• Registered: 2019-07-14
  • Posts: 222

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

oh, and you can reduce the gap to .025 from .045 also...
see if that makes it fire through the muck.

  • Registered: 2018-07-02
  • Posts: 266

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

Pulled the head off today. It's obvious something is happening on #10. Cylinder wall looked perfect.

Weird thing. Cyl #8 valve guide is sticking out?  Strange.

Swapped another cylinder head, and swapped lifters with another cylinder.  Problem is still there.

Looks like its definitely something with the piston/rings.

https://i.imgur.com/6xe8ksD.jpg

https://i.imgur.com/jp9XVCn.jpg

2018 Where the Elite Meet to Cheat - Organizer's Choice Award
2019 Rust Belt GP - Spirit of Entropy Award
2019 The Tony Swan Never-Say-Die Memorial - Index of Effluency Award
2020 The Tony Swan Never-Say-Die Memorial - Class C Lap Winner
  • Registered: 2013-08-12
  • Posts: 563

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

Swap injectors?

29 Reply by billstewartx (edited by billstewartx 2020-05-27 05:28 AM)

  • Registered: 2019-07-14
  • Posts: 222

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

rlchv70 wrote:

Swap injectors?

+1

And swap coils/ plugs

  • chaase
  • Lemons Staff Stalker
  • Offline
  • From: East Meadow, NY
  • Registered: 2009-08-06
  • Posts: 1,555

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

rlchv70 wrote:

Swap injectors?

/agree

That cylinder is really clean. Fuel washing the cylinder?

1992 Saturn SL2 (retired) - Elmo's Revenge -  Class B winner, Heroic Fix winner x2
1969 Rover P6B 3500S(sold) - Super G-Rover - I.O.E Winner, Class C Winner
1996 Saturn SW2 - Elmo's Revenge (reborn!), Saturn SL1  Dazzleshipm Class C x2 and IOE winner
1974 AMC Javelin - Oscar's Trash heap - IOE,”Organizer's Choice" and "I got Screwed" award winner

31 Reply by darkostoj (edited by darkostoj 2020-05-27 06:38 AM)

  • Registered: 2018-07-02
  • Posts: 266

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

I put some more miles on the car, and it looks like it may be fixed?  After we did some quick testing a fresh plug was still dark.  After a few more miles it looks better now. I'm thinking now it could have been from cylinder residue from being not running properly for so long? I'm crossing my fingers.

2018 Where the Elite Meet to Cheat - Organizer's Choice Award
2019 Rust Belt GP - Spirit of Entropy Award
2019 The Tony Swan Never-Say-Die Memorial - Index of Effluency Award
2020 The Tony Swan Never-Say-Die Memorial - Class C Lap Winner
  • Registered: 2017-10-18
  • Posts: 107

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

chaase wrote:
rlchv70 wrote:

Swap injectors?

/agree

That cylinder is really clean. Fuel washing the cylinder?

Definitely fuel washed looking.  Maybe faulty injector or coil issue, fouled plug after running improperly over time.  My guess is the rings and valves/valve seals are fine.

Petrosexual Racing - 4.9 HT swap/Trashback Miata
https://forums.24hoursoflemons.com/view … p?id=35746
BFE GP '18 - 1st in C, High Plains Drifter -19 - 1st in B/Overall
Uh oh, Spaghettios...
  • From: Cleveland, OH
  • Registered: 2011-09-03
  • Posts: 2,227

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

I assumed he cleaned it to inspect.

Mistake By The Lake Racing (MBTL)
88 Thunderbird "THUNDERBIRDS ARE GO!", Ex Astris, Rubigo / Semper Fracti
A&D: 2014 Sebrings at Sebring (NSF), 2014 NJMP2 Jurassic Park (SpeedyCop), 2012 Summit Point J30 (PiNuts)
2018 Route Sucky-Suck Rally Miata, 2019 World Tour Of Texas 64 Newport

Guildenstern's Website

  • Registered: 2018-07-02
  • Posts: 266

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

Guildenstern wrote:

I assumed he cleaned it to inspect.

Nope, that's what it looked like when I pulled the head off.

2018 Where the Elite Meet to Cheat - Organizer's Choice Award
2019 Rust Belt GP - Spirit of Entropy Award
2019 The Tony Swan Never-Say-Die Memorial - Index of Effluency Award
2020 The Tony Swan Never-Say-Die Memorial - Class C Lap Winner
  • From: WPB Fl.
  • Registered: 2010-10-27
  • Posts: 1,571

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

Fuel washed because oil fouled plug not burning?

Homestead Chump 5th-Sebring 6th-PBIR Lemons 9th - Charlotte Chump  CrashnBurn 9th
Sebring 6th again -NOLA Chump 1st -PBIR Chump Trans Fail 16th
Daytona 11th - Sebring 6th - Atlanta Motor Speedway 2nd - Road Atlanta Trans Fail 61st-Road Atlanta 5th
Daytona 13th - Charlotte 9th - Sebring 2nd-Charlotte 25th broken brakes - Road Atlanta 14 10th-Daytona 14  58th- Humid TT 19th Judges' Choice!

36 Reply by fleming95 (edited by fleming95 2020-05-28 12:27 AM)

  • Registered: 2009-06-10
  • Posts: 558

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

Everyone loves working on someone else's problems... since we don't need to bark our knuckles on the hard stuff!

Talking out my $500 azz, so I can learn from this -

- in the hive mind's experience, would a leakdown or vacuum test on that cylinder relative to a 'normal' cylinder show a difference?   I'd say little to no difference if the oil ring is broken, since the oil ring isn't a sealing ring anyway

- once the injector and coil are proved fine, howzabout starting with a new plug on #10 and another cylinder, disconnecting the injectors, then running it for as long as it took to taint the plug, then comparing plugs and scoping the cylinders?  No disassembly required -

The clean piston and dirty valves on #10, and the opposite on the other cylinders, is something obvious staring at me I can't figure.

37 Reply by jbl (edited by jbl 2020-05-28 07:40 AM)

  • jbl
  • Ripened Lemon
  • Offline
  • From: Philadelphia
  • Registered: 2011-01-26
  • Posts: 219

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

darkostoj wrote:

When we put a new plug in, the car runs great and feels like it has full power.  After about 10 minutes on track it starts to break up and power loss is really noticeable.

How much difference--from an inspection/diagnosis point of view in general--does checking the plug after a cool down and idle period vs immediately after load and still hot make?

NJMP '11--#132 (Speedycop), NJMP '12 to '16--#215 (Philthy Motorsports), NJMP '16--#75 Most Heroic Fix, NJMP '17--#75 (still drying out), NJMP '18--#75, NHMS '18 - #75 Datsun 510
  • Registered: 2019-07-14
  • Posts: 222

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

darkostoj wrote:

I put some more miles on the car, and it looks like it may be fixed?  After we did some quick testing a fresh plug was still dark.  After a few more miles it looks better now. I'm thinking now it could have been from cylinder residue from being not running properly for so long? I'm crossing my fingers.

you could have a coil working intermittently.

it could go back "on the fritz" any time

  • Registered: 2018-07-02
  • Posts: 266

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

To bring this problem to a resolution.

It was a faulty fuel injector.

During testing at the track we found the fouling plug would follow the fuel injector after moving it around.

Put a new one in, and no more issues.

2018 Where the Elite Meet to Cheat - Organizer's Choice Award
2019 Rust Belt GP - Spirit of Entropy Award
2019 The Tony Swan Never-Say-Die Memorial - Index of Effluency Award
2020 The Tony Swan Never-Say-Die Memorial - Class C Lap Winner
  • Mr.Yuck
  • Mr.Yuck
  • Lemons Staff Stalker
  • Offline
  • From: Brookeville, Md.
  • Registered: 2013-12-09
  • Posts: 1,012

Re: What would cause 1 spark plug to oil foul?? Viper Engine #3

darkostoj wrote:

To bring this problem to a resolution.

It was a faulty fuel injector.

During testing at the track we found the fouling plug would follow the fuel injector after moving it around.

Put a new one in, and no more issues.

good deal.

"get up and get your grandma outta here"