Jump to content

Recommended Posts

Can anyone glean anything from the coloring of these plugs? I'm replacing them with standard electrode plugs but they look pretty good to me. Plugs are in order 1-4 from right to left. Age/mileage unknown. I've had an occasional miss at idle and have read platinum plugs can cause this so thought I'd try something different.

#4 plug electrode is more black/ less brown because there was a bit of oil pooled in the plug hole from a slight leak that I believe I have addressed. I touched the electrode to the oil while removing. Anyway, disregard color of #4 electrode.

Daron posted a link a while ago to www.4secondsflat.com/plug_chart.html and I'm reading these on the hot side of good. Anyone disagree?

post-47476-0-59969100-1415578547_thumb.j

Link to comment
Share on other sites

Thanks. They're BPR6EGP. Will platium plugs read hot? This carb was probably installed/tuned when the car was still tested in California for emissions, so I guess lean wouldn't be surprising.

I haven't opened up the carb to check jetting. It seems to run well enough, so I was planning to just leave it alone but if it's lean enough to worry about, I'll reconsider.

Link to comment
Share on other sites

Our 02s seem to run a little better without the "R" (resister) NGK plugs. If you don't already have them you might want to opt for BP5ES of BP6ES versions.

Several previous threads here over the years support this choice.

A lean adjustment can make the car run very good, but can be detrimental over time to the engine. (Ask me how I know). A little rich is preferable for engine longevity.

Bob Napier

Link to comment
Share on other sites

Our 02s seem to run a little better without the "R" (resister) NGK plugs. If you don't already have them you might want to opt for BP5ES of BP6ES versions.

Several previous threads here over the years support this choice.

A lean adjustment can make the car run very good, but can be detrimental over time to the engine. (Ask me how I know). A little rich is preferable for engine longevity.

Bob Napier

 

Yeah, I've read lots of threads on the topic. I'm replacing the plugs largely because they're platinum as they seem to be universally loathed for these cars and several threads indicated that switching from platinum back to standard plugs cured an occasional miss at idle (the reason I pulled them in the first place). Resistor vs non-resistor seemed to be more mixed in the threads I read, with non-resistor being a nice to have.

 

The plugs I found for now are WR7DC Bosch. I know there's a fair bit of dissatisfaction with Bosch plugs as well but they should at least help me troubleshoot whether the plugs are to blame. I'll order some NGK BP6ES. It looks like there's no need to go hotter since I don't seem to have any oil deposits on the plugs, nor have I noticed oil in the exhaust.

 

That's two votes for hot/lean so I guess I better check the jets. It's been forever since I opened up a Weber. Is the top gasket reusable or should I have one on hand? I'll open it up in the next few days and see what jets are there vs the numerous recommendations that are available here in old threads (C.D.iesel's prescription and variations thereof). I guess I better go to Amazon and order those Weber books that Toby recommended to me a while back, too.

Link to comment
Share on other sites

Based on your attention to detail and tendency to make improvements, I predict that you will be installing an exhaust gas analyzer in the near future... opening up the carburetor and getting jetting just right.  :)  

 

Ha! Yeah, I'm waiting for the stainless downpipes to come back in stock at IE and I'll have the o2 bung welded in prior to installation. Jeremy thought these would be in stock 'any day now' so I'm keeping an eye out for it to show on their website.

Link to comment
Share on other sites

BPR6ES is the most common heat range for carb'd m10 engines.  Maybe try a slightly colder plug - BPR7ES.

 

I don't use Bosch plugs anymore myself, as I've had some defect issues with them in the past.  I replaced the stock NGK plugs in my 2005 X5 V-8 with the appropriate Bosch plugs.  After about 3 months I started to hear a slight knocking sound coming from the drivers side bank.  I removed the coil pack cover and the sound got a bit louder.  I started to feel the top of each coil pack and a couple of them I felt a tapping sensation.  I removed those plugs and discovered that the seal between the porcelain insulator and the outer metal housing had failed.  This was causing the knock and also was letting some compression out of the cylinder.

 

As a matter of fact, allot of newer BMW's come with NGK plugs from the factory (NGK along with BMW printed on the porcelain). 

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Upcoming Events

×
×
  • Create New...