to how one would perform an optic bump(i know you have to move the sensor maybe a dime's width) and what tools i'd need. i'm wondering if a scanner is needed and what i'd have to remove to get to the location of the optical sensor. if i've got to remove a lot of stuff it's not getting done, at lesat not yet. i've been reading it gives you more power and can also give better mileage and at $4.89 a gallon i need all the MPGs i can get. thanks everyone.

sensor? scanner? no, and no.

Maybe do a search, whole meal deal is there, for the searcher to behold.

you're welcome

sensor? scanner? no, and no.

Maybe do a search, whole meal deal is there, for the searcher to behold.

you're welcome


if you could read my post i did search. all your doing is trying to fight with me, go ahead try to fight with me and i'll report it. simple as that. knock it off.

I have my eye on this thread. Keep it civil.

Tony

nope. just sayin' is all.

everything is there that you want, I just did a search...to verify

No fib

Though it has been posted before, it was hard for me to find a good post with the information, so I don't mind answering.

Dave, I don't have pics, but in a nutshell what you want to do is remove the cover of your IP. I believe that they are T10 or T12 Torx bolts. Careful not to pull the harness apart, as there is a harness that connects to the cover. Underneath the cover there is a T40 torx bolt. It is torqued down pretty good, I actually got a 1/2" drive socket and used that to break it loose. Then, what you want to do is look at it closely. The torx bolt goes through a bracket looking job into the Optic Sensor. Along the passenger side edge of the bracket is where I scored it to mark where it originally was. Also, note that the whole assembly will move side to side without much effort, so I scored the location into the IP body.

Next, I took a screwdriver and put it between the bracket I mentioned earlier and the side of the IP casing. Then, using another screw driver, I used the leverage of the IP casing and slightly pushed the OS to the passenger side. You can tell if you have the right part if the screwdriver is kind of tight fitting along the drivers side.

Move about a millimeter, then torque down the Torx bolt and continue to reverse the process.

I need to try bumping mine a bit more. I was a bit on the conservative side in my bump, though I did notice a decent amount of improvement.

Good luck. If you can't find anything searching, PM Me. I'll go take some Pics and email them to you.

thanks jbsaxman. how's the truck running by the way?

It's running as good as can be expected, considering I wasn't able to replace my bad piston and I have a slight knock from from that cylinder, though I think it might be air in the injector line. I also have an oil leak, but I also think that is caused by a bad CDR, I am just strapped for cash right now. $3100+ in a month an a half on my truck is hard to swallow. I am going to try and bleed that injector again tomorrow. If I have time, I'll re-do my optic bump and take some pictures. PM me your email address and I'll email them to you.

Does someone have pictuers of the process? I'm kind of a visual guy and that would at least help me a ton.

I found the best picture on pirate 4x4 message board. That forum is HUGE, but it honestly was easiest to find over there.

http://www.pirate4x4.com/forum/showthread.php?referrerid=57133&t=393142

About searching: this thread was number 3 on google images search of "optic bump", and took about 4 seconds. So when someone says "search", try google also.

Jay

That was great, Thank you.

http://www.mamut.net/royh/newsdet9.htm

http://www.dieselplace.com/forum/showthread.php?t=37960&highlight=optical+bump&page=2

there is a pic on post 13..


and yes the bump made a difference on the burb...doesn't kick down pullin' hills with the cruise on...

I have been thinking about doing this for a while now, but haven't mustered up the courage. I have already done the "feed the beast" and I think this would be a nother good advantage. About how long does it take to do? Is there anything I can permanantely mess up by doing this? How do I know if I have "bumped" too far? How much of a difference did you guys really notice from doing this?

Thanks, Jacob

took me about 20 min's...if you go to far your SES light will come on...take a awl and mark where it is before you start...if gave mine more mid range pull(1500 to 2000 rpm's) and doesn't crank near as long to start...

Well, I tried this tonight. I got everything apart and done the first time when I got to thinking after everything was back together that I moved it the wrong way. I looked at the picture on here and sure enough, I thought it was the square piece with the screw on it that had to move towards the passenger side, but after looking at the picture saw that it was the bottom piece that had to move. So, I took everything back apart and moved it so that the space between the top square and the line I had scribed got larger. Had everything back together this time in about 15 min. Started right up with no SES. I am going to go try it now to see if anything changed.

How do I know if I can go farther, or if it just right or what?

Thanks, Jacob

Drove it around for a while with no problems and no SES light. There was a noticable change, and more black smoke. As for the shifting, it is deffinately different than it was, but I have not come to the conclusion of whether or not it is better or worse yet. The shifts are a lot smoother in that you can't feel them as much as you could before, but it seems to shift at different RPM's than before. What do you guys think?

Thanks, Jacob

Higher RMP shifts? Does the seat of the pants gauge tell you anything? Do you like it? what do you have your boost set at? I'm thinking about trying this,, Hmmm what shall I tell my wife as to why I'm ripping into my just fine running truck? LOL

Tell her it's a fuel-economy thing... women seem to fall for that one

okay so im a little confused. just to clarify, the square plate under the screw doesnt move right? the whole big peice under that that slides toward the pass side? so what are you marking, the relationship of the square plate to the big peice? so basically just take something sharp and draw a line along the square plate? sorry i read it all like 4 time and i just wanted to clarify before i did it wrong. also, negative effects of doing this? THANKS

okay so im a little confused. just to clarify, the square plate under the screw doesnt move right? the whole big peice under that that slides toward the pass side? so what are you marking, the relationship of the square plate to the big peice? so basically just take something sharp and draw a line along the square plate? sorry i read it all like 4 time and i just wanted to clarify before i did it wrong. also, negative effects of doing this? THANKS


yes, you have it right. hold a screwdriver against the passenger side edge of the square plate an pry on the big piece underneath with another screwdriver from the drivers side. What you are doing is moving the bottom piece in relationd to the top piece. The space between the square plate and the line you scribed along it to mark the stock location should get larger the more you push it towards the passenger side.

Hope this helps.

thanks, thats what i thought but was just checking.

Tell her it's a fuel-economy thing... women seem to fall for that one

LOL you da' man Jifaire!!! :D

Is there any ill effects to doing this?,, other than using more fuel,??,,, as your flooring it all the time to see how well it's working??:eek:

Ok after searching somemore,, I see that a few of the great ones, both here and at the DTR.com site,, dont' think this is a wise move. For what reasons, I can't seem to find.
If I could get a little performance from it, WITHOUT hurting anything,, then I'll try it this weekend. But if Bill Heath is said to of looked at you funny when you mentioned it,,, I get to thinking ,,, well lets just say, that some of that nagging chit my wife say's about leavin well-enough alone, starts to chime in my ears. followed my a big Homer DOH!

Well after doing a lot of reading and thinking I had it down I spent the day doing the optic bump on my 96. It turns out, from what I can figure, that my scanning software indicates positive TDCO where most other scanners indicate negative TDCO. I'm using OBD-2.com's program and cable for my laptop. Here's my results for today, I'll let you all be the judge.

Started with a TDCO of 1.23 and all the general consensus says to set it at -1.5 to -1.94. So I figure I'm way out and will see big gains. Off with the upper intake and the top plate on the IP, everything looks normal. I loosen the T40 and adjust the pump part under the locking plate closer to the passenger side. Should make TDCO go towards the negative, right? Got 2.46. Hmm. After all that reading I went the wrong way. It's happened before. Didn't even drive it. Amazing idle though, the LOD meter on the scanner dropped from ~25% at idle to ~10% and the throttle was really snappy.

So, readjusted it and got it to a -1.08 after a couple of trys. Took it for a drive and WHAT A DOG! The truck would barely pull it's own weight up a hill, the shifts were brutal, and the load meter was showing about 40-45% at idle. On accelerating from a stop the load meter would show around 80-90%. It was no wonder the PCM was telling the tranny to hit hard. So I'm thinking after about a 40 mile test drive that there's no way this'll pull the horse trailer even empty. I pulled out into a lane and almost got T-boned it took so long to accelerate.

Right now I've got it adjusted back to +0.88 and it's tolerable. Transmission shifts much better and the truck can get out of it's own way. I'm going to try for +1.7, +/-.2 tomorrow.

I THINK the moral of my story is that some software reads TDCO differently and I got one. If I recall correctly someone mentioned a SnapON scanner that read TDCO in a strange manner. Unless you know how your scanner reads TDCO, your first move is just to see what you're scanner is reading. From a performance-gain perspective, the instructions for adjusting TDCO in this thread are correct. My meter was bas-ackwards.

Comments welcome, I'm outa town Saturday morning pulling a full load to Burning Man. :D

man am i lost. basically all we do is move it 1 mm to the passenger side of the truck

heeath strongly does not recommend doing this. i never did this to my truck after hearing that. if heath opposes it its probably for a good reason. the computer swap from stock to HP4 gave my truck all the throttle response it even needed over stock.

heeath strongly does not recommend doing this. i never did this to my truck after hearing that. if heath opposes it its probably for a good reason. the computer swap from stock to HP4 gave my truck all the throttle response it even needed over stock.

Now the truth comes out LOL, just kidding.

Optic bump and -1.94 setting are two different things, from what i've read.
The -1.94 TDCO setting requires moving of the IP.
The optic bump requires moving the optic sensor.
Optic bump sounds like more of a shot in the dark to increase power and throttle response..........Whereas the TDCO is more controlled and can be helped and checked with certain scantools and software.

This is just my understanding of these two procedure's from what i've read................I'm sure someone will chime in with more technical info

JMO.....maybe I am wrong, it's happened before.


Louis

After hearing that Heath is against the optic bump, I had to ask a Diesel fuel injection specialist who is very knowledgeable on the 6.2/6.5/DB-2/DS-4. According to him, there is no danger other than over-doing it. Stop and think about it, IIRC, a Diesel fuel injection specialist first brought this trick to DP. For this reason, methinks that almost all 6.5 vendors/specialists will say not to do the optic bump purely to cover their rump. If they told someone that had no clue what they were doing that the optic bump is safe, and to go ahead and do it, then they may end up getting a major headache.

http://www.dieselplace.com/forum/showthread.php?t=14231&highlight=Optic+bump

Plenty more where that came from, search "Optic Bump"


Louis

Optic bump and -1.94 setting are two different things, from what i've read.
The -1.94 TDCO setting requires moving of the IP.
The optic bump requires moving the optic sensor.
Optic bump sounds like more of a shot in the dark to increase power and throttle response..........Whereas the TDCO is more controlled and can be helped and checked with certain scantools and software.


Ah, but, every time I did the "optic bump" and did the PCM re-learn (key-on-accelerator down for 45 seconds-key-off for 30 seconds) my scanner showed a change in TDCO (Top Dead Center Offset). I also tried a couple of re-learns without moving the optic sensor and there was no change in TDCO. This is just one of two different ways to adjust the initial timing on the pump. The other way is to loosen the pump bolts (much harder to get to) and move the pump body (with optic sensor inside) in just as precise of a move as you do the optic sensor.

Unlike some of the threads I studied I could definitely feel differences in power and I could see the differences in the EGT and the %load meter. I just have not yet nailed that magic 1.94 yet..:D

Mike

LOL you da' man Jifaire!!! :D

Is there any ill effects to doing this?,, other than using more fuel,??,,, as your flooring it all the time to see how well it's working??:eek:


After I did this, the only 'ill effect' that I noticed was that when I tapped the TPS (accelerator pedal) expecting to see a 100 or 200 RPM change, it jumps just a bit more, like 300 or 400 RPM. I had read that this is a side effect of the Optic Bump.

Ah, but, every time I did the "optic bump" and did the PCM re-learn (key-on-accelerator down for 45 seconds-key-off for 30 seconds) my scanner showed a change in TDCO (Top Dead Center Offset). I also tried a couple of re-learns without moving the optic sensor and there was no change in TDCO. This is just one of two different ways to adjust the initial timing on the pump. The other way is to loosen the pump bolts (much harder to get to) and move the pump body (with optic sensor inside) in just as precise of a move as you do the optic sensor.

Unlike some of the threads I studied I could definitely feel differences in power and I could see the differences in the EGT and the %load meter. I just have not yet nailed that magic 1.94 yet..:D

Mike

Does the PCM relearn on its own after a while or do you HAVE to do this?

Check out this very old post from 03 and make up your own mind.



http://www.dieselplace.com/forum/showthread.php?t=15792&highlight=optic+bump

Ah, but, every time I did the "optic bump" and did the PCM re-learn (key-on-accelerator down for 45 seconds-key-off for 30 seconds) my scanner showed a change in TDCO (Top Dead Center Offset). I also tried a couple of re-learns without moving the optic sensor and there was no change in TDCO. This is just one of two different ways to adjust the initial timing on the pump. The other way is to loosen the pump bolts (much harder to get to) and move the pump body (with optic sensor inside) in just as precise of a move as you do the optic sensor.

Unlike some of the threads I studied I could definitely feel differences in power and I could see the differences in the EGT and the %load meter. I just have not yet nailed that magic 1.94 yet..:D

Mike

Thats why I think the "bump" is more of a shot in the dark............much more controlled way to achieve -1.94 TDC Offset is with scan tool and IP wrenches.

so your changing the timing of the pump? doesnt a chip do this, with a tm and doing this is there a reason for the chip?

Chip or reflash is much more technical, changing many variables of the engine to work with each other much more effeciently and controlled.
The bump would never achieve the gains that come with a reflash/chip. IMO

I installed my ECM from Heath last weekend...straight from Heaths instructions...

2.
Anytime an ECM is replaced, it is recommended that the ECM and fuel injection pump be coordinated by way of the "TDC OFFSET LEARN" procedure. Any GM dealer can accomplish this TDC Offset Relearn, which will provide an opportunity to establish the timing offset at the minus 1.94 setting we recommend for peak engine performance.

Installed my ECM and the black smoke is worse. I don't feel comfortable doing the TDC offset myself, but then again I don't trust the dealership. I also haven't removed the vacuum pump and the EGR so that could be it as well. I may give Heath a call tomorrow. If anyone has done this before, would you mind PM'ing your phone number just incase I have questions. I doubt i'll try it this weekend but may depending on the schedule.

Thanks,
Cody

Ok now I am really confused, if I understand the last comment correctly Bill Heath suggests I take my truck to a stealer and pay them to key-on-accelerator down for 45 seconds-key-off for 30 seconds........??????? Now I am no truck mechanic, but I am pretty sure I can accomplish this much, especially if I had already managed to install Heaths upgrades, I don't get it.

Also what happens if you do an optic bump/relearn then install a Heath ECM after? Are you just plain screwed? The reason I ask is I dont have the funds for Heath ECM right now , I could do the optic bump tommorrow but wonder what effect that will have after I do install the ECM in a couple of weeks?

Ok now I am really confused, if I understand the last comment correctly Bill Heath suggests I take my truck to a stealer and pay them to key-on-accelerator down for 45 seconds-key-off for 30 seconds........??????? Now I am no truck mechanic, but I am pretty sure I can accomplish this much, especially if I had already managed to install Heaths upgrades, I don't get it.

Also what happens if you do an optic bump/relearn then install a Heath ECM after? Are you just plain screwed? The reason I ask is I dont have the funds for Heath ECM right now , I could do the optic bump tommorrow but wonder what effect that will have after I do install the ECM in a couple of weeks?

The reason he says to take it to the dealer is you need a scan tool to accuratly set it. It also requires moving the pump to set it.

Optic bump and TDCO relearn are two different things. Heath actually suggests not to do the bump. Relearn, there's no reason you can't do it, install ECM, and do it again.

:smoke2: Thanks dude!

So the end result to performing the bump is increased fuel economey and power? In a summary can anyone comment on how that occurs from bumping the sensor, in a very basic way, does it increase fuel injected or...?

Just for interest.

Tony

PS - Seems like a good thread to add to FAQ, JMO.

hi chris

Use Search j/k

If I knew I would help you :)

by moving the Optic sensor you are adjusting point that it reads the timing so in essence you are adjusting the timing either by advancing or retarding what ever it was set from the factory with. this is my understanding of it so correct me if im wrong. when you adjust the timing for the injection pump you are adjusting the point that the fuel is injected in the combustion chamber. so there is no change in how much fuel is injected the change comes from having more time for the fuel to burn resulting in a more complete burn of the fuel. so more power and more economy from the same fuel doing more work!

Justin

Thanks for the insight Justin, your take on it makes sense to me.

This (http://www.dieselplace.com/forum/showthread.php?t=10790) contains a lot of information on how our pump works, and what the optic bump does.

This (http://www.dieselplace.com/forum/showthread.php?t=10790) contains a lot of information on how our pump works, and what the optic bump does.

did you find that using the search function, RC?):h

did you find that using the search function, RC?):h


I did, just not what I was looking for. Kind of an accident, but I thought of this thread as I read it.

Well I found this place called Chatham Fuel Injection, they are about 1 hour away from me. Read through a lot of their website, and decided to shoot them an E-mail asking about doing an optic bump on the DS4 pump, and what they thought of it. Also requested some flow numbers and specs on their +40hp injectors versus the stock injectors. If they give me some answers I'll post them, as after looking over their site, it seems like they have a metric ton of experience, and the most advance equipment, bonus I can drive there!

Well I found this place called Chatham Fuel Injection, they are about 1 hour away from me. Read through a lot of their website, and decided to shoot them an E-mail asking about doing an optic bump on the DS4 pump, and what they thought of it. Also requested some flow numbers and specs on their +40hp injectors versus the stock injectors. If they give me some answers I'll post them, as after looking over their site, it seems like they have a metric ton of experience, and the most advance equipment, bonus I can drive there!

Think you will find they don't have the facilities or know how to flow test a 6.5L injector. If they do ask for some pics. i'd like to see it.

Specs they may have. I already posted that here.

Well if I get an E-mail back, and am in need of some parts (or just really bored) I might just stop by there and take a look for myself.

ok, maybe i missed it but im trying to figure out if the optic bump we are doing is retarding or advancing the timing of the injection cycle? and also if the point of injection is before or after Top Dead Center before the bump and also what it is after the bump.

Dracor85, I was also wondering, I mean if it advances the timing, then why does it kick out more black smoke? (or so I've been told).

Dracor85, I was also wondering, I mean if it advances the timing, then why does it kick out more black smoke? (or so I've been told).

Thats a good question, if its buring fuel more effiently and advancing timing then why more black, which is wasted fuel?

Did Bill Heath give a reason for not recommending it?

wouldent advancing the timing make the injection happen later in the cycle and retarding the timing make the injection happen earlier in the cycle? if so then advancing the timing would make sense for more black smoke, and retarding the timing would make more sense for more power and more mpg. so you would think that the optic bump would be retarding the timing.... any one know if this is right or if its backwards?

What I would really like to do is put my truck on the chassis dyno, get some good solid numbers, then do the optic bump and make a few more pulls, see if there is a difference. I run the Heath GLE PCM so I'm very skeptical on doing this to my truck. I personally am not going to (apparently Heath doesn't recommend it). Now, if I had the stock PCM I would do it, and dyno test it. When I get the new injectors in my truck, and spring rolls back around I plan on doing some dyno testing, and testing out some of my own ideas.

As far as the timing part. I always thought that advancing the timing would make the start of injection point closer to or before Top Dead Center. Hence when I got a code (P1214 I think) my injection pump was too far advanced, and the engine would "knock" louder (if that's the correct term), so I rotated it towards the passenger side and problem fixed, no loud "knock". I am thinking that is why our trucks sound louder when they're cold, timing is advanced.

chevyinlinesix i would have to agree with every thing you said. i may have been a little mixed up in my thoughts of advance and retard, but thats why i was asking about it. I would love to have some dyno time to try diffrent settings with the optic sensor as well as with the Heath chip. im gonna have to check into local dyno shops to get a base run in before i do any thing to my truck.

http://www.dieselplace.com/forum/showthread.php?t=28752&highlight=optic+bump

I just tried this on my truck and now it starts really hard. It cranks for along time before it starts. I was wondering if it takes the computer so time to adjust to this or did i move it to much?

I believe the computer is "blind" to this change (it doesn't know that you've done it, but don't quote me on that, just telling you what I've found from reading a whole lot of posts on this topic) so it shouldn't need to adjust for anything. Hopefully someone else with more experience will answer your question about the hard starting after bumping the optic sensor.

Oh cool, I finally get to tell someone "Welcome to The Diesel Place!" I've had a lot of people on here help me with my problems, either by posting new threads, or by using the search function on the website. It's definitely an active site, and a very good one at that with many knowledgeable people with good ideas.

The search function works great, as long as you take the time to figure out how to use it. I just always choose "advanced search" from the drop box, as it really narrows down the results so you don't have to look through 500+ pages of unrelated information.

I just tried this on my truck and now it starts really hard. It cranks for along time before it starts. I was wondering if it takes the computer so time to adjust to this or did i move it to much?

Did you do the re-learn proceedure when you adjusted the pump or optic sensor?

I unhooked the batteries for a while, but i didn't try a relearn

I just tried this on my truck and now it starts really hard. It cranks for along time before it starts. I was wondering if it takes the computer so time to adjust to this or did i move it to much?

Computer is blind but the IP cam ring isn't you have mechanically advanced the optic sensor beyond the range it is supposed to work at.

This is but of one reason many of us poo-poo the idea for optic bump, if you do it incorrectly you have operability issues, since computer is blind it doesn't know how much it's moved and can not properly control the TSM as it thinks it is starting from within the normal "window" of timing advance of the cam ring ramp.

These bumps gone too far really rear their ugly head when cold weather comes, and PCM does a cold weather/engine time advance to get engine started/warmed up and optic is already mechanically where PCM wants to electrically take the timing, & TDG & QM the guys that promoted this bump as the be all IMO weren't the swooftest guys we had around these parts for what is best for the 6.5, bumps work but not for the novice to do, better is use TDC advance. -1.5 to -1.94 from factory of -.25 to -.75.

Best bet is to put optic back where it belongs and to a TDC offset, which after doing the TDC learn the PCM will know were the optic is and advances/retards in timing are corrected accordingly.

But what do I know I'm just an infrequent tourist here

But what do I know I'm just an infrequent tourist here

Holy Diesel Smoke!

You logged back in over on the other site. :D