Disco 1 runs worse after plug/wire replacement
 

Hi all,

I just replaced my plugs and wires--Kingsborne 8mm wires, and NGK BPR6EGP 7084 plugs--and the engine is running worse than it was before I did that. I have no idea what to think.

Then reason I replaced is the engine has been misfiring a bit lately, and I had a couple of weird manufacturer control codes--searching them suggested that plugs and wires was the first place to start. Pretty sure the old wires were original, and the plugs were not (Bosch), but they looked pretty bad. One even broke in the ceramic part when touched it.

To be transparent, the NGKs were a different socket size--which I didn't have. I finger tightened them as well as I could, and headed off to AZ to get the right size socket so that I could tighten them properly. As I was driving, I got tons of misfiring and backfiring and next to no power. When I got to AZ--five minutes away--I popped the hood and 4 plug wires had come loose--so I was running on only 4 cylinders. Bought the socket, tightened everything up, made sure that all wires were snug on the on the plugs, and headed home. A little better performance, but I'm still backfiring like crazy. Most recent code is P1316--which it had before.

Any thoughts? Only other thing I can think to include is that the new plugs seem long--at least 1/4" longer than the ones I replaced. Plenty of the ceramic is exposed. I know the wires are in the right order--I did them one at a time and matched length just to be sure.

Any and all help is appreciated.

What year is this DI?

oops--sorry. 1999 with a GEMS.

IMHO I wouldn't (and don't) run Platinum plugs. A BIG YES to NGK, but a #7131 (Gap .032" - .038").
BUT if you are going to run the #7084's did you check the GAP of every plug?

And again IMHO, Kingsborne Wires are GARBAGE. Others will disagree(let the flames begin) but I've had these wires fail right out of the box on more than one car/truck. Never again! STI 633 work very well in LRs.

Have you replaced the ignition coils recently/ever?
And I know you checked the wires, BUT check them again for placement and fit on the coil pack.

Ok--thanks. I didn't check the gaps--I (naively, perhaps) figured they were pre-gapped. I'll probably start with replacing the plugs and see what happens there. You might be right about the KB wires--I just nabbed them because they are affordable and plenty of people sing their praises.

https://cimg4.ibsrv.net/gimg/landrov...001c626332.png
No worries, you'll get it sorted. The STI wires are half the money :pointup: and work spot on. > https://www.fcpeuro.com/products/lan...scovery-hls102

If you decide to do coils RockAuto has Standard Motor Products UF-143 (LR: ERR6269) for about $22.00 each.
You'll need 4 > More Information for STANDARD MOTOR PRODUCTS UF143

Ok--thanks for all of this help. I swapped the NKG plats for the NGK 7131 coppers--maybe a 15-20 % increase in performance, but still not what it was before changing anything.

Tomorrow I'll double check the firing order, re-check the plug gaps, etc. But still, I'm baffled.
Also--didn't mention: I changed the air filter with a new OEM one. The old one was filthy. I really thought this was gong to change the way the engine ran--but just not this way.

The P1316 emissions fault misfire is counted every 1000 revs and without any particular cylinder being identified it's an overall condition which would be air, fuel and spark. If the air filter was really dirty then the MAF most likely is, not a bad idea to clean it with MAF cleaner. You've taken one step back with spark but get that sorted and then hit the MAF. MAF (Mass Airflow) sensor. As far as fuel I'd suggest replacing the inline fuel filter.