Diagnose this bad pull

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,497
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Central OH
You drained oil then ran comp test :confused:

If those gas ports work like how they should, you need some good cranking speed for it to shove the rings out. The low/no oil shouldn't be an issue, if you hit the cyl with oil and compression comes up considerably, good sign rings are toast. Did you remove all the glow plugs and then test one at a time? Need to have a fairly high cranking speed.

Did you drag test the rings before assembly?
 

x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
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I didn't assemble the short block. Do you really need fast cranking speed??? Well there's my problem I guess it's all good lol. I have half dead batteries with all the glow plugs removed at the same time. And it was still slow cranking. That solves everything but the coolant missing


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x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
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Does anyone have any other ideas? I'm still fighting the issue of it basically just shutting down. Everytime I add pulse to it, it goes alittle further. It's like it quits burning fuel and just turns into a dang air compressor. Going off memory there are a few voltage pids. Does anyone know the ecm voltage pid? It's a long shot but maybe my electric fans are wacking out the computer


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x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
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I got the heads resurfaced, had more than enough time to fully seat rings. I haven't checked compression since I got it back together but compression isnt the problem.
 

dirty_max

Member
Jan 27, 2013
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eureka il
Have you checked for exhaust leaks?

as long as he still has good boost a leak wouldn't be the problem. exhaust leaks lead to low boost. I know you don't think its the compression, but could you put a blowby meter on it? could it be an issue that's only popping up once its good and hot? I ask because ive had issues before with engines that had high blowby but would only act up when hot and in a certain rpm range.
 

x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
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I have also had kinda a hard time with the 1.25 96mm turbine. Everyone else is able to run it fine. Dodges mostly around here, but the few Duramax they run it too. I've had to put a 1.0 on it.


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x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
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Lexington, Ky
as long as he still has good boost a leak wouldn't be the problem. exhaust leaks lead to low boost. I know you don't think its the compression, but could you put a blowby meter on it? could it be an issue that's only popping up once its good and hot? I ask because ive had issues before with engines that had high blowby but would only act up when hot and in a certain rpm range.


I've got a lot of blow by but I think that's normal with a low compression engine like mine. It's 14:1. Leaves a pretty good oil spill at the end of the pull. But that's just like every other pulling vehicle out there. Everyone has an oil spill. There is a funny oil pressure forsure though! It goes up and down really bad about half track, guess it could be related. But I don't know what issue that would show... I've since put better oil in it with Lucas stabilizer and it's helped that out a bunch. It will be like 70 then 5 frames down it will go to 30, then back up and down up and down


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Bonestock

Active member
Aug 9, 2010
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Worland Wy
as long as he still has good boost a leak wouldn't be the problem. exhaust leaks lead to low boost. I know you don't think its the compression, but could you put a blowby meter on it? could it be an issue that's only popping up once its good and hot? I ask because ive had issues before with engines that had high blowby but would only act up when hot and in a certain rpm range.

I tend to disagree on this a bit. If you have a boost leak the chargers will overspin running way out of their map to achieve set amount of boost. Generally speaking a leak will cause them to still make the same boost #'s on a gauge but having to work 10 times harder and out of their operating range to do it. Just my experience. ...
 

x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
7,535
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Lexington, Ky
I tend to disagree on this a bit. If you have a boost leak the chargers will overspin running way out of their map to achieve set amount of boost. Generally speaking a leak will cause them to still make the same boost #'s on a gauge but having to work 10 times harder and out of their operating range to do it. Just my experience. ...


But that's only for compressor leaks right. The small leak I had was just the exhaust


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Ne-max

I like turtles
Nov 15, 2011
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But that's only for compressor leaks right. The small leak I had was just the exhaust


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No. Exhaust leak will cause less drive pressure to build boost. You are loosing that energy. A little little exhaust side leak will cause a huge power loss up top.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Phoenix Az
I've got a lot of blow by but I think that's normal with a low compression engine like mine. It's 14:1. Leaves a pretty good oil spill at the end of the pull. But that's just like every other pulling vehicle out there. Everyone has an oil spill. There is a funny oil pressure forsure though! It goes up and down really bad about half track, guess it could be related. But I don't know what issue that would show... I've since put better oil in it with Lucas stabilizer and it's helped that out a bunch. It will be like 70 then 5 frames down it will go to 30, then back up and down up and down


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compression and blow by dont go together. just cause you have low compression pistons doesnt mean you should be experiencing alot of blow by. rings, valves, and HG dont care what the compression is of the pistons. if those dont seal, you get excessive blow by. if you setup the ring gaps to be loose and the piston to sidewall to be loose, that can create more blow by than factory.