E32 750iL questions to electronic gurus (long)
Have tried to help a friend here in Japan yesterday.
The VIN is DC55265, it is a Japanese model E-G50. Built 05/1990.
Here what he posted on roadfly:
This afternoon for the first time, I started my car and the engine had this vibration and it sounded low pitched. I thought maybe I was in limp mode so I popped the hood to check. Both sides were running. So I shut the car off.
Now a little history:
Just prior to starting I checked the fluids and added about a liter of water to the resovoir tank. (Note: I had recieved a check coolant level in the past couple months and have been topping up) I can not see any coolant leaks and I am afraid it could be a head gasket? The oil level hasn't changed nor is there any usual signs of coolant and oil mixing (ie white sludge under oil cap, frothy oil on dipstick)I couldn't smell any coolant burning nor was there any on the ground. I started it up again and noticed a little bit of white exhaust (I live in Tokyo and the temp is above 0 celcius but still a little cool) After warm up the white exhaust disappeared. I think this is normal. The engine still has the vibration, and after driving around the block and letting the engine warm up the temp gauge reads normal (12 o'clock), with no overheating problems prior.
In the past month I changed the catalytic converter on the left side, from the exhaust manifold to the muffler with a non OEM part (BMW after market part bought from ArizonaAZ)The catalyizer did not have a spot on the pipe to insert the exhaust temp sensor. I doubt however, this could be the problem as there have been no instances of this vibration until today. The funny thing is that I drove the car this morning and aside from it being cold from the night before it ran normally.
Does anyone have any ideas on what I should be looking for? I know I have to find the coolant leak, but is that the probable source of the problem?
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I have driven the car and could compare it with my 750iL. There is almost no power, hardly can climb up a small hill, engine revs up very slow.
Checked with the PEAKE: left side bank (drivers side LHD) says OA = emission (lambda) control.
It looks to me the engine runs in limp mode, but I have never had my car in limp mode, so I am not sure.
The temp. sensor on the new cat from USA has not been connected and hangs loose, see pic. The next pic is the other old oroiginal cat on the right (pass side) with the temp sensor connected.
We have a query for all the experts
is the exhaust temp sensor within the engine control loop?
nothing shown in Bentley Repair Manual
Car occasionally runs well but most often it sounds like its dieseling, vibration does not disappear with higher revs, is worse when cold, better when warm
intake manifolds look to be tight
the exhaust smells very rich and fuel consumption is poor
very little power.
Also posted question on the German board. One comment was, that maybe the cat(s) are partly blocked and we should remove the exhausts from beg. of the cats and then rev the engine to see if any change.
That we will do asap.
But apparently no one knows about the function of this temp sensor and what effect it has when it is not connected.
Any advise and comment is welcome. Thanks for reading the long posting.
PS: The leak in the cooling system we found apparently. It has nothing to do with the power problem of the engine, just a leak at a place difficult to find.
it has, Winfred, I was also surprised to see it
and there is nothing on the Bentley book about this temperature sensor.
look at number 28 http://www.realoem.com/bmw/showparts...44&hg=18&fg=05
Did not pull yet the spark plugs, as it is a pain in the a** on the V12, especially the number 12 plug. Started to get dark in the evening. Will do that next Saturday. Removing all 12 spark plus on a V12 takes more than 2 hours (and ones wishes to have the arms 3 times broken or rubber arms to get to all these places in that packed engine room).
As you know, I know the V12 M70 very well, and also Mike (Hairywithit) from roadfly was here. He is also not that unexperienced on the V12, as we usually wrench on that car together. But we could not yet solve it.
Will continue next week. Just need some opinions and ideas what to check next.
We are now somehow fixed to that temp sensor, because we do not know what effect it has on the Motronics. As you know, there are DME 1 and DME2, and all is somehow supervised by the EML.
Both throttle valves are synchron in running, so that was checked by us already, as this is often the case that the car goes into limp mode.
EML light comes on at the beginning and goes off after 2 seconds as it should do. Battery voltage and alternator also o.k., enough charging voltage.
One DME has now the signal from the one side temp sensor, the other side does not have this info. But does that have so much effect, that the car runs like in limp mode like a 50 HP car? So the one DME now always gets the signal "cat cold" we assume. So the DME will change the fuel air ratio so that the cats reach the required temp of at least 300 degree Celsius.
Well, lets see, maybe someone has the correct wiring diagrams and knows to which pin this temp sensor sends the signals and what it does with it. The online wiring diagrams do not have it. I already checked that.
Thanks, Winfred :)
Here is what Real wrote after further tests
-quote-
ECT readings
I was able to (finally!) get to the ECT a little tight in there. I tested it and I had the 5 VDC and 4.9 VDC (from both sides of the connector) and on the sensor itself I got a proper reading (I don't have my Bentley's in front of me right now). I then checked the sensor itself, the coolant temp, was tested with thermometer in resovoir and was 106.6 F and the reading I got, I can not remember at the moment, was right in the middle of the two readings in the Bentley chart, 11 ohms maybe?
I have recieved corrensondence about a possible CAT blockage as being the problem. As I just replaced the left side and the right is the original, should I try the orginal one (on right side) even though a PEAKE check gave a 0A fault for the left side?(probably because the exhaust temp sensor is not attached) In my opinion the new one should be good, so I'll try the old first. Should I notice the difference in the idle if I just disconnect the CAT from the manifold to the resonator (ie before CAT)? If I do this the O2 sensor will probably not work seeing as the exhaust is not travelling trough the pipe. Will that still cause a problem and an inaccurate idle? If there is an increase in RPM I will completely remove the CAT and clean it out.
Furthermore, I checked the engine cold and when I first started it (running for about 10 seconds) I tried to rev it up and it hestiated climbed to about 2500 RPM then almost stalled.
Looking into an electrical issue further I tested the coils with the key in the stop position. As per Bentley's I tested the ohms across terminals 1 and 15 and I got a good reading on both (I'll send the numbers later,(I am at work now), however, when I tested the 15 and 4 terminals and when I put the multimeter leads to the top of the coil point #4 I didn't get any readings, when I placed it deeper inside on the bottom of the pin I recieved a reading of 10.4 and 10.35 Kohms. This didn't seem right to me, any ideas?
My apologises for the unclear numbers in the readings, however at the time I checked them my Bentley was there and the readings were within range except the coil reading as mentioned above.
-unquote-
Any comments on this which I can pass on?
Thanks to all for reading.