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1980 528i auto feels like it is fighting a slight head wind when accelerating above 65 mph. Engine does not mis-fire and still accelerates well, it just feels like it is being hit with a slight head wind. Changed the O2 today because light was flickering but no change in this problem. Any ideas would be appreciated.

Sorry I can't help, but am interested in your diagnosis and resolution.

Start with the timing, then check the fuel pressure.

Ignition Timing:
Check the Haynes manual, but I think it's 25 degrees BTDC. There is a ball on the flywheel you time to. Remove the vacuum lines from the distributor and plug everything. Set the engine at 2200 RPM and get the ball in the window on the bell housing. Tighten the distributor, reconnect the lines. Done.

Ignition timing can make a big difference, sound like there's not enough advance. My automatic car pulls all the way through to 125 mph, around 5000rpm in "D".

Fuel pressure:
Add an inline gauge from summit racing, I would be concerned with anything less than 45 lbs, but that pump should be up around 80 lbs.

Good luck

Borrowed a timing light and dwell/tach from a co-worker. I plan on changing plugs, air filter and do the timing this weekend. The timing specs for my car is 22 deg. BTDC @ 2200rpm. I've read the FAQ and ready to go. I will post results.

I tried timing the car today. There was no change in advance or retard as the vacuum hose was removed or replaced on the distributor. Something is not right. So it is off to the mechanic for a vacuum test or distributor rebuild. I will also have them check fuel pressure.

paronoff wrote:I tried timing the car today. There was no change in advance or retard as the vacuum hose was removed or replaced on the distributor. Something is not right. So it is off to the mechanic for a vacuum test or distributor rebuild. I will also have them check fuel pressure.

Did you check to see if there was vacuum on the hose. The advance side goes to ported vaccum and there should not be vacuum at idle.

Mostly they get sticky and a little spray oil seems to free them up. Don't forget to oil the felt pad under the rotor (where centrifugal advance can stick; which could be your issue)

Mechanic checked out timing (spec), vacuum (no leaks), distributor (okay). Fuel pressure was not okay. 30 psi which is below spec. Fuel pump is suspect, hum is not constant. It goes up and down in pitch slightly, not with the gas pedal just at idle. Looking up FAQ to see if change out is DIY. There are supposed to be 2 fuel pumps for this car. In tank and outside the tank. Any suggestions on how to test them?

paronoff wrote:Mechanic checked out timing (spec), vacuum (no leaks), distributor (okay). Fuel pressure was not okay. 30 psi which is below spec. Fuel pump is suspect, hum is not constant. It goes up and down in pitch slightly, not with the gas pedal just at idle. Looking up FAQ to see if change out is DIY. There are supposed to be 2 fuel pumps for this car. In tank and outside the tank. Any suggestions on how to test them?

If a full tank makes it run better, in-tank pump is suspect.

30 psi with vacuum hose connected is pretty close. What is the pressure with the regulator vacuum hose disconnected? Should be 36-38 psi

No change. It stayed at 30.

paronoff wrote:No change. It stayed at 30.

That seems low
Full tank?

No. 3/4 of a tank. Passed smog though.

I agree that the regulator is probably stuck open relieving too much pressure.

Pump could be weak, but I think the pressure would be moving around a lot if pump was weak

An old clogged muffler would also cause similar symptoms.
And check your fuel filter before replacing the pumps. A clogged filter will also cause a loss of fuel pressure.

Muffler is new. Filter has less than 10,000 miles on it but it certainly would be a good place to start.