1992 Misfire and rough idle

[ayyno]

It started out two weeks ago on the highway, I was going a bit fast at about 85 in cruise control, so maybe like 3k rpms? I could be wrong there, but regardless, I suddenly felt a loss of power and the speedometer started to drop to about 75, so right away I pulled over and my engine was missing and idling at about 550 rpms as opposed to 650 or so. The engine was not running hot at all, temperature gauge never went hot, so I don't think it's a blown head gasket, at least I hope.

I changed my spark plugs today, changed them last about 10k miles ago, I just put bosch copper cores in today, and it isn't running any better. Two of my spark plugs looks like the tips were melted/broken off, and 3 out of 6 were very dirty, however I just ran a can of seafoam through the other day, so that was expected. I also checked the coil pack, which is fine, spark to all 6 wires via arc test.

I ran a few things of fuel injector cleaner, and my next move is to use the 3M cleaner that hooks right into the fuel rail.

I'm going to do a compression check tonight or tomorrow morning.

Basically, I'm asking for suggestions. What to check, where to look...If you guys need any more information, I will gladly do the necessary tests to receive it.

I appreciate any and all input!
Thanks

 

[Roadrunner777]

It looks like you are going down the road of dirty injectors, and I don't see the connection. This was a sudden event, and injectors don't suddenly get too dirty to work.

(So, brains, what is my problem?)

Almost universally, I like to see two things for a diagnostic guess:

1. Fuel pressure at Key on, running, and after shutdown.

2. Engine scan codes.

Also, can you tell us what spark plugs came from what cylinders?

My little old blind guess: I think you are running lean. Suddenly running lean can mean fuel pressure regulator, or fuel pump. Fuel pressure test will confirm or deny this guess.

 

[ayyno]

Sorry for my lack of a response, hopefully today I'll be able to get that done for you. I'm not sure if it helps at all, but my fuel pump no longer turns on for a few seconds then stops....it just stays on until i start the truck(wired to push button for other various problems...probably ignition switch)

it also takes two or three tries to start my truck after it's sat for over 24 hours or so...it'll sort of start for about 2 seconds, then die down...then second try it'll run and idle at about 1k for 5 seconds then down to 550 or so.

 

[ayyno]

I've searched high and low...does anyone know where I can find, or have pictures of where each of the vacuum lines connect? Not some black and white diagram...maybe even a picture of the engine with a quick few lines drawn on MS paint to show the vacuum lines or something. I have a broken like on the tube on the AC, it breaks right after the T connector thing...only the one side is connected. Also had no line on my FPR.

 

[Roadrunner777]

I took my camera out to my truck to see how this could be done. The problem is that a lot of lines are hidden under other things. But, for now, I can say this:

The port on the FPR must go to manifold vacuum. It is critical to the operation of the fuel injectors. This is a plastic line running forward from under the coil pack. This is really your first order of business to get the engine running again.

Get a picture of the AC Tee and I'll tell you what is missing.

 

[ayyno]

Got too dark to snap pictures, but tomorrow i'll take some pictures of my whole situation and draw a diagram on paint or something to make it easier to understand, since like you said...alot of things aren't able to be seen.

 

[Tbars4]

I've searched high and low

..There are a bunch of stickies at the top of this section and the search function works great 24/7..
http://www.explorerforum.com/forums/showthread.php?t=232576

..Your truck won't like your new plugs and curious if you changed your wires too?

...From all you changed and did to your truck in the first post, you should have changed your oil and plugs right away..Motorcraft and Autolite plugs work best in your truck.

..Your electrical shorts/problems won't do you any favors trying to diagnose this..

 

[ayyno]

Sorry I should have been more clear...I've seen all of them...I was looking for actual pictures so I could see exactly what line goes where, not schematics.

Regardless...I plan on changing the oil and plugs tomorrow, I put the new plugs in with this existing problem...so they're probably toast from the heat of running lean...if that IS what's happening in the first place. I haven't changed my wires, since I have Bosch premiums that have maybe 10k at most in them.