Sparkplug - carbon buildup - causes?

Nheels

Petty Officer 2nd Class
Joined
Mar 8, 2021
Messages
118
Hi all,

Changed out plugs on both motors (2008 VP 5.7 gi-j). Port appears to have a lot of carbon build up, starboard appears to be okay (picture also attached for reference). Probably about 100 hours on the plugs if I were to take a guess.

All appear to have about the same amount of build up, so that tells me it isn't a single stuck open injector. Motor doesn't bog and appears to run fine. Maybe an O2 sensor? If that was the case, would it throw an error?

Any thoughts or suggestions? Non-issue perhaps??

Thanks!
1000002926.jpgView attachment 396492
 

Nheels

Petty Officer 2nd Class
Joined
Mar 8, 2021
Messages
118
Hi all,

Changed out plugs on both motors (2008 VP 5.7 gi-j). Port appears to have a lot of carbon build up, starboard appears to be okay (picture also attached for reference). Probably about 100 hours on the plugs if I were to take a guess.

All appear to have about the same amount of build up, so that tells me it isn't a single stuck open injector. Motor doesn't bog and appears to run fine. Maybe an O2 sensor? If that was the case, would it throw an error?

Any thoughts or suggestions? Non-issue perhaps??

Thanks!
View attachment 396491View attachment 396492
1000002913.jpg
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,568
My guess it the CTS is reading low and the motor never gets out of cold start mode.

Have you checked fuel pressure?

Do you have Rinda?
 

Nheels

Petty Officer 2nd Class
Joined
Mar 8, 2021
Messages
118
My guess it the CTS is reading low and the motor never gets out of cold start mode.

Have you checked fuel pressure?

Do you have Rinda?
Hmm that sensor is right beside the thermostat housing isn't it?

Fuel pressure has not been recently checked. I will though.

I've been tossing a Rinda. Cant decide between the techmate or diacom though... If I could run the diacom on an iPad, that would be ideal. Cant though.
 
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