Shaking between 45 and 50mph after replacing coils

[mr49erguy]

Good afternoon all. Over the last month I have been hard at work on my 1998 Expedition. With the help of a friend, I replaced the heater core after removing the entire dashboard. Whew, what a job. Glad that one is done.

This week I removed the intake manifold to replace gaskets and a couple of hoses in order to resolve what I believed was a vaccuum leak. The truck was idling high upon start (1300 rpm). After having it since March, I really wanted to get that resolved. Well, I see to have successfully lowered the startup rpm to 850-900 which I'm thrilled about, but I now have a shake that can be felt and heard when going between 45-50mph. It just does not feel right. Almost like a coil is unplugged or defective. In the process of removing the intake manifold, I replaced all 8 coils and 7 of the 9 spark plugs. The one in the rear passenger side (#8?) will not come out as I cannot get the spark plug socket to seat onto the plug. VERY FRUSTRATING, but I do not believe that this plug is causing my issue as it was running without any shaking before this endeavor.

I really want to avoid pulling all of the coils and especially the plugs if possible, but will obviously do that if I have to. I decided this morning to pull the electrical connector to each of the coils, one at a time and running the the engine to see if I could determine from sound and the way the engine ran which coli could possibly be causing my issue. No discernible sounds or funny running could be observed when doing this. I found this very odd.

I checked connections to each of the fuel injectors and they were solid. NO smell of fuel coming from the fuel rail.

What I am thinking now is that I may have plugged in one of the many hoses into the wrong place. There are a few that go into the throttle body. I have some before pics that I took, but do not have a good enough angle of some of the areas to be able to know for sure if I have them in the correct place. Does anyone have any pics of their engine bay, specifically the throttle body area that they would mind sharing for me to take a look at?

 

[98eb5.4]

let's see yours, been in there quite a bit recently dealing with a p0401 evap insufficient flow thing,

might see something from your pix and i'll get pix of mine,

had coil & misfire issues & got 2 separate codes when dealing with that but i guess no codes for you?

 

[98EXPnSRQ]

As far are the spark plug you can't get a socket on, you might want to read over this thread.

http://www.expeditionforum.com/f42/spark-plug-questions-26691/

There is a Dorman cylinder head repair kit that repairs blown out spark plugs. The insert is, I believe a 17mm deep socket and it uses a funky spark plug. Here it is on Amazon.

http://www.amazon.com/Dorman-42025-Master-Cylinder-Repair/dp/B000TYVU1U/?tag=viglink23361-20

 

[jacks3am]

If you have a shake at a different rpm or while driving it may not show up when unplugging coils at idle. It sounds like one of the cop boots may not be properly seated. Dielectric or silicone paste the ends of all coils and try to reinstall making sure they seat well on the plugs. Also if you dropped a plug before putting it in the engine it may have cracked the porcelain on the plugs which would cause a miss, things to check for!

 

[mr49erguy]

Thanks guys. Jacks3am, I think you may be exactly right. I think the coil is just not seated all the way. I drove it about 35 miles for the first time since doing the engine work and received a P0304 (cylinder 4 misfire detected). The plug is old, but the coil and boot are both new and dialectric grease was pushed into the end of the boot, but I think its just not seated well.

98EXPnSRQ - I went through the thread you recommended. Thank you! It was helpful and I may end trying a 17mm deep socket to see if that helps me. I kind of hope it does not urn out to be the case, but in some ways if it is, at least I know for sure that this plug had blown out previously and needed an insert placed in the plug port.

 

[98EXPnSRQ]

The #4 cylinder is the back passenger side, the one you can't get the plug out. That spark plug is likely the problem, so I would work on getting it out.