Car Stalls a bit between 2k-3k RPM

[MontesCarlos]

I've read a lot about this problem in the Archive folder, however I haven't found one that matches my problem exactly.
Like I mentioned in the title, my car tends to want to stall between 2-3K RPM.
I thought maybe it was the exhaust system that is installed on this car. It has a throaty sound and it may be an aftermarket low restriction exhaust. Not sure though.
I recently started to suspect the O2 sensor, I have some questions though.
Is it possible for the O2 to be bad and the computer not flag it as bad?
When I disconnected the O2 sensor and drove the car with it disconnected, the car ran the same. I did however get a Check Engine light.
The problem is reproduceable, but when I had an overheating problem recently the problem was much more severe, and the car stalled when stopped or when the gas peddle was quickly pressed.
This all started when I put new Platinimum 4 spark plugs. I quickly put the old ones back on but that didn't help.
The car does idle a little rough. I recently put 87 Octane in the car and the car runs much much better, however with noticeably less power. I used to put 92 Octane in it.
What would cause the car not to stall anymore, by using less Ocatne gas?
Do you know if BAVAUTO sells original Bosch or a knockoff?
BMA has it about $15 cheaper and I'm suspicious about its quality. What do you think?

Thanks!

[632 Regal]

either bosch or NGK stock plugs ONLY.

Reboot the computer and then check for codes...or it might run fine but definetly change out them platinums.

[MontesCarlos]

I put the old ones back on. They were Bosch Super 2's. Do you think I should go with the stock plugs still?

I forgot to mention which I think is very important. The stalling only happens when the car is in gear and moving. If I put the car in neutral, the engine runs smoothly all the way to redline.

[Kalevera]

As Jeff said, use Bosch F7 or F8 LDCR or NGK BKR6 (BMW branded) ONLY.

Personally, I'd go with the F8LDCR as it probably results in a cleaner burn.

No platinum nothings, no old spark plugs.

Three weeks ago, I got a call from a regular customer/friend. He'd recently replaced the spark plugs on his M50 525 and the thing started misfiring under load when at less than ~4k rpms. I asked, "Were the correct plugs installed?" He said, "Yeah". Get the car in about a week later -- they're platinums.

The dealer parts department will give you the *wrong* plugs for this car. Be sure to specify what you want and check it if buying parts through that venue.

best, whit

[MontesCarlos]

Thanks guys. I'll give that a try. Whit, you sound like buying the plugs from the stealer is ok. What would the stealer charge for plugs (BMW Branded).

[Kalevera]

I can't tell you what the dealer would charge for the plugs, because each dealer uses its own methodology for determining retail parts price. The reason I mentioned checking the part is that I've been told that some versions of ETK will list the platinum plugs for the M50, and the parts guys will hand them to you without knowing the difference. So, be sure to check and see what they're selling you before you surrender the money.

BMA can probably give you a better deal on it, any way you shake a stick at it.

If replacing the plugs doesn't fix it, inspect the coil packs for caramel candy (do a search on that -- I wrote a lot of posts on it in the past few months).

best, whit

[genphreak]

I use platinums in my M30. It was all they had when i needed neweys. No arguments here though. When I next give her a checkup I'll post pics of how they are looking after 5000 miles.

That said, the M30 is (very) different to M50 design-wise Nick

[Qube]

To quote Winfred from a post way back...

"bosch platinum's suck in all but the cleanest burning cars, they suck because the actiual [sic] platinum center electrode is surface mounted and about the size of a gnats cock, it takes almost nothing to fowl it and reduce it's effectivness.

Can this be more blunt?

[genphreak]

To quote Winfred from a post way back...

"bosch platinum's suck in all but the cleanest burning cars, they suck because the actiual [sic] platinum center electrode is surface mounted and about the size of a gnats cock, it takes almost nothing to fowl it and reduce it's effectivness.

Can this be more blunt?

Yes it'll be interesting to see how long they last. Mine is a new head, so if they go wrong with me its curtains for their application in other M30s...

[MontesCarlos]

Ok guys. I'm amazed. I replaced the plugs and now the problem is completely gone. It's so hard to believe that plugs could cause so much trouble!
Don't get upset guys, but I bought some cheapy $1.15 Autolite Resistor plugs just to have something to put in the car while I obtain the FXLDCR's, and sure enough the problems went away.
Just for fun I'll ask this question. What if I left these Autolite cheapies in? Like I said don't freak out on me. Just wondering. The car seems to be running ok now.