Ok guys. I have a 97 5.4L with 108,000 miles. I just took a 300 hundred mile round trip and pulled back a 5,500 pound load. It ran great. After I unloaded and started driving, the check engine light came on. It still ran fine. The next day while driving I started having a major misfire. I scanned it and came up with #8 cylinder misfire and P1151 code. All day today, I changed the plug and ignition coil for #8 (All plugs were changed out 20,000 miles ago). I also took the throttle body and EGR valve off and gave everything a good cleaning. Put it back together and it is still running like crap. It runs slightly rough at idle and clunking during acceleration. I drove around a few miles to try to get the service light to come back on so I can have it read again but it has not yet came on. At idle it feels like maybe one cylinder is not firing. Would a bad O2 sensor alone cause this behavior. Or how can I find out if it might be a bad cat or injector gone out. Or could a bad plug do this. Im scratching my head cause I don't know what my next step should be.

 

Fuel filter?

 

Crank it up and have someone put it in gear and give it a little gas until the miss is really apparent.

Start pulling the injector connectors loose 1 cylinder at a time. It should run a little worse each time you disconnect 1.

Reconnect it after you see it runs worse and move on to the next one. When you get to the cylinder that isn't firing, you won't notice any difference with the injector disconnected.

Then you can look at the COP, plug, injector, etc. for that cylinder.

 

I'm guessing its a vacum leak. 1151 means unable to adjust fuel because of lean condition or something like that. Did you use motorcraft plugs? no code for missfire? Probably a pretty big leak. Check the pvc elbow at the back of the throttle body and just check everywhere for vacuum leaks. Might want to replace all your coils at some point.

 

Thanks for some of that advise. The fuel filter was changed about 15,000 miles ago. That would not cause what Im experiencing. BMAN, I will try what you suggested in the morning. That could help pinpoint it a little better. JETHAT, I did check all hoses when I had the throttle body off, I could not find any obstructions, holes, or collapses in any of the hoses. I'm ruling out a vacuum leak for now. Would a bad EGR valve cause it to run this way?

 

The PCV elbow behind the intake under the throttle body is a high failure item. It rots and cracks.

 

5500 ? I think you have the wrong plugs installed... OR, 5500 will open up the front wheel well on a 1/2 ton - #8 will get nailed with water if you pull in the rain.

1151 suggests a leak in the EGR pipe. You prolly were pulling heavy in the rain weren't you - Yea, I don't like pulling that much with mine. That whole side of the motor takes a beating - keep an eye on your dip-stick, it can dis-lodge as well.

 

JBREW, no rain at all that day and was about 45 degrees out. I did put Autolite plugs in when I changed them out a year ago. It has always ran fine. Yesterday when I had everything apart, I pulled all 4 COP's, plugs, and injectors and inspected them each. I also cleaned each connector and spark plug end. I replaced two of the injectors o-rings and end caps that had small crack. When I put everything back together, I did switch everything around from where they were originally to see if things changed. But now I cant get the service light to come on. I thought the P1151 from what I read mostly indicated the 02 sensor on left upper bank. That's why I asked if a bad 02 sensor would cause the engine to act like that.

 

How do you get away with running Autolites and I can't? I'll never understand that. Heat range is way off and they puke out... I tried these and only went 40 miles before they misfired on two cylinders..

Well until you get the right plugs in that model, I can't help. Sorry.

Honeywell doesn't make an Autolite for our model. Honeywell has the Motorcraft for us..


EDIT: I think Autolite has a Copper series that's suppose to work, but I'm not sure. - Motorcraft is fail-safe, - thro a set of those in there .. This 5four is picky, it wouldn't start when I tried Bosch way back when..

 

Yep, I think the Autolites break down way too soon. Get some Motorcrafts in it.

 

Update....I got the engine light to come on after some more driving and headed down to Oreillys. This time code P0357 popped up. Said something like ignition coil primary / secondary (G) malfunction or similar to that. Im doing research right now to see what that code is.

 

Could be your coil boots are shot after all those years and pulling them off putting them back on and all. If it were me I'd replace the coils and boots and I'd replace the autolites with motorcraft specified plugs. you can do that now for less then $150

 

Tell me how the boots could be shot. They are just rubber. None have any cracks and look good. i put plenty of di grease in the boots each time.

Doing the research, it looks like the problem is coil #7 now. I did not put anything on that cylinder from #8 when I changed everything the other day that was not replaced with new. I put everything on the #5 cylinder so I could get to it easy. I can not figure how to get the coil screw off without removing the fuel rail. My small swivels don't even fit under that round thing thats on the fuel rail. Im going back at it again. At least I think Im getting closer to the light. Thanks everyone

 

It depends on the boot /connectors you have. Ford got cheap in 99, they newer style wow's out at the bottoms and invites moisture.

New style on the bottom -



NOTE: The spring/connector at the top of the pic. Spring is off-set so it will not loose connection.

You have to clean the spring where it connects to the plug if your using the bottom set up in the pic (another thing I don't like about those) - I've installed those on another truck before. Here's what I do with those suckers, - I stretch the spring a little after installing the boot onto the coil/ Dip the end in gas/ blow the di-electric off the spring with compressed air. Also , the springs pull off the coil blade pretty easy. You connect the spring to the blade FIRST. - In a way that it won't loose it's connection. It will loose it's connection if you over tighten the coil bushings. Coils are meant to move freely on that bushing when alls said and done. If the the coil momentarily looses connection while active. You'll short the coil , thus compromising it's windings. - Meaning = It's toast.

What you have to be careful of with boot #2 - The boots will buckle if you don't twist them down right. - From one side to the other. Those boots are very weak.

BTW - Remove the fuel rail bolts on that side/ lay some rags down / flip the rail up onto the manifold.

 

My dealer strongly recommends changing them when changing plugs. The heat gets to them, too.