 » Site Navigation | | | | » Recent Threads | | | |  |  |  |  01-04-2009, 04:52 AM | #1 | | Junior Member Join Date: May 2008 Location: Louisville, KY Posts: 2 |  mass air flow sensor replacement
When you replace the MAF sensor, how critical is it to clear any fault codes in the DME system? Or will they clear on their own once replaced? THX |  |  | | 01-04-2009, 05:15 AM | #2 | | Senior Member Join Date: Nov 2006 Location: Stamford, CT <-> Boston, MA Posts: 1,393 |
I'm not sure anyone can field that question easily. But if you're replacing the MAF, why not just clear the codes? I'm sure your local autoparts store has an OBDII reader that can clear the codes and I'm willing to bet they wont charge you. Just ask to have your codes read & reset. __________________ 
BMWCCA #403399
2012 Mini Cooper S Clubman, 6-Speed
Loaded
2001 325xi, Winter Package, 5-Speed
Traded
1998 318ti, Active, Automatic, TOTAL LOSS R.I.P. 10/20/08
Bilstein Sport Shocks/Struts . H&R Sport Springs . Strut Reinforcement Plates . RSM Reinforcement Plates . Fogg Airbox . X-Brace . Bosal Brospeed Catback | | | | | 01-04-2009, 05:19 AM | #3 | | Senior Member Join Date: Jan 2008 Location: New Orleans Posts: 970 |
weve had some that clear themselves some that dont, easiest way is always to clear it though, id try to find someone to clear it for you __________________ 
^being rebuilt^
until then:
daily car:
96' Blue DASC'd ti with koni coilovers
slowly progressing...
weekend car:
85 1/2' 944 Porsche
no a/c, p/s, gutted cat, loud as hell exhaust, loud as hell sound system | | | | | 01-04-2009, 05:35 AM | #4 | | Senior Member Join Date: Apr 2008 Location: Austin Posts: 3,059 |
It should clear on it's own as long as it's the right type. __________________ Come get a ti-shirt
Quote: | From the e30 M3, evolved the e36.
They were "Keepin it Real" when they introduced the 318ti ClubSport in '95 and the 318ti Sports from '96 to '99.
After that... well nothing else really matters. ~Jess | | | | | | 01-04-2009, 07:07 AM | #5 | | Senior Member Join Date: Nov 2006 Location: Pittsburgh, PA Posts: 1,224 |
If the cause of a code goes away, after whatever number of driving cycles or intervals necessary for that test to have been run occurs, the code will go away. | | | | | 01-05-2009, 01:00 AM | #6 | | Junior Member Join Date: May 2008 Location: Louisville, KY Posts: 2 |
Thanks to all for the quick replies. I replaced the MAF unit per local BMW dealer who said it was the cause of the rough idle problem, but it didn't fix it. After a few seconds of idling, the engine RPM's drop and it nearly dies before revving back up to about 1000 RPM and settling back to about 800, then it repeats - sometimes every 5 seconds, sometimes 30 seconds or so. It runs great otherwise. Any ideas would be appreciated. THX again! | | | | | 01-05-2009, 02:51 AM | #7 | | Senior Member Join Date: Nov 2006 Location: Stamford, CT <-> Boston, MA Posts: 1,393 |
Check all your vacuum lines for cracks/broken seals.
Also check your intake boot for cracks. The best way to do this is to remove it and flex it a bit to visually inspect it. __________________
BMWCCA #403399
2012 Mini Cooper S Clubman, 6-Speed
Loaded
2001 325xi, Winter Package, 5-Speed
Traded
1998 318ti, Active, Automatic, TOTAL LOSS R.I.P. 10/20/08
Bilstein Sport Shocks/Struts . H&R Sport Springs . Strut Reinforcement Plates . RSM Reinforcement Plates . Fogg Airbox . X-Brace . Bosal Brospeed Catback | | | | | 01-05-2009, 04:42 AM | #8 | | Senior Member Join Date: Apr 2008 Location: Austin Posts: 3,059 |
Or spray some brake cleaner on your boot and see if it revs. __________________ Come get a ti-shirt
Quote: | From the e30 M3, evolved the e36.
They were "Keepin it Real" when they introduced the 318ti ClubSport in '95 and the 318ti Sports from '96 to '99.
After that... well nothing else really matters. ~Jess | | | | | | 01-05-2009, 06:17 PM | #9 | | Moderator Join Date: Jun 2003 Location: Bouncing off the rev limiter in CT! Posts: 3,156 |
Do those engines have a MAP sensor? if so, check that too (after all the other suggestions have been looked at first).
PS MAP sensor is
Manifold
Absolute
Pressure
Sensor
It checks the vacuum in the intake and adjusts, well, everything, using that data. If it goes bad, the car could run like crap, or not at all.
I never had one go bad on a BMW (and I'm sure it would throw a code if it did) so I can't even tell you where to look for it (but probably under the intake where it is impossible to get to). | | | | | 01-05-2009, 06:34 PM | #10 | | Senior Member Join Date: Jan 2004 Location: Northern Michigan Posts: 867 |
Quote: Originally Posted by twilhoit  Thanks to all for the quick replies. I replaced the MAF unit per local BMW dealer who said it was the cause of the rough idle problem, but it didn't fix it. After a few seconds of idling, the engine RPM's drop and it nearly dies before revving back up to about 1000 RPM and settling back to about 800, then it repeats - sometimes every 5 seconds, sometimes 30 seconds or so. It runs great otherwise. Any ideas would be appreciated. THX again! | ...having the exact same issue...been pretty cold here but...  I renewed the idle control valve which did nothing. I'm doing the O2 sensor next. __________________
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