Subject: How to screw things up..... Author: eliasazem : member since November, 2006 : 339 posts Posted on: 2008-07-09 13:29:31

I'm having a white smoke coming out from my exhaust....750 M70..1992...more noticeable when steping hard on gas or when releasing the throttle.
But let me rewind some time in order to give you a full PANORAMA.

1- About 3 months ago I begin to smell fuel vapors upon engine start...couple of days after an erratic idle started. Continue to drive once in a while as I usual do....very few actually.

2- Some days went by and I kept driving few times and really short distances....did a batt cable reset...no good....started noticing that my car became eager for fuel...consumption increased much above a *normal* fuel system malfunction. About 30 to 40%.

3- Meanwhile I also noticed some oil sprayed to the hood....it's coming from the thin hose that's attached to PCV....picture attached...it was only on the left side at first. Guess maybe it was clearly viewable because my insulation hood is off.




4- By now things had started to worsen because of a BLACK smoke coming out of exhaus. Posted and read some threads on this board and despite all the advices I've messed around with both MAF's. Leaned the mixture some what before making the engine to stall. But it did no good to the BLACK smoke. At this point, I guess smoke started to become WHITE. It was obsviously oil...I could tell this by it's strong acid odor mixed along with some fuel odor also.

4- Looked for a scanner tool on next morning and found out that I had a bad Temp probe....oops...found out the begining of all my problems....system wasn't getting the right water temp input and went crazy. Scanner told us on how the ignition timing was out as well other data related to it. But then I screw up really bad...Turning on those factory sealed screws on any MAF to either direction would'n result in any mixture data movement in the scale...I mean..mixture reading was going back and forth...So I made a big mystake and turned the MAFs to full rich!!! so I left the shop with both MAFs literally putting out some good fuel signals....completely out of settings....oooohhh man.....That's what I call SMOKE...it was like my engine didn't have any piston rings...I was afraid of causing a traffic accident by reducing local visibility on the streets :) If you love your car like I love mine you should know by now how upset I was then. Really pissed off.

5- Stopped by my mechanic's shop and asked him to check the water temp probe....problem was fixed...just a bad wire. Then Shogun gave some docs to look at and Patrick and Alv12 and other guys gave their opinion. My car does not have O2 sensor as many of you have. Patrick told me to look for fuel canister valve and stuff....but PO had removed the whole canister system...*&^%$!!!

6- Since then: opened the right MAF...sorry I didn't have any camera for some pics....found out inside was ok...broke 2 parts of the plastic around the lid....*&^%#!!...had measured all MAF pins...voltage is ok...also we left pins 3 and 6(it has a 0.00 to 0.96 range)at 0.81. Fuel consumptiom had improved a lot...getting better mileage...and idle consumption is around 2.9 to 2.7 L/H on OBC test code number 3. Also had reved the engine past 2000 rpm in order to check if the MAF was glowing...it's glowing...both MAFs are good and DME is receiving it's signal.

7- WHITE smoke had improved a lot. More noticeable when pushing a bit hard and releasing the throttle.

8- Took it for 2 scanings...a MODIC II and a GT1 at local dealer..no help at all...they say my car does not have a special feature that shows optimun mixture adjustment band...they just read the actual settings.

9- Now found out some oil sprayed on the right hood side...it's the right PCV. Removed and cleaned both PCV systems a week ago...smoke continues. I bet my intake manifold has oil waiting to be burned out.
I used to have a small amount of smoke sometimes...only at first start of the day and having at least a couple of days sitting down, figure out it's that usual valve seals issue common to our cars. My mechanic says that some fuel may have contamined engine oil when mixture was set way too rich and made it thinner...making it easier it's way up thru piston rings. Engine is running smooth as always....despite a small vibration at idle because of *blind* fuel settings.

How many problems does my car have? 1 or 2? Vacuum sucking oil to the intake manifold for some reason? or it might be engine oil going thru piston rings? valve seals?

I wonder what to do next....should I start by replacing those PCV valves and getting an oil change at the same time? Should I take intake manifold for a wash at the same time to get rid of that oil in there? Engine oil is relatively new...I'm using Castrol Magnatech 10W40....Oil level is slightly below max and I'm monitoring it.

I guess my next step concerning fuel is to take my car to a shop that has a gas analyzer so we can adjust the CO2.

Does your car have had any symptoms described above? I'm all ears to suggestions and opinions.

Sorry for the bad English and for being so long. Thanx to all of you in advance.

1992 750ia VIN DC08363

• How to screw things up..... (pic) - eliasazem 2008-07-09 13:29:31 (350 views)
  • I have the same problem..... - mcf 2008-07-28 10:29:23 (42 views)
  • whoooo hell yeah whats your trick for making the engine look so good!!! (nt) - beach911 2008-07-10 00:21:08 (72 views)
    • I want to know that also (nt) - steinway 2008-07-10 11:16:52 (56 views)
      • I had chromed all bolts, clamps and whatever I got my hands on.. (url) - eliasazem 2008-07-10 17:01:41 (96 views)
        • www.flickr.com/photos/bimmer_750 (nt) - eliasazem 2008-07-10 17:32:32 (95 views)
          • that looks exquisite - steinway 2008-07-11 05:44:18 (48 views)
            • left the engine in it's place and removed some parts...look (pic) - eliasazem 2008-07-11 08:33:10 (143 views)
              • what's that in the trunk at the right? - steinway 2008-07-11 13:58:28 (50 views)
                • Looks like a storage compartment where the 2nd battery usually is at with a 750 (nt) - Johan750 2008-07-11 17:53:13 (52 views)
                  • Never heard of a second battery usually in a 750..... (nt) - eliasazem 2008-07-11 18:04:23 (45 views)
                    • so have you looked what's behind it? - steinway 2008-07-12 02:55:51 (41 views)
                    • It's not big enough....do you have a pic to show me...thankx (nt) - eliasazem 2008-07-11 18:05:29 (44 views)
                      • all Highline for example have a 2nd battery (url) - shogun 2008-07-11 23:14:41 (72 views)
  • Change the oil - erwin 2008-07-09 14:40:45 (80 views)
  • Rings probably OK - Patrick C 88 750 160K 2008-07-09 14:09:05 (80 views)
    • i was burning oil at same rate 400mi/qt - ridgelyrocket 2008-07-10 21:19:08 (60 views)
    • Patrick is right. - alv12 2008-07-10 11:36:44 (58 views)
      • Re: bring banks in sync - steve209 2008-07-10 14:03:42 (77 views)