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Discussion Starter #1
Just wondering why my engine would idle rougher after it warms up? When I start the truck it has a perfect idle but after it reaches the operating temperature it shakes the inside of the cab just a little bit. It's not bad and it doesn't sound like it's missing but I just wish it was a bit smoother.
 

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Sounds like you have a bad injector or two. Hot oil = thin oil. With bad/questionable orings the oil can leak by internally much easier and cause weak injector.
 

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Discussion Starter #4 (Edited)
I'm guessing that even though the truck runs great when you give it a little throttle it could still be the injector? It runs great going down the road too, but it has started to put out a little more black smoke than normal when getting on it. The truck has 220,000 miles on it.
 

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I'm guessing that even though the truck runs great when you give it a little throttle it could still be the injector? It runs great going down the road too, but it has started to put out a little more black smoke than normal when getting on it. The truck has 220,000 miles on it.
It'll run fine going down the road as there really is very little load on the engine, and the PCM isnt calling for much ICP pressure to run the injectors. Add a 10k trailer and go up a hill for 5 miles and then you will see the difference.
 

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Discussion Starter #7
Small update on the truck. A few weeks ago I used the truck to pull our RV, and after arriving at our destination the truck was idling really rough, the worst it’s been. I figured this was because pulling the trailer got the engine hotter than normal so the oil was even thinner exasperating my warm engine rough idle issue. I let the truck cool down and everything went back to normal. I decided to stop by a parts supply store and get some heavy duty oil stabilizer for the trip home. I was going to get some Lucas heavy duty oil stabilizer because I figured that’s all I could find, but got lucky and found a place that carries Schaeffer's products. I bought two pints of Moly E.P. and put both in the truck before the drive home. On the way back we stopped for gas and the truck seemed to be idling like it did on a normal day, not good but also not too bad. I have now had the Moly E.P. in the truck for about three weeks and my truck is smoking about 80 percent less when I get on the gas and it idles about 80 percent better too. Sometimes it’s even idling great when warm now. It’s not perfect but at least I can deal with my driveline issues before tackling more problems on the engine.
 

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Discussion Starter #8
Had some more work done on the truck. Had new cups, new o-rings on the injectors, new valve cover gaskets, and under valve cover harnesses installed. I was hoping this would fix the rough idle when warm but it only helped the issue. I didn't want to get new injectors yet because I wanted to see what the compression was first, and I'm at 375 across the board. I'm getting much less smoke but the truck is going to need new injectors to fix the problems completely. The computer is showing fuel trim numbers at +6 for cylinder #2 and +4-5 for cylinder 3 I think, so I'm getting too much fuel. They also said the injectors looked stock to them.
 

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Had some more work done on the truck. Had new cups, new o-rings on the injectors, new valve cover gaskets, and under valve cover harnesses installed. I was hoping this would fix the rough idle when warm but it only helped the issue. I didn't want to get new injectors yet because I wanted to see what the compression was first, and I'm at 375 across the board. I'm getting much less smoke but the truck is going to need new injectors to fix the problems completely. The computer is showing fuel trim numbers at +6 for cylinder #2 and +4-5 for cylinder 3 I think, so I'm getting too much fuel. They also said the injectors looked stock to them.
Thanks for the update, I'm having the same issues as you, except my is accompanied by a tick/knock I've been told due to loose injectors, seems more loud in the pass side, I torqued them and they were loose but didnt help much, despite the knocking it starts fine and it runs fine til the engine warms up, then it shakes not in a missfire type shake but more like idle up and down, little rough. Wondering if its worth trying new injector seals before throwing 1.6k for new sticks.


 

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Discussion Starter #10
If you do the work yourself it's not too much for new seals. That tick is interesting, hope someone here watches the video and knows what that is. Also fyi you can get a set of rebuilt full force injectors for about 1,100
 

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The 7.3 injectors are super easy to rebuild. You can get the kit and holding tool for 270$. Enough to do all 8 injectors. I got mine from bitterrootdiesel.com, an afternoon of time and a case of carb cleaner and I was good to go. Crisp clean idle. They have a couple videos showing how to do it. You'll struggle a bit on the first one, but after that its cake.
 

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If you do the work yourself it's not too much for new seals. That tick is interesting, hope someone here watches the video and knows what that is. Also fyi you can get a set of rebuilt full force injectors for about 1,100
Yeah mine runs rougher when fully warmed up, been having icp pressure dip to the 390 psi which is below 450-550ish idling specs and fluctuates up and down, runs better with the icp unplugged, which leads to the pcm to use its stock pressure of 725psi and it settles the idle, but the ticking gets worse when I shift to drive. I tested by resealing the injectors and swapped 3 to the opposite bank, and the tick followed just like in the video, so I hope its my injectors in that bank going bye, wont know for sure, I tried a new icp and same thing, IPR stays within spec 10,9% duty cycle and doesnt jump up or down. I will update here too since we have similar symptoms just for entertainment purposes since you too suspect injectors, if thats cool with you ofcourse.
 

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Discussion Starter #13
The 7.3 injectors are super easy to rebuild. You can get the kit and holding tool for 270$. Enough to do all 8 injectors. I got mine from bitterrootdiesel.com, an afternoon of time and a case of carb cleaner and I was good to go. Crisp clean idle. They have a couple videos showing how to do it. You'll struggle a bit on the first one, but after that its cake.
I can see this turning into me towing my truck to the shop with a box of parts in the back lol

Yeah mine runs rougher when fully warmed up, been having icp pressure dip to the 390 psi which is below 450-550ish idling specs and fluctuates up and down, runs better with the icp unplugged, which leads to the pcm to use its stock pressure of 725psi and it settles the idle, but the ticking gets worse when I shift to drive. I tested by resealing the injectors and swapped 3 to the opposite bank, and the tick followed just like in the video, so I hope its my injectors in that bank going bye, wont know for sure, I tried a new icp and same thing, IPR stays within spec 10,9% duty cycle and doesnt jump up or down. I will update here too since we have similar symptoms just for entertainment purposes since you too suspect injectors, if thats cool with you ofcourse.
That's fine with me, maybe it will help someone in the future
 

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I had a Chevy HD diesel, that started doing exactly what you said until the point that it would not even start until I gave it several hours to cool down.

I replaced the injectors, the lines between the injectors, and the cups, and solved all my problems.

BTW, I did not present with smoke from my exhaust as one would expect.
When I got the injectors, you could clearly see which injectors were having issues, the crap in the fuel intake for the injectors was really bad.
 
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