I’ve tore this apart 3 times and can’t get the vanos timed correctly. If there’s anyone who can help me please let me know. No matter how many times I do it I can’t get the P0300 (random misfire) to go away. I wasted all kinds of money replacing parts that were functioning properly. I’m absolutely frustrated and I am considering getting rid of the vehicle at this point. I’ve spent all the money I can afford at this point trying to repair this car. If there’s anyone that can help me please let me know.
pm’ed
replied
Subscribed.
I dont think that’s causing your code. [/peanut gallery][/useless post]
I think it’s a bad MAF. I overlooked it because it was just replaced this past year. It still looks new 
I unplugged it, started the car, and the misfires went away. Although the car kept stalling out. I’m just frustrated with the constant problems this car has. I just spent $200 on both pre-cat O2 sensors this week because they were both trowing codes. When I pulled them out one was cut and spliced back together and the other looked like it was molested by a 4 year old with a hammer. I’m going to try to clean the MAF. I really don’t want to shell out another $200 for another one.
There is a spray by CRC for MAF cleaning at local parts stores.
I’m sure it uses similar chemicals to other cleaners but I don’t know an equalent you may have already (brake cleaner is possible).
Why is the light on now? What code?
^ I’m pretty sure there isn’t an equivalent spray cleaner. I’d use CFC Maf cleaner only.
For some reason, the CEL does not illuminate. Someone was obviously trying to hide issues with this car… With the MAF unplugged, I get the p0101 and P1188.
When I plug it in I get P0300 (random misfire), P030X (totally random), P1250, P1188, P1189.
I’m going to head to the parts store in a few minutes to get the cleaner. I’ll let yo know how this turns out.
I was going to suggest a vaccuum leak and then found this link which sounds similar
http://www.obd-codes.com/forums/viewtopic.php?f=2&t=3786
Horrible misfires due to vacuum leaks dont always cause a CEL, I’ve had a Chrysler with this issue. The car would skip and hope hop like crazy, stall sometimes and no CEL, lo and behold broken rubber hose.
It would also make sense as when you unplug the MAF it goes into default mode, but with MAF plugged in a vac leak past MAF would cause a diaster with expected data and real data.
Just keep remembering how much fun they are when you’re finally done.
The MAFs are wear item. If its throwing the code, even blinking light or no light, get a replacement. They are super cheap used if you just want one to swap in to diagnose.
Edit: How are you reading codes? Cheapo advance auto one? They often read different codes for certain faults, even the snap on ones. Id recommend borrowing a peake code reader or make a friend with someone at keeler…
Used brake cleaner before you could buy MAF cleaner. Never had a problem. Make sure the MAF sensor is dry before reinstalling and turning the key on or it will burn the residue on to the sensor wires, even worse light a fire and destroy your sensor.
If you have an aftermarket air filter or intake this needs to be done more often.
I cleaned the MAF and it still threw the P0300. I unplugged it and drove for 20 min, on the highway, and the car ran without misfires. I would stall at idle, but does run better with the MAF unplugged. As soon as I plugged the MAF back in, the misfires returned.
Does anyone have a MAF they want to sell me for a reasonable price?
- 1 to everyone’s rep for their help! I really appreciate it!
I’ve bought 2 cars from Keeler BMW, so maybe I could email one of the salesmen who sold me the vehicles. For my I have the cheapo advance auto one.
Any updates?
I ordered a new MAF. It should be here tomorrow. I’ll let you know if it corrects the problem.
I just replace the MAF and it still does the same thing…no change…
The current codes are:
P0300
P0304
P0305
P0306
…all on bank 2
I don’t know what to do at this point. I’m considering dumping the car. To make things worse some asshole pulled out in front of me, I hammered on the brakes, heard a pop, and I am losing brake fluid to some unknown place.
…now they just jumped to bank 1 and bank 2 is now clear of misfires…
If you like the car no point in dumping yet over a few most likely small issues.
A BMW with leaking brake fluid and random misfires will be low balled as all hell as well so financially it’s wise to fix it even if you sell it.
If it just jumped a bank it seems that’s it’s not related to anything on the motor itself, nor to the MAF, which means the problem is in between further leading me to persue a vac leak theory.
Check all the rubber hoses make sure non of them are stiff.
Take ignition fluid and spray it on the hoses as the car is missing and see if it goes away.
A long shot chance is that the leak is in the gasket for the intake manifold but that typically results in a misfire in one cylinder not on a number of them.
If you want there are a few BMW savvy members on here who do work on a side as well, “Fn skanks” in particular. He’s been a mechanic for as long as I remember and has his fleet of BMW’s. Could be a plan B of sorts.
If you have a garage put cardboard along the sides of the car going to the back wheels and under the engine to find out where the leak is.
I have the M50 intake on it, which adds a bunch of hoses to make it OBD2 compliant. I never had issues with it before. I’m wondering if this could be a root cause. I’ll try to put the S52 intake back on it and see if anything changes. Each cylinder has its own gasket. I’ve try spraying it, to see if it sucks the fluid in, and have had no luck. What confuses me is that when I unplug the MAF it no longer misses. It just throws the P0101 code for the MAF circuit. Once the MAF is plugged back in, the car surges, misfires, and has no acceleration.
When you unplug the sensor it goes into a default mode as now it can’t take a data a reading off anything.
When you plug it back in, it gets one data from a sensor which doesn’t match the actual amount of air in the combustion cylinder causing a misfire.
The amounts being wrong can be caused by injectors, plugs or unaccounted for air in the system. To me it seems like the latter.
For what its worth.