Spark Plugs W124 1987 300E

[murphysf]

Hello

I have had previous posts about recently failing the california emissions / smog check.

I just recalled when I last changed the spark plugs I believe I put Bosch Platinum plugs in. I recall these vehicles not liking platinum plugs.

Could this be part of my HC issue?

I am thinking it might be best to switch back to copper plugs. I think Bosch stopped making the copper plug for this vehicle but perhaps I could use the Denso T16EPRU 5022 or the NGK TR5???