What's this stuff on my plugs?

turbovert91 · 11-11-2008, 02:17 PM

OK, my car started running jerky/hesitating on accel after 1/4 tank of fuel just after being tuned. I pulled the spark plugs and this is what they look like:

Does anyone know what the residue on there is? I'm running the NGK race plugs (R6725-105) and 110 octane leaded race gas. The plugs look like they've been overheated to me but I'm not sure. I made sure the plug wires were tight, cleaned the plugs and drove it again. The first few times I boosted it it wasn't any better, then it started boosting smoothly again.

Has anyone seen this before? Could there be another problem with my ignition? I have the HKS twin-power but the jerkiness sure seems ignition related (to me anyway). Could there be a problem with the fuel I'm using? These plugs are $34 each, they should have lasted more than 1/2 tank of fuel...any input/thoughts are appreciated, thanks.

Cp1 · 11-11-2008, 02:21 PM

are you sure thats not just gunk that might have got stuck on when pulling them out? ive never seen anything like that come out of a running engine... it may have just been on the spark plug hole or landing or a bit too much antiseize or something.. but yes it otherwise appears done for.

turbovert91 · 11-11-2008, 03:16 PM

Actually all four plugs looked like that with the leading plugs being the worst. The trailing weren't quite as bad, but that stuff was on all of them...

It cleaned right off though, almost looked watery when I smeared it before taking them to a wire wheel/brush to clean them off...I wonder if the race fuel I'm using is screwed up somehow?

classicauto · 11-11-2008, 04:40 PM

the plugs went into a rebuild? or an already running engine?

What kind of AFR's are you running? Timing? any aux injection?

what were they gapped to?

turbovert91 · 11-11-2008, 05:09 PM

They were swapped into a running engine just before being tuned/dynoed, I was running the stock 9s all around before.

AFRs in the low 11s under boost, pretty lean the rest of the time. Not sure about the timing, Steve Kan tuned it. I have meth injection but it's turned off, just running race gas only.

They are gapped to .025, that's what Steve told me to gap them at, but I've heard a lot of people don't go quite that large...

Nexcis · 11-11-2008, 05:37 PM

You might want to check your fuel tank. I've seen gunk similar to that from an old fuel tank where the epoxy liner meant to keep the inside of the tank from rusting started to pill off.

classicauto · 11-11-2008, 07:33 PM

hmmm Yeah gas contamination is a real possibility, how old is the filter?

The gap sounds a little high for me, I had trouble with those same plugs (except I had 11s in the trailing) and gapped them down to .20 (but to be honest I don't recall where they were before....they may have been wider then .25) and had better results. So as far as the trouble running is concerned I'd try closing the gap a bit.

Is this engine premixed or no?

Also, aside from the gunk, the plug looks healthy though - appears to be running strong.

Barry Bordes · 11-12-2008, 07:57 AM

Quote:

Originally Posted by turbovert91

OK, my car started running jerky/hesitating on accel after 1/4 tank of fuel just after being tuned. I pulled the spark plugs and this is what they look like:

Does anyone know what the residue on there is? I'm running the NGK race plugs (R6725-105) and 110 octane leaded race gas. fuel...any input/thoughts are appreciated, thanks.

Not to be a wise guy but it looks like fuel additives collecting on hot plugs, i.e. lead. This is what it looks like on aircraft plugs.
Barry

turbovert91 · 11-12-2008, 09:27 AM

The stuff did wipe off easily, almost like water, and taking the plugs to a wire wheel cleaned them up nicely.

So it's not a big deal? Or are the plugs getting too hot? I've got lots of other plugs to try; Iridium 10s, B10EGVs, B9EGVs, or the stock BUR9EQs...

RICE RACING · 02-14-2010, 12:45 AM

You have water in the system somewhere as that picture looks 100% like a rusty plug, I have in my collection of hundreds of plugs ones that look like that, I will try to find them and take a picture.

Ironically this is what plugs should look like even in a water injected engine like I run (details included for reference)

For those not familiar with rotary engines: (leading plug holes have a large opening to the combustion chamber and trailing plug holes have a smaller shielded hole) I use this visual check + EGT reading to balance any differences in the fuel air balance.
FL = front leading spark plug
FT = front trailing spark plug
RL = rear leading spark plug
RT = rear trailing spark plug
NGK 10 heat range plugs are 2000km old, run a 0.020" gap, Optimax Shell 98 Ron fuel, Mobil 1 engine oil (oil injected into motor), and Sthil 2 stroke premix at 180:1 mixed in with fuel also
10.9:1 AFR with 1.20kg/cm boost and 500cc Water Methanol at 50/50 mix, engine operating temp is 77~79 deg C

In case anyone is bored! Look On !!!

Front Rotor

Rear Rotor

http://images.google.com.au/imgres?i...a%3DG%26um%3D1

^ This site a bloke does a running analysis of thousands of miles of various plugs in his mazda, though of little relevance to this its a nice read anyway, with lots of relevant pics.

RETed · 02-14-2010, 03:18 AM

It's the leaded gas.

-Ted

RICE RACING · 02-14-2010, 05:03 AM

I have never seen tetraethyl lead/lead bromide deposit rust oxide on plugs in my life at any AFR ratio. Have dozens of cars running it and plugs just don't come out looking like that (but could always be a first for it I guess).

http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html

I say you had water in that fuel or somewhere in your system. Or extreme overheating from lean running? though again I have seen engine destroy themselves and spark plugs shatter in rotaries (or in NA misfiring due to being to lean) before generating such heavy deposits like that pictured in such a short space of time.

11-11-2008, 02:17 PM	#1
turbovert91 Rotary Fan in Training Join Date: Mar 2008 Posts: 40 Rep Power: 0	What's this stuff on my plugs? OK, my car started running jerky/hesitating on accel after 1/4 tank of fuel just after being tuned. I pulled the spark plugs and this is what they look like: Does anyone know what the residue on there is? I'm running the NGK race plugs (R6725-105) and 110 octane leaded race gas. The plugs look like they've been overheated to me but I'm not sure. I made sure the plug wires were tight, cleaned the plugs and drove it again. The first few times I boosted it it wasn't any better, then it started boosting smoothly again. Has anyone seen this before? Could there be another problem with my ignition? I have the HKS twin-power but the jerkiness sure seems ignition related (to me anyway). Could there be a problem with the fuel I'm using? These plugs are $34 each, they should have lasted more than 1/2 tank of fuel...any input/thoughts are appreciated, thanks.

11-11-2008, 05:37 PM	#6
Nexcis Rotary Fanatic Join Date: Mar 2008 Location: Spartanburg, SC Posts: 216 Rep Power: 18	You might want to check your fuel tank. I've seen gunk similar to that from an old fuel tank where the epoxy liner meant to keep the inside of the tank from rusting started to pill off. __________________ '94 VR FD - Mod List

02-14-2010, 12:45 AM	#10
RICE RACING Don Mega Join Date: Dec 2008 Location: Utopia Posts: 1,688 Rep Power: 18	You have water in the system somewhere as that picture looks 100% like a rusty plug, I have in my collection of hundreds of plugs ones that look like that, I will try to find them and take a picture. Ironically this is what plugs should look like even in a water injected engine like I run (details included for reference) For those not familiar with rotary engines: (leading plug holes have a large opening to the combustion chamber and trailing plug holes have a smaller shielded hole) I use this visual check + EGT reading to balance any differences in the fuel air balance. FL = front leading spark plug FT = front trailing spark plug RL = rear leading spark plug RT = rear trailing spark plug NGK 10 heat range plugs are 2000km old, run a 0.020" gap, Optimax Shell 98 Ron fuel, Mobil 1 engine oil (oil injected into motor), and Sthil 2 stroke premix at 180:1 mixed in with fuel also 10.9:1 AFR with 1.20kg/cm boost and 500cc Water Methanol at 50/50 mix, engine operating temp is 77~79 deg C In case anyone is bored! Look On !!! Front Rotor Rear Rotor http://images.google.com.au/imgres?i...a%3DG%26um%3D1 ^ This site a bloke does a running analysis of thousands of miles of various plugs in his mazda, though of little relevance to this its a nice read anyway, with lots of relevant pics. __________________ www.riceracing.com.au Worlds best Apex Seals Coil on Plug Water Injection ECU Calibration

02-14-2010, 05:03 AM	#12
RICE RACING Don Mega Join Date: Dec 2008 Location: Utopia Posts: 1,688 Rep Power: 18	I have never seen tetraethyl lead/lead bromide deposit rust oxide on plugs in my life at any AFR ratio. Have dozens of cars running it and plugs just don't come out looking like that (but could always be a first for it I guess). http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html I say you had water in that fuel or somewhere in your system. Or extreme overheating from lean running? though again I have seen engine destroy themselves and spark plugs shatter in rotaries (or in NA misfiring due to being to lean) before generating such heavy deposits like that pictured in such a short space of time. __________________ www.riceracing.com.au Worlds best Apex Seals Coil on Plug Water Injection ECU Calibration

11-11-2008, 03:16 PM	#3
turbovert91 Rotary Fan in Training Join Date: Mar 2008 Posts: 40 Rep Power: 0	Actually all four plugs looked like that with the leading plugs being the worst. The trailing weren't quite as bad, but that stuff was on all of them... It cleaned right off though, almost looked watery when I smeared it before taking them to a wire wheel/brush to clean them off...I wonder if the race fuel I'm using is screwed up somehow?

11-11-2008, 04:40 PM	#4
classicauto crash auto?fix auto Join Date: Feb 2008 Posts: 816 Rep Power: 18	the plugs went into a rebuild? or an already running engine? What kind of AFR's are you running? Timing? any aux injection? what were they gapped to?

11-11-2008, 05:09 PM	#5
turbovert91 Rotary Fan in Training Join Date: Mar 2008 Posts: 40 Rep Power: 0	They were swapped into a running engine just before being tuned/dynoed, I was running the stock 9s all around before. AFRs in the low 11s under boost, pretty lean the rest of the time. Not sure about the timing, Steve Kan tuned it. I have meth injection but it's turned off, just running race gas only. They are gapped to .025, that's what Steve told me to gap them at, but I've heard a lot of people don't go quite that large...

11-11-2008, 07:33 PM	#7
classicauto crash auto?fix auto Join Date: Feb 2008 Posts: 816 Rep Power: 18	hmmm Yeah gas contamination is a real possibility, how old is the filter? The gap sounds a little high for me, I had trouble with those same plugs (except I had 11s in the trailing) and gapped them down to .20 (but to be honest I don't recall where they were before....they may have been wider then .25) and had better results. So as far as the trouble running is concerned I'd try closing the gap a bit. Is this engine premixed or no? Also, aside from the gunk, the plug looks healthy though - appears to be running strong.

11-12-2008, 09:27 AM	#9
turbovert91 Rotary Fan in Training Join Date: Mar 2008 Posts: 40 Rep Power: 0	The stuff did wipe off easily, almost like water, and taking the plugs to a wire wheel cleaned them up nicely. So it's not a big deal? Or are the plugs getting too hot? I've got lots of other plugs to try; Iridium 10s, B10EGVs, B9EGVs, or the stock BUR9EQs...