Repeated burned exhaust valves -94 GS

[4-G-rim]

There can be several factors that can cause you valves to burn...replacing the valves only fixes the burnt valve issue, but the underlining issue hasn't be resolved why you had another burnt valve.

Incorrect timing can cause valves to burn like if the cam holds the valve slightly open. The valve head does not transfer its heat to the MUCH cooler valve seat area in the cylinder head. The valve burns.

If the car is N/A..having staight piping or eliminating converters will cause burnt exhaust valves due to lack of backpressure which helps the cooling cycle.

As what MKO said..a non effecient or an inoperative EGR system, which by design lowers the combustion chamber temperature , can contribute to valves burning.

Bad fuel/air mixtures also can cause the issue too either from bad FPR, bad injector, etc

Insufficient cooling system also can contribute also as the cylinder head isn't cooling effeciently causing overheating (Even though it may not register enough on the dash) to cause a burnt valve.

As you can see there are different factors...hope this helps.

[StockGS]

thanks for the tips....no, i haven't found the root cause..
i was thinking wrong about the cat / backpressure....I thought that if i eliminated the cat... it would help cool the exhaust at the header / valves etc...

the EGR is suspect.....it and the path-ways were completely blocked one of the several times i went through this..

i am running rich per the smut on the back bumper.....i need to get an OBD I tool and find out what's going on.

really appreciate the help!......gives me something to work with..

[4g63lover]

For sure check that AFR. pre-ignition could be at fault as well.

[StockGS]

thanks!......i don't hear obvious pinging, but i guess it doesn' have to be audible to be detrimental..

i've been running prem octane........but, would a lower octane be better or worse for this issue?

[DOHCstunr]

lower octane would be worse. The GS has a knock sensor and automatically pulls timing when knock is present.

With that said, if you are still on your original knock sensor... I could just about guarantee that its past its prime or worse.
You should consider replacing it with a new 2g eclipse one(same) when you get a chance.

I'm not saying that this is the source or even related to your problem. Just something to consider.

Also, always run premium fuel in your GS. You will lose both power and mileage if you reduce the octane.


Have you ever replaced your fuel filter? Have you routinely run fuel system cleaner?

[StockGS]

....yes, original knock sensor, and fuel filter. its amazing it runs at all !!

i've got plenty to do.......thanks!