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97.5 H1 Hummer 6.5TD need help

Will L.

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No on the resistor.

With timing so bad off or ip not right- what ever it is- I couldn’t say crank sensor is 100% bad, because with optic undone the crank sensor will let it runnbut barely. Yours may be so bad it should run with just it, but we dont know. Kinda the only change one part at a time thing biting here.

New ip- is it brand new or a reman? Do you still have the old one or was that from previous owner?


Definitely between rock and hard place. Unless someone else has ideas- it is start deciding which is less annoying to you. “Waste” money on new crank sensor?
Pull apart and verify timing isn’t off?
 

WarWagon

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Anything is possible, but, I have yet to get the IP gear to skip a tooth with all the pumps I have changed the same through the oil fill way. It's always been something else. IMO It's not possible to get it to skip a tooth. I will verify this on my project engine later today.

How is the diesel rattle? Combined with white smoke you may be thinking timing and be correct. My current project turned into a loss of compression requiring advance to the point of engine damage to run. Another 1992 project was eating the timing set key and keyway on the crank sprocket. Weird the things that affect timing, but, it ran fine before new parts so...

From your first post indicating the Stepper motor isn't doing anything on the IP... (Yeah, any codes?)
Extensive "Trons" troubleshooting steps for the IP buried in a PDF here:
https://www.thetruckstop.us/forum/threads/dtcs-cal-resistor-range-ds-6-5-db2-5-7l-info-online-from-stanadyne.26581/
 

mk1spyder

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What is the proper time set / TDCO procedure? I honestly don't remember exactly where I got it from but I think the place was located in TN I can do some more digging on that front see if I can find any receipts.

Is it possible I have the wrong IP? The thing is though it ran ok but I wouldn't say fantastic under the old IP either though.

I can't find any way to see if the IP gear is in time without taking the whole front of the damn engine apart which on a hummer means removing the entire cooling stack and ALL of your fluids too. Endoscope won't fit in there.

Now I'm worried I might have harmed the engine having timing this far off. Makes me want to just give up and toss the whole truck. This is such a waste of my time with such an old PCM / diag tool why does it not have the ability to reset to a fresh slate? It seems like it just learns on top of learns and gets so far out it can't run anymore.
 

mk1spyder

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I did some research and I def got the pump from diesel care may of 2017, so it is past their 1 year warranty at this point.

If I went to buy another one just to throw money in a dumpster fire what is the best place to get a trouble free unit?
 
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WarWagon

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I did some research and I def got the pump from diesel care may of 2017, so it is past their 1 year warranty at this point.

If I went to buy another one just to throw money in a dumpster fire what is the best place to get a trouble free unit?
New, not, patched/fixed/rebuilt... Site vendor @Burning oil
http://leroydiesel.com/product-category/fuel-delivery/

It takes a load with advanced timing to do damage. Idle just isn't enough heat. Just enough manual IP advance to clear the white smoke. I am assuming the glow plugs are all working and this isn't just a cold engine white smoke?
 

mk1spyder

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The diesel in the clear return line is clear and smooth not a single bubble plenty of flow/pressure that is not my issue. Aeroation is not my problem.

I don't want to just throw parts at it but I have no reason to believe the PCM is bad it ran fine before, the original CKP was probably fine, would a bad/new CKP cause it to run that friggin bad if the OS was fine? For future reference if I do the TDCO on the tech2 do I have to wait for it to switch itself to off or can I stop it when the new value is learned on the screen i.e. how long should that process take?

I doubt one tooth off would run that bad and it is progressively getting worse. I think the most likely is I just got a crap rebuilt IP from diesel care.
 

ak diesel driver

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The time set info you read about is OBD1. The only thing your worried about is the actual TDCO. If the CPS or OS is bad it can run pretty bad. I had a bad CPS that the scanner didn't show any missed counts. Started it with the CPS unplugged and it purred. Guy I got it from had it to several shops that couldn't figure it out.
When you unplug the CPS you do realize it will take quite a bit of extra cranking and when it starts it's in limp mode.
 

mk1spyder

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I did it again letting it crank plenty, with ckp unplugged it runs about the same.

With the OS unplugged it will not start, every 4 seconds of cranking it trys to bump but that is it.
 

ak diesel driver

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sounds to me like the crank sensor is bad or bad connection. I'd check that connection and the one for the OS to make sure you have good contact.
 

mk1spyder

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The wiring as far as I have seen thus far is in great shape so I doubt that is the issue but I will check from the PCM connector to the component per the manual.
 

Big T

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When I had the front of the engine off to replace water pump and timing chain on the ‘99, I had pulled the Crank Position Sensor (CPS). When I pulled it, the metal bracket came off the CPS. I just slapped the bracket back of thinking no big deal, it just holds the CPS in place. Wrong. The bracket and CPS go in one way. I went through hell trying to figure out the problem in a thread here and solved it with a new CPS. The symptoms you’re describing are very similar, though I am not suggesting a backwards installed CPS. More likely, just a bad CPS. AC Delco are the gold standard. $42 at rockauto.
 

WarWagon

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On another ride We went through several ABS wheel sensors and 2 ABS modules before the bad connection at the wheel sensor was fixed. Bad connections are not easy to find.

If new parts x2 isn't solving it replace the connector.
 

WarWagon

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1 tooth off?
@mk1spyder I attempted this with the engine I have on the stand. Officially this is IMPOSSIBLE to do. There is simply not enough room in the chain/gearcase housing to allow the IP gear to jump a tooth. The loose IP Gear hits the wall (top sides etc.) before it can un-mesh with the cam gear. It simply can not skip a tooth with the IP removed.
 

mk1spyder

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That's what I thought when I did it, I felt it hit the sides and thought to myself well that is a half way decent design to stop you from jumping a tooth. Now to be fair my chain could be stretched and have jumped a tooth on the cam to crank relations but it wouldn't explain it running fine and then as soon as I start messing with the TDCO it runs like crap. The first time I tried to set the TDCO I remember going through hell to get it to come up with the same results twice.
 

nobby

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@mk1spyder I attempted this with the engine I have on the stand. Officially this is IMPOSSIBLE to do. There is simply not enough room in the chain/gearcase housing to allow the IP gear to jump a tooth. The loose IP Gear hits the wall (top sides etc.) before it can un-mesh with the cam gear. It simply can not skip a tooth with the IP removed.
Well that's good to know and indeed makes sense, in my experience over the years diesels are indeed set up that way with tight timing housings for pump changes. Trouble is I have come into a job on a different engine after a prior mechanic did a pump change that ran like shit and indeed I found that teeth had jumped. So whilst it is most unusual it is plausible on some engines so until I see inside the cover to corrobate hard to rule it out and I have yet to see inside the timing cover of a 6.5 despite owning one for over 100,000 miles! Guess I should be thankfull LOL!

Cheers
Nobby
 

Will L.

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As for being a tooth off:
Usually the timing off is damaged chain or gears between crank and cam or someone took apart the front of the engine to do the ip swap and hit the oops button.

Otherwise the timing being off is a stepper motor not keeping up with either chain stretch, worn ip, cps issue, or jammed up traffic on the electron hiways.

My biggest bad timing issue as of late seems to be me getting taco bell when the wife decided she wanted pasta:cool:
 
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