Bosch WR8DC wrong plugs for '79 528i???

under the radar · Post by **under the radar** » Thu May 28, 2009 6:08 pm

i have these in my car right now and am still having problems with intermittent bogging and power loss as the car gets warm. not when cold and not when its up to temp but in between. i start the car and its fine, after about 6 minutes, it throws a fit and wants to die. but then it gets better and runs fine. please help. thanks. i've changed out "everything" else i can think of. CTS, o2, ingnition control box, combo relay and on and on...

Bruce · Post by **Bruce** » Thu May 28, 2009 9:05 pm

Not sure, but I think the original plugs for the 528 has silver electrodes (Bosch WR9DS).

T.Hanson · Post by **T.Hanson** » Fri May 29, 2009 8:19 am

Factory owners manual likes Bosch WR 9 DS.

Not too spendy so you may wish to switch out, but your problem sounds heat related (?). You changed out the Ignition ( aluminum box inside fender by air cleaner) unit.

I'm not the ace trouble shooter but stuff needs to be right. All grounds ( brown wires, braided straps ) clean. All vacuum lines, dip stick, valve cover, tubes, rubber parts no leaky.

Set timing, do the throttle body FAQs. Clean, adjust Nemo or idle control valve ( FAQ.) Fuel filters clean.

After that it's AFM check, input from Mike W. here.

Mike W. · Post by **Mike W.** » Sat May 30, 2009 12:14 pm

Yep, AFM would be my first guess, but nothing more than an educated guess. I will tell you it's not the plugs. I think the heat range is off by one, but that would have such a minor effect on things it's not worth worrying about. Silvers were spec'd, and will last longer, but I've gotten 25K or more out of coppers before too.