Power loss/ rpm loss

[backdoorbimmer]

I just had an interesting afternoon drving my 94 530i. While I was driving in the parking lot on my way to lunch I started to drop rpm's while my foot was pressing the pedal farther towards the floor. I pushed in the clutch and downshifted into first. As I gave it gas the rpm's started up, I began to accelerate again... only to loose rpm's and decelerate while holding the gas pedal down. I repeated this process several times to the same end result. No matter what I did the car would rev a little then cut out. It felt like the car wasn't getting gas when I pressed the peddle down. I would get spurts of power but overall went nowhere. I put it in nuetral and opened the hood to hear how the car idled. It was pretty rough and I could hear a knocking sound (although I don't believe the sound was metal on metal). I turned off the motor and waited 5 min. I then turned the motor back on, the check engine light came on and I could hear the same noise's/rough ideling. I turned the car off again and then back on. All of a sudden the car began to idle like normal, there wasn't a knocking sound, I could hear the normal purr of the engine I was used to. The check engine light also went off. I am trying to make sense of this and figure out what my car is trying to tell me is wrong. I know that the car had been just sitting for at least 2-3 months before I bought it last week. My only conclusion is that the spark plugs weren't firing correctly, the fuel pump freaked out, fuel filter issue, or there was a blockage in the fuel line that passed. I have since driven over 40 miles on the car without a hint of this same issue. Anyone have any advice on what the problem could be?

[moroza]

First things I'd do are check are the sparkplugs, and replace the fuelfilters. If you get a CEL again, do a stomp test to read the codes (search this site, and e34net for how to do it).

[backdoorbimmer]

I have decided to replace my spark plugs, spark plug connectors, fuel filter (I am under the impression that the 530i has two, correct me if i'm wrong), air filter, do an oil change, and also replace the fan clutch. I took the vehicle in for a state inspection(required by texas dps ) and apparently it's miss firing. The place I had it inspected gave me an estimate of 890$ for this tune up. I can get all the parts I need off pelican for around 230$ (350$ cheaper than the dealer would charge me just for parts). I feel competant enough to replace the plugs, oil change, and fuel filter. My question lies in the fan clutch. Are they difficult to change? do you need any specially fitted tools for the job? or just dw40 and man hands.

[jimoreno]

The 530 had 2 fuel filters until 4/1995 and one after that. For the fan clutch removal you will need a 32 mm wrench that you can get at a bicycle shop and keep in mind that the nut is reverse thread (loosens to the right). Put the wrench on it and give it a wack or 2 with a hammer.

[DoctorZaius]

Ya, pull the codes. Bad vacuum leak?