hello all my 93 7.3 na is missing i can realy tell it at idle it has a little vibration but i can deffinatley tell from the exhaust sound from the tailpips it sounds like ch ch ch ch ch kinda like a train it seems to run fine and there isnt no excessive smoke either where should i start i had a old 454 years ago that sounded the same and it was a bad valve seat and guide does that sound like it could be the problem how do i tell wick cylinder is misfireing any help will be apreciated thanks
chris

 

Crack the line on top of each injector 1 at a time while idling,you should hear a difference on each one,if you find 1 that makes no diff,then thats the offending cyl.Wear eye protection and gloves.

 

thats it chris ... the nose knows. I do suggest that you give all of the connections a loosening before you start the engine. just resnug them before starting. that way you wont be struggling to loosen each one of them. you want to crack them just enuf to make fuel leak. be careful around rotating parts. you may find it is just an injector making the thing have a hissy fit or it may be a valve.
the injectors can be "pop tested" by an injection shop. I believe they open at 1475 psi and a machine is needed for this. if you are strapped for money, like most of america, you can test them on the truck as above and just take that one for testing and replace it, but eventually, they all will need it ... depending on the mileage.
good luck ... let us know how ya make out.

 

thanks for the replies ill try cracking the lines tomorrow ill post what i find

 

If your 93 has about 160K+ then it could be a valve/valve spring as they are known to start wearing the guides around that mileage. A compression test will tell you head condition too.

 

My '91 did the same thing...after chasing around other things for a month...it took new valve guides to solve the problem...runs great now...

 

well i just broke the injectors loose the front pass side makes the least difference so im sure that is the offending cylinder i switched 2 injectors and it made no difference so i know it isnt the injector i guess i need to do a compression check next can i use a gas compression gauge if i can fine a adaptor for the glow plug hole also is it possible to pull the head off the pass side of mmotoe while in truck thanks chris

 

no you can't use a gasoline compression tester and yup you should be able to pull the head without pulling the motor at least i can on my 91's

 

Here's the problem, when you have bad quides you will get false compression reading...that's why sometimes it will make a difference when you crack an injector line and sometimes it won't...the valve will seat sometimes and sometimes it won't....pull the valve covers and grab the top of the spring and see if it moves(wobbles)..if it does that's the problem...


EldoMike

 

ill try that tomorrow weather permitting it was like 20 out when i was working on it today ouch too cold also does anyone know where i can get a return line kit after switching injectors the front pas side is leaking from where the roung thing that the two lines connect on goes over the other thing i saw it had 2 o rings on it sshould i just change them or can i get a new kit somewere thanks
chris

 

Its called a fuel return line kit,it will have the o rings and new caps as well,although i wouldnt install it untill i was finished poking around in there.

 

You can get a kit from http://www.dieselpage.com/ just cut and paste it into another explorer.

To get a real honest indicator you would have to depress the valve stem then wiggle it. I had similar rapping noise out of the exhaust on hard accel ended up to be a valve spring broken.

 

well i pulled the valve cover the 1st and 3rd valves wobble i can deffinitley tell when i pulled the rockers off lots of sludge in there too i can hear the ch ch ch sound too from somewere in that area it is at the exact time in doesit fro mthe exhuaust swo id guess i need valve guides ill comence to pulling the head asap any ideas on what it costs to repair the heads thanks chria

 

Just remember to remove the heads in the reverse torque pattern 1/4 turn at a time so as not to crack them. Also ensure the heads are not milled below the minimum thickness as required by Ford and IH and AERA.

Per AERA specs:
Stem to guide clearance (intake & exhaust): .0013" - .0055"
Valve height (measured from top of valve to "deck" height)
Intake: .042" - .054" Exhaust: .051" - .063"
Minimum head thickness (from "deck" to valve cover surface): 4.7950"

Costs would depend on what was done to repair them, ensure they are vacuum, pressure, and magniflux tested for cracks.

 

well i have been driving it still missing its weird it does NOT miss when cold the warmer it get the more it misses and it still runs good even with the miss i ordered a return line kit because they are leaking i need to pull the head but after priceing gaskets alone itll have to wait till i get some $$$ saved i cracked all the injector lines again they all make a difference just seem some make a bigger difference than others the front pass side seems to make the least difference but it does make a difference deffinitley misses more when i loosen it oddly enough that is the one that the return line is leaking too if i had a cylinder not fireing at all wouldnt i have smoke from the exhaust? it doesnt smoke at all just at startup until it warms up im getting stumped anyone have any good ideas ill be doing a comp. test this weekend