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Thread: No actual ip timing signal

  1. #21
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    That tiny bit of color should not even be seen in 40 gallons of fuel.
    (1) 1995 Suburban 2500 4x4
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    THIS IS BOW TIE COUNTRY

  2. #22
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    That's what I was figuring, but with the discussion of how finicky the optical sensor is I wasn't sure.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  3. #23
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    Default Well well well

    Guess i cracked the whiskey bottle too soon...

    Their baaaaaaaaaaaack.



    Went out and started it up the next day to warm up so i could to the time set/tdco, and got distracted.
    Shut it off and about 1/2 hr later went back to start it, and they were back. Fooled with it over the weekend, and same as before, HARD codes. Also back to 0.0 on the actual pump timing. I can clear it with Key On, Engine Off, and it comes right back. Check the commecter at the pump and have good power/ground.

    1. Will it set those codes if the OS is too far out of adjustment? And if so, will they go away on their own once its in adjustment, or do they have to be cleared?

    2. Does the engine have to be under any certain parameters to use it, or is it as soon as you crank it?

    3. I cant do the timeset or tdco if there is a code, so that sucks. Any other way around it?

    My current tdco shows -2.54, and wont change no matter where i move the pump. So i assume it is just “stuck” at the last reading it had when the OS quit working? And just stays at that figure until is gets corrected?

    Does anyone have advice on basically “starting over”?

    I have moved the pump and the optic so much, im sure they are out. So how can i “start over” like i was installing a pump without a timing mark, and replacing the OS at the same time?
    Its the perfect storm, lololol

  4. #24
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    So something interesting i just found.

    I have removed my original inlet to the IP, and installed a brass t-fitting. So i have my fuel pressure gauge plumbed into this tee.
    I have had good fuel pressure, as i should with a new holley pump, water separater/filter, and no more fuel module.
    All 3/8 line.

    I took the top of the pump off today and it was EMPTY. So i key on and have fuel pressure at the inlet tee, but the pump body remains empty. Command the pump to stay running with the tec2, and nothing... 13psi at the inlet, and the pump remains empty.

    I needed to get back to work, so i didnt get a chance to crank it or anything, im gonna do that tonight.

    Any ideas?


    Edit results.
    Messed with it tonight, had to crank it a good bit to get the pump full. Started to come up in bubbles through a little hole in the back right hand side of the pump inside. But the whole time i had steady 13 psi at the inlet.

    Also...lol... i went to roll the engine over by hand to check the OS ring. I turned it a good bit and felt a clunk, i was like “thats not good”.
    Turned it back, and clunk. Sounded like a rod. It is the balancer hitting the bolts!!!! Completely shot. I have a new one already, so just gotta slam it on.
    No way that could give me the IP issues though right?
    Last edited by High Toned SOB; 04-17-2019 at 17:47.

  5. #25
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    So i got the new balancer on.
    Here are some pics of my optic, is it “normal” to look like it was getting chewed on by a rat? Fuel temp still reads, so i know that part still works. The biggest wall im up against in the troubleshooting is where i need to use a meter that reads mhz. My fluke is older and i dont have that function.

    Since the actual timing is read by the OS, i guess im gonna order one. Problem is i have a dude out here parting out a 93, i can get the pump, pedal, and trans controller for the same price as a new optic.
    What to do, what to do
    Attached Images Attached Images

  6. #26
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    Also wanted to pass on a couple pics i took that might help someone out. At first, i was NOT adjusting the OS correctly. I scribed a line on the OS itself, beside the holddown thing that the bolt goes through. Not the camring

  7. #27
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    Quote Originally Posted by High Toned SOB View Post
    So i got the new balancer on.
    Here are some pics of my optic, is it “normal” to look like it was getting chewed on by a rat? Fuel temp still reads, so i know that part still works. The biggest wall im up against in the troubleshooting is where i need to use a meter that reads mhz. My fluke is older and i dont have that function.

    Since the actual timing is read by the OS, i guess im gonna order one. Problem is i have a dude out here parting out a 93, i can get the pump, pedal, and trans controller for the same price as a new optic.
    What to do, what to do
    Buy the mechanical conversion stuff.
    The pictures of the flat black box on the cover,What is it?
    I changed the optic sensor in one of my trucks and don't remember that.
    I was having electrical issues constantly with my 98.Went through a couple of remote mounted PMD's,optic sensor,ignition switch,the list went on.This sucked more than normal because it was a tow truck and not used as a daily driver,sometimes it would sit for weeks..Having issues in remote Yukon in the winter isn't exactly fun or warm.

    I had been collecting the parts needed for the conversion. Then one day i went to start the truck after i drove it into the shop,it would crank but no fire.That was the last straw,so i began the conversion.Truck started right up after it was a mechanical injection truck.Never had any more issues till the crank became a two piece crank.
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  8. #28
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    Yukon i assumed that was the fuel temp sensor and maybe some kind of conversion box for the OS.
    It looks like if you take the snap ring off the top, the connector would come out theough the bottom of the lid, and that black box is just part of it.

    I really dont want to convert, because i teally dont plan on keeping this truck. I have a few others, but none are electric.
    But i might just buy the stuff since its a deal.

    Im am pretty mich convinced at this point the OS is dead. Parts stores dont list it, so i guess ebay?

    Does anyone have any specs for like resistance of the OS?
    Last edited by High Toned SOB; 04-19-2019 at 11:56.

  9. #29
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    Quote Originally Posted by High Toned SOB View Post
    Yukon i assumed that was the fuel temp sensor and maybe some kind of conversion box for the OS.
    It looks like if you take the snap ring off the top, the connector would come out theough the bottom of the lid, and that black box is just part of it.

    I really dont want to convert, because i teally dont plan on keeping this truck. I have a few others, but none are electric.
    But i might just buy the stuff since its a deal.

    Im am pretty mich convinced at this point the OS is dead. Parts stores dont list it, so i guess ebay?

    Does anyone have any specs for like resistance of the OS?
    When i changed mine i got one from a dead pump,i got lucky and it was a good one.
    Buy the stuff for later,it's getting harder to come across.
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  10. #30
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    Default Updatess

    So i got a used optic sensor and slammed in it my pump. Now everything is reading, i am gonna attach some pics..



    But.........

    Now it is starting right up at 1000rpm. Within 5 seconds it will creep up to 13-1400 and stay there. Meanwhile, it has a fishbite/miss steadily every 1/2 second, pretty fast.
    It revs great, SUPER responsive. I love that. But theres no way you could put it in gear without punishing the trans...

    Fyi, when i got this truck i put a new EBAY PMD on it. It would start and immediately rev to 4k, then drop to idle, back to 4k, idle, etc etc. smoking badly the whole time. The new pmd fixed that.
    It has about 5 hrs of run time on it. Relocated to the grill area. How could it be bad again?

    But at least the optic is reading now, im thankful for that. Now this coincidental new issue..

  11. #31
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    My tdc offset is at -1.54 i think i will leave it until i get this new problem figured out.
    Its reading 0mm of fuel. So the computer is pulling fuel trying to slow the engine down, but the pmd is still fueling.
    So it looks like the pmd just randomly crapped out after 5 hrs of use. At the same time it decided to run good

  12. #32
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    Sounds like the PMD needs to be tested at the lake.
    What kind did you get?
    I bought a aftermarket one that didn't last very long,they replaced it and the next one started to act up shortly after as well.
    I ended up using a used stanadyne till something happened and the truck would not start.At that point i had had enough and the mechanical conversion happened.
    The truck started right up once the mechanical pump was inline,ended all the electrical issues the truck had.
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  13. #33
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    Well i messed up again. The reason it was missing at idle was thefuel was at 0-1mm. It seemed to rev good and very responsive, but idle was terrible in park or nuetral ONLY. In gear it idled great.

    So i moved the OS TOWARDS THE DRIVERS SIDE AND IT GOT ALOT BETTER, but had a mild surge. So i moved it a little more and ended up at 4mm idle and it was smooth.

    But i lost a lot of my responsivness. So that sucks. Now its just “normal”. Timing is good, act and desired match.
    Tdc is -2.54, so i am gonna work on that a little.

    Cant beleive the OS is as “touchy” as it is. When you guys say “barely” move it, you mean “barely” move it, haha.

  14. #34
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    Quote Originally Posted by High Toned SOB View Post
    ....Timing is good, act and desired match.
    Tdc is -2.54, so i am gonna work on that a little.

    Cant beleive the OS is as “touchy” as it is. When you guys say “barely” move it, you mean “barely” move it, haha.
    If your TDCO is that far off, you are in default fuel programming. -2.54 is pretty far out there. Get that correct (at least -1.94, any less and it'll code and default) at your soonest possibility, then address what's left, if anything. The PCM is pretty good and forgiving with correcting calibration variations, but if the TDCO is out of range, it can't.

    Yeah, "barely" is a lot, and often too much. Fractions of barely is sometimes too much. These are originally calibrated in an engineer's environment. Adjusting in place is like swatting mosquitoes with a shotgun or kite string. Not much in between.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  15. #35
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    Quote Originally Posted by High Toned SOB View Post

    Cant beleive the OS is as “touchy” as it is. When you guys say “barely” move it, you mean “barely” move it, haha.
    Yes it is! After going through what I did on swapping the OS on my '95, I vowed to never do that again! That's why all official documentation says it is not a serviceable or field replaceable part (should only be done by a Stanadyne dealer with proper test equipment). But, that doesn't stop folks from trying and getting lucky from time to time. The whole "optic bump" you read about online causes more problems than anything, in my opinion.

    Casey
    1995 K1500 Tahoe 2 door, 6.5LTD, 4L80E, NP241, 3.42's, 285/75R16 BFG K02's; 1997 506 block; Kennedy OPS harness, gauges, Quick Heat plugs, and TD-Max chip; Dtech FSD on FSD Cooler; vacuum pump deleted, HX35 turbo, Turbo Master, 3.5" Kennedy exhaust, F code intake; dual t/stats, HO water pump, Champion radiator; Racor fuel filter

  16. #36
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    Quote Originally Posted by DmaxMaverick View Post
    If your TDCO is that far off, you are in default fuel programming. -2.54 is pretty far out there. Get that correct (at least -1.94, any less and it'll code and default) at your soonest possibility, then address what's left, if anything. The PCM is pretty good and forgiving with correcting calibration variations, but if the TDCO is out of range, it can't.
    It seems like i have lost the “quickness revving reaponse” completely now. I really liked that, made it so much better to drive.

    Can someone explain simply the correlation between the OS and the TDCO (how they are different, if going from factory setting to -1.94 is just as good as an optic bump, etc). I am having a hard time understanding a significant difference.

    I slso snagged this tidbit i found from someone else for info;

    Quote:
    First off, lets cover the DESired timing issue first. There is NOTHING you can do about this. DESired timing is what your ECM determined to be optimal advance timing as calculated by temperature, load, throttle position, RPM etc. There's no "normal" DESired timing. 8.5 or so is a ballpark for a warm HD engine at idle, LD guys will notice lower warm idle DES readings (about 5 deg) because they have an EGR to warm the charge air entering the combustion chamber.
    Second is ACTual timing, this is the advance position the injection pump is ACTually at. All thats important here is that the pump is doing what its told. If your DES is 8 and your actual is 12, you have a problem, if DES is 8.2 and actual is 8.5 or 8.0 its fine. Now lets re-discern between 'Time-Set' and TDC Offset. Time-Set is a tool designed to help technicians get the pump in an appropriate position so that TDC Offset can be successfully relearned. Its a pretty good tool, but it CANNOT be solely relied on. Here's the trick, ALL 6.5L injection pumps should be 3.5 deg advanced from TDC (0 deg) crank. So the Time set function puts the pump at full retard (0 deg internal advance) and shows you how close it is to the 3.5 degrees you want. Here's the problem, whatever genuis wrote the code for doing the Time Set functions, and from what I've seen this is true on ALL scanners (Snap-On, Tech2, OTC you name it) all calculate the existing TDC Offset value into the equation. Because they are using an old and no longer accurate value, which will be the case any time the pump is moved or replaced, it will affect your reading. Now, to TDC Offset, As stated above, this is the calculated difference in degrees between 3.5 degrees before TDC and the full retard position of the injection pump. Thats ALL it is! When the pump is replaced, this must be relearned so the ECM knows that the injection pump is in proper position relative to the crank so that it can move its internal advance (ACT) to any position the ECM determines appropriate (DES). Different year models have different ranges for 'acceptable' TDC Offset. '94-'95 are the most finicky and the only ones that require a TECH1 or TECH2 to relearn and they must fall between -0.25 and -0.75. '96-'97 are quite a bit more lenient at something like -0.1 to -1.9 (don't quote me on those values)and can be commanded to relearn with the key cycle/pedal method and any scanner to read the data. For some reason '97s are the WORST about hanging while tryin to relearn and can cause lots of headaches if you don't know what its doing. It's caused by a programming error and I don't know if there is an update to fix it but beware! ~'98-'02s are even better, they actually relearn on their own just to check periodically. Acceptable to them is +2.46 to -2.46, thats a BIG window!

  17. #37
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    The OS is the sensor that reads the actual location of the rotor in relation to the rotor head porting (the moment in rotor rotation that allows for a fuel injection event at specific cylinders). If the OS is too far out of range, the PCM won't be able to fire a cylinder injection event with rotor not presented to a cylinder port. This causes the DTC's and default physical/mechanical timing and minimal fuel volume (default/limp). The "OS bump" is usually a temporary perceived improvement, as it's reset at the next complete diagnostic cycle (likely why your snappy throttle response went missing). Doing both, the OS bump and TDCO minimization can, and often does, default once all the values are realigned. If the physical ranges are exceeded, one or both, it will default. The OS bump is not advised, and can prevent proper pump timing correlation with the calibration. It's best to have it correctly calibrated, or within the middle of the acceptable range (the lucky shot), and leave it there. Mess with timing by updating the calibration (chip or programming), and/or TDCO.

    A simple comparison in old school language of the timing acceptable range might be that of a distributor cap and rotor on a gasser. The cam/reluctor of a distributor presents a range for spark timing, but the rotor contact must be in acceptable range of distributor cap cylinder contact before a spark happens. It doesn't matter when a spark is commanded, if the contacts aren't close enough to complete the arc circuit. The same applies to an rotary/axial fuel injection pump. If the injection event is commanded, but the rotor port isn't presented to a head port at that time (out of phase/range), the injection event can't occur.

    TDCO is the virtual compensation by the PCM, in relation to the physical index/rotation of the IP housing. The offset is the compensation value the PCM forces the timing into an acceptable range that can be varied and controlled. Too much physical advance (less than -1.94) and the PCM will determine it can not acceptably control timing variations. Setting the TDCO to a minimum creates a physical barrier that prevents the PCM from forcing more retarded timing. Fortunately, the PCM doesn't monitor the actual IP index at higher RPM's (like when under load). It "presumes" the index timing to be in relation to the previous measured, ideal condition (at idle), and compensates on a scale according to the timing map (the "calibration"). Setting the TDCO at -1.94 simply places the physical IP index timing at the edge of the range the PCM will accept. This results in the maximum timing advance before the PCM has a fit.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  18. #38
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    Quote Originally Posted by Yukon6.2 View Post
    Buy the mechanical conversion stuff.

    [snip]

    I had been collecting the parts needed for the conversion. Then one day i went to start the truck after i drove it into the shop,it would crank but no fire.That was the last straw,so i began the conversion.Truck started right up after it was a mechanical injection truck.
    So, what all is needed for the conversion? Is there a post/article that steps you through the conversion? I have a mechanical pump I picked up for the '94, but have been hesitant to do the switch until I know everything I need. The '94 has a 4L80E, but I also have a spare NV4500 I could swap into it at the same time to get rid of those electronics as well.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  19. #39
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    Seems I found my answer here: The DB2 Conversion Guide - by Bobbie Martin
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  20. #40
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    Quote Originally Posted by trbankii View Post
    Seems I found my answer here: The DB2 Conversion Guide - by Bobbie Martin
    Thanks for the link!

    Casey
    1995 K1500 Tahoe 2 door, 6.5LTD, 4L80E, NP241, 3.42's, 285/75R16 BFG K02's; 1997 506 block; Kennedy OPS harness, gauges, Quick Heat plugs, and TD-Max chip; Dtech FSD on FSD Cooler; vacuum pump deleted, HX35 turbo, Turbo Master, 3.5" Kennedy exhaust, F code intake; dual t/stats, HO water pump, Champion radiator; Racor fuel filter

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