7.3 with low power - Ford Powerstroke Diesel Forum
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  #1  
Old 11-23-2013, 11:50 AM
If it aint a CAT itsa DOG

 

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7.3 with low power

Ok guys I have owned a ton of different ford diesels over the years and this is my 4th 7.3. This and and my other ones are all super duties 99-01. I just bought this thing and it has 202k on it. It is way slower than any other 7.3 i have ever owned. It seems like it takes for ever to build boost. I changed my oil to Delo 5w40 synthetic, AFTER i did this i get a loud engine knock after it warms up, but only at idle. Here is a list of what is going on and what i have tried.

-no abnormal smoke
-starts good
-no missing
-has a SLIGHT exhaust leak on one up pipe, but i've had others with this before. Its not blowing soot onto the firewall.
-its only building about 16psi of manifold pressure on my AE, but takes forever to get there.
-#8 cyl fails contribution test (could be normal)(part of knocking sound?)
-all injectors pass buzz test
-haven't had time to change fuel filters, but truck was maintained well with paperwork to proove
-CAC boots seem to be ok except for oil soaked
-can barely hear the turbo spool up like i could on other ones

Anything else I might be forgetting? Also that engine knock was not present when i bought the truck, only started doing it after i changed oil to full syn. I had this happen on my 01 with the #8 cackle, but this seems a lot louder, almost like all the injectors are starving a little. Any more ideas would be great.
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Old 11-23-2013, 12:02 PM
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When you stomp down on the throttle all the way does it blow black smoke like normal? My first thought is that it's not getting fuel to the cylinders for some reason. If it does blow black smoke like normal, then my next thought would be that the turbo is not responding correctly to the exhaust you are giving it. This would indicate that your turbo might be due for a rebuild. I have heard of turbos giving out around 200,000 miles or above. Have you drained your fuel filter lately to see if you have water? Water in the fuel can cause everything you mentioned. Sorry if any of this is dumb, I'm no mechanic.
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Old 11-23-2013, 12:12 PM
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leaky up pipes kill boost.
and the only way to tell if the CAC boots are leaking is if you pressurize the system with the truck off.
build your own boost leak detector or buy one from dieselsite.
bad ipr on my truck caused low boost as well.
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  #4  
Old 11-23-2013, 04:14 PM
If it aint a CAT itsa DOG

 

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I don't get any black smoke, but in all fairness to these trucks, when they are untuned i never got black smoke unless it was during the summer and i was running 15-40 dino oil. When i switched oils to synthetic it would always get rid of my black smoke. I haven't had a chance to check the ipr or icp yet or drain the fuel bowl. I just bought the truck and time has been short with it. It has was only 5 degrees outside today so not fun to work on the truck. You guys have a diagram of a homemade CAC leak checker? The other thing i forgot to mention was i did take off the red waste gate line and it seemed to give it more power, so maybe she is sticking?
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Old 11-23-2013, 04:53 PM
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Yeah, mine barely smokes, but if I floored it and didn't have any boost or acceleration I bet it would smoke a lot. Of course, I know my truck really well and yours is new to you. I would definitely check for water though with the lack of power and knocking. Brian from BTS told me that water can grenade your injectors. A boost leak might be it, but that doesn't explain the knocking.
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  #6  
Old 11-24-2013, 11:43 AM
If it aint a CAT itsa DOG

 

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Ok i will check that stuff out again when i get a chance. Thanks guys
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  #7  
Old 11-27-2013, 10:37 AM
If it aint a CAT itsa DOG

 

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Well i checked out my ICP sensor today and it was full of oil, its was pushing oil out around the weather pak connector. So i am going to go get a new one and see if that does anything.
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