lacking power

[jacobrheaume]

I have a 93 325i with 233K on the odometer. Lately I have noticed that I am underpowered in the lower gears, particularly first gear. The car just doesn't have the pep it once did. I have checked all the spark plugs by pulling each coil one at a time while engine was running and I replaced them not that long ago so that is not the problem. Today I changed the valve cover gasket because I was burning a bit of oil and I also changed out the mass air meter boot. I ran a can of BG44K through the tank too. I don't think I have a blown head gasket because there is no oil in the radiator and no coolant on the dipstick. Does anybody have any ideas? Thanks!

[Manolito]

When you put your hand by the exhaust opening, can you easily feel the individual bursts of exhaust? If not, there is an exhaust obstruction, most likely in the catalyst.

How old is the fuel filter? Remember that the fuel filter affects the fuel pressure on this car as well as the total fuel delivery.
Fuel_Filter

Coil grounds secure?

I don't know what BG44K is, but I know that Techron works as well as any fuel additive can work for cleaning up injectors. With that kind of mileage, it may not hurt to pull the injectors and send them to someplace like Cruzin Performance or Witchunter to be ultrasonically cleaned and checked for flow and pattern.

Make sure some critter has not made its home in your air box intake (woudn't be the first time)

[jacobrheaume]

BG44K is a fuel system cleaner, it costs 20 bucks and lots of folks swear by it. Think the fuel filter has been replaced, my friend sold me the car. How long do they go for? The coil grounds, are those the wire like things on two of the coil packs that attach to the posts? I think on cylinder three and six? Thanks for the imput. I will suss out these issues. When you say exhaust opening do you mean the tail pipe? Thanks again.

[Manolito]

I intend to replace fuel filters every 50k miles, but I usually forget and let them go 100k or so.

You are right about the coil grounds. They are the woven straps that attach to the coil bolts.

Yes, the tail pipe.

Oops, something I said was not correct, your fuel pressure is regulated at the fuel rail, not at the fuel filter. You should check your fuel pressure regulator as well. The first test is to pull the vacuum hose off of it and see if it is holding vacuum and the hose is not full of gasoline. If it passes that test you may still want to get a gauge and check the fuel pressure at the rail.

[Jeron]

How is your clutch?
Is it low on power or does it feel unresponsive, like a small delay? (if unresponsive then check the engine mounts)

Pull the whole intake section and carefully inspect for cracks.

[jacobrheaume]

Thanks guys! Clutch feels fine, will proceed with fuel pressure regulator when I get a sec. You guys are great!

[markdas]

Does it roll on level ground okay? I am thinking binding brakes or wheel bearings?

Check diff oil and gearbox oil levels and condition, cheap and easy to drain and refill those!

Air filter, fuel filter and MAF could be a cause?

[jacobrheaume]

Yeah, it rolls on level ground just fine. The only problem is that it lacks pep, particularly in first gear. I did the brakes about a year ago and they are fine.

[markdas]

Maybe do a compression test, get a feel for the engine condition.

If you find a low figure on the quick test, move onto a cylinder leakdown test and take it from there.