Hi all - I posted a week or so ago about my misfiring problem. '99 Discovery Series 1.
For the record, here's the codes I am receiving via autozone.
1447
1187
0451
0307
1316

I did the following things to remedy the situation.
Engine Flush
Oil Change with Castrol Synthetic
Two tanks with Lucas Fuel Injector Cleaner
Sea Foamed twice
New Plugs and gapped
New Wires (Not the Magnacor unfortunately, NAPA premium)
New Air Filter
Cleaned Throttle Body with Carb Cleaner

After that didn't work, I picked up a new ignition coil for cylinder #7. Just installed it, and I'm still misfiring.
Help!
Any advice much appreciated-
Josh

 

How much were those plug wires?
What grade of gas are you using?

 

Wires were 105+
I'll order the magnacor's up on my next paycheck, but I figured for now the premium napa brand should get me going.
Gas is only Premium blend.
I did notice an improvement after the engine flush, and then a week later after sea foaming, but its been getting progressively worse since then. No power up hills or if I punch the gas - just misfires.
Thanks!
Josh

 

What plugs and gap?
You have 2 evap fault codes, neither of which will cause a no start/miss. That 1187 is an 02 heater circuit malfunction, again not a start or misfire issue.
Are you sure you got a new coil pack, not a used one?
PM me your tele number and lets talk.
Mike

 

Well the only other thing that I can think of with the new information is the VSS, vehicle speed sensor.
The VSS is a govoner and when they go bad they will cut injectors to cut your road speed.
When they go bad the truck will act kinda like yours is.
It could be a clogged fuel filter and the fuel pump cannot push enough fuel to keep up with the higher demand of a jack rabbit start.
I doubt it is carbon build up on the valves.
Cam sensor goes bad it will go into a default mode, it will run but poorly.
Crank sesnor, either runs or it doesnt.
The only two possiblilties that I can think of are fuel filter or VSS.
www.atlanticbritish.com

 

Hang on guys, let's all get back to basics. You need to do a compression test. If you changed the plugs you were right there. You can't band aid repair a bad cylinder.

Plug wire quality is over rated most of the time. The premium wires from Napa shoud do just fine as long as they're routed properly and fit well.

Since you've changed the plugs, wires, and cleaned the injectors that's not likely the cause.

Is this a dead miss or does it get better after it's warm? Are you losing coolant?

Mike is right, the evap fault and O2 faults will not cause your miss.

 

I dont think anybody said that the EVAP and O2's are causing the mis fires.

 

Alright all - thanks for the thoughts today. I talked with Disco Mike on the phone for twenty minutes also.
This evening I changed the fuel filter and did a quick compression test. It's awfully cold out there, so I only tested the suspect cylinder (#7) plus cylinders 1 and 4. All three cylinders came out at 160 with a warm engine block.
At least that is some good news.
Changed the fuel filter - didn't seem to make any difference. I also rechecked all the wires, sprayed with water to check shorting, and double-checked tightness of the spark plugs, as I was surprised that number 1 wasn't very snug when I installed the tester.
Now, I also bought a scangauge II today as autozone is an hour away for free testing. When I plugged it in, same codes. I took the liberty of clearing the codes, and am still waiting for the rover to give me a new check engine light.
One more piece of information though - with the new scan gauge I was able to watch the engine loading percentage as I drove. Misfires would only occur if I put the engine between 79 - 89 % of load. If I really hammer it, and get above 90%, there is no backfire. Below mid 70's, no backfire.
This would concur with my experience last week - in all the snow we got in portland, I was in low 4wd most of the time. With the extra power gained, I rarely was backfiring.
Any more thoughts? I've got a call in for a VSS, but will have to wait till Monday to pick one up.
Thanks again all-
Josh

 

Where did you get your Scangauge and how much did you pay?
I have a link to their site but I am looking for it cheaper of course.

 

Picked it up here in Portland at a racing shop. Only ten bucks off the 169 price on Scangauge's website. Well worth it though - I had been thinking about picking one up for a while to use in my prius.