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As some of you may know I am working on a 7.3 that just got a new cam. Now this problem has me stumped. Engine idles rough and has a vibration but does not smoke, starts up great. I know a diesel mechanic that couldn't figure it out and all he could guess was a bent connecting rod. But compression checks out on all cylinders. And like I said, no smoke. I always expect there to be a smoke symptom of some kind because for me there always is when these engines run rough. My only guess is something that has to do with turbo or exhaust. This is my first factory turbo idi so I'm not used to dealing with them. Since my only guess leads to exhaust I checked it out and I have 4 problems, crossover pipe has a dent in it, down pipe has a small leak, exhaust manifold has a leak, and the compressor wheel on the turbo is chipped up . I'm going to disconnect the exhaust pipe tomorrow in case restriction is an issue. If any of you guys have a suggestion I could use all I can get.
did you double check the valve train and pushrods etc.etc. if you just changed the cam.....that's where i'd start. i take it the "running rough" your talking about is at idle? what grind cam and manufacturer did you put in it?
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02 f-350 4x4 7.3 dump bed insert
96 f-250 4x4 7.3 e4od
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How long has it been sitting??
you might try checking the injectors if its been sitting a while. crack the lines on the top one by one and if you crack it and the idle doesnt change much you found your issue.
the engine i put in my truck recently had sat for around 9 months, had a slight miss at idle and shook a little turned out to be a bad injector.
I replaced all the lifters and pushrods, also the rockers on the cylinder that blew a lifter. #1 cylinder had a lifter go bad and by bad I mean shredded, that is the reason for this tare down. It has the type4 cam.
I ran it with some of my spare injectors for a while and it had this problem and then put the originals back in. There was literally no change between either set of injectors. I cracked each injector anyway and each one made the engine run worse. I'm taking them out to get pop tested today just to get that idea out of my mind. Wouldn't there be some kind of smoke with a bad injector?
did you double check the valve train and pushrods etc.etc. if you just changed the cam.....that's where i'd start. i take it the "running rough" your talking about is at idle? what grind cam and manufacturer did you put in it?
It is manly rough at idle but if you accelerate the engine by hand it does smooth out, though if I look at it I can tell it still is not right.
You actually got me thinking about valve springs with a different cam being in there but springs are not supposed to be an issue with it unless I missed something. I just figure there are some kinks to work out on this motor that I never noticed because of the cam/lifter problem it had.
See if that works. I talked to him about it before and it's not supposed to require different springs. And I checked them out and they seemed fine. But my mind is definitely open to possibilities. I'm going to go out and install my other spare injection pump and see if that changes anything. I don't see a problem with the pump, being there is nothing showing up by way of smoke, but maybe I'm thinking too big here. Maybe it is a small problem with the pump that I never noticed when it was on the other truck.
I thought about the balance but I was told that being out of balance would not effect the way it runs, just cause the vibration. In this case it doesn't run right.
Timing is different for this camshaft itself. Its completely different from the old one....thats what changes thigns oin this engine.
I went ahead and installed my rebuilt pump off my bronco since the thing is going to be parked for a while. It definitely runs better and seems to hold idle better but still has the vibration. Wondering if I have two problems here and maybe the vibration is separate from the running problem. I am relying on my tach so I'm going to hook up my timing system tomorrow and see where it's at.
I'll look back in my emails or pm Russ and find out what the timing is supposed to be. I thought it wasn't much different than stock but I may be wrong. I have moved my timing to the limit in both directions in the past and I remember there being smoke in both cases. But this is a different cam, so I won't pretend to know exactly what to look for.
im guessing some amount of bad injectors or pump. is it possible when that lifter went it bent a valve, wait ,nevermind, you said compression was good.
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91 f 350 cc 4x4, 3:55 gears. zf 5, 7.3 ATS 093 with bigger comp wheel, intercooled with cutdown 7,3 ps IC all gauges ignored with good aftermarket ones. Head studs, balanced . 12 psi 1k pyro under load way better mileage than the 460.
218/461 on the dyno. after 80k miles, wanted to make sure she was broke in. sandeater1@gmail.com
I got your email Russ, thanks for the quick reply. Yeah, I thought bent valve too but I decided to throw some money at this engine because it held good compression. Injectors are being tested and should come back tomorrow. The originals are in right now. I set my timing at 8.5 today and that along with the new pump made things a lot better. I'll set it at 9 and see how that does. The problem seems to be more vibration than a running problem now but it is not as bad as it was. I should have known there would be a difference between a good pump and a new pump . One thing that got me was my tach, which doesn't work right until it gets above 1000 rpm. When I was timing it the idle came up fairly steady at around 700 rpm.
Yep, got the gears lined up fine. Even marked the position of the pump gear to the housing for future reference.
Thanks for all the help guys. I'm slowly getting there. Now I need to do something about this turbo. There is quite a bit of slop in the shaft and I already mentioned the chips on the compressor wheel. I don't want to let this go until it blows up. Can anyone point me in the direction of a good garrett rebuild kit? Any upgrades for the turbo besides the downpipe I should do while the turbo is apart? I was half thinking of adapting over my powerstroke turbo that is sitting here without a home but stopped myself lol. Don't want to go crazy on the boost.
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. I'm going to disconnect the exhaust pipe tomorrow in case restriction is an issue. If any of you guys have a suggestion I could use all I can get. 
. One thing that got me was my tach, which doesn't work right until it gets above 1000 rpm. When I was timing it the idle came up fairly steady at around 700 rpm. 
