Home Technical Discussions BMW E32 7 Series 1988-1994 (735i/iL, 740i/iL, 750i/iL)

BMW E32 7 Series 1988-1994 (735i/iL, 740i/iL, 750i/iL) 1990 750il running only on six cylinders,1-6 "---ASC---"


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Last Post: Mar 27, 2011 3:23 AM Last Post By: incogkneetoe
justin750il

Posts: 20
Registered: 08/17/09
1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 17, 2009 2:29 PM
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I have a 1990 BMW 750 il that i purchased in march.It has 209,200 miles.It did not run when i got it.The battery was dead,spark plugs were fouled,power steering leaked,at the low pressure hose,charging system problems,cracked radiator,but other then that i can find no other problem.I have done a tune up on it.but it still wont run right.
The thing is,that when i start the car,it runs perfect for about 2 seconds,one time it ran perfect for about 30 seconds.Then a display pops up on the instrument cluster,on the bottom,not the little light,which reads ---ASC---.Now, in the owners manual it says that that comes on when the ASC is in control.from what i can tell,the ASC is telling the EML to retard the timing to compensate for some kind of load,or something of that nature,or wheel spin.From what i can tell there is no load ,or wheel spin.Ok<Ive checked everything,everything seems to work.ive gotten to the point that im at the ABS/ASC control module.Im trying to test every circuit going in or out of the control module,but the information on page ELE-142 of the bentley manual is incorrect for my vehicle. the date of production is 09-89.From what i can tell, this production is different then any other.In the book, it says that the right front wheel sensor is supposed to be pin 12&13. but in reality it is going to pins 12&32.Do you know of anywhere I could get the right wiring diagram for this particular model.The ABS/ASC control is,BOSCH 0 265 106 005,BMW 34.52-1 159 246.I can find nothing on this control unit.I dont think that there's anything wrong with the control unit,it looks like the previous owner had had it replaced,along with every other thing i have tested.Ive checked everything. When I say everything,i realy mean everything.I even did a compression test and it had as much compression as it when it was new,according to the bentley manual. The guy i got it from took it to the dealership and they obviously could not fix it.I've been working on cars for 26 years and this is literally the first car i haven't been able to fix.This has become the most important thing of my life.Ive been working on it just about every day since i got it in march.i just cant find out what is wrong with it.I failed to mention that it is getting fuel spark and air.The spark plugs on the non running side show virtually no ignition,While on the running side they show poor detonation "black soot",covered.Obviously timing related.Now for the first initial first 2 seconds it runs perfect,starts within the first 2 or 3 revolutions,then will barely run,as if something switches.I've tried to check every relay but the bentley manual is vague on relay functions.Could you tell me of anything that i might have missed that isn't in the bentley manual. PS.Under these circumstances the ASC will not turn off by the switch.Because some fault was initialy found.the switch and its function work.
I realy need your help on this one.
Thank you so very much,in your time in reading this and your premeditated patience.
Justin
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 17, 2009 2:38 PM   in response to: justin750il in response to: justin750il
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I would suggest you try and scan the car with a factory scan tool. Could be a number of things causing your problem, such as the EML throttle drive system throwing the ASC light. Common for the engine to run only 6 because complete redundant fuel system for the other six. This is a complicated engine, would be great to bring it to someone who knows that engine well.
justin750il

Posts: 20
Registered: 08/17/09
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 17, 2009 3:25 PM   in response to: Charlie in response to: Charlie
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Thank you for the reply,
there are no fault codes,that is still a mystery.
From what i have deduced i have learned more about this car then anyone around here knows,Including the dealership.every time i talk to anyone I end explaining the concept of the entire system of the car.That just isn't right.They tell me ,"Oh just bring it in."Now why on earth would i take this car to someone that i just had to educate about the functionality of the vehicle.Wheres the integrity of people these days.I've spent hundreds of hours on this thing.I couldn't imagine the price it would cost to have someone less intelligent then me try to figure it out.
Im not going to have someone poking around on something they know nothing about.Trust me, there is no one around that would want anything to do with this thing.Granted electrical work fetches a pretty penny,but after a hundred hours or so theyll give up,charge me and give it back to me in pieces.Thats probably why its got this problem in the first place.
Do you have any other suggestions,or know anyone who actually knows about this car Remember its an 09-89 production model.It has ASC,not ASC+T.That confuses everybody.The dealer said that the vin # says that this car is not supposed to have ASC.Well,guess again.It most certainly does.I wish it didn't.Such a shame.It's such a beautiful car.And it runs excellent,for 2 seconds.It doesnt smoke or anything like that, except for the unburnt fuel coming from the side that isn't working.Its in excellent condition for a 90.
Thanks for your time and effort in helping me with my problem.
Justin
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 17, 2009 3:38 PM   in response to: justin750il in response to: justin750il
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Sounds like your seriously vested in this thing. I would strongly suggest you buy a 24 hour subscription to www.bmwtechinfo.com and gather as much info as you can, including full wiring diagrams. If you send me your last 7 digits of your vin I'll see what I can find what equipment your car originally came with. ASC used the EML motors to control wheel slip on take off, this could be the route of your problems. The EML system is problematic and replacement parts are very expensive. How about try swapping EML motors from left bank to right to see if the problem follows. Also try swappping the DMEs as well.
justin750il

Posts: 20
Registered: 08/17/09
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 17, 2009 4:18 PM   in response to: Charlie in response to: Charlie
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Thanks,here's the vin #,WBAGC8314LDC76347, what would be the reasoning behind switching the "DK's"? they both appear to be working,I've tested them,they checked out ok,it just seems to be timing related.I just started it a couple minutes ago and it ran perfect for exactly 5 seconds,then it drops it instantly,like flipping a switch.There isnt a relay that i might have missed is there?Thats what it seems like.I forgot to mention that there is no instant throttle.It takes off when its good and ready,you can floor it and it takes its time getting to 3,000 rpm.But once there,it seems to drive somewhat normal,just on six.I haven't driven it on the freeway because im trying not to mess anything up.Transmission seems to work fine,it isnt in limp mode.It seems like the eml actually thinks its doing what its supposed be doing what its doing. do you have a subscription to carfax it has 22 hits but i really dont have the money to spend on it right now.I have a back door to BMW techinfo bot they have nothing on this specific production model.Its like BMW has removed any literature from existence,to try to fade out this mistake of a design. what they should offer the remaining owners some sort of compensation,instead of leaving people hung out to dry.
Once again,thanks a lot,
Justin.
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 17, 2009 4:37 PM   in response to: justin750il in response to: justin750il
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How about swapping the DMEs? Maybe try going through and checking inputs to the DMEs. Should have a pinout table in the wiring diagrams. Check signal from crank sensor. Coolant temp sensor? Have you checked fuel pressure? Bypass fuel pump relays to confirm pumps working. Try and look at all the things that could affect running and go through step by step and check all inputs. If not problems are found, likely the DME is bad.

Vehicle information

VIN long WBAGC8314LDC76347
Type code GC83
Type 750IL (USA)
Dev. series E32 (2)
Line 7
Body type LIM
Steering LL
Door count 4
Engine M70
Cubical capacity 5.00
Power 220
Transmision HECK
Gearbox AUT
Colour ALPINWEISS 2 (218)
Upholstery NATUR VOLLEDER (0237)
Prod. date 1989-09-13

Order options
No. Description
240 LEATHER STEERING WHEEL
288 LT/ALY WHEELS
439 Zierleisten Aluminium hochglaenzend
488 LUMBAR SUPPORT DRIVER/FRONT PASSENGER
494 SEAT HEATING F DRIVER/FRONT PASSENGER
640 CAR TELEPHONE PREPARATION
694 PREPARATION FOR CD CHANGER
925 SHIPPING PROTECTION PACKAGE

justin750il

Posts: 20
Registered: 08/17/09
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 17, 2009 5:50 PM   in response to: Charlie in response to: Charlie
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Thank you for the advise.Sorry,I don't mean to sound redundant but i believe i have checked everything.I switched the DME's, it has new fuel pumps,filters,fuel pressure,I've swapped everything from the right side to the left,excluding the DK's,i couldn't see the point.I'm Actually trying to find where the calculation comes from for the ASC and its involvement with load bearing attributes. it has to sense a load somewhere.and why would it accuont for it in park,not having a load at all.Or am I misunderstanding the concept of it retarding the timing.There not being any forward motion would dis-count wheel slippage as a factor.it just does not seem possible
and why would it not put itself into limp mode?
its as ai has accepted the fact that it will only be using six cylinders.It it scientifically impossible.
Thats why i was trying to get the correct info for wiring.The bentley doesn't have it for 09-89.The diagram is incorrect.
Thanks,
Justin
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 9:41 AM   in response to: justin750il in response to: justin750il
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Justin,

The wiring is on the factory website. Given your situation, you'll need *all* the wiring information, including component locations, grounds, and power distribution diagrams.

-Charlie
justin750il

Posts: 20
Registered: 08/17/09
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 10:47 AM   in response to: Charlie in response to: Charlie
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Good morning,Charlie,
What factory website are you referring to?and how do I go about getting this information?
Thank you,Justin
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 11:00 AM   in response to: justin750il in response to: justin750il
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www.bmwtechinfo.com. Attached is an example of the wiring.
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 11:02 AM   in response to: Charlie in response to: Charlie
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Trying attachment again (maybe too big).
justin750il

Posts: 20
Registered: 08/17/09
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 11:18 AM   in response to: Charlie in response to: Charlie
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Did you send me a link with an attachment? If so how do i open the for mention attachment?
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 12:05 PM   in response to: justin750il in response to: justin750il
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Attachment e32_90.a.pdf (2.3 MB)
Too big I think. I'll try here with an a smaller one.
justin750il

Posts: 20
Registered: 08/17/09
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 12:29 PM   in response to: Charlie in response to: Charlie
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I got it.I got a question,in testing the wheel speed sensors,it says that reading must be >999k-ohms at the sensor unplugged. I tested the sensor it is 1.023,would that be acceptable?Info here http://www.bmwtechinfo.com/repair/main/481en/index.htm
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 1:30 PM   in response to: justin750il in response to: justin750il
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Long time ago, the wiring was also on Cd-ROM, but not sure it runs on xp or anything newer. Another really cool product was the Diagnostic manaal in paper. Think it was a three volume set. Your car was included in this., think it was the E34 too. I'd try Barry Schiff, Schiff European literature in Providence RI to see if he has a copy. Could be just the thing you need. Lots of testing data, pinout charts, nominal values, etc.

Re the wheel speed sensors, resistance check is to see they are not open. Spin wheel and check for small A/C voltage. That is the real test. Resistance checks are just a little better than nothing, imo :)
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 1:33 PM   in response to: justin750il in response to: justin750il
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Attachment e32_90b.pdf (2.6 MB)
Another
justin750il

Posts: 20
Registered: 08/17/09
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 1:36 PM   in response to: Charlie in response to: Charlie
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Thanks I'll check the info,so basically it couldn't be the wheel sensors that are causing the problem,because the car is not in motion?

Message was edited by: justin750il

justin750il

Posts: 20
Registered: 08/17/09
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 4:12 PM   in response to: justin750il in response to: justin750il
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I mentioned that my power steering had a leak that I had fixed.Do you know if the system will bleed itself or if not bleeding it could cause my problem?It also has ATF in it I assume,it's red.I put the old fluid back in it until I can get the car running.I don't want to spend entirely to much money on it until I know if it's ever going to run right.
Thanks,Justin.
Charlie

Posts: 4,776
Registered: 12/09/03
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 4:27 PM   in response to: justin750il in response to: justin750il
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Will self bleed. Trun wheel lock to lock slowly a few times and recheck fluid level. Either ATF or Pentosin, but since its red, think you've got ATF. Reservoir cap should be marked with fluid type.
justin750il

Posts: 20
Registered: 08/17/09
Re: 1990 750il running only on six cylinders,1-6 "---ASC---"
Posted: Aug 18, 2009 4:57 PM   in response to: Charlie in response to: Charlie
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Yes, it does say pentosin,but I did get it from someone who never did a tune-up.
Thanks,Justin.

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