Bad Miss

mondtster said:
Once you get beyond the basic troubleshooting that has been suggested in this thread, I would strongly suggest a leak down test. Of course that is assuming that you don't find a simple problem that takes care of the issue along the way.
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You mean a leak down test via the coolant system? I'm used to working on gassers and a leak down check is as simple as hooking up the correct tool in place of the radiator cap. Is this the correct way of doing the test on a 12 valve?
 
npe3484 said:
You mean a leak down test via the coolant system? I'm used to working on gassers and a leak down check is as simple as hooking up the correct tool in place of the radiator cap. Is this the correct way of doing the test on a 12 valve?
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No, a cylinder leakage tester. It is the same thing regardless of whether you're talking gas or diesel piston engines, it is just that outside of aviation and the automotive performance industry people seem to rarely use that method of figuring out where the problem is, or have even heard of it.
 
Well I cracked the lines loose today and it seems the number 4 cylinder is the one with the miss. The idle barely changed at all when I cracked the line. But there was plenty of fuel coming out of all the lines so I'm hoping it's not the pump. I think I'll check the valves before I get my injectors pop tested and if that doesn't fix it I'll check timing.
 
Don't bother with timing if #4 cylinder didn't change the idle. Yank the injectors and have them tested.
 
oh ok, so after i have the injectors tested and check the valves where should i go from there if it doesnt fix the problem.

and i just wanted to say thanks to everyone for your help, i really appreciate the help.
 
Check to make sure the gsk's are tightened the same amount of clicks, and make sure they aren't too tight. Most folks find it easier to adjust them through the top of the pump by pulling the afc housing off and taking the fuel plate out instead of through the cover on the side of the pump.

After testing the injectors, this would be my next step if it were my truck. Just my $.02
 
mondtster said:
No, a cylinder leakage tester. It is the same thing regardless of whether you're talking gas or diesel piston engines, it is just that outside of aviation and the automotive performance industry people seem to rarely use that method of figuring out where the problem is, or have even heard of it.
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How would you go about doing this test on a 12 valve? I imagine you'd need some sort of adapter to a pressure gauge that would go in place of the injector?
 
npe3484 said:
How would you go about doing this test on a 12 valve? I imagine you'd need some sort of adapter to a pressure gauge that would go in place of the injector?
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Yes, put the cylinder at TDC with the valves closed and apply pressure through the injector hole. Same way you would do it on a gas piston engine, just doing it through the sparkplug hole instead.
 
well thanks to a fellow member (tarter6bt) i discovered a local pump shop that will pop test 12v injectors for $2 a piece! so ill have them into the shop first thing monday morning.
 
cosmo22nov said:
well thanks to a fellow member (tarter6bt) i discovered a local pump shop that will pop test 12v injectors for $2 a piece! so ill have them into the shop first thing monday morning.
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Where is this shop?
 
hope you get it figured out. I got a 94 that idles great but has a miss on #5 above idle. i'm down to either a bad injector, worn barrel, or low compression on that cylinder. need to swap an injecter in and see if that changes it.
 
Try switching the injector to another hole to see if the problem is the injector.
 
CL2000 said:
Try switching the injector to another hole to see if the problem is the injector.
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injectors have already been sent off to be rebuilt, they are original and have 312k on them so i figure they should be rebuilt anyway
 
I have the same problem with my truck. It's in the Chrysler garage and they can't figure it out. #4 is the problem cylinder and the injectors are fine. I'm near kc. What's the name of the shop you took yours to? I'm gonna try to get ahold of Cunningham and floor-it diesel tomarrow. Any recomendations??
 
im trying to diagnose it myself, i could be you head gasket, something in your valve train, your injection pump, or even bad rings.
 
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