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View Full Version : E32 750iL questions to electronic gurus (long)



shogun
03-05-2005, 10:35 PM
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?
-----------------
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.

winfred
03-05-2005, 10:55 PM
have you looked at any spark plugs yet? our cars don't have temp probes just 02 sensors, i would carefully pull plug wires while it's running looking for which holes aint firing (another way without possibly getting zapped is to pull injector wires), i am not up on all of the v12 tricks and tips so i can't be too specific on how to check it out without getting my hands dirty

shogun
03-05-2005, 11:16 PM
and there is nothing on the Bentley book about this temperature sensor.
look at number 28 http://www.realoem.com/bmw/showparts.do?model=GC81&mospid=47354&prod=19900500&btnr=18_0144&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 :)

winfred
03-05-2005, 11:22 PM
you don't need to pull all of the plugs, just a few from each bank just to get a idea of how it's doing, fuel filter/filters? plugged cat? nasty burned up cap/rotor?

shogun
03-05-2005, 11:27 PM
Thanks, will do so. No misfire at all.
That is why the assumption of blocked cats is an issue. Will do that checking as suggested next Saturday, as it is too cold here to do the job outside and we can only get into the garage of a friend next Saturday. Till then, any new idea welcome, gents.

winfred
03-06-2005, 12:04 AM
i've come across a few cars that the fuel pump has gotten real weak and is only mantaining 20 odd psi, if it's running smooth look for common shared systems, had a 95 740il with one plugged cat and a blown pcv plate that was a pisser to figure out, it wouldn't get out of it's own way the computer was trimming the mixture 50% lean on one bank and 50% rich on the other among other weird readings (damn i am getting to hate the later cars, they get pissed off and then over correct and snowball) the early cars are easyer to figure out when things get weird

shogun
03-06-2005, 07:58 PM
-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.

Whit
03-07-2005, 02:13 PM
Is he getting a good spark at each plug? The old fashioned way is to pull one boot with plug in it and hold it near a good ground (insulate the boot or wear a rubber glove or something), you can pull it first and crank the engine or just do one at a time while the car is running. You should get a nice blue spark. Do it for each plug. If you don't have spark on one side or you have a weak-looking spark on some plugs, it could be one bad (or failing) distributor. Not sure about my 750il, but I have fixed my old muscle cars with this test. Heck, there are two distributors on this car--maybe one is dying. It could also be gummed-up plugs or a bad plug wire set on one side put in by a previous owner.
The O2 sensor should be working, however. Can you set up (or splice or rig or beat with a hammer) the inputs from both O2 sensors, so that they will read from only one side or the the same exhaust cat? Just to test? Seems like you could trick the computer into working that way if it is just an O2 sensor issue. My in-laws own an engine shop and they say most of the "drivablity" problems that they encounter are from disconnected or bad O2 sensors. I would think that you should get that thing working first, just to eliminate it. A good muffler/exhaust shop could tap in a bung or at least a place for that sensor to sit and read properly. Maybe they could repair the connection to the old 02 sensor. Just throwing out ideas...

shogun
03-07-2005, 08:08 PM
Whit,
it is not the O2 sensor which is not connected, it is a temperature sensor at the end of the cats. The cat from USA does not have a connector for this. See top the link with the pic to item 28.
The japanese owners manual says, that if the cat is overheated, there will come a warning signal. Switch engine off and let cool down and then drive to the next available dealer with max 50 kmh. There is danger of fire.
I still do not know if this temp sensor is connected to the DME and the DME reads cat cold/warm/etc., or if it just gives a signal to the check control as a warning.
Not sure, if this is only on versions for Japan specification but not for other countries.
Will report later when Real has done further checks at night.

Whit
03-07-2005, 11:20 PM
Well, I guess my idea/question still stands:can both temp sensors be rigged to read only one cat? Or can one temp sensors send the signal to both sides? you know? Just to test?
By the way, what is the actual temp involved? Can you measure each with an infrared/laser temp checker or something else? Is it really hot? If you cannot find a way to check temp, when a cat is blocked and the exhaust manifolds are actually getting hot, check them at night (along with the head exhaust pipe) they might glow red-hot. I had a blocked cat on a Jeep once and it glowed red at night on the exhaust manifold. New cat & new muffler, no red glow. Not a BMW, just my experience with a different vehicle.
What about the distributors and the spark at each plug wire?

shogun
03-08-2005, 08:31 AM
Just could call him and he sent me emails:

Well I think I finally found the problem. One more 5:00 am morning checking things before work!!

After checking and swapping MAF's, DME's, DME relays, I made a breakthrough discovery, My car was in a sort of Limp Mode. I crawlled under the car to check the CATS and noticed that the one side was cold to touch. Thinking spark or fuel issues I checked the fuel pump relays, coil, induction test on the plugs, vacuum lines, fuses - all checked ok. After recieving an idea from Shogun and Harywithit I was heading to Johan's site for the fuel pressure regulator change. Part way through it details jumping the fuel pump relays to check for fuel quantities. Sure enough, the side that wasn't working wasn't receiving any gas!

All I can think of is in the morning I'll check the connector at the tank to ensure everything is good to that point, before coughing up $200 or so for a new fuel pump.

Having said all this and seeing the light at the end of the tunnel, does anyone have any other ideas in case this doesn't pan out?

Real
---------------------------------------------------
That is the status as of now.
If any ideas/proposals, just me me know.
I am checking now for a used pump in Japan. Or does anybody know what other maker than Bosch can be used. BMW p/n for the pump only is 16141179710.
Bosch p/n (not sure) is E300-150664
Regular price is $ 306,-, so it will cost here in Japan abt. double that price.
Checked various online vendors in USA like expressautoparts.com, autopartswarehouse.com, prices 237,22 and 215,47.
But there is a pump at bavauto.com with their p/n GFP316 which costs $ 199,95.
That seems to be not a Bosch pump. Does anybody know the maker of another brand for this pump and/or the specification/size etc. for the pump? Maybe they are also available in other japanese cars, so then we could get a pump much quicker and probably cheaper herre in Japan.
Thanks

Whit
03-08-2005, 01:55 PM
Sounds like he is on the right track. Hey, not a cherry-red cat or manifold, but an ice-cold one, eh? Interesting.
I would try this test (only if the car is NOT a daily driver): take the known working fuel pump and swap it with the one that is not working. Swap them both to the opposite sides and hook them up.

1. If there is no change and everything works the same way then both fuel pumps are good, but something else is preventing the pump from working on the "cold side." Repaired connections will fix.
2. If the hot and cold sides are reversed, the pump that started out on the "cold side" is probably bad. New pump will fix.
3. If everything stops working then you may have 2 things wrong: both bad pump and a bad connections from that "cold side." Need both repaired connections and new pump to fix.
4. If everything suddenly works, you got lucky and shocked the monkey or scared the ghost in the machine. Knock on wood, ask no questions and be happy for a while. I once had a starter solenoid that would not work in a classic Mustang, but worked great in an old Jeep. It still works. Why ask why?

The "swap" test could tell you whether or not you need to shell out $200-300 for a new fuel pump. You might not need it. The problem could just be the way the pump is connected, blocked or bent fuel lines, fuel filter, electrical signal, etc. I would try this test before I bought a new pump (I am cheap), but only if the car was not a daily driver. Wish him luck.

Whit
03-09-2005, 04:32 AM
I edited this when I realized there were some more possibilities.


Sounds like he is on the right track. Hey, not a cherry-red cat or manifold, but an ice-cold one, eh? Interesting.
I would try this test (only if the car is NOT a daily driver): take the known working fuel pump and swap it with the one that is not working. Swap them both to the opposite sides and hook them up.

1. If there is no change and everything works the same way then both fuel pumps are good, but something else is preventing the pump from working on the "cold side." Repaired connections will fix.
2. If the hot and cold sides are reversed, the pump that started out on the "cold side" is probably bad. New pump will fix.
3. If everything stops working then you may have 2 things wrong: both bad pump and a bad connections from that "cold side." Need both repaired connections and new pump to fix.
4. If everything suddenly works, you got lucky and shocked the monkey or scared the ghost in the machine. Knock on wood, ask no questions and be happy for a while. I once had a starter solenoid that would not work in a classic Mustang, but worked great in an old Jeep. It still works. Why ask why?

The "swap" test could tell you whether or not you need to shell out $200-300 for a new fuel pump. You might not need it. The problem could just be the way the pump is connected, blocked or bent fuel lines, fuel filter, electrical signal, etc. I would try this test before I bought a new pump (I am cheap), but only if the car was not a daily driver. Wish him luck.

shogun
03-09-2005, 12:23 PM
Just got the following ifo from someone on another board:

careful . . . .

. if your car is in limp mode (you previously indicated it was not), a shutdown of the cpu will shut off the fuel pump to the disabled side, as the control signal for the fuel pump relay is routed through the dme (safety reason--not good to flow raw gas through one side of the motor and into the exhaust).

In other words, you might be seeing a symptom and not the cure.
----------------------------
Hmmh,
could not talk to him today. Let's see what he found out. Will keep you updated.

Whit
03-09-2005, 04:17 PM
Wow, it looks like he needs to find out if he is really in limp mode. These cars are just too darn sophisticated--I need to do a lot more reading. :( I still think a bad fuel pump or a poorly connected one could show the same symptoms and that a fuel pump swap (from side to side) would be worth the trouble. It might even help diagnose a limp mode (if the car runs the same way after the swap) and would also let him know that both fuel pumps work. Keep me posted.

shogun
03-10-2005, 05:10 AM
We found a used fuel pump in Japan and it will probably arrive today or tommorow.
Time is important.
Just to be sure that we are on the right track with the pump: how to check the installed pumps with a multimeter best without running them dry when removed from the tank? Resistance?
There is something on Johan's page where Sean checked it, but he is also asking for a better way
http://bmwe32.masscom.net/sean750/fuelpump_replacement/Fuelpump.htm
Will keep you updated.

shogun
03-10-2005, 08:58 PM
Well I thought it was the fuel pump and it still maybe. I was pressed for time so I went ahead and installed it without checking if there was fuel between the pump and the fuel filters. I checked at the engine and I still do not have any fuel to the left bank (7-12 cyls?).

Jim and others mentioned "Limp Mode" is there a way that the engine can go into limp mode and not display an EML or other warning? As I stated in a previous post I have swapped MAF, DME, DME Relays, Fuel pump relays, inductve spark check on both sides. The problem remains on the left side.

The only other thing I can think about is that I will rout a piece of hose from the sending unit to a bucket to see if I have fuel there, if so, I'll check the fuel filters. I doubt that if it is a fuel filter issue that it would have clogged so abruptly (working in the morning and not in the afternoon). Any ideas on this. If there is fuel at the sending unit the only thing between there and the engine bay is the fuel filters right?

Shogun has asked about the EML. Prior to start up it lights for a couple seconds and then shuts off.

Does anyone know of any other reason why fuel is not making its way to the engine?

Still plugging away at this, hopefully it will be solved soon.
---------------------------------


I tested the fuel pmup in the engine bay as described in the previous post. At that time I checked the fuses again and noticed that since I installed the new pump my fuse #24 (fuel pump) was blown. I changed it out with a new one had then had my wife check the car after starting it. That same fuse is burnt out again. Is it possible knowing what I know now that the fuel filter may be pugged solid not allowing any gas to go through, in turn causing the pump to over work and blow the fuse?

Whit
03-11-2005, 01:24 PM
Is it blowing the fuse right away or did you say it works for a while? If it works for a while, can you test the wiring connections with a multimeter for continuity with a ground and with surrounding wires? A loose connection or a frayed/melted/hanging wire could be grounding and blowing the fuse.
Could be a blocked fuel filter, or kinked/crushed/blocked line, but you need to see if fuel is getting to the engine WITHOUT the fuse blowing. If you can keep the fuse from blowing, I would do the bucket test, you might get some flow. It it will be hard to tell what the proper flow is--if you test it at the rear it might actually flow back there. I would do it at the front of the car, so you can tell if fuel is actually getting up there--there could be a blockage along the way. If you get some flow, then check the good pump too. See if you can compare the flow rate visually and then the volume in the bucket of each. I don't know if you could really do that, but it might be worth a shot if you get both to flow for a while and not blow the fuse.
I don't know, but my gut tells me that the pumps are good and that this is a wiring short (the blown fuse) or just a clogged line or filter that could be overworking the pump (the blown fuse). On the other hand, your old "problem side" pump and the new/used one could both be bad and blowing the fuse. Hmmm...I would put the known working pump on the problem side--swap it with the new/used one just to eliminate possibility of bad parts. I once had two sets of new points and I tried to use each for a tuneup. BOTH were bad and it took me forever to figure out the problem. Bad parts are not impossible.
Shogun, sorry, I just am used to old Jeeps and classic muscle cars--they are much easier to diagnose and fix. My other cars in the US are under the manufacturer's warranty, so I let them do the wrenching. ;) I am slowly learning that the computer controls and electronics on these 7-series cars need to be respected and I have to keep learning. Wish I could be more help. Good luck to your buddy.

shogun
03-13-2005, 11:55 AM
Thanks, Whit.
Passed the message on and now this reply: (I distributed it to get some more feedback)
quote:

Help! Can't find short

I checked and it appears the Cats are on correctly.

Here is what I know at the moment I attached this to the original thread before seeing this reference post:

After extensive checking I am having trouble locating the short or electrical problem that I am having.

At the present I am still blowing fuse #23 (fuel pump) but only when I start the car. If I have the key in position 2 the fuse doesn't blow. I believe is the problem may be with an overvoltage protection relay, more on this later. Here is part of what I know let me know if this gives any clues:

1. Key in off and I attempt to jumper 30 and 87 at the fuel pump
relay nothing at either relay;
2. Check with a multimeter 30 and 87 and there is nothing;
3. Turn the key to position two and I get just above 12 volts on
both relays at 30 and 87;
4. With the key still in position 2, 30 and 87 jumpered, I checked
voltage at the connector and I get about 3.4 V at 4,5 and 4,6 on
the connector;

The only time the fuse blows is when I start the car. I am not exactly sure of the direction of electricity flow but it appears to be ign coil - fuel pump relay - fuel pump - fuse, with the main (DME?)relay, DME, and some overvoltage protection relay(any one know where and what this is?) connected also.

I have just about given up here and may have to breakdown and go to the dealer to check this out....HELP PLEASE!!!

Whit
03-14-2005, 02:06 PM
So, the pumps are each fused individually, right? The "bad side" keeps blowing. It still sounds like a defective pump to me. OK, I am going with my original advice: replace the fuel pump on the "bad side" with the one you know is good. You need to swap the good side and bad side pumps. That used one that you bought could be just as bad as the one it replaced.
After the swap, if it blows on the SAME side, the connections are the problem. If it blows on the opposite side, it is the pump. Swap them or you won't know for sure if it is the pump or the connections. You need to eliminate one possible cause before you can move on.



Thanks, Whit.
Passed the message on and now this reply: (I distributed it to get some more feedback)
quote:

Help! Can't find short

I checked and it appears the Cats are on correctly.

Here is what I know at the moment I attached this to the original thread before seeing this reference post:

After extensive checking I am having trouble locating the short or electrical problem that I am having.

At the present I am still blowing fuse #23 (fuel pump) but only when I start the car. If I have the key in position 2 the fuse doesn't blow. I believe is the problem may be with an overvoltage protection relay, more on this later. Here is part of what I know let me know if this gives any clues:

1. Key in off and I attempt to jumper 30 and 87 at the fuel pump
relay nothing at either relay;
2. Check with a multimeter 30 and 87 and there is nothing;
3. Turn the key to position two and I get just above 12 volts on
both relays at 30 and 87;
4. With the key still in position 2, 30 and 87 jumpered, I checked
voltage at the connector and I get about 3.4 V at 4,5 and 4,6 on
the connector;

The only time the fuse blows is when I start the car. I am not exactly sure of the direction of electricity flow but it appears to be ign coil - fuel pump relay - fuel pump - fuse, with the main (DME?)relay, DME, and some overvoltage protection relay(any one know where and what this is?) connected also.

I have just about given up here and may have to breakdown and go to the dealer to check this out....HELP PLEASE!!!

Whit
03-16-2005, 02:48 PM
Shogun, did your friend figure out if he had a bad fuel pump or bad connections or something else?

shogun
03-23-2005, 07:13 AM
:D Got the following email:

Erich & Mike,

The car is running!!!! It is amazing what happens when you get a working
part. Thanks for the help that you and Mike have provided.

This is what i posted on Roadfly this morning:

The problem has been solved it was a fuel pump. The new fuel pump that I
purchased was defective which caused the fuse to blow. This did not occur to
me as a possibility at first so I assumed it was a short somewhere else.

In the future I suggest the following in troubleshooting a rough running
engine with no power and hard shifting. Bear in mind this is what I found
would have helped me resolve this problem more quickly:

1. Check and see if the EML light turns on during start up - No EML suggests
Limp mode;
2. If you are not in Limp Mode check the exhaust pipes between the engine
and CATS - helps identify if both banks are running;
3. If one side is hot and the other is cold than I considered the problem to
be fuel or spark related. Check the fuel supply by following the procedure
to check if fuel is making it to the engine as detailed in Johan & Sean's
webpage at:
http://bmwe32.masscom.net/sean750/fuel_pressure_regulators/FuelPressureRegulators.htm

If no fuel at the engine check the fuel pumps as detailed at:
http://bmwe32.masscom.net/sean750/fuelpump_replacement/Fuelpump.htm
Note: When I tested my voltage I did not get reading that were similar to
what people suggested I should get;
5. A good way to check the pump is to apply 12V directly to them. Keep in
mind that these are immersed in the gas tank and that the petrol is what
cools them so when testing do not allow the pump to run for long periods of
time. Also, because it is a pump expect a shot of petrol to come out of the
pump, use caution in where this petrol will fly;
6. If there was fuel at the engine as described above, I would consider
spark as the next check;
7. I was able to check the spark by using an inductive timing gun and
attaching the connector to the individual plug wires at the distributor. I
loosened the tubing to the MAF to provide better access;

At this point I had no electrical problem so I will not proceed any further
along this vein. Bentley's does detail a series of tests for the coil and
other electrical components.

I understand that there maybe better or easier ways to accomplish what I
have detailed above,but if this can help one person I'll be happy. Thanks to
all who assisted on this adventure!

Real

Whit
03-23-2005, 02:00 PM
Great! He should have swapped that used pump with the known working one a long time ago! That blowing fuse was a good indicator of the bad pump, too. Oh well. Live and learn, eh? ;)

hgjacobsen
03-24-2005, 11:20 PM
Have you tried pulling the vacuum lines off of the fuel pressure regulaters? If the diaghram is busted gas will be present where there normally will be vacuum. If there is gas,(my opinion), you would not build up enough pressure to activate the injectors, you'll be running rich due to gas being sucked into the intake and therefore you'll be smelling gas out the exhaust.
Fuel pressure regulaters should run about $115.-140.00.

I'm running into a silmilar problem and recently replaced the fuel pressure regulater,fuel pump and a MAF sensor (not to mention new cats and O2's). I've been told by a lot of old school Bimmer mechanics that it may be an intake gasket leak. Sucking air, causing it to have a rough idle, run rich, etc.
The codes I was pulling were not consistent. I think if it has to do with fuel there will be hardley any codes ( my reasoning is that there are no sensors that tell the computer if there is enough fuel pressure either at the fuel pump or at the regulater). Also nothing to tell the computer if you have a physical problem such as a leaking gasket.
I'm open to suggestions, hopefully I've given you some help.
Henry

shogun
03-26-2005, 01:26 AM
Henry,
the car runs again. It was a defective fuel pump. The first replacement pump (used) was also defective. I have tested the car and it was still running on 6 cylinders, no big difference in idle compared to 12 cylinders running. Amazing.
Only when I drove the car one could feel the difference.
I have now made a test: removed the plug/connector at running engine from one MAF, idle just dropped for a second and then the car runs as if nothing happened. Only when you drive the car you feel that not 300 HP are there, but still can be driven.

shogun
11-21-2013, 11:10 PM
cat info for Japan spec. BMW owners

Japan was one of the few markets that required temp sensor on the back of the cats to warn you when the cats are overheating... this isn't a bmw only thing, i'm pretty sure its all cars in the japan market, I've seen a number of gray market toyotas and nissans with the same temp sensor on them. I suspect if you look at japans equivalent to the epa pollution rules for cars you'll see that theres a requirement for cat temp sensors as a safety device. A badly overheating cat will glow cherry red and ignite any paper or grass etc that its parked over.


As someone from Canada asked me this question again as he imported an E32 750iL from Japan and has the cat warning, here is a pic of the special relay for 870 degree Celsius which is located under rear seat driver side
ImageShackŪ - Online Photo and Video Hosting (http://imageshack.us/photo/my-images/252/thermoswitchjapancat.jpg/)
Just pull it out and the problem is solved. But you could try to repair it. If you want a used one, you probably won't find these in N.A., I should have some used on stock.
Another solution:
the cable white/purple/yellow goes from this module to another plug on pin 20 to the CCM. If you cut off this cable and connect it to ground, that has the same effect.

Then download these Japanese spec wiring diagrams
https://skydrive.live.com/?cid=c83d03b3ea789fc2&id=C83D03B3EA789FC2%21955&authkey=

shogun
12-30-2013, 10:17 AM
Update info:
p/n 1382095 made by DEGUSSA, Germany. New p/n 61311382095 Thermo switchgear, no longer available new, I found one new at a German shop:
61311382095 Thermo Schaltgeraet 196,10 EUR = US$ 270

Partnumber 61 31 1 382 095
Delivery discontinued by the factory
Production Oct '87 - Feb '94

shogun
07-16-2018, 05:04 PM
This 750 is still running, recently someone contacted me as he found this thread thru the VIN search, it is now in Canada