e34 530i problems, help!

[richardb]

So after lots of searching, I only found one post (on bimmerforums) that sounds exactly what my dad's car is doing:

"Intermittently, during acceleration, the car will hit what feels exactly like a rev limiter, only rather than be at red line, it would happen much lower, 3000, 4000, 5000 rpms. The check [COLOR=blue ! important][COLOR=blue ! important]engine [COLOR=blue ! important]light[/COLOR][/COLOR][/COLOR]
would flicker, and the engine would just rev up a bit cut back some back up and down until i got off the gas, then I could shift to the next gear."

* It has CEL for 02 sensors, never replaced those. Plugs/fuel filters done about 3 years ago, maybe only 18k miles since then.

* I started it and let it run, then unplugged the MAF and it made no change, drove it and it drives the same as always- plugged it back in and made no difference

Do I have a bad maf? Bad ecu? Crank sensor?

Thanks in advance

[M.R. Performance]

well if the maf isnt responding like that, sounds like it could be a bad maf

bad ecu the car most likly wouldn't start

[PeaveyBassist]

Bad MAF.

[whatt18yahoo]

check your vaccume lines a friend of mine at the shop had the same issue i guessed maf turned out it was a vaccume line. check em out

[richardb]

Thanks guys... Im going to check the CEL right now and clean the maf/inspect any lines. I'll update tonight

[quickervicar]

If you unplugged the MAF & noticed no improvement, doesn't that point to something other than the MAF? If, after unplugging, it ran better but just down on power from normal then I would blame the MAF.

[richardb]

OK just got back. The tube going from the intake to ICV was half way in, and leaking for some reason. Plugged that fully in and it revs past 3k now... but may be an intermittant thing still. I also pulled the ICV and cleaned it.

The throttle body gasket is leaking (idle increases when sprayed with carb clean).

The scan tool won't communicate with the ecu through the diagnostic port, we checked all the fuses both under the hood and under the rear seat, everything is good. So not sure why the scan tool won't work... last time we scanned the car about 2 years ago it said 02 sensors.

[richardb]

Despite the tube for the intake being loose, I started the car this morning and pulling out of the drive way it falls flat on its face like hitting a rev-limiter at 2k rpms, CEL is on still.

Any ideas?

[Bin_jammin]

It could be a failing fuel pump. Do a fuel pressure test. Where in CT are you? I'm busy nights, and tomorrow is no good, but maybe sometime this week I can take a peek.

[Jb325is]

I'll bet it's intake seal/throttle body gasket. Replace those, they're cheap, then go from there.

[krazykraut]

Look to see if your EML light comes on (in the center of your gauge cluster)....If this happens your car is sent into a safe-mode, and power is reduced via the computer.....Usually the transmission or engine mounts are trashed and allow the engine to move and trigger the sensors, thus cutting 80% power.

[BlueBMW]

I had this EXACT problem on my 95 530i. Drove me absolutely bonkers trying to figure it out.... I finally found it. Turns out at high RPMs my crank pulley would run out of round and wig out the crank sensor. I replaced the crank pulley (with crank sensor pickup teeth) and the problem has never come back. I guess there is a rubber piece between the two pieces that make the crank pulley and it gets worn out over time. I saw it by having someone rev the motor while in the air and I could watch the crank pulley start to wobble.

I bought a used pulley for a 540i for around $50 and it worked perfect. A new one is something like $400.