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Thread: Resurrecting 1991 850i 6 speed - help needed

  1. #26
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    Update.

    Got a generic scanner - Foxwell NT510 and I was able to scan DME and get some live data readings as well.

    When I started the car, I got the following code on both banks: 201 Oxygen-Sensor control



    Oxygen-sensor voltage.





    Few random live data readings.









    I didn't rev the engine so it didn't misfire. I put Liqui Moly engine cleaner and it just idled for 10 minutes and then I replaced the oil and filter. Oil that came out actually looked clean and good color.

    201 code is pretty vague but I did search for it and found few threads that I need to go through. Seems the most common cause is an air leak. There's mentioning of intake manifold leak, MAFs, O2 sensors...

    Pretty sure O2 sensors are orginal. Should I simply replace them due to mileage and age as a starting point?



    I should also mention the engine is full of condensation. I recently replaced VCV valves but it's still early to drive the car and get everything moving.

    Comments appreciated!


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    Last edited by sreten; 11-26-2018 at 06:14 PM.

  2. #27
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    when you replace the O2 sensors, be sure to MARK the connectors on the car L/R before you unplug them... very common that these get installed crossed and causes all sorts of strange issues
    '91 Dinan 860 Stage III (new 6L engine)
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  3. #28
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    Good tip, I was planning to change them one by one and avoid the possibility of crossed install.

  4. #29
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    i had the same problem making new exhausts... according manual one bank had a white tag on the plug.... which wasn't there anymore. So i had to find which plug was DME 1/2 with a test wire…. not a big job if you doubt.

  5. #30
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    Considering they didn't bother with changing the air filters for 24 years, I don't think anyone messed around with O2 sensors so I'll connect them in the same way.

    Ordered 2 original Bosch O2 sensors for 98 euros shipped. In the meantime, I'll poke around and see if I can find any air leaks, check all of the fuses and reseat relays.

    I still need to make sure my PS pump is dead before I order a new one. Power steering is simply not there when I turn on the car, the steering wheel is the same as if the car is turned off.
    Last edited by sreten; 11-27-2018 at 10:31 AM.

  6. #31
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    (I must say that Foxwell is a lifesaver..it pointed at my O2 sensors as well...)

  7. #32
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    Quick update before I hit the bed.

    I started the car and surely it started misfiring again once warmed up and when I rev the engine.
    When I shut it off and the car is still warm, it will not start again, the engine runs for like a second and immediately cuts off.

    Besides code 201, I got this code as well - 73 - Road-speed signal.



    I also think I found one of the reasons for 201 code and likely an air leak.

    Some genius decided to leave only one fuel tank breather valve installed in the car, chop off the factory connectors, splice some wires and make vacuum lines out of electrical tape.

    Don't know if I should laugh or cry.













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    Last edited by sreten; 11-27-2018 at 07:13 PM.

  8. #33
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    Quote Originally Posted by Chillax View Post
    (I must say that Foxwell is a lifesaver..it pointed at my O2 sensors as well...)
    I was actually pleasantly surprised it was able to connect to DME and read out the codes.


    Would this mess with fuel tank breather valves contribute to the car going into limp home mode and misfiring when warmed up? Also not wanting to start when warm?
    I think there's probably more to it then just breather valves but if anyone can shed some light it would be great.

    Basically what they did is this: left only 1 vent valve installed and removed the 2nd valve, cut factory electrical connectors, spliced some wires and created 1 electrical connector.
    So now vacuum lines from each throttle body go into Y connector and then into the breather valve and then into the charcoal canister. They used electrical tape on vacuum lines so I'm pretty sure there are some air leaks there.

    I'd try to re-do all this mess back to stock. New vent valves are rather expensive and Bosch catalog says they were discontinued in 2012 so getting them from the dealer is the only option.

    I also found 2 more wires that look cut and I have no idea what they are for.






    I still cannot understand why would anyone do something like this.

  9. #34
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    haha, they made a "good" ? 2 in 1 system with the valves..... now follow that cut wire and see were it go's ?

  10. #35
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    You never know why people do the things they do. Could have been a frustrated and disreputable mechanic, seller, or a inexperienced diy'er. Take your time and make it right. Before you know it, you will have a car to be proud of that you can maintain and repair.
    Desecrator of all things Sacred

  11. #36
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    Quote Originally Posted by Belgiumbarry View Post
    haha, they made a "good" ? 2 in 1 system with the valves..... now follow that cut wire and see were it go's ?
    I checked the purge valve yesterday and it's getting 12V and resistance is 43 Ohm. I'd need to cut open the wiring loom and trace that wire...

    Quote Originally Posted by 72tpik5 View Post
    You never know why people do the things they do. Could have been a frustrated and disreputable mechanic, seller, or a inexperienced diy'er. Take your time and make it right. Before you know it, you will have a car to be proud of that you can maintain and repair.
    Thanks! With a project like this, it's bound to come with surprises. Cars like this are rare in Europe or anywhere else for that matter, and not every mechanic will know how to work on it.


    I poked around the car last night as well.

    Worlds filthiest cabin filters from the '90s.






    Clean on the inside though.



    Found a fuel leak on the back of the engine and sorted it out.






    Checked the fuses and reseated all relays as well as the connectors. Judging by the condition and the way screws snapped when loosened, pretty sure this box hasn't been open since it left the factory.



    At this point, I exchanged around 3L of PS fluid and it's starting to come out greenish looking. Going to continue with the drain/refill process and even the PS pump sprung back to life, it's very noisy but power steering is there.

    The coolant has been flushed, and I drained and refilled 3 times so far and the water is now looking pretty clean.

    This time, I started the car with O2 sensors disconnected - didn't make much difference. As soon as the car starts to warm up and I try to give it gas, it will hesitate, misfire and just run very poorly.
    Once I turn it off and try to start it again, it will start for 1-2 seconds and then stall, it won't stay running.

    I connected the scanner and with O2 sensors disconnected - DMEs had no codes at all!

    However, EKM is full of codes.











    And codes from ZKE.



    Can anyone share some thoughts on these codes?

    I'm planning to test the fuel pressure over the weekend and try new O2 sensors. The battle continues...
    Last edited by sreten; 12-02-2018 at 05:21 PM.

  12. #37
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    A couple of things comes to mind:

    The probable reason that the car (when warm) starts and then dies withing 2 seconds is probably a lack of Cylinder Identification signal from the CIS sensors on plug leads 6 and 12 - in the absence of a signal the engine will run for 2 seconds and then the injectors will be inhibited to prevent wash-down of the cylinders. The sensors are usually OK - they pick up a signal by induction from the HT pulse going to the plugs - and that means if you have the wrong sparkplugs (wrong resistance) or if any part of the HT system is failing then the signal will be disturbed.

    You will get no error codes from the DME's and EML if the battery has been disconnected - the codes are volatile and are only stored in RAM
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  13. #38
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    Thanks, Timm, good tip. I will be looking into that.

    Spark plugs are correct - NGK BKR6EK. Ignition wires and coils I haven't touched yet. I have new HT leads sitting at home, but I still need to order CIS sensors and I'll probably order a new set of coils as well and refresh the complete ignition system that way.

    I do disconnect the batteries every time, I'm afraid to leave them connected in case of a drain and I have no electricity in my garage so I would have to take them home to recharge them which is a pain. I scan for codes when the car is running and starts to misfire.
    Last edited by sreten; 11-29-2018 at 07:16 AM.

  14. #39
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    seeing some of your water hoses , i'm i right , you have also a Webasto aux heater ? ( which i want to remove next week... )

  15. #40
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    I honestly have no idea. How do I check?

    In other news, finally got INPA to work with E31!



    I didn't even start it and intake and coolant sensors are showing faulty readings.



    I'll check again when I actually start the car and if this changes, but possibly faulty senors/wiring?

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  16. #41
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    I don't think diagnostics will help much with your present problem. But old-fashioned tests will:

    Find out what is stopping the engine running when warm by removing one of the plugs leads (1 or 7) and fit a spare plug to the lead and rest the plug on an exposed part of the engine - get someone to crank the car and watch the spark at the plug - does it stop while the engine is still spinning? If the spark is lost while the engine is turning you can be sure you have y=lost the Cylinder Identification signal.
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  17. #42
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    Quote Originally Posted by Timm View Post
    I don't think diagnostics will help much with your present problem. But old-fashioned tests will:

    Find out what is stopping the engine running when warm by removing one of the plugs leads (1 or 7) and fit a spare plug to the lead and rest the plug on an exposed part of the engine - get someone to crank the car and watch the spark at the plug - does it stop while the engine is still spinning? If the spark is lost while the engine is turning you can be sure you have y=lost the Cylinder Identification signal.
    One of my cylinder identification sensors died on me recently. I used old school techniques to diagnose as you suggest. With the dead sensor my car ran, but on six. It threw an undocumented stomp code that escapes me at the moment but I can find it and post if useful. Makes sense to be one of these sensors as they are the kind that may give different signals at different heats when broken.

  18. #43
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    Quote Originally Posted by Timm View Post
    I don't think diagnostics will help much with your present problem. But old-fashioned tests will:

    Find out what is stopping the engine running when warm by removing one of the plugs leads (1 or 7) and fit a spare plug to the lead and rest the plug on an exposed part of the engine - get someone to crank the car and watch the spark at the plug - does it stop while the engine is still spinning? If the spark is lost while the engine is turning you can be sure you have y=lost the Cylinder Identification signal.
    Thanks, Timm! I did look into that. I got a cheap spark plug tester off Amazon, however, I ended up replacing ignition wires with new donut sensors just preventively for a piece of mind.

    That wasn't the issue though but I did get to the bottom of it which I'll write below.

    Quote Originally Posted by NickF View Post
    One of my cylinder identification sensors died on me recently. I used old school techniques to diagnose as you suggest. With the dead sensor my car ran, but on six. It threw an undocumented stomp code that escapes me at the moment but I can find it and post if useful. Makes sense to be one of these sensors as they are the kind that may give different signals at different heats when broken.
    That was a nice and good fix for you. Good werk on pinpointing the problem.


    Here's a big update. I was sick, parts got lost in the mail so the progress took a while.

    I reverted back to stock the whole mess with the purge valves and wiring. This is what the idiots did.






    Gotta love vacuum lines out of electrical tape.

    The wires that were cut and sticking out of the loom turned out to be just leftovers of the original wires for the purge valves, they were just too lazy to remove them.







    Traced back the original wires for the connectors and re-did them with new wires and new connectors. These are just normal Bosch EV1 connectors.






    Bought one purge valve new and tested the old one, the resistance was good (around 44 kOhm) and it held the pressure when I tested it with a hand vacuum pump.
    The original Y piece is NLA so I got one made of brass, worked perfectly. New vacuum lines from the carbon canister to the throttle bodies, tested that connectors are getting 12V and finally put everything back together.





    Next were the ignition wires. Here is a quick write up for installing cylinder identification sensor on new wires that I created. Big thanks to Shogun! - https://www.bimmerforums.com/forum/s...1#post30128141

    Actually rather simple once you get the hang of it. New wires ready to be installed.



    Out with the old wires. I found that the wire on cyl #4 was actually dead, no connection and no resistance when tested with multimeter. The rest showed good resistance.



    New wires neatly labeled and put back in the original bracket which was without any damage and in good condition.





    Earlier I measured the resistance on the crank position sensors - 488 kOhm which is kinda on the limit so I got a pair of new sensors and replaced them. I had to unbolt the PS pump to get enough room to remove/install the sensor. I beat up my hands pretty good when doing this job.



    New replacement plug caps for the vent holes on the throttle bodies. The old ones were cracked and perished.







    After all of this, the car was still running like a turd - no change.

    Then I turned to test the fuel pressure which I had plans to do a while back just didn't get around it. I bought a cheap fuel pressure gauge which was a total crap and leaked all over when I attached it on the lines at the back of the engine, but even with it leaking there was hardly any pressure, less than 1 bar when the car was running for a brief moment.

    That was no bueno and I decided to pull the fuel pump assembly out. Luckily I bought new pumps some time ago because I was planning to replace them preveniently.

    With the pumps out, I found that both rubber lines inside had sizeable cracks in them.







    Combine that with old pumps and they simply didn't supply proper fuel pressure. No wonder the car was running like crap.

    The strainer was crispy and falling apart.



    The bracket that's holding fuel pumps removed.



    Original pumps.



    New Polish pumps worked a treat. Very happy with the quality and the design was identical to Bosch pumps.





    Everything reassembled and ready to go back in the fuel tank.







    I read somewhere that the new gasket for the fuel tank is a must so I got one.



    I think the most annoying part was replacing these 2 short fuel lines going from the pump to the metal pipe connection in the underbody, but I had to replace them since they were rock hard and they would surely leak. Also, lining up the fuel pump assembly with the new gasket was a pain. I counted 2 and 1/4 turns when removing the plastic lock ring so I went with the same when putting it back.





    Fired up the old girl and lo and behold a different car! It started after just a couple of seconds while before it used to crank and crank.

    Inspired by this, I took her for the maiden voyage out of the garage the next day.













    She is working beautifully! Engine sounds sweet and idles great, cold start is also good. There was a lot of condensation and I let the car work for 30-40 minutes and eventually it all cleared up and exhaust was smoke-free.

    I drove it up and down the courtyard and clutch is great, I got it up to 3rd speed and it slots in all gears perfectly and without any slop. Even the power steering pump is working noise free!

    Here's a little video. Injectors are clicking loudly since the sound insulation is removed. So far so good and I'm very happy that this 8er sprung back to life.


  19. #44
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    Great stuff - I love a story with a happy ending!
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  20. #45
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    Congratulations! Looks like you are doing a great job reviving your car.

  21. #46
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    Kudos for persistence and a job well done!
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  22. #47
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    haha , second proof of the Webasto aux heater ….. had already seen the extra water hose and metal pipe on top engine in the back , now i see also the fuel pickup at the pumps unit ( the small hose ) that go's to a small fuel pump under the car in front of the RR wheel.

    Meanwhile i removed all that stuff.... if it was not running the last year(s)… i'm afraid repair would be expensive and many items NLA …. and we don't need it , even in winter over here . Sure not when in a garage.


    Alot of hoses, clamps, heater , extra water pump etc.... that only can give water leak problems….. for a useless option in our climate.
    PS i could remove the heater ( passenger side ) as i have the inlet manifolds demounted for the moment.... not sure if it's possible with the manifolds in place .. ??


    SAM_2592.jpg

  23. #48
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    It seems that the upper tank vent valve was installed in the wrong direction: they should both point in the same direction, with the connectors at the vapour reservoir side (away from the engine).

  24. #49
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    Quote Originally Posted by Timm View Post
    Great stuff - I love a story with a happy ending!


    Quote Originally Posted by JDP530 View Post
    Congratulations! Looks like you are doing a great job reviving your car.


    Quote Originally Posted by TedBobo View Post
    Kudos for persistence and a job well done!
    Thank you for the support, fellas! I'm glad I persevered and this 8er is running again.

    Quote Originally Posted by Belgiumbarry View Post
    haha , second proof of the Webasto aux heater ….. had already seen the extra water hose and metal pipe on top engine in the back , now i see also the fuel pickup at the pumps unit ( the small hose ) that go's to a small fuel pump under the car in front of the RR wheel.

    Meanwhile i removed all that stuff.... if it was not running the last year(s)… i'm afraid repair would be expensive and many items NLA …. and we don't need it , even in winter over here . Sure not when in a garage.


    Alot of hoses, clamps, heater , extra water pump etc.... that only can give water leak problems….. for a useless option in our climate.
    PS i could remove the heater ( passenger side ) as i have the inlet manifolds demounted for the moment.... not sure if it's possible with the manifolds in place .. ??


    SAM_2592.jpg
    I had no idea it had Webasto. You're right, it probably won't ever be used but I have bigger things to take care of at the moment.

    Quote Originally Posted by Albert850i View Post
    It seems that the upper tank vent valve was installed in the wrong direction: they should both point in the same direction, with the connectors at the vapour reservoir side (away from the engine).
    Nope, both are installed correctly - arrow pointing away from the carbon canister going to the throttle bodies.

    One valve is the old orignal valve and the other is a new valve that you recommended. I think you noticed that the new valve has the air flow arrow pointing toward its power connector, this is opposite on the old valve so that might throw you off.

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  25. #50
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    if i were you , i would at least disconnect electric that little fuelpump .... you never know for what reason that pump could be activated….. fuel hose enters heater just near the exhaust !

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