Buzz test -all passed, but Cylinder Contribution Test fails #3... - Diesel Forum

olddieseldude · 02-18-2007, 04:17 PM

I attached Auto Enginuity to my truck the other weekend. The buzz test was good but #3 failed the Cylinder Contribution test. I've not lost/used any oil in the last 2500 mile. Does this mean a new injector is needed at that location?

The truck has always (purchased 10/05) had a bit of a miss at idle but very faint (wife couldn't hear it) and AE previously showed all cylinders doing their part. My fuel mileage has been good (18-19 city) until the last 3 months or so. My fuel mileage is down a little now (1-1.5mpg city). I had a substantial fuel leak at the Fuel Filter Drain Valve but that's been stopped. Now cold weather, less than 20 degrees for a month. Once warmed up I'm not seeing anything from the tail pipe except some steam in single digit weather.

I just have a definite miss developing at all rpms. Friday I drove round-trip from Indy south to the Madison In, a 1-3/4 hour drive one way. The truck sat for 3 hours before making the return trip. The miss was present the whole trip. The miss used to come and go a little, shutting the truck off and restarting it could produce a smooth idle, but seems to be constant now. The miss is visible in the exhaust plume in the cold weather.

Other than this the truck starts quickly, easily, and runs good. There are no leaks.

What do you think?

catdiesel0631 · 02-18-2007, 04:46 PM

I think I would put a injector in the #3 hole

Kickin Y2K · 02-18-2007, 05:08 PM

Move injector 3 to another hole and see if that new hole shows up as failing before spending money on an injector.

grounder · 02-18-2007, 05:34 PM

while your under the V/covers inspect the Interior Harness plug good.If its loose get the cheesey clips for it to keep it locked together or replace it

JimTJr · 02-18-2007, 08:19 PM

Just making sure, did you have it well warmed up when you ran the test? (oil needs to be up to temp, from what I understand)

olddieseldude · 02-18-2007, 08:34 PM

Thanks for the all the responses.

JimT,
Yeah, I had driven it for at least 30 minutes prior to that test. It was shut down just long enough to get my laptop out and hooked up to the truck.

**Excavator** · 02-18-2007, 08:40 PM

First I would suspect a poppet screw loose.

Second I would check armature clearance on that injector as well as check for oil flow from the oil spout and compare it to other injectors

olddieseldude · 02-18-2007, 09:35 PM

[ QUOTE ]
First I would suspect a poppet screw loose.

Second I would check armature clearance on that injector as well as check for oil flow from the oil spout and compare it to other injectors

[/ QUOTE ]
Jim,
Help me out here. You're talking to a relative newcomer to the diesel thing. What and where is the poppet screw?

Is it in this picture?

Edited:
I may have found the answer in this post...

**Excavator** · 02-18-2007, 09:43 PM

When you have the valve covers off you start engine and look at each injector. You will see oil spitting out of each injector from the spout. You can't miss it. If one is spitting not the same as the others, then susspect that the poppet screw is loose or armature plate clearance is out of spec. The way to check poppet screw is to remove the 4 screws that hold down the solenoid on top of the injector. Then remove the spacer and you will see a square armature plate. In the center of the plate is poppet screw.

olddieseldude · 02-18-2007, 09:52 PM

Thanks Jim,
The other post that I found just as you were replying makes it sound like the answer is still a new injector because I won't be able to fix the problem myself anyway, do you agree?

**Excavator** · 02-18-2007, 09:54 PM

it could be just a loose poppet screw and you sure could check that.
Here are some pics, look at pics 1 ,2, 3 and 4
pics

olddieseldude · 02-18-2007, 10:11 PM

So you think the screw shown in pic 4,5,&6 could be worth a few hundred dollars to me? Cool! Can that be checked on the truck? If not I probably need an injector oring kit at a minimum, right?

**Excavator** · 02-18-2007, 10:42 PM

no need to remove that injector to check the screw,just dont drop any screws that hold the solenoid on. If you were to do all injector orings then yes pull all of them out. I would still at least check the armature plate clearance before reinstalling.

SprintCarCowboy · 02-19-2007, 09:33 AM

I have never done this but if there is potential for dropping anything make sure you stuff shop rags or something onto any potentially exposed areas that would allow a screw to fall into your engine!

Joe

olddieseldude · 02-25-2007, 10:52 PM

Well folks, since I work outdoors under a carport and it's colder than you know what around here and I had never attempted anything like this before, I decided that could not afford to spend too much time diagnosing the problem while the valve cover was off. My window of opertunity is small this time of year. Yesterday was low 20's here but today made it to 40 by late morning, so I decided to go for it. I needed to just get in and get out as quickly as possible.

I had purchased a Ford remanufactured injector from the PowerStrokeShop Friday and proceeded to change out the injector, inspect electrical wires and connectors. Thanks to all those who have contributed to this forum I successfully changed it out. The patient is alive and running as good as before, but that's the problem, it's running exactly the same. My problem remains the same, #3 fails the Cylinder Contribution Test.

Remember it passes the buzz test. Where do I look next?