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97 hummer has 6.5 turbo diesel engine lost power, doesn't do over 2500rpm

The cam system refers to the timing from the optical sensor that reads where the shaft of the IP is, which tracks at the same speed as the camshaft, which is half that of the Crankshaft.

So it is an IP code, but it can be caused by "blinding" the eye of the optical sensor with dark fuel, cloudy fuel or air bubbles. So far evidence points to most likely an OS failure, but the tests for air dont take too long and arent that complicated. 4psi pressure is enough that its not straining the IP at idle to pull a vacuum post filter. So although not necessarily a fuel pumping issue, this code can come on due to other fueling issues. Verifying pressure just eliminates the fuel lines from the LP to the IP as a possible cause. Although if you did not seat the fuel filter correctly it can still actually suck in air while there is pressure.

The fuel filter only goes down one way, it is keyed, so that is something to check. And make sure there is a gasket on it, not two or three old ones with it.
 
hey buddy thanks for help! it was OS (optical sensor),,, I do have ??? is there adjustment on the OS for reason,,
 
Did you find yourself a replacement OS?

Yes there is adustment. First you need to have a scanner. And you need to read the warm idle fuel rate in park. You adjust the position, laterally, of the OS, put it back togther, fire it up and want to see about 7mm3, give or take 1mm3. If it is out of range adjust the position and repeat.

Once that is done, you must run the TDCO relearn. You can initiate this with some scanners, or there is the key on key off (KOKO) method for OBD2 6.5 trucks. You still need the scanner to verify the final value is where you want it. TDCO is a value, but it represent a timing in some ways. You want a TDCO of like -0.75 to -1.5. A lot of people shoot for the max which is -1.94. Stock they set them to -0.25 to -0.75 TDCO. Setting the TDCO is setting the base timing, and in some ways it affects the fueling.

If you are only replacing the OS and not the whole IP then the IP should be in a position with a TDCO in tolerance, but if you never did a relearn yourself I would never assume the last person to time it did it correctly.

If you have to get into timing the IP, will cross that bridge....
 
I had pick up a used reman injection pump few days ago,, so took OS of it,,put it on and put back together and she fired right up,, has all her power back,, but idle a little loopy,, not bad,, thats why I asked about adjustment of OS,,, but tomorrow will try the new info,, and again thanks,, you saved us from a lot of work,, we would have change the hole IP,, you know your stuff
 
If you need a reference for the OS here are a couple, obviously youve already successfully swapped it. When adjusting the OS, pictures and info on the "optic bump" are helpful, because they bump it (move it laterally) to fool the PCM on how much fuel it is commanding. This is why the idle is loping, because its bumped too much and the PCM is probably sitting around 0-2mm3 of commanded fuel at idle, which makes it lopey, because of a poor feedback loop. When its around 6-8mm3 at idle the PCM can control idle smoothly. The bump also can make the fuel pedal more sensitive.
http://www.mamut.net/royh/newsdet9.htm
http://www.dieselplace.com/forum/showthread.php?t=14231&highlight=Optic+bump&page=2
 
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