Carbon deposits on all four spark plugs on the RH cylinders only?

[Blownrunner]

91 ZR-1 with 29,000 miles. I changed my O2 sensors and noticed that the RH sensor had a powdery type coating on it and the LH sensor looked a normal gray. I cleaned the muffler exhausts a month ago also and changed the plugs when I did the O2 sensors. Today I checked and the passenger side exhaust interior, which was noticeably more powdery than the right. I pulled the plugs and the drivers/LH cylinders had plugs that looked a normal gray insulator around the center electrode. The Passenger/RH cylinders had a coat of the black powder on them evenly. The car runs strong and starts up great. The injectors are also new along with the coils.

Doing a quick search on plug fouling, it looks like I have carbon deposits, not oil because I do not think the plugs are 'wet', instead a light powder. Isn't the LT-5 basically two four cylinders side by side?
Two separate O2 sensors makes me believe that the sides of the engine are individually monitored and controlled.

Any idea what is going on here? I am thinking that an oil leak is out because it would be in one area of the engine, not all four cylinders on the RH side. Could it be running rich? Would the RH head need to be re-torqued? Is there a faulty sensor other than the O2 sensor? Maybe the grounds on the back of the heads under the plenum?

I am stumped here. Thanks.

BTW, The carbon looking deposits accumulated in the last 9 months/1,000 miles.

[cuisinartvette]

Are you babying the car? I would not retorque the heads not needed
You can always have someone scan the car but if it runs good just drive it
Clear it out once in awhile too.

[mike100]

Do you have an exhaust leak upstream of your O2 sensor? False air could trick it into thinking it is running lean so the system would add fuel unnecessarily. Do you have one weak cylinder with incomplete combustion (source of unburned oxygen)?

The best way to see that is plug a scanner in and see what the o2 sensor voltages look like along with the fuel trims.

[Blownrunner]

The exhaust leak is a great idea, I guess I could get a mirror and flashlight and inspect around the header for exhaust leaks. I do not baby it, it is a blast to accelerate going up to 6k rpm. I do not feel like the engine is even breaking a sweat doing it either. I need to get a tech1, which will prove invaluable like the FSM.

After thinking about it, I don't think it can be a burning oil problem. I also want to make sure the O2 sensor is heating up correctly which could throw things off. The FSM gives solution to the problem if I got a code for rich condition, but many of the things to check I would think would effect both sides.

Thanks, guys.

[Bearly Flying]

If you like 6k rpm, imagine trying 7k rpm.......

You might like it..

[Paul Workman]

Originally Posted by Bearly Flying

If you like 6k rpm, imagine trying 7k rpm.......

You might like it..

Yep, I A-gree.

Blownrunner....Ifn you're only running to 6k..you are babying it!!