Hello all, My wifes explorer has developed a misfire on cylinder 3&4 consistently. I did have cylinder 2 misfire once. But have not had it come back. The explorer is a 2006 4.6 limited with 130000 miles. Originally it was misfireing on cylinder 3. So I swapped the coil packs between 2&3. Cleared the codes. Still got a cylinder 3 misfire. So I went and bought new plugs for it. Cleared the codes. Still misfire on cylinder 3. Swapped injectors 3&1 .I took it out and romped on it and now i get cylinder 3&4 consistently misfireing. Now I got me to thinking that the only side that is misfireing is the pass side. I was going to swap o2 sensors but couldnt get the driver side out so I went and bought a new o2 upstream for the passenger side. Still get 3&4 misfire. Thought it might be fuel related so I pulled the filter. It was kinda tough to blow through so I put a new fuel filter in it. How the hell can I check the fuel pressure without a fuel fitting? Please anyone have any advice before I pull all my hair out? I am now thinking it might be fuel pump, plugged cat, or low compression

 

Slow down, take a deep breath. stop guessing...

You need to validate the engine first.. remove all plugs, cut the fuel and spark, WOT and take a compression reading on 3&4....

Get back with the results..... Philip

 

Well I wanted to do a compression test today but I dont have the right adapter. I am going to try and buy one local tomorrow. But I may have to order one.

 

Be prepared to follow up with a leak down test on the engine.... Philip

 

Yes I am already thinking the worst. I own a cylinder leak down gauge. But I need the adapter to use either that gauge or my compression gauge. The adapter is not available anywhere local and I had to buy one online. Should be here some time next week. I am not really digging how Ford changed up everything. What was the purpose of using a spark plug thread different than any other engine ever? Why did they remove the schrader valve for the fuel system? How are we supposed to check fuel pressure?

 

Well its confirmed. Cylinder 3 has bad rings and the head gasket between 3&4 is popped. This sucks. I cant believe this motor at 130k is this bad. I change the oil every time the light comes on withen a few days. I just cant fathom it being this bad. Ive had cars where I never changed oil and never had any issues!

 

Sorry for you grief, that is exactly what I expected...

What are you going to do about it, pull and R&R?.. Philip

 

Yes im already looking for a used motor with good compression.

 

Did you consider doing a re-ring on the one cylinder and a head gasket, in frame..

Of course that depends on the results of the compression in the other holes... Philip

 

I am going to pull the motor this weekend. I will open it up and see what it looks like. I did not think about doing just one set of rings. I may judt rebuild the motor anyway. Seems junkyard motors are 1500 bucks. I figure im close to that in parts. Machine shop might not be to bad if my heads are ok. My cylinders were.
1- 168 170
2- 169 170
3- 160 150 150
4- 140 145 140
5- 168 168
6- 168 170
7- 160 165
8- 165 170
With cyl 3 on TDC air was rushing out dipstick tube
With cyl 4 on TDC air was rushing into cyl 3

 

There may be a chance it is still the head on cyl 3. Yesterday i was pissed when i found the motor bad. I forgot to put some oil in to check the rings. So today i am going to rerun the compression check on both 3&4 with a little bit of oil in the cylinders

 

Ah!

I had wondered about the second set of readings, seemed tight enough to indicate valve issues.... Philip