89 325is running very slow lately...

[Andi 1]

I have a 1989 E30 325is...The cars mods are Mark D 93 octane chip,magna flow exhaust and lots of suspension work.Anyways I've so far replaced the rubber fuel lines and fuel filter.I also just did the fuel pump and injectors.I also changed the plugs and wires but the car runs very slow.I've lost to my Volvo 740 wagon,a 1987 325ES and a 1990 M20 525!! My third gear seems to lose power around 4000 rpm.Today I'm going to replace all the front seals,timing belt and water pump.My tranny is also in great shape and shifts very smoothly.I know something is wrong because I drove a friends 325i 4 door sedan thats automatic and stock from 1989 and it pulled nice and hard.Its so depressing having such terrible luck in my E30 when it comes to power.Can anyone help? I know these cars were known for torque and power so somethings gotta be real bad.Ive done a compression test and everything was fine down through all 6 cylinders...i have not performed a leak down test yet.Any help would be awesome

[jlevie]

Even though you've replaced the filter and pump it would be a good idea to check the fuel pressure at the rail throughout the power band. You should also use an ohmmeter to see if the AFM's resistance smoothly changes as you move the vane. And if the O2 sensor has over 80k on it replace it.

If both of those check out okay I'd try replacing the crank position sensor.

[Andi 1]

Even though you've replaced the filter and pump it would be a good idea to check the fuel pressure at the rail throughout the power band. You should also use an ohmmeter to see if the AFM's resistance smoothly changes as you move the vane. And if the O2 sensor has over 80k on it replace it.

If both of those check out okay I'd try replacing the crank position sensor.

OK thanks!! I'm going to do my front seals,Tbelt,waterpump and tensioner as soon as it stops raining and also look into how to check the fuel pressure through out the powerband with an ohmmeter. I might upgrade to an M30 intake and larger injectors from a 5.0 Mustang.The O2 sensor was replaced but re wired to a new location. I'm going to also try your advice and change the crank position sensor.I really want that S50 thats for sale on this site but can't get the buyers attention.I found an M50 swap for $1700 on E30 tech forums.What do you think would be a easier less pricey swap? M50 or go the extra mile with an S50? And why does the S50 seem to fit harder than an M50?? insnt it just a larger bore and crank on a M50?

[Mr Deagle]

Did you replace the injectors with used dirty ones? That could be your problem.

[pedal2metal]

cap and rotor? carbon tracking visible?