Hey all,

I am new to the forum...and my Christmas may be totally ruined here.

2003 Disco II S 55K, bought it back in February and I love it (except for the constant maintenance...the after-market warranty helps ease that pain somewhat though)

About a week ago I had, what my mechanic described as, a "sluggish" O2 sensor replaced. I have an aftermarket warranty, and I suspect they covered some after-market (cheaper) part. Nonetheless, the steady check engine light I had at the time was gone...for a week.

Today, at the onset of my 9 hour drive home to my family for the holidays, I engaged the cruise control on the highway (around 72mph) and immediately started getting a flashing check engine light (a bad thing...I know, this means stop driving).

So I turn around, I find an open Monroe to run a diagnostic (free I might add), and I got the following codes: P0300; P0304; and P0307. Then I headed back home to Pittsburgh (luckily, I had only traveled about an hour).

So I have multiple gross misfire, and the 4 and 7 are misfiring as well.

First reaction is that I need new plugs and wires...they should be done now anyway. Notwithstanding, is there some sort of vacuum leak coming off the cruise control that could have started this? Also, would the fact that the O2 sensor was just replaced (possibly improperly or cheaply) contribute to this?

Finally, am I correct in assuming that 4 & 7 are paired in some way...like on the same (possibly bad) coil?

Any help would be much appreciated, as I am either off to my mechanic first thing Monday morning, or hitching a ride to the parts store and attempting to follow one of the pictured diagrams on this forum for changing plugs and wires.

Thanks!

PS: I am told DiscoMike is the person I might be looking for on this forum, as he is extremely knowledgeable about these issues. Mike, if you're out there, any expertise would be most appreciated. Thanks.

 

PM me your tele number so I can call you early this morning and get you thru this.

 

Mike:

Just PM'd you my number. Thanks so much!

 

Figured I would post the solution here for those other poor souls who might get stuck with this 4 & 7 misfire. Sorry my response is a few weeks delayed.

After a conversation or two with DiscoMike (thank you, sir), and after looking at the RAVE, we narrowed it down to the plugs and wires. The RAVE diagram shows that the 4 & 7 are paired together on the same ignition coil.

After not getting a bad ignition coil code from computer, I figured a bad coil was ruled out...WRONG.

The plugs are wires were good (or relatively good to get me home for the holidays), and the coil was actually bad itself. Go figure?

Thanks again to DiscoMike, and best of luck!

 

I own a 2003 discovery 63000 miles on it andI am having the same issue I already swapped out the coil pack on the driver side that contains the 4 and 7 plug on it before i spend anymore money can someone give some insight please!! thank you

 

Ok update on my situation it was just my plug wires i bought the magnecor 8.5's and everything works great I bought them from Ultra Rev They were like $130 shipped great price for magnecor's