I've been bringing this L67 Buick Ultra along. Looking for some input. I have already found a misfire & replaced the wires and plugs with NGK stuff. The plugs are iridium.
I get a ratcheting noise under power at higher rpm. Originally was at 4000 revs so I swapped in the coils from my other car and the ratcheting went up to 4500 rpm.
I'm thinking sure coils, but is that how these cars act when there's a clogged cat? No engine codes are being displayed, though I do have a trans problem code (PO741) that I am separately working on.
Which coils do the best? And would a voltage upgrade sometimes help? This car is loaded with power accessories.
