Advice On Blinking Check Engine Light

[mrogers]

So my check engine light has been on for a little while, I haven't had the power I used to have, and when I floored it (once), the light started blinking at me. That scared me so I didn't do it again. The other day I took it to a trusted mechanic who said I had three codes in the computer--bad cam shaft sensor, and two cylinder misfires. So he replaced the cam shaft sensor for me, and recommended (given the 90k miles on the car) that I do spark plugs, fuel filter, and air filter. I haven't gotten around to the fuel filter yet, but I just replaced the air filter and spark plugs (with OEM ones). So I reset the check-engine light (by pulling the battery), start her up, and drive for a bit. Everything seems fine. She's running smooth, no lights on the dash, etc. So I goose it a bit; and when I hit a little over 5k rpm, right as I think "wow this thing still doesn't have the kick that it should", that damn check engine light starts blinking at me again. It blinks for about 30 seconds and then stays on solid.

Right now I don't have the time or the money to bring it back to my mechanic yet again. I was hoping some of you could provide me some educated guesses on what might be causing this. Given the lack of power, I'm personally thinking I'm still having cylinder misfire problems. What else could cause that, apparently only at high rpms?

Thanks for any ideas at all.

[GILLES]

I had a 97 540I w/ the same problem this may sound bizare but after research I had to replace both cat converters w/where getting parcialy block.This is not a cheap solution. Gilles.

[mrogers]

Wow, OK. What research, exactly, led you to determine that it was the cat converters as opposed to other parts of the system? And how much did it cost you to get it done? And finally, what causes cat converters to get blocked?

[GILLES]

This was last year, after all the usual test w/dianostic equipment and swithing coil packs and new plugs.and checking the ecm my teck is part of a group of 60,000 teck's on the net where they exchange info.
After submiting the problem to the forum 15 emails came back from these teck's and 9 of them and the same answer (replace cat converter w/oem parts not after market) I live in canada so price was $2600.00
p.s. sorry about my spelling mistake my main language is french.Gilles.

[Dirty_Tool]

Cats are common causes of misfires on the 540's. Usually they break apart inside and the pieces cause the blockage. You can easily see if they are broken apart inside by getting under the car and tapping the cats with a rubber hammer. If they rattle its because they are broken apart inside and need to be replaced. Which cylinders had the misfires stored BTW? Did you try swapping coils around? Coils are another common item.
Good luck,
DT