Help me diagnose? [Archive] - Bimmerfest - BMW Forums

: Help me diagnose?

11-10-2009, 03:03 PM
So, i recent bought a 1991 BMW 535i. But, its giving me a few weird problems, that maybe you guys can help me diagnose:

Car: 1991 BMW 535i Automatic, with 208k miles.


1.) Car fails to start sometimes. Upon turning the ignition key, occasionally it wont turn over. Sometimes takes multiple tries to get it started. Sometimes if its being really picky, after it not turning over after 10 or so tries...upon next turning of key, it literally does nothing, doesnt even try to turn over. Waiting a min seems to fix it, to where it tries to turn over again, and eventually starts. Most times its ever taken would prob be about 15 tries to start. 70% of the time it starts right away. (Symptoms happen while both hot and cold)

2.) Car idles funny. The car normally idles at 600-700 RPM, but ocassionally drops down to 500 or so RPM's, making the car shake a lil bit, and acting like its going to die out. Light chugging feeling while its doing this. Also, while at a standstill, and in say a stoplight, it will do this, and will try lurch forward just a tiny lil bit, like it wants to take off running. Car idles a bit noisy, and rough. (Hot and cold)

3.) I completely drained my oil, changed canister and oil...yet the numbers dont seem to match up. The bently repair manual says it holds something like 5.6 quarts, yet i put in about 4 quarts, and the dipstick read it was more than full, above the full line. This reading continued to show, even after cycling the oil thru the car, running it a bit, and even letting it sit overnight. I drained a bit out, to make it just touch the full line, and have let it be.

4.) My driver side door lock doesn't open using the key, so i unlock my car via the trunk. At first, sometimes when unlocking, it would immediately lock again. This happened first week i got it. This no longer happens though. What gives?

5.) The temperature gauge is stuck, reading medium temp at all times, while my dash light gauge under the text indicator only shows two blocks, the yellow and red ones at very end of meter. Always, hot or cold. My Radio and temp indicator (text) on dash always read -35F.

6.) Car acts like its going to die on me sometimes while driving. While driving, it seems to run great at higher constant speeds/rpms. But in stop and go traffic or around town driving, when stopping at stoplights it does the rough idle, bouncing back and forth between 500-700 RPM, sometimes chugging when the light turns green and i step on the gas. Has died on me twice from a standstill at a stoplight. Light turns green, i step on gas, car chuggs and shakes, then dies out. Takes a couple min, and about 10 tries to start again. Also, from a standstill, almost consistently, if i punch the gas, it will go nowhere, and chugg a bit till i release gas pedal a bit. (These symptoms happen both hot and cold)

Things I've done: (In this order)

1.) Changed the Fuel Injector O-rings, soaked injector tips in Rubbing Alcohol, cleaned with Q-tips (cotton swabs). (I read that the car not starting while warm could be attributed to leaky fuel injector O-Rings.)

2.) Added Marvel Mystery Oil to Gas tank, to help clean the injectors.

3.) Did the Seafoam Hot-soak which is highly recommended around these forums to clean out the carbon buildup in engines. Looking at my injectors i had noticed quite a bit of resin-like carbon buildup. Let it soak for 3 hours, ran it all out. Proceeded to step 4.

4.) Changed Oil, Filter. Filled with 10w-40 Castrol GTX High Mileage. Added a lil bit of Marvel Mystery Oil to crankcase. (Couldnt add too much, as stated above, 4 quarts of Castrol filled my car above the full line of dipstick. Also, the underside of my car..the Oil pan where the Oil drain plug is, has been covered with oil that has hardened like resin. It looks as though lava has poured over it, dried. And then done it again. The thing is damn near black, and sticky resin-like, yet is not dripping any oil to the ground. Im assuming at one point the oil was leaking around the pan gasket? Again, no oil touching ground.

After all this, im still having all of the problems stated above. Any help you guys can give GREATLY appreciated.

11-10-2009, 03:27 PM
By the numbers:

Does the starter motor engage with the key in the start position but sometimes the engine doesn't fire, or is there no starter action sometimes? If the engine is turning over but not firing it could be fuel, fire (ignition), or the ECU. If not turning at all sometimes, check the Fusible link in the power lead from the battery. These sometimes crack and make intermittent contact causing random elictrical problems.
Bad idling and rough running could also be ignition or fuel related, but the most common cause is vacuum leaks. Check all the hoses connected to the intake manifold for cracks or leaks.
My Bentley manual shows 6.1 quarts for the 535i engine so 4 quarts does seem a bit low even if some oil is trapped in the oil lines or cooler (if you have one).
I had the same drivers door locking problem with a 325i we used to own. The electrical switch on the door lock wears or gets dirty and won't make contact in the unlock position. Even though you are turning the lock, all you are doing is switching the power locks to lock or unlock. You will probably find that the doors can also be unlocked from the passenger door.
Temperature Gauge problem could be a bad sensor or connector but more likely a bad gauge.
This is probably related to item #2.

Good luck.

11-11-2009, 12:59 PM
1.) I believe the starter is engaging yes. its only after a number of tries of it not starting, that it then does nothing for a attempt or two. I'll check the fuseable link. My headlights do seem dimmer than they should be, but i dont really notice many other electrical problems. The lights inside or out never die out on me completely.

2.) Ill check the vacuum hoses and get back to you on that.

3.) About the volume of oil my car is taking...There is much oil hardened around the underside of my oil pan. Im thinking maybe someone used the product "StopLeak"? Its like a quart of oil, that is thick, and supposedly stops leaks between seals and whatnots. But ive also heard, and this may be wrong, that the stuff is no good, cuz it will sit in the bottom of your pan, and harden like goo. Is this true? Could this be why im a quart or so less in avail volume for oil in my case? Becuase someone used this stopleak before i bought the car...and its done its trick, but the rest of it is taking up space in bottom of pan?

03-20-2010, 10:44 AM
1... almost sounds like a bad battery..a good battery wont dim out much at all

3 sound a bit far fetched yeh it gets sticky but not a hard goo that wont drain out
try the atf treatment see if you get anything odd with that ..inspect the filter
good luck.......just saw how old this was haha whatever

03-20-2010, 12:41 PM
5. those two block lights are the oil lights to tell you when you need a change ill send you a pic and tell you how to reset it if you just got one and they didnt fix it

03-20-2010, 12:45 PM
1. check all wires and terminals then check the battery at like a schucks or somethin then check starter if not relay

2. my car does the same thing i am gonna try cleanin the maf but it feels like it needs a good tune up bein at 201k

3 id get that cleaned out and why you dont id do more frequent oil changes
this is what i got from the e36 forum
so turn the ignition key to position II, but don***8217;t start the car. Get out of the car and go to the data port. Always connect pin 7 first. Once you***8217;ve inserted one end into pin 7, insert the other end into pin 19 and hold it there for 4 seconds. Then remove the paperclip. Check the dash and the oil inspection lights should be reset. The reset occurs upon removal of the clip

03-22-2010, 08:11 AM
clean your mass air sensor, idle sensor and change your fuel filter. it also sounds as if your battery is weak. get it charged or changed. these cars act funny if the battery is low. as stated earlieer, make sure the intake boots and hoses are not cracked or dry rotted. replace where necissary.