my #5 piston for some reason isnt firing like it shoud.... i checked the wires and the plug and they are fine, but when i pulled the wire off the cap, there is no change in the motor...... the plug was a little fowled but still was capable of firing after i pulled it off and grounded it to check for spark.... what could possibley be my problem... a mechanic suggested the valves?? i wouldnt think so

 

The '91-'94 OHV's are known to have problems with the lower intake manifold coming loose and causing various problems. And these problems are often associated with cylinder #5. First thing I'd suggest is to see if any improvement comes from tightening the lower intake bolts. This usually fixes it, but if the gasket is in bad enough shape, the gasket may need to be replaced.
Other things to do: check the #5 fuel injector to see if it's firing. compression check to see if #5 is significantly lower than the others.

 

im not too highly knowledged in the fuel injection motor area..... how hard would it be to change this gasket and what are the basic steps... will i have to drain the cooling system and stuff like that, etc.... and what other gaskets will i need?

i havent really noticed a significant difference in my cooling level dropping... and i dont really understand how this would make cylinder not fire off.... could you go into more detail

 

mrshorty's advice is what I would have said, too.

You might also consider a cooling system pressure test, as well. You can borrow both the pressure and compression testers from most autoparts stores.

Another way to try and confirm a gasket problem is a Used Oil Analysis (http://oilguard.com/oil_analysis_prog.php). If you find potassium & sodium in your oil, then you can be sure pretty sure it's new gasket time, sooner better than later. Here's my 4.0L intake gasket story:

https://www.ford-trucks.com/forums/s...d.php?t=232373

 

thanks for the help.... another question real quick, how would i test an injector, pull it out and put it in a cup or something and see if its spraying, websites says even if it is clogged 15% it will cause a missfire

 

Check the wire harness connector to the fuel injector. Pull it off and spray it down with electrical contact cleaner, then re-attach it snugly.

Also, get a long screwdriver and press your ear against the handle and listen while you touch the tip of the screwdriver against each fuel injector body. You should hear a consistent clicking sound in all 6 of them. You may be able to tell if # 5 sounds "funny" this way.

You might also try swapping injectors with another cylinder, to see if if the suspect injector causes a misfire someplace else.

 

thanks for the very good tip..... might be a little hard with the bad injector being under the intake body... but ill try it out this weekend...thank you very much... ill keep you guys updated.... CEL light is gettin checked out tomorrow to see what it is

 

computer came up with a bad fuel injector..... so im gonna change it this friday and see what that does

 

I hate to second guess another guys diagnosis, but I couldn't find any EEC-IV trouble code that, by itself, pointed to a bad fuel injector. For that matter, the computer doesn't even control each injector individually; they're controlled in batches of three. What were the actual codes that the computer came up with?

 

I'm sorry folks, but I have to eat this one :embarrased I just learned that, starting in '94, the 4.0 OHV came with sequential fuel injection (SEFI) instead of multi-port fuel injection (MPFI). On an SEFI system, the EEC-IV computer is capable of performing a cylinder balance test, which (I presume) is how you got the computer to say that cylinder 5 was bad.

 

got it all back together and it runs like a brand new explorer... but now im gettin a check engine light again.... this time it comes up sooner, after maybe 5 min of driving.... i hope i got th eintake all sealed up and isnt giving me a lean code
i did mess up the EGR?!? tube that runs from the driver side manifold up to the side of the intake, and has two vacuum lines running off of it.... i did what i could to repair it but still dont think its all there...... im gonna have to ran through sometime to check what it actually is.... but i just wanted to check with you guys to actually see if you knew what it was

 

Check the codes ...probably related to the EGR issue.

 

the tube that goes to the exhaust to the egr valve body is suppose to be air tight supposidly, and its not... prolly egr pressure problem.... or i didnt get my vacuum hooked up right.... i need a vacuum diagram