95 525i Spark Plug choices

[keve34]

1995 525i Manual, Black, silver interior, 164K miles. What spark plugs to use? The Bentley manual specifies spark plugs as Bosch F7 L DCR, but the Owner's Manual says Bosch F8 L DCR - which, according to Bosch's website, is one notch "hotter" than the F7. Meanwhile, I have seen plenty of old posts that say to use NGK BKR6EK. Why do I care? Just misses passing Calif. smog for HC at 15 mph on the dyno (passes at 25 mph). CO and NOX are fine. Already replaced fuel pump, filter and pressure regulator, as I am sure they were original (filter was really nasty inside the dirty side - yikes!). Still just barely over that HC limit at 15 mph, but starts and runs great. Plugs are not very old but figure new ones can't hurt, and have been told it's a good idea to replace the coil boots at the same time (I am sure they are original, so I agree). Anyway, what's up with spark plug choices? Gotta pass smog to drive the next 2 years!

[califblue]

was your car warmed up when you went to the test? ...hot enough the catalytic converter was ticking and I always use minimal fuel in the tank too.
Is you car chipped?
I have a Mark D chip and mine runs so clean the test guy says they are going to come and test his machine...LOL :)

[keve34]

was your car warmed up when you went to the test? ...hot enough the catalytic converter was ticking and I always use minimal fuel in the tank too.
Is you car chipped?
I have a Mark D chip and mine runs so clean the test guy says they are going to come and test his machine...LOL :)

Thanks for the response! Yes I had driven 40 miles at highway speed; car waited about 8 or 10 minutes before he started testing. Aftermarket cat with only about 3K miles on it. Premium fuel about half tank. The car is stock, not chipped. This was the second time it just barely failed - the first time I thought perhaps I just had not driven the car enough after re-connecting the battery (for the computer to get the fuel trim right), but then I also replaced the fuel pump, filter and pressure regulator prior to this re-test. Afterwards talked with an indie shop guy who suggested NGK plugs and new coil boots - I had not considered chip; was not sure that was OK in Calif.

[winfred]

i like the bkr6ek's more then the f7ldcr's. aftermarket cats are that great for the record

[keve34]

Seems as if the NGKs get more votes all right - thanks for that. And yeah the aftermarket cat might not last as long as I would like - yet it buys me some time (I hope) to fix other stuff - drivers window, a/c, radio. Already did suspension, head gasket, transmission (I had blown 2nd gear). Typical big-project (for me) stuff.

[genphreak]

Seems as if the NGKs get more votes all right - thanks for that. And yeah the aftermarket cat might not last as long as I would like - yet it buys me some time (I hope) to fix other stuff - drivers window, a/c, radio. Already did suspension, head gasket, transmission (I had blown 2nd gear). Typical big-project (for me) stuff.

One option is to buy a cat from a later model that will fit, you will need to check inlet and outlet sizes and have a good shop tig it up of course. I gave up using Bosch plugs ages ago, the NGKs are fine, nothing wrong with choosing them. Make sure she doesn't have a small air leak- both the connection to the brake booster (it has a small plastic nipple right on the right angle inlet to the booster that is very brittle. It breaks when you look at it, if it isn't snapped off already. Normally it is blanked off w a rubber bung, but if broken there will be a 1.5mm hole visible on the plastic connector, where it once was). Also, other places the vacuum can be leaking- oil cap seal and the multi connector going into the back of the plastic inlet manifold, directly behind the throttle plate where you can't get to it. You have to remove the alternator and all sorts to reach it. It has an o-ring, and is held in by a plastic clip that sticks out and breaks. Cheap to buy new with the ring, just grease the ring first as sometimes they are hard to seat- I've seen lots that haven't been fitted properly.

Oh and the valve cover gasket, it can leak air, and the two seals around the plugs that poke through the valve cover. If you find oil in the plugs, it's a telltale sign that the these VC gaskets are bad- all of them. You'll probably need to replace the rubber nut seals too- they can be bought together as one lot easily enough.