My 98 EB Exp. w/5.0 V8 and 99000 miles, is running really bad. Took it to AZ to have code read and it came up P0304. Replaced plugs, wires and coil packs. To no avail. Started reading this forum and realized this is a common problem. I cleared the codes when I was checking things out, and it ran alot better. Other half drove it and within 1/4 mile it was back to running terribly. She told me that it started acting up right after she turned the AC on. I read about the heater hose clamp not sealing up properly after awhile.Is this related to the AC unit(never really work on cars) How do I fix this buy a new clamp the kind that you screw into place or buy the whole hose assy. I hope someone can point me in the right direction. Unfortunately I need to fix this by monday morning since I am leaving on vacation.Thanks in advance to anyone for their help.

 

Is this what AZ told you that the code is? ( Cyl. 4 misfire detected) if so I'd start with spark plugs. Make sure they gave you the right plugs. AZ gave me the wrong plugs one time truck ran like crap, look the same but were not. Go to NAPA get some seafoam and try it. There are some threads on seafoam read them.

 

My brother in law put in the plugs wires and coils. So I trust him that they are right.

 

Did you replace the plugs??

 

Yes plugs were replaced forgot to add a comma in between plugs and wires.I noticed while poking around that #4 injector was looser than the others. Is this a sign of a bad injector?

 

No, but it can couse a miss fire if it's not down right. You can pull it and see if the O-ring is gone if so, get a new O-ring for it and put it back in.

 

Before you pull the injector, spray a little carburetor cleaner around the base of the injector (where it is loose) with the engine idling. It is safe to do so, just don't spray all over the engine, or on the exhaust manifold. If the engine speeds up, the o-ring seal around the injector is bad. Remove the injector, and take it to an automotive parts store. They should be able to match something up, even if they don't have the specific part for your truck in stock (which they may well have).

If you don't know how to get the injector out, ask the forum. Also, with a engine with that many miles, it is very easy to ruin the o-ring just by pulling the injector out. So be prepared to replace the o-ring on any injector you remove. They are inexpensive, and it is a good practice anyway unless the engine is low mileage.

 

Thanks for the O-ring info. I will have to check it out tomorrow. I cleared ths codes on the computer while checking everything out. I then drove for about 5 to 10 miles, all different types of driving(stop and go, highway and around town)w/out the AC on and the Exp. ran fine. Let the other half drive it and as soon as she got about 1/4 mile away with the AC on it started running like crap, sputtering, missing and backfiring. Wiped the codes clean and tested this myself, drove @12 miles without AC on, on the way home turned AC on and the light started blinking again. Any clues on where to look for the cause of this? Thanks again to everyone for making me feel welcome here.

 

If the code is for cylinder misfire, that is your problem. The added load/heat of having the a/c on, especially at idle or near it, can have a cylinder that is prone to misfire misfire. It may not do so when running above idle, or without a load. If you keep getting a P0304 code, that is telling you cylinder 4 (rearmost cylinder on passenger side) is not firing all the time. I would replace the spark plug (even if it is new), and check the wire to the plug - all the way from the coil. On these engines, also, if there is any grease or anything (other than non-conducting dielectric grease) on or around the spark plug wire where it snaps into the coil, the wire will arc over. Be certain also that the plug wire is not pinched against metal, and not melted by exhaust manifold. The wires take a long and winding road to the back cylinders.

And, check the injector as described in earlier email. Especially at idle, a leaky injector that is sucking air around it will make the cylinder involved run lean and misfire, especially under load.

I had a similar problem with my 1997 Explorer with 5.0 V-8, and the problem was a smear of grease under the right hand coil bank, that was arcing across two cylinders intermittantly. To be certain the coils are clean, use spray brake parts cleaner (not carb cleaner - it leaves a residue). Pull the wires out of the coils one by one, and spray the connectors on the wire and in the coil. Be sure to wipe and dry them with a rag before snapping the wires back in.

So, if the codes continually tell you cylinder 4 is the problem, check the spark and fuel to that cylinder.

 

Here's some self-tests you can do...

1. Idle engine when it's super dark outside, see if you see any jumping spark around the wires/plugs, etc.

2. Now spray a light mist of water on them...if there's a "weak link", that spark will jump out.

 

Is there anyway possible I can get the injector out without removing the intake manifold and all? I took the advice about checking for jumping spark and saw none. Don't have any carb cleaner to try the other test, not 'til morning that is.

 

The intake manifold is going to have to come off bro, doesn't appear to be that big of a job. (just looked at my '00 5.0) It's a dry gasket so if AZ doesn't have a replacement you can fabricate one with gasket paper fairly quickly.

Just reading the thread I think it would be a mistake not to address the loose injector, sounds like it's a good bet that's your issue.

 

Thanks fellows. Off to my brother in law my Exp. goes again.

 

Thanks for all the help. My brother in law replaced the plugs and wires again and the exp. is running better than it has in ages.