Stiction in a 7.3?

JD3020

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Background on my truck, 01 F-450 with 299k miles. I replaced the engine winter of 2014 with one i pulled out of a buddies truck. BUT it wasn't the original engine in his truck either, it came out of an 01 school bus with 140k miles. He put about 15k miles on it before he totaled his truck and i got the engine. I've put 20k more on it so far. So we think it has 180-190k miles, but nobody knows. Its never really ran "right" since i put it in my truck, not that its ran bad, just seemed a little down on power and harder to start than it should. But my OBS hasn't had stock injectors in it since 2010 so i'm not really familiar with what a stock 7.3 is like.

This winter i've been noticing an issue that seems to slowly be getting worse. Truck hates cold starts, i know the GP's are good and it turns over fine, but takes it a while to fire. Blows a puff of white smoke and then light haze till it starts to warm up, normal for a 7.3. But it runs rougher than ****, and has no power, like its down a couple cylinders. Being a manual you can really feel it once you start to let out on the clutch, even in low or first gear. The first day it got really bad i basically had to limp this thing a couple miles up the road till i got on a state route and had to bang some gears to beat traffic. As soon as it clicked over 2k RPM's it came to life and was good to go. Ever since then i've been revving the engine past 2k before i leave the driveway and its fine the rest of the day.


So is this stiction that i'm getting due to higher miles on the injectors? I've always ran conventional 15-40 oil in it, 3-4k mile OCI's, and the truck rarely runs below 40* so its not like i'm battling cold temps.
 

superpsd

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So the injectors run good once warmed up and it fires off on all 8 once you punch it right? Sounds like typically poppet valve wear. As the poppet sinks the armature gap clearance goes beyond. 002" of clearance. When cold the armature will stick to the body top. So technically stiction due to wear. When I built my injectors I played with some core injectors. I didn't touch the oil sides as I wanted to roll the dice and see if they would run. I had two injectors that had the same exact symptoms. You can check armature gap clearance without removing the injector. I fixed my two lazy sticking injectors without even removing them. I used a surface grinder and took some material off the back side of the armature plate to retain good clearance without affecting poppet travel. I made it thru the winter seeing day after day of cold starts not plugged in at 20° without issue. In fact starts fast and on all 8 with out any lope.
 
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JD3020

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It does it at all temperatures, just have to rev it up to get them all firing. The one day it was close to operating temperature and was still running like crap, but as soon as i ran it north of 2k RPM's it cleared up. This morning it ran for maybe 2 or 3 minutes before i revved it up in the driveway and it cleared up.

But once its cleared it up it runs fine all day long.
 

PowerstrokeDiesel95

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What's yalls thought on injector nozzles?? I want to go bigger on injectors but tryin to go with out havin to do a full injector swap, ive got a 97 7.3. How big of a nozzle will a stock injector push??
 

superpsd

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To change nozzles the injectors have to be removed and torn apart. There is no point putting nozzles on stock AA injectors which are only a 98cc injector. You will see no gain. Start reading up around here if you want to start modeling these 7.3s
 

79jasper

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Could it be possible the hpop reservoir or rails are draining?
Or does that give a different symptom?

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

superpsd

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A buzz test is the easiest way to confirm a injector with low armature clearance as you will hear a muted injector when cold. In fact after a few buzz tests the injectors may fire off running on all 8. I had tried this a few times with worn poppets. My worn poppets didn't care that it was the middle of summer they still started horribly. It will run better an smoother as it warms up. Or lay your foot down ICP will spike and force the injector to actuate correctly. Hence the light switch effect of a engine running rough then bang its running smoothly. An injector that had upper seat wear but OK clearance will start well but be low on power and have low ICP once up to temp as the thinner oil can leak much easily pass the upper seat. An injector that runs rough hot or cold can likely be fuel side damage.
 
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Bobs 7.3

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I had this with my old injectors and switched to 5w-40 rotella t6 and a lot easier starts and smoother running for another 3 years then swamps were just put in last month as I had a cracked injector cup. That oil works great for worn injectors. Im still using it as I have been for the past 4 years.
 

lincolnlocker

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It does it at all temperatures, just have to rev it up to get them all firing. The one day it was close to operating temperature and was still running like crap, but as soon as i ran it north of 2k RPM's it cleared up. This morning it ran for maybe 2 or 3 minutes before i revved it up in the driveway and it cleared up.

But once its cleared it up it runs fine all day long.
what oil are you running in it?

live life full throttle

god bless america and the farmer who feeds your fat ass
 

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