skirkland1980 Posted February 13, 2013 Share Posted February 13, 2013 I pulled the BPR7ES plugs in my L28 turbo today and I noticed 2 plugs appeared rich. I'm not really sure what's going on. These plugs have about 1000 miles on them and probably 20 eighth mile passes. I gapped them to.....030" or about .035"...I don't quite remember (6 months ago). The car runs great, no misfires, especially under boost (15 psi). I'm just not quite sure why only 2 plugs look like this, #2 & #6 Which I've noticed problems before with deformed head gaskets on those cylinders. Any ideas? Thanks. Quote Link to comment Share on other sites More sharing options...
steve260z Posted February 13, 2013 Share Posted February 13, 2013 Don't look rich to me. The white part should have light brown specks on there. Running rich usually has carbon all over. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted February 13, 2013 Author Share Posted February 13, 2013 Don't look rich to me. The white part should have light brown specks on there. Running rich usually has carbon all over. Yes, but that would be a case of very rich. If you look at the porcelain, 4 of the plugs are white, 2 of them the porcelain is black almost all the way to the tip. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted February 13, 2013 Author Share Posted February 13, 2013 I guess I could do a compression test. Maybe my head gasket is pushing out again...But my plugs dont show signs of detonation...? Could it be time for a metal head gasket? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 14, 2013 Share Posted February 14, 2013 Put an O2 sensor on it if you're worried. Plug reading is hard to do, and if you showed people those two plugs individually you'd probably get "that plug looks good" for both of them 9 out of 10 times. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted February 14, 2013 Author Share Posted February 14, 2013 Yes, the car has a wideband. Are you saying I shouldn't worry about the black covering 80% of the porcelain? It may look like a shadow in the picture but it's black soot. Quote Link to comment Share on other sites More sharing options...
Xnke Posted February 14, 2013 Share Posted February 14, 2013 The plugs with the white insulators clear back are actually running hot enough to stay self-cleaning...the ones that are all carboned up except for the very tip are not getting hot enough to stay clean...but they're getting hot enough to not foul out. If your AFR's are good, then I'd say let'em run. You're not hurting anything with plugs like that, and the white tips with the light tan markings show that the mixture is pretty close to right. The carbon further back in on the ceramic is from the plug running a little too cool. (or perhaps those two are the only correct ones...and the other four are running a little too hot? You'd have to ask a spark plug manufacturer or someone who really knows plugs.) Quote Link to comment Share on other sites More sharing options...
30 ounce Posted February 14, 2013 Share Posted February 14, 2013 (edited) Try one step hotter plug. There is a lot of deposit on the threads that would indicate a slightly cold plug. There should only be black on the first 2-3 threads. And it looks like your timing is a little too advanced. The color change on the ground strap should be right at the bend. Yours is almost to the base (threads). Edited February 14, 2013 by 30 ounce Quote Link to comment Share on other sites More sharing options...
Gollum Posted February 21, 2013 Share Posted February 21, 2013 You've got some good advice in this thread. If it were me, I'd be thrilled to see plugs that close together! You might be seeing differences as small as intake manifold flow inconsistencies. Generally if I run a plug for over 1k miles and I've got any amount of whitish porcelain I'm pretty happy with the way it's running. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted February 21, 2013 Author Share Posted February 21, 2013 I guess I won't worry about the plugs. The car does run great. I've beat it up pretty good. Driven 80+ miles to the drag strip, made several 1/8 mile runs shifting at 6500 rpm and driven home. Did that about 6 times. I'm really pleased overall but I still want to go faster. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 21, 2013 Share Posted February 21, 2013 7 is colder than the factory recommended 6. As I understand heat range, you want to be hot enough to keep things clean (no carbon fouling), but cool enough to avoid damage. You've got a pretty good coating on your electrodes. Might be better of with the factory 6. I just had my plugs out last night and noticed that #1 porcelain is very white and clean compared to the rest, 3 and 4 seem a little brown and the rest look "normal". This has been common for the only two engines I've had, both with the same N42 intake manifold, one an N42/N42 head/block before and N42/N47 now. Seems like cylinder 1 might be getting extra air, making it a little lean or it runs hot. It's hard to tell which, or how to confirm. The flow imbalance idea seems reasonable, I've often wondered why my idle seems rougher than it should be. Quote Link to comment Share on other sites More sharing options...
rejracer Posted February 22, 2013 Share Posted February 22, 2013 In my experience the threads getting fouled up is typically caused by not sealing, try putting a torque wrench on them to check to see if they are tight enough. I find it hard to read plugs after too many miles as there is too much cruising, cold starts, and short trips to tell me what I need to know for mixture. Throw an engine with oil consumption and all they will tell you is your engine is worn out. The way I read plugs is to start with clean plugs, run it at full temp and WOT and shut it down ASAP. Pull the plugs and read. What are your compression numbers? When replacing the head gasket did you notice any oil in #2&6 intake? Could be as simple as inlet valve seals letting go. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted February 22, 2013 Author Share Posted February 22, 2013 The last time I pulled the head it was to replace the valve stem seals. I decided not to do the compression test since the engine runs so good with no blow-by. When I pulled the plugs I was really just looking for signs of detonation. I was concerned that my plugs were inconsistent. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 22, 2013 Share Posted February 22, 2013 Me too. Driving around and then reading plugs is worthless. You have to do a WOT run. I used to bring a ratchet with me and pull the plugs by the side of the road. Then I got an O2. If you really want to know what is happening in each cylinder, EGT will do that. I still think there is nothing to worry about. The way I read plugs is to start with clean plugs, run it at full temp and WOT and shut it down ASAP. Pull the plugs and read. Quote Link to comment Share on other sites More sharing options...
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