Is the optical sensor adjustable on a 98-6.5?

[wlrdlr49]

I am replacing the optical sensor on my 98- 6.5. There is what looks like a pointer on it & the bolthole is elongated. Is it adjustable & if so how do you do it?

 

[guybb3]

I am replacing the optical sensor on my 98- 6.5. There is what looks like a pointer on it & the bolthole is elongated. Is it adjustable & if so how do you do it?

You are supossed to scribe a line where the old one is so you can put the new one back in the old spot. You can move it about 1 mm to one side (I foget which direction) and gain a little bit of performance. Search for "optic bump".

 

[wlrdlr49]

Well I guess I screwed up already I already took it off!! I will check out optic bump. THANKS !!!

 

[Acesneights1]

ooohh..Not good.

 

[Slim Shady]

Well I guess I screwed up already I already took it off!! I will check out optic bump. THANKS !!!

If you really don't know where the old optic sensor went, then you will need a scanner and a lot of patience. Start out with the cam ring centered and install the optic sensor dead center. This will get you in the ball park. Then look at your fuelr at eat idle it should be around 7 to eight maybe even 9 mm3 if you are on the money.

If not adjust the optic sensor to the passenger side if the fuel rate is greater than the numbers mentioned. If lower then you need to go the other way towards the driver side. Optic bumps are not for the faint of heart and can cause some real bad side effects if not done properly, *with a scanner*.

 

[wlrdlr49]

Thanx for the response! I am going to have to replace the pump. Is there a thread or an area on this site w/directions for replacing the pump so that I don,t mess that up?

 

[NVW]

Why do you have to replace the IP? The OS can be replaced

 

[wlrdlr49]

The encoder ring on the pump is bad.

 

[dazed]

Then look at your fuel at eat idle it should be around 7 to eight maybe even 9 mm3 if you are on the money.

I had to replace mine...and the fuel at idle on mine is 4.5mm3

The Truck is running great and more pedal responsive......Is it ok not to be at 9mm3?

Will less fuel at idle damage anything....my thought is less fuel consumption and less chance of fuel washing the cylinder walls down at long idle periods of low RPM....

My truck is a 1995...

 

[ak diesel driver]

IIRC Buddy said it should be around 7mm3

 

[buddy]

You can run at less than 7mm3 warm idle, but just know its not really less than that, you are just fooling the PCM. So the Optic bump is offsetting your commanded fuel rate. You might gain a little top end performance too. Although with a power program the optic bump is less useful when that same throttle response could be programmed in on the fueling curve. Actual fuel use is about 8mm3 at idle.

Having it at 4.5mm3 at warm idle is not too bad, its just real bad when you get down to less than that, where engine may have to hunt for idle fuel rate and RPMs, which can screw with coasting and shifting as well. The fueling can also be offset in the software, to correct the commanded fuel rate up or down.

Once youre done positioning the OS, I think its a good idea to run a TDCO relearn, and retime the IP if necessary.

 

[dazed]

So Buddy, when I finally get around to getting a chip from you.... I should set it back to stock at what... 7mm3, 8mm3, or 9mm3.
I know about having it less than 4...think i got it 2 to or 3mm3 and it would barely idle.

 

[buddy]

With any program having it set right should make the truck ride a little better, quieter and smoother perhaps. But if performance is the goal I think you would be ok. I would think 5mm3 as a minimum there for having a good feedback loop for the PCM, and youre about there.