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Old 02-09-2018, 10:19 PM   #21
Rig Wrench
 
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I almost guarantee his low boost hi egt is the cal. Almost every 870 that I see using the stock turbo does this woth the egr delete. When the tune is done it locks it in non egr mode. If you have a stock one and unplug the egr valve. It will do the same things. Often the tuner will put more fuel to it to try and overcome the lose pf power from the low boost, but it just runs hot then. Theres only a few people ive seen that can actually do the 870 right.could you havr the stock calibration put back in to try and see if it runs better?

Last edited by Rig Wrench; 02-09-2018 at 10:28 PM.
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Old 02-09-2018, 11:00 PM   #22
Leiffi
 
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Quote:
Originally Posted by allan5oh View Post
Does anyone know the max sustained get for the holset cm870 turbo?
EGT ? 760 celsius pre-turbo like any other turbo.
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Old 02-09-2018, 11:04 PM   #23
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High EGT at low load is actually good for fuel economy if it is because of VGT setting not pumping excess air to the engine. It might also be retarded timing to compensate lack of EGR which is not good.
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Old 02-09-2018, 11:11 PM   #24
Ram12vcummins

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Quote:
Originally Posted by Rig Wrench View Post
I almost guarantee his low boost hi egt is the cal. Almost every 870 that I see using the stock turbo does this woth the egr delete. When the tune is done it locks it in non egr mode. If you have a stock one and unplug the egr valve. It will do the same things. Often the tuner will put more fuel to it to try and overcome the lose pf power from the low boost, but it just runs hot then. Theres only a few people ive seen that can actually do the 870 right.could you havr the stock calibration put back in to try and see if it runs better?
I read this was a big issue. Was assured by the guy who removed diesel spec tune that his was a proper one and a few people vouched....not that it means they are right. The mechanic took the egr plug apart and ground out the contacts for some stupid reason instaead of just taping up the ends. I guess to look stock. The tuner assured he can tune it either way. I can try and see if we can go about trying out the factory tune. But how would that act with the egr deleted? I would also have to rejoin the wires which isnít that big of a deal.

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Originally Posted by T-MAN View Post
This is why i asked about the boost, I had a cm870 after a head install that had crazy egts, narrow powerband and low boost. pressure tested cooler, tested boots vice grips on turbo actuator, timing on cams...ect drove me nuts. turns out the guys who put the head on used the ecm shoulder bolts in the ecm cooling plate and it was tight but wouldnt hold more them 25# of boost. The bolts topped out before sealing the plate to the head. Honest mistake but they walked away from it.... worth a look
I donít understand how an ecm being bolted to a head causes this issue? Does the ecm seal off the intake?

Quote:
Originally Posted by Leiffi View Post
High EGT at low load is actually good for fuel economy if it is because of VGT setting not pumping excess air to the engine. It might also be retarded timing to compensate lack of EGR which is not good.


As I understand the guys who tune these improperly advance the timing to hide lose of power?


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Old 02-10-2018, 03:09 AM   #25
Leiffi
 
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Originally Posted by Ram12vcummins View Post
I read this was a big issue. Was assured by the guy who removed diesel spec tune that his was a proper one and a few people vouched....not that it means they are right. The mechanic took the egr plug apart and ground out the contacts for some stupid reason instaead of just taping up the ends. I guess to look stock. The tuner assured he can tune it either way. I can try and see if we can go about trying out the factory tune. But how would that act with the egr deleted? I would also have to rejoin the wires which isnít that big of a deal.



I donít understand how an ecm being bolted to a head causes this issue? Does the ecm seal off the intake?





As I understand the guys who tune these improperly advance the timing to hide lose of power?


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if they did it right, there would be no need to unplug the EGR, it should be done inside the software, just set EGR solenoid PWM to zero. I have heard many problems eith EGR deletes, one is that VGT control will close VGT completely and cause very high turbo speed and backpressure, turbo rpm control will limit overspeed. That is what PDI did and their solution was to raise turbo RPM limit which resulted in turbo explosion. They told customers that those VGT Holsets are just crap and they must buy their VGT delete kit.

Another problem after EGR delete is that ECM still tries to control NOx by retarding timing, that causes high EGT and high fuel consumption and possibly low power.

Needs a good tuner to realize and solve these problems but those tuners are very hard to find, most just wants your money and most get away with it because their customers dont understand engines.

I am not sure but I also believe that Cummins HPI system is not understood by tuners, it's like old PT system that most of the "gurus" dont understand even if they write articles about it for some magazines. Scania used same system in some of their engines and many of them failed after ECM tuning. I believe timing is overadvanced without them knowing when they add fuel to it.
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Old 02-10-2018, 06:40 AM   #26
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Yes behind the ecm there is a huge window for a different style intake, only a rubber oring gasket and 4 bolts hold the plate in place, so even one of the incorrect bolts would cause a leak but only under boost.
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Old 02-10-2018, 11:54 AM   #27
Ram12vcummins

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The unplugged egr was done by diesel spec mechanic. The guy who said he could fix it said it didnít matter he could do it with it hooked up or not hooked up. Does someone know if it can be programmed either way?

T-man
We will replace turbo boots and pressurize whole intake to check any other clamps or possible leak spots.
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