not sure what the problem is

hi, i have a 85 bmw 528e manual 5 speed
after a month of buying it, i decided to do a tune up. I replaced the original bosch spark plugs with bosch platinum 4 plugs. At first, i didn't notice a difference but as time passed i noticed some engine hesitation at high speeds especially in the last gear. A week after buying the car i had raced the car to 120 with normal hesitation but after replacing the spark plugs it was being a little too slow. Also i had lost some power because i remember being in fourth gear doing 2000 rpm and going 65, now i try to do the same and it has to be doing 2300 rpm and it'll be going at 60 in the same gear. i've changed the spark plugs to regular bosch platinum and it doesn't improve acceleration. The only improvement that i have seen is in smoke emissions since that's what made me change the plugs, the bosch p 4 were making the car smell like raw fuel and now it's a little better. i'm no expert , so i really don't know for sure what's causing all this problems.


all conditions of the car is as follows

bad acceleration

starting problems (due probably to one of the pumps but not sure)

car rpms moving from 500 to 1000 when idling when it's cold or after turning off then on again (sometimes it'll start superfast even on freezing mornings)

bad emissions (raw fuel and some sputtering of mixed oil and gas)

when replacing the plugs for the second time discovered that two of them were a little oily

Hi, Pollo-
First: Bosch platinum plugs will NOT make your car run better. Platinum is a bad conductor of electricity. You probably lost some performance just from using a plug with poor conducting material. You were better off with Bosch non-platinum plugs.
Second: E28s are famous for idling problems, especially the surge you described. You can find some useful information and links about this and other problems here:
http://member.rivernet.com.au/btaylor/BMWText/technical/E28CommonFaults.html
I'm also a big fan of the unofficialbmw web site. Do a search there, as well.
If two of your plugs were oily then you might have some more serious problems, namely rings. I'd recommend doing a compression test on each cylinder. You can buy a cheapie compression tester at autozone for about $40. Better and more expensive ones can be bought at Sears.
Good luck!
4DF

Here's a link to unofficialbmw:
http://www.unofficialbmw.com/frame_e28.html
I found some GREAT information on how to fix stuff yourself there!
Flunky
PS-Are you a member of the BMWCCA? My chapter in Albuquerque is actually very helpful and knowledgeable when it comes to problems like the ones you describe. Even though lots of the members have wayyyy more money than me, plenty of them do their own work, and at least 20% have older cars, too.

Thanks for all the info and any help will be very useful since i'm not a mechanic; this car will help me learn more. I'm not really worried if i mess up since i got this car for 13 hundred. Maybe you're right about platinum not being a good electricity conductor. I should change the platinum plugs to regular plugs since that's what it had originally. I'll also follow your advice on checking compression. I'll do some research in that page that you said. I'm pretty sure that if there's bad compression it should be the reason why it's lost power and it has bad emissions. One last question, do you have any idea of how much will it cost if i get someone else to rebuild the engine. I will take it out myself and install it to make it cheaper.