Jerky Acceleration when pedal to the metal

[saneesh8]

When you open the oil filler cap, it should not die. It should change bit and have some slight vacuum (like to hold a A4 paper, but not sucking in). If it is sucking too much, as far as i know, there is something wrong.

Crank case ventilation system?

http://www.bimmerfest.com/forums/sho....php?p=5989795

[Bilito]

I was reading up and watching repair some videos on You Tube and this guy was doing a class thing about intake and fuel system sensors and how they worked and how to check them. The first one he showed how to check was the MAF. He said the simplest test on an MAF is to start the motor and while it is running unplug the MAF, the motor should immediately stall if it is good, if it is not good, the motor will keep on running
So just now my wife started the motor and while it was running I unplugged the MAF and the motor kept running, as matter of fact it instantly smoothed out and picked up some revs. WHAT? I did it again and the same thing happened. I stumbled into something I never expected to stumble into, I have a bad MAF. WOW.

[328 Power 04]

You give too much credit to those amateur youtube videos. That kind of test depends on so many factors. For instance, the ecu may be programmed to immediately switch to prewritten (limp mode) engine running maps if there is a loss of maf signal, and keep the car going.

The best MAF test is to log real time sensor data, either in kg/h or MAF Volts at idle condition and driving conditions.

The rest is guessing, with capacity to get lost in so many variables.

[Bilito]

The car immediately went from a very rough idle around 500 rpm to a very smooth idle around 700 rpm when I unplugged that MAF. Tomorrow I am goona get some of that MAF cleaner and see what it does.

[Bilito]

Got that MAF Cleaner and also throttle body cleaner, removed the filter box and the MAF and cleaned and cleaned it with the spray. MAF electrodes went from dingy looking to bright and shiny, I ended up splitting the throttle body and my wife held the gas pedal down while I looked inside behind that throttle plate and it was all black a gunky looking in there, the throttle body cleaner did nothing so I tried Formula 88 on a Q tip and that really loosened up and got the gunk out, took us around 30 minutes to get it all clean and shiny top and bottom using a mirror. While I had all that stuff out of the way I took a good look at all the vacuum lines I could see and reach, they looked and felt to be in good condition, no visible cracks, and neither hard or soft, put it all back together and started it up.
Absolutely no change what so ever, right after the start it proceeded to run rough. and if I disconnected the MAF, it smoothed right out and gained 1-200 rpm.
I went to ebay, found a deal and ordered a new one, be here next week sometime. All I can do at this point is see what, if any difference a new MAF makes and go from there.

[Blacklane]

Several people here have bought and installed cheap MAF sensors on these cars and had them not work right. The MAF sensor on these cars seems to be one place where you need to stick with OEM.

[Freaksonly]

Hi. I've been having problems with my bmw i 323 2008 ...rough iddle..shaking...hesitation at low speed etc. So i unplugged the MAF sensor and now its alot smoother.
But question is... is it safe for the engine to keep on driving it like that.

[328 Power 04]

Hi. I've been having problems with my bmw i 323 2008 ...rough iddle..shaking...hesitation at low speed etc. So i unplugged the MAF sensor and now its alot smoother.
But question is... is it safe for the engine to keep on driving it like that.

The MAF disconnect test tells you that you either have a vacuum leak, or that your MAF is bad (less likely).
Many times people replace the MAF and still have vacuum leaks causing the issues. Congrats, you just shot and replaced the analyst for telling you something's wrong.


It's safe to take it home or to the shop and fix it... You really need to be measuring the air coming in correctly (also your intake temp sensor is likely in the same circuit). Improper air to fuel mixture is not safe for the engine. The ECU will try to correct up to a point using other sensors, but it's just that, up to a point. After that, the engine suffers.

[Bilito]

HI ALL, We in S Florida have been without electric for 8 days, just got mine back at 7 pm today, Last Tuesday after the storm my new 22.89 cent MAF arrived, I installed it on wed afternoon and if you all recall, my Certified BMW Mechanic across the street said, if, after you install the new MAF and if, the car responds well to it well the engine should start quickly, rev a little, slow down to 6-7 hundred RPM and if, it works property after driving 20-25 miles the car will adjust and turn of the check engine light. It did exactly what he said it would do and now the car is running perfectly, he told me today that all the cleaning and other stuff I did, plugs, oil change etc does not hurt either,

BTW, at exactly 21 miles the check engine light turned off

Now my next issue, my after market radio lights up, but I have no sound out of any of the speakers any ideas where to look, I did check fuses.

[colb]

You wetre lucky the non OEM MAF worked for you, had bad experience with cheap MAF, bought a Bosch oem one and it immediately fixed my bad running problems.
Like you I was hunting for a non existent air leak codes set similar to yours, its very easy to be led in the wrong direction and fit sensors that are not the actual issue when reading codes. Always a bit of lateral thinking needed. Unplugging the MAF will cause the ECU to go to a default setting for the MAF and the car will run but not as good as when you have a working MAF.

[Mr Bingley]

Has the aftermarket radio ever worked, or did it work at one time and now it doesn't?

[Bilito]

Yes it worked perfect right up until IRMA passed by our way, I was in the side yard and got some rain, but it was dry inside, turned on the radio, no sound at all, I could see the equalizer bars jumping around and the face plate was lit up and that was it. Do all the speakers get power thru that Amplifier in the trunk?

[z3forlife]

If it's stock other than the hu then yes all speakers are powered by the trunk mounted amp. First thing I would do since it's a aftermarket hu is pull it out and check the harness connections. You may find sloppy work that failed/oxidized due to the moisture or dumb luck. The small white wire at the amp is the remote turn on circuit. Check it for power and if it's good then your amp may have failed

[Bilito]

There is a big clear plastic covered deal that has a 60 watt fuse in it, I did not have any power to the primary wires from the battery to the amp but I did have power from the small white wire at the amp to ground. I could not tell if that fuse was blown or not and I could not test of continuity because the wires are sealed into that plastic cover with rubber grommets, so I took the plastic cover off and when I did the wire and fuse deal moved, I left my meter inside the car and when I went to get I thought what the hell, let me turn on the radio, and it worked, just that small movement made contact, so I just tightened up the connections on each side of that fuse as best I could and put it all back together and then sat back and listened to the Sat Night Fever soundtrack, my ex and I were at that time, dancing machines, almost s good as Travolta, those were the days my friends, yup, those were the days.,
All is working just fine now , just have a dash light out and gotta change that tranny fluid