1st August 2012, 02:09
Join Date: Jul 2012
Location: Atlanta ga
91 34 m5 silver
Thanked 3 Times in 3 Posts
Originally Posted by crowdaddy
At the least, learn how to test the MAF and be sure before you start buying things. I read somewhere that you can check the voltage and it would give you an idea of how the wire is holding up.
Found this relating to a Porsche, but same thing...maybe...lol:
MAF TESTING - DIRECT VOLTAGE METHOD
0. Remove the LH connector and lookup the MAF output signal and ground signal. Connect a good DVM to measure the output. Put the DVM into mV mode and keep a spreadsheet or note paper on standby.
1. Ignition on
2. Engine not running
3. On each MAF measure DC voltage between
pin 3 (ground) and pin 5 (signal)
4. Reading should be 1.75 V. The closer to 1.69 V the better. the dirtier the MAF the higher the voltage will be.
5. Start the engine, and drive the car until fully on operating temperature.
6. Re-test 4) Value will drop to approximately 1.69 V.
7. Make a full test cycle at idle, running various rpm's as indicated in our spreadsheet. This gives a good insight of the output compared to our reference MAF and other benchmarks.
8. After running the engine over 3500 rpm you can see the MAF do a burn off cycle. You need to remove the air filter and air filter box to be able to see this. It is visible in a low light environment.
If this procedure gives a reading in step 4,6 or 7 that is outside tolerance the MAF is definitely contaminated or otherwise damaged. Possibly the electronics have drifted from specifications.
I would imagine that the vacuum lines aren't the issue or the removal of the MAF wouldn't have changed anything. Maybe one the experts will chime in.
The flap that the MAF controls may just stay open all the way when the MAF is not hooked up. Just a guess. Or maybe it's getting stuck in various positions and contributing to the problem.
Trying to understand how the MAF being unhooked would allow the engine to run properly. Maybe its a faulty flap. Or the potentiometer that controls the idol maybe? Did you witness the car running without the MAF? How did it sound?
No I didn't hear it run. The guy at the shop just informed me that it did. He seemed to think the maf was the culprit. I didnt put a new 02 sensor in I will add this as an option. I just really wanted to start with less expensive things though so 02 1st I guess.
Guys I really appreciate the input and help thus far!