I have a 1997 F150 with the 5.4L engine. It just crossed 100,000 miles and the check engine light came on. Had the code pulled at an auto parts store and the person said it had a misfire code (guy did not know how to use reader and could not tell me the exact number). I put in new plugs (Autolite XP103) and it seemed to idle much better.

When changing the plugs all looked like normal wear except #5 which was oily and had some accumulated black crusty stuff on the plug. I also appeared like the plug had been dropped before it was installed because the gap was small and the tip appeared bent.

After the plug change I noticed a tick that sounded like lifter noise or exhaust leak. After reading threads related to spark plug blow outs I decided to re-check the plug torque (bought a torque wrench and rechecked everything OK). But I did find that the new #5 plug tip was bent and the new plug was already oily. (I definitely did not drop the plug on install). I checked the compression on the cylinder and it was above 110lbs. I also put in a an old plug with some colored grease on the tip and rotated the engine manually and then pulled the plug to look for grease on the piston and I did not see any. I then put in a new plug and turned over the engine, then pulled the plug again and it looked OK. I have not seen any posts related to spark plugs being hit by valves or pistons but something is wrong with this cylinder.

The other problem I have noticed which only appears to happen when driving above 50mph and then stepping on the gas hard is that the truck will begin to miss very badly, like it is running on 4 cylinders (no check engine light). If you let up on the gas it seems OK then accel again it misses. This lasts for maybe 10-30 seconds and then if you are easy on the gas it just starts running OK again.

I am not sure how all these relate to the #5 cylinder being wet and the spark plug tip being bent.

What I have done so far is: spark plugs, fuel filter, battery (original lasted 100K), air filter, ordered set of COPs (not yet here)

Does anyone have any other suggestions? Has anyone else had similar issues with #5 cylinder?

 

Did you replace plug wires, I noticed on mine they where cracked right next to the top of the boot that went on the spark plug.

 

I would find a bore scope to put gown that hole and see if there is a something in the cylinder. Not the first time to find a screw or a nut in the cylinder. It has to be hitting something to bend the tip.

 

Eric:
There could be an unrelated reason for the hesitation. What is the situation with your EGR System?. Try to make a full check on the EGR Valve, and vacuum lines before going too deep into the engine repair on the 5.4; particularly if you had not serviced this valve in recent years.
Also you might check on the fuel filter (s) along the frame rail if this had not been replaced within a year or so.

 

Well, I changed the COPs and still having intermittent trouble.

The problem was getting worse, it now started to have the stuttering during normal city driving. I ended up driving to a Ford dealer and of course, right before turning into the dealer the check engine light came on. (later found the code was a cylinder #5 misfire)

The plug appeared wet with oil when the tech checked it (but not yet bent again)

The tech did:
a relative compression test which it passed.
changed #5 plug (no difference)
checked COP (tested OK)
check injector (tested OK)

pulled valve cover to inspect for cam follower problems (no problems found)

used a bore scope and said the top of the piston was damaged. (but did not find anything floating around)

Into the repair about $400 only to have service tech reccommend a remanufactured engine for $6000.... ouch!!!

Now comes some choices and I am looking for ideas suggestions etc...
I can't see spending $6000 on a 1997 truck with 100K miles, so I could, try to just pull the head myself (Is the head easy to pull?)and see if it can be salvaged and try to find out what is floating around or just find a longblock somewhere and change it myself. ( I have changed lots of motor before, but have not done any in 15years. I am wonder if this engine is relatively easy to pull (what body parts need to be removed etc..)

I also need a vehicle, so I am debating on just trading it in at the Ford dealer or looking at something else... (this truck had a new engine at 25K due to piston slap and now 75K later the second engine is toast, this does not give me alot of confidence in another Ford product)

Any suggestions would be much appreciated....

 

I have 255000 on mine. I would recomend getting an engine from a salavge yard. I have used many junk yard engines with no issues and they usually have a short warrenty.

 

the 97 is destin to be a classic.
if i invested 6thouthan dolllaaas
it would be a kick *** crate engine

 

if you do go to the dealer for trade in, find one thats NOT the dealer that just serviced your truck. not that they're bad or anything, just they know whats wrong and will ding you hard for it.

 

If I were you... just throw a new engine in it... the truck itself will last a longggggg time.

 

I would try using the right plugs for it first - those are the wrong ones.

I did the same thing (except for loosing something in the cylinder) and tried using Autolites - My truck misfired badley and lasted about 40 miles before it puked.. I put my old Motorcrafts back in the 98 5.4L and she was golden again.

I wrote the manufacturer a nice letter . They replied "That's why we make Motorcraft and Autolite spark plugs - Motorcraft Plugs are Ford Spec , Autolites are NOT.. That came right from Honeywell..

The difference was like night and day..

 

The autolite plugs did fix the initial problem of poor idle. The motorcraft plug in #5 was oily, fouled and appeared that something had bent the tip when I pulled it originally (the other 7 looked normal beside 100K of wear).

I did try to get motorcraft, but it was Sunday and neither of the local auto parts store had them. Since, that time I have read more on this site and would have looked harder for motorcraft plugs if I had only known.

I believe the Ford tech did use a motorcraft plug for his tests.

I poured over all of the posts related to rough idle and missing and was hoping for an relatively easy fix (COP, Plug, EGR, Injector) But after having the second plug tip get bent I had a bad feeling that something worse was going on.

I looked into the cylinder using a flashlight, tried a magnet and then a vacuum cleaner to try to get anything out of the cylinder but did not find anything.

Has anyone heard of valve seats getting loose? Or know where any other small parts could dislodge themselves from the valve train or intake and get into a cylinder? (Engine has not had any work other than oil changes, until this problem)

 

Take one of your old coils , throw a half way decent plug in it. Disconnect the harness plug in from #5 and plug into your old coil. Make sure you have the plug inserted into the old coil - run a wire with an alligator clip @ both ends - one end connected to the metal on the plug and the other end connected to that big bolt on the front of the motor just below the valve cover . Start it up and monitor your spark - you getting spark ?

If so, plug #5 back in , unplug #6 and and plug that connector into the test coil . Start it up and compare . Are you generating the same spark , more or less? Is there a difference in generation between 5 & 6 ?

I'm guessing you may have one of two harness problems. Either a wire that's shorting out between the connector and the MEGA fuse block on the firewall. OR, your wiring harness is to close to the AC accumulator which will create havoc on these ignition systems..

You have compression , the cylinder is clear... There's know reason why it would not fire internaly. The injector was checked correct? You can try swapping it with another to be sure, that's if nothing else above seams to isolate the problem.

With what you have accomplished so far , it has to be one of these problems I mentioned above. These motors will last twice the miles you have currently . You do need to get a good set of Motorcrafts in there though as soon as you get #5 firing again..

I'm NOT kidding - we have the same motors!! Here I have a pic of the Autolites I pulled out of my truck after I had multiple misfire isues. Take a close look , the plug was running so hot it discolored -



You really need to pay attention here if you want it fixed , I have 230,000 miles on my 98 5.4L...

 

You have physical cylinder damage, caused by whatever. No amount of messing with plugs, cops, injectors, etc. is going to fix it. At the very least, you need a new piston and rebuild the head on that side.

 

Whatever he had inside the cylinder must have been cleared. It's evident the cylinder and valves are fine. Dealership did a compression test and it passed . There's know reason for that cylinder should not to fire. A nick and or indentations doesn't fail spark or keep that cylinder from firing. That is the extent of piston damage he must have..

I wouldn't go through an engine replacement yet. Am I missing something here?

 

SOMETHING is wrong in there or the plug tips wouldn't keep getting peened.