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.

couple of thoughts...

- make sure you have the top of the air filter compartment securely fastened
- check that firing order
- make sure connections at both ends of plug wires (coil pack and plug) are securely fastened. I had one pop off at the coil pack end when I drove over some rough cobblestone roadway.
- if you clean the MAF do it when the MAF is cold (ie the truck has not run in a few hours)
- OverRover is one of the best posters here, huge knowledge, super helpful. I'm not going to flame him, but I've had very good experience with Kingsborne so reasonable men can disagree. :)
- ihscouts, that new avatar saddens me.

Thanks for all of this help. I fired it up this morning just for fun, and pulled a random misfire and misfire in 1, 5, and 6, which I think are all right next to each other on the coil pack. But, it's snowing and I needed coffee, so when I warm up I'll go back out and check the firing order and gaps.

Does it matter if the wires touch each other at all?

Anyway, this is Nashville's first real snow, and its killing me that I'm not out tooling around!

Doesn’t matter if wires touch. Now, if a wire was sagging real low and ran up against say, the exhaust manifold, and it burned through the wires insulation then you’d have a problem.

Ok, guys, I'm an idiot. I had the 6 and 8 wires mixed up on the coils. switched them, and it fired right up. ADHD--what can I say.

I did notice that it still missed a little under acceleration up a hill. It's MUCH better than it was, obviously, and is drivable. But still a mystery. I've got a fuel filter to install, and will clean the MAF--those were next on my list.

I cleared the codes, and will report back if something comes back.

At any rate, thanks for all of the helpful responses: sorry it wasn't something more exciting.

Still here Walt with all my Rover knowledge just happen to be fond of the original.

Like a middle finger!

Ok,

I'm back. The engine starts and idles as well as it ever has--it used to start rather hard, but now it fires right up. However, at any RPM level past 2500 +/-, the engine begins to stutter and misfire pretty dramatically (it doesn't back fire--just that "wump wump" that has always meant misfiring in my limited experience). Driven quite a bit since I last posted, but no CEL to indicate what might be happening. This was not the case prior to the plug/wire replacement (or, at least, not nearly the extent that it is now). Have I opened a pandora's box? Or is it possible that this is just more user error.

I have one of those WiFi scanners with an app on my phone--just installed it today. I've got a little bit of data from that, but nothing that I really know how to interpret. But if knowing engine load, MAF flow rate, etc., is helpful, I can post that too.

So, again, any and all help is appreciated. I can certainly drive around if I stay under 2500 rpm, but that means it now takes like 2.5 minutes to make it to 50 mph, so it's all surface roads for now.

Thanks!

Sounds like, at over 2,500, you are running out of fuel (dirty filter) or have a weak coil/coils.


Good deal & fair enough.

Ok,

Haven't had a chance to clean the MAF or change the fuel filter yet, but trying to learn how to use this diagnostic tool. What I've learned is that my LTFT for both banks is 24.22, which, if I understand correctly, is crazy high. My STFT for both banks is constantly moving--for bank 1, betwwen -18 and +24, and for bank 2, between -14 and +17 (these are approximate-ish--my free app doesn't store info, so I have to watch while I'm driving). Generally speaking, idle or coasting or braking gives negative values on both banks, and working under any kind of load moves into positive. Because of the misfire, I can't seem to get the engine above 80% load. But at that load, 2500 rpm, at either 45 mph or 70 mph, we're looking at 20-24% STFT on both banks.

Thoughts?

Ok, back again. Last night the Disco died as I pulled out of a parking lot. I killed the battery trying to get it started again, so had it towed home.

Started just fine this morning with a jump start. Currently showing a P0138, P1179, P1177, and P1316.

I cleaned the MAF--while cold--a couple of days ago, the check engine came on shortly thereafter. It ran pretty well, and then right before it died it starting missing again.

I think my route now is to go ahead and change the fuel filter, replace all of the vacuum lines, check for an exhaust leak, and then measure fuel pressure. Does this make sense?

Is there something else I should pursue? From what I've read, this doesn't necessarily mean that the O2 is bad--correct?

Any and all help appreciated. Thanks!

I think you have a sticking injector just by the codes your getting. Over fuels and the computer is trying to compensate both fuel and air. The side of motor with the #1, 3, 5 and 7 cylinder, drivers side I believe. I'd rattle test em. Pain in the butt to remove the rail so you just lift it high enough to pluck the injectors out one at a time. Shake them, if they rattle they're considered good, if one does not it's stuck. That would kill your rpm/power just like your experiencing. I had one full open and it flooded the cylinder, no spark at all. Could smell the fuel. It happened while on the freeway, killed the power big time. Normally you'd get a misfire code as well but if it's just sticking/unsticking then it could pass the rev counts for a misfire code?

Thanks, ihscouts--I'll give this a shake and see what happens.

I did find that the vacuum hose that goes from driver side valve cover to the throttle body was basically made out of play dough. Also, the ports that hose was connected two were pretty gummed up with carbon. Cleaned the throttle body fairly well--but didn't really know how to clean the valve cover one--didn't want to accidentally flush all that gunk down into the engine. Replaced that with a piece I had lying around and that eliminated two of my codes--now I just have the P1179 and P1177--those two together make what you suggest about an injector pretty coherent.

Will update. Thanks!

Quick update--still haven't had a chance to check the injectors, but replaced vacuum hoses and cleared the codes--stayed off for a day, then came back with P1177, P1448, and a cylinder 1 misfire.

When I was replacing hoses, I noticed that the nipple where the gas tank vacuum hose connects to the charcoal canister is nearly completely broken off. I imagine that is messing with vacuum pressure, which certainly plays into all of this. Anyone have any great tips on how to fix that/find a replacement charcoal canister? I hate to replace the whole part if I don't need to, but at this point, I need to pass emissions pretty soon, so am anxious to get there.

Thanks.

If I understand what you are describing, it is your purge valve. A Dorman brand replacement (which also happens to be used on a Kia, can be purchased at Amazon.

thanks, WaltNYC--ordered it, and will update when I have it on.

Ok, I'm back with an update and still a problem.

Replaced the purge valve and shored up the leaking spot in the charcoal canister. Cleared the codes, and they stayed off and I passed emissions (yay!)

Engine performance was exactly the same, however, and in perfect timing, after getting check, the CEL came back on--this time, it's p1177 and p1179 together.

SO: grabbed a gauge from AZ, and sure enough, pressure at the rail was super low--with key on, engine off--it will eventually make it's way to 19-20 lbs. With engine on, it holds at 15 lbs, and under load it drops below 5.

So: fuel pump?

yes. fuel pump. see the write ups in this forum. You can generally get away with just replacing the electric pump and filter/sock for <$40. Airtex 3270.

awesome--thanks, esp. for the tip on the airtex. will update when i can.

Ok--update, and perhaps (hopefully) closure. Just put the airtex in, as well as a new filter. Disco started right up (no hard start, which had become the norm) and ran quite well. No stutter, no hesitation, full power, everything--it runs great. I haven't tested the pressure yet at the rail, but my hunch is that it's normal, based on the way it's running. I'll stop by AZ later and get a gauge just to know what it is.

I guess my only question is, should this correct my crazy fuel trim numbers? They're all over the place (and have been for as long as I've known how to track them). I noticed during the test run today that they were both very negative--bank one hitting -25 a few times, and bank two in the -15-19 range. Or should I start a new thread for that?