Vacuum leak, maybe?help

[IV318]

I drive a 96 ti auto just turned 150k. I have had a problem with a rough idle since I bought the car, when in park or neutral the car idles rough when cold and when it finally warms up it is fine, but in reverse or drive it idles rough all the time when stopped. If I give it a little gas (all good). by rough idle I mean low idle almost like it wants to cut out. Now as a home mechanic of sorts I have tried to find a vacuum leak (none so far) I have cleaned to ICV and even disassembled the intake manifold (replacing gaskets) and still no luck.
HELP!!!!!!! any advice would be helpful.
also the entire car has a little vibration with the idle issue

[Platanos]

I had the same problem. It ended up being a bad hose, the one coming off the valve cover. Its actually one hose attached to another. Check this out, I hope it helps.

http://www.318ti.org/forum/showthread.php?t=12473

[IV318]

That hose seems to be fine but Im wondering if I should go ahead and replace it along with a few others (especially brake booster to intake) to end my head ache?

[snwbrdrbum10]

check your THrottle psotition sensor.

[IV318]

checked that when I bought it. that was my first thought, besides that would throw a code would it not

[pdxmotorhead]

Not always.... It could be borderline and mess you up.. Without a code.

Dave

[IV318]

Whats the best way to check that? I've just been eyeballing it and swabbing it with some throttle body cleaner. it looks fairly good.

[atlanta318ti]

What type of plugs are you running? Like an idiot, I swapped the OEM NGKs for some Bosch Platinums and the idle started giving me problems. Duh, I should've known that a platinum tip versus the standard tip might create an electrical difference that the ignition system might not be designed to fully handle. It wasn't immediately noticable, so I thought it was the IAC, TPS, clogged air filter, etc...

So today (6 months later) I finally swapped my 97TI back to the original BMW NGKs-NGK BKR 6 EK (I save my prior plugs and date them w/cylinder# for later reference), and WA-LAH. The idle is now back to normal.

[buddhajono]

could be that you need a new mass airflow meter, check engine light only came on after a while when my engine was idling very unsteadily. Cost me 500 for a new one

[pnosker]

Atlanta318ti... I use Bosch platinums and don't notice any difference between them and OEM plugs.

[IV318]

My check engine light came on a few days ago and I checked it the code was air injection flow incorrect flow. this happened after I put the original air box back on. ????????????

[aceyx]

Did you reverse the MAF or any connectors?

[IV318]

No Everything is just as it should be. It goes on and off every couple of hundred miles. its very strange. also I found that vacuum leak two of the hoses were not sealing properly, zip ties are my current solution untill I can get to the dealer.

[MD318ti]

i had that same problem but it was my diaphragm for the crankcace ventilation(black round thing with a vacum hose going to,right behined/on the intake manifold)(front of booster) it was loseing vacum throught the bottom of it, because it had warped. good luck with it!

[weezer]

I know exactly what's wrong; when I cleaned the MAF I accidentally installed the MAF backwards (watch the arrow) and the vehicle backfired with rough idle. Check the MAF and make sure the arrow is pointing towards the intake.
Good Luck!!