03 explorer misfire

[mbryan0790]

Hi new to the forum. I have an 03 explorer with the 4.0 that has come up with a misfire pretty bad it started in one day not a slow thing. I didn't drive it for a week or so and then when I drove it it was misfiring so I put all new plugs in thinking it was that and nope. I plugged it in and get misfir in 1,2 and 3 and random misfire code plug misfire in first 1000 revolution code not exactly sure where to start digging any help would be appreciated

 

[Number4]

A misfire on 1-3 would indicate you’ve jumped time. The guides and tensioner for this are in the back. Meaning you have to pull the engine to fix. If it jumped time, you’ll also need to remove the pass. head and install new valve stems.

Before doing this, look into the coil. But it’d be odd for the coil to fail on 1-3.

 

[mbryan0790]

Since this post I got some pretty bad nerve damage to my bracial plexus nerves and haven't had a chance to touch it. I might be able to starting looking into it again in a month or so I will swap the coil pack first and see. Any other ways to check for jumped timing?

 

[Number4]

Since this post I got some pretty bad nerve damage to my bracial plexus nerves and haven't had a chance to touch it. I might be able to starting looking into it again in a month or so I will swap the coil pack first and see. Any other ways to check for jumped timing?

Compression test.

 

[mbryan0790]

Ok well I did the comp test this is the results I also saw that the very bottom corner of the pass side valve cover is now cracked

 

[Number4]

Pretty sure you have 4 bad cylinders.
1-3, 5

 

[mbryan0790]

I think I'm gonna try and get the valve cover off and see if the plastic part that guides the chain is messed up and go from there. The lower number on the pass side was odd cause it got 135 once and 115 once so I just went in between. Is taking the cover off gonna let me see if it's bad?

 

[mbryan0790]

Issue found

 

[mbryan0790]

Do I have to pull the flex plate to get the lower bolt out or is there an opening in it I can use to get the bolt out. Also how hard is it to retime the cam?

 

[Number4]

Do I have to pull the flex plate to get the lower bolt out or is there an opening in it I can use to get the bolt out. Also how hard is it to retime the cam?

You need to pull the engine, remove the passenger side head and put in new valves.

If you have a borescope (camera that can go in spark plug holes) you can look at the drivers side piston tops for valve contact marks. But you probably have a similar issue there too.

You have to remove the engine. Cloyes has a pretty good video on re-timing the engine. There’s a master timing tool set you’ll need to buy or rent.

All in all, if you have the space, it’s not a hard job to do.

Here’s the valve marks on the pistons:

And here’s what it looked like via the borescope:

 

[410Fortune]

Sohc is interference engine pistons smack the valves when it loses time

Time to Pull the engine

 

[SyberTiger]

Issue found

View attachment 445144

View attachment 445145

View attachment 445146

I'm not familiar with this engine. What are the blurry photos showing? Missing timing chain tensioner?

 

[mbryan0790]

I'm not familiar with this engine. What are the blurry photos showing? Missing timing chain tensioner?

Yeah the plastic part the chain sits on is gone

 

[Number4]

The rear guide appears to be completely gone.

 

[SyberTiger]

Hmm, looks like you might want to pull the oil pan to fish out the plastic-nylon parts.

 

[mbryan0790]

Swapped the cassette and runs better then ever thank you guys for the information on what was up