Hello all -

I have an '01 Disco named Matilda that I've babied for years that has about 120k miles. I've got a significant misfire situation and I basically am looking for some feedback on my hypothesis and my intended course of action.

I only drive it about 4,000 miles a year or so for off-roading, mountain adventures, etc. From 2018-2021 I was outside of the country most of the time and she sat in storage and was only driven intermittently every 6 months or so. Unfortunately, there was a period where it was left without sta-bil in the fuel and the tank was left at only 1/4.About 6 months ago it developed a bit of a rough idle. I ran some sea-foam through the tank, and it got really bad, flashing engine light, knock sensor code, lean condition, misfires (I believe it was for multiple cylinders, but I don't recall now, I assumed it was an injector issue after having sat the way it did for the periods of time that it did).

I did run some BG 44K through it, but as it was running so poorly by that time I didn't want to cause any damage by continuing to drive it to run a full tank through (I got about 25% through the tank). Oddly, all of the issues went away for about 4 days and I was happy as a clam, thinking that the BG 44K helped knock something loose. Unfortunately, though, the misfire came back and has remained persistent since then.

My hypothesis is that the injectors probably didn't fare too well as a result of the vehicle sitting for extended periods, and potentially compounded by the additive breaking even more varnish or other gunk free, and of course by the improper storage and stabilization of the fuel for a period. My plan is to 1.) Replace the injectors and seals, etc., 2.) Replace the coil packs while I have the intake manifold off.

I'll also note the condition of the plugs and wires (I don't have a place to work on/further diagnose it here in the city, I've gotta have it hauled out to my garage), etc.

About 15k miles ago in 2018, I did the head gaskets, new plugs & wires, valve cover gaskets, belt, all new hoses, thermostat, K&N air filter, etc., and I've tried to keep ahead of most other maintenance.

I'm pretty confident I'll resolve the issues with these repairs, as the symptoms (to me) seem to reconcile well, but I wanted to throw it out there to see if any veterans have further suggestions or insight, or anything else they recommend doing while I'm at it. I may just throw new plugs and wires in again; the cost of the parts is less than the lost time and effort of having to haul it back to my garage and tear it apart again.

Also, should I do the valve cover gaskets again? Open to any suggestions.

Thanks for reading, and happy Rovering.

P

PS: Has thrown different codes since it started but the codes currently are P0332 and P0308 (Cylinder 8 misfire). I'll try to pull the plug on 8 tomorrow to see what it looks like.

 

The scenario: ran bad, ran good, ran bad again makes me think wiring or connectors, rather than injectors. First, I'd check #8 spark wire connectors for rust/corrosion, coil pack metal terminal too, and ohms of the wire itself. Work through the codes.

New spark plugs are nice, though. That way you can read the old ones to see how your new head gaskets did for 15k miles. Easy to check compression while you are there.

 

Good points. I will see what I can come up with today!

 

Pulled the #8 plug

 

Maybe try the next higher heat range next time. Does the engine burn some oil?

 

My theory is that the plug is fouled as a result of the issue causing the misfire... It also hasn't had a highway speed drive in months. I also lean towards the coil pack as the culprit. I don't really have the ability to swap the wires around even to check the coils right now, but I'll test when I get it into the garage before I tear it down just to have as much knowledge as possible.

In response to your question JohnZo... she does burn some oil. If I had to guess I'd say it's about 2/3 quart every 1000 miles, no more than five years ago though.

Any other thoughts out there?

 

I don’t think 2/3 qt in 1000 miles is a worrisome amount.

 

Not terrible, but could make the plugs turn black and oily, especially if the valve stem seals leak a bit.

 

Plugs, wires, new filters, throw some injector cleaner in there.

 

I'm no expert but when I got mine it had a similar issue and people said that the coil packs were the common issue because they get hot and break down after a while and an intermittent issue especially if it was on the same cylinder(between when it first occurred and after it stopped and started again) is most likely electrical so maybe the sender to the injector is loose or the coil packs have gone bad, if you do replace the coil packs make sure to do the relocation kit so that they're away from all that heat at the back of the engine and easier to work on if it ever goes wrong again.