I drove my car around today so now I have put about five hours driving time in it since registering the car a week ago. The car has a quirky response once in a while at highway speeds. I can be running along at 60 or 70 mph just fine but when I want to accelerate engine/trans lose power, like its being strangled, and it hardly picks up any speed. Sometimes it just wants to slow down. But if I let off accelerator pedal for an instant I can resume accelerating at a much fast rate.
Engine seems to run very smoothly and it will accelerate hard up to the red line through each gear. Its just odd how it will hardly accelerate from a steady pace once in a while. Most of the time it will accelerate quickly like it should. I did change out the pedal bushings when I r&r'd the GM.
Thanks,
Any warning lights come on when that happens?
For example:
ENGINE APPEARS TO MISFIRE OR STUMBLE INTERMITINTLY
MODELS AFFECTED:5 Series(E34), 7 series(E32), 8 series(E31) all equipped with ACS.
FAULT:Under certain specific conditions an apparent engine misfire or bucking may occur. This is not an engine misfire.
CAUSE:Short (less than 100 milliseconds) fuel injection cut-off, as a result of MSR (engine drag torque control) regulation. This is a normal ASC function that may occur under these conditions: -The vehicle is equipped with ASC -Vehicle speed between 45 and 60 MPH -A rough road surface (e.g. potholes, railroad tracks) -Light throttle(accelerator pedal only depressed 1/8) -ASC not switched off.
http://www.bba-reman.com/us/content....w_abs_problems
Shogun tricks and tips for the E32 series are HERE!
In my experience, high resistance spark plugs seem to cause this behavior. What plugs are you running?
Shogun, thanks for info.I don't see any warning lights on the dash.
It does feel like a momentary fuel cutoff and as soon as I lift throttle I can start accelerating again. Engine runs very smooth and there's no bucking or misfire when it stalls. And, as I mentioned above, this only seems to happen when I'm running at a steady speed and try to accelerate but not every time.
Can the abs/asc be switched off?
Dr T, I am using new NGK BKR6EK plugs, wires, dist, rotors, cam and crank sensors, injectors, pumps, and filters.
Fault does sound like an ABS / ASC control module problem from what Shogun identified.
Last edited by JDP530; 02-25-2018 at 12:30 PM.
I did install new Bosch coils. I also disassembled the DK motors, polished armature, cleaned gears, and throttle bodies. I believe I followed the 'sync' instructions correctly, running engine up to 5000 rpm in first gear, deaccelerating, and repeating once more. Again, this only happens sporadically, but I haven't driven the car much since putting it on the road.
Thanks,
My car acquired this exact behaviour when I put in new spark plugs. My mechanic swore up and down he had original spec F8LCR's, but then put in FR8LC+ plugs.
All the symptoms are as you describe, and what I actually think is happening here is that one entire bank of 6 cyllenders is shutting down temporarily. (thus the drop in power). As far as I am told, you will need better spec plugs or new coild.
I did install new NGK BKR6EK plugs that many on here have recommended. And, I have installed new Bosch coils. We just got back from driving around outside of town and engine did not exhibit the 'loss of power' that I experience once in a while when cruising on interstate at a steady rate of speed. I will have to get on the expressway later and see what happens.
I tried to keep new batteries maintained while car was in storage. I will check voltage later. I dont have problems with starting the engine and as I mentioned above, I did not experience the loss of power this afternoon while driving at moderate speeds outside of town. Engine runs great otherwise, accelerates hard, does not stumble at all.
Thanks,
Last edited by JDP530; 02-25-2018 at 04:40 PM.
Maybe it was just a one time failure, keep driving and report back when the problem comes again. The NGK BKR6EK are o.k. And the Bosch coils are o.k.
Low voltage limpmode, quote: Low voltage will set EML only if it drops below 11V for more than 90sec. Low voltage will also cause problems with the IKHA (heater/ac), memory for seats/steering and transmission will go into limp mode. Mismatched tires WILL set EML light if vehicle has traction since it reads all 4 wheel speed sensors and gets an "implausable" reading. Just for clarification: I am a 20 year BMW Master with 3 PhD's from Germany in Engineering and I know these systems better than almost anyone. I did 12 years of R&D on these system for a manufactorer in Germany, so I am not some "Key Board" mechanic or read some crap on the internet. Ronald Trochelmann, Performing Imports
Shogun tricks and tips for the E32 series are HERE!
Shogun, I just got home and I am still experiencing the loss of power but only when I want to accelerate from a highway cruising speed. But, if I let off the gas pedal for an instant, I can continue accelerating and engine pulls hard. I ran it up to 90 and 100 mph a couple of times coming home. Just odd that it suffers a loss of power until i left off gas pedal. Car will cruise along fine at a steady rate like 70 or 80 until i want to accelerate to a higher speed. Engine pulls hard from a stop or rolling start shifting through all gears at red line without stumbling.
I put new tires on it two weeks ago, running 245/40r18 and 275/35r18 so diameters are very close within 0.15" difference in diameter.
I ran the car with the ASC switched off and it did not make any difference. Everything else seems to work fine. Scott did replace capacitors in GM for me. Car will cruise along around town without any issues also.
I appreciate your help because I am not well versed in auto computer technology. Thanks,
PS Would a scanner like the Foxwell help diagnose the problem? I wonder if a error code would show up indicating where the fault is?
Last edited by JDP530; 02-25-2018 at 10:43 PM.
Not sure if the Foxwell works on the E31, Schwaben by Foxwell reader tool for use on pre-OBDII cars does not work on E34/E32, comment from Greg:
"This is a great tool, unfortunately, it does not work on my 1993 (1/93 build date). Since I have two OBD-2 BMW vehicles I plan to keep it. As this vehicle is pre-OBD2, I used the 20-pin adapter. The tool recognizes the car and displays the seven digit VIN so it appears to communicate with the ECU. It scans (both auto and separate systems) but most of the scan categories do not show codes or no codes and it simply displays a question mark. It did not recognize some major systems like the instrument panel and ABS and displays a message that the component is not recognized. Lastly, it does not enter the re-set mode to allow oil service updates, and it does not allow the removal of airbag fault codes. Bottom line: still looking for another tool for my E34."
Just a shot in the dark: if the throttle valves run out of sync more than 2%, then the EML switches to limpmode, there are many other factors which can cause limpmode, see here http://www.europeantransmissions.com...MW/EML-BMW.pdf
The scope of EML design on BMW engines provides:
• Throttle valve positioning for optimum starting
• Precise idle speed regulation without the use of an external idle control valve/circuit
• Progressive throttle opening curves matched to the driving program (with EGS/AGS interface)
• Cruise control operation without additional control modules and linkages
• Automatic synchronization of the throttles (airflow balancing) for two independent banks,throughout the entire engine speed range (M70, S70, M73 engines only)
• Intake air volume control for ASC/DSC (Automatic Slip Control/Directional Stability Control) systems
• Maximum road speed limiting
• Emergency “Failsafe” operation in the event of component failures
The EML control module is a link in the total scope of Engine Management Control. The EML is interfaced with other control modules to complete the management system, which includes:
• ECM(s) - Except E46 (EML integrated in MS42.0 ECM)
• EGS/AGS
• ABS/ASC
The main components of the EML system are:
• Accelerator pedal position sensor (PWG)
• Accelerator pedal position sensor (driver’s wish sensor - integrated in throttle housing,E46 MS42.0)
• Throttle valve assembly/assemblies with electronic control motor(s) - DK/MDK
• EML control module (MS42.0 ECM - E46)
Shogun tricks and tips for the E32 series are HERE!
Thank you for the info! I will try the stomp test tomorrow and see if there are any codes. BTW, I do have a 2" hole in bottom of one air box that I will repair in the next day or two. Maybe the difference in air flow could cause the occasional fault.
My car had the exact same symptoms. If the sensor on cyl 6 & 12 ignition lead is faulty or doesn't detect a spark, the bank will shut down causing the loss of power. Check plugs and leads on cylinders 6 and 12 (the ones with the donut sensors attached) and, if they're okay, it will likely be a failing sensor. Mine came and went because the lead had a bad connection and was okay some of the time (or the spark was jumping).
Yes, this is what I was trying to get at with the plugs inquiry since I too have experienced the same symptoms.....Loss is power during steady-state highway cruising restored right after accelerator is released and then reapplied.
I too believe it’s the stupid donut inductors (cyl identification) that aren’t working correctly. However, I have oem spark plug wiring and still experience this on occasion. I have tried repositioning them with some success. Why do they fail? How do you test them?
I have read on the German forum about a case where the owner installed a new donut (cylinder identification sensor) and that bank did not work properly. Turned out that the installed the donut the wrong way on the wire. I explained the details here
http://www.bimmerboard.com/forums/posts/1265857/
In another case on the German forum the problem was a haircrack in the distributor and rotor. We had also here in Japan cases like that, pics here where we found it http://e32b12.blogspot.jp/search/label/Distributor
Testing data:
M30/M70 ignition system data accdg to Bentley
Coil primary, coil code # 2051118335 terminals 1 (-) and 15 (+) resistance 0.50 ohm
Coil primary, coil code # 20510171101 terminals 1 (-) and 15 (+) resistance 0.37 ohm
Coil secondary, coil code # 2051118335 terminals 15 (+) and 4 (ctr.) resistance 6.0 kohm
Coil secondary, coil code # 20510171101 terminals 15 (+) and 4 (ctr.) resistance 9.0 kohm
spark plug ends 5.0+/- 10% kohm
shielded plugs 1.0 +/- 20% kohm
spark plug wires 0 ohm (approx.)
rotor 1.1 +/- 10% kohm
M70 firing order: 1-7-5-11-3-9-6-12-2-8-4-10
crankshaft position/rpm sensor:
540+/- 10% ohm
from workshop manual
distributor rotor 1+/-20% kohm
angled/shielded connectors 1+/- 20% kohm
spark plug connectors 5+/- 20% kohm
cylinder identification sender coil resistance at 20 degree C (68F) <1 ohm
pulse sender/crankshaft position sensor coil resistance 540 +/- 10% ohm
But ocassional loss of power can also be caused by other sensors like ABS, ASC+T etc., these cases are also often, dirty sensors, non original wheels/tires...
Last edited by shogun; 02-26-2018 at 10:09 PM.
Shogun tricks and tips for the E32 series are HERE!
I figured out the 'stomp' test today and found a 1247 code (Ignition Secondary Monitor) but I am not sure the description is correct for the M70 engine. If so, where would this lead me to look for problem?
This intermittent issue appears to be an ongoing problem for some years with other owners on here. Here is a thread where a couple of people experienced same issue and it doesn't look like issue was solved: https://www.bimmerforums.com/forum/showthread.php?2304936-Power-loss-at-50-75mph&highlight=msd
But, Tedbobo did correct problem with OEM wires and sensors, yet Dr T couldn't with new wires.
I have not found info on Bosch coil output but I am wondering if a stronger coil, maybe the MSB Blaster at 40,000 v, might produce a stronger pulse signal so donuts work better?
Maybe the DK potentiometer has a worn or dirty spot, but someone else in another thread couldn't correct issue with new/rebuilt DKs.
The original Bosch ignition coil is fine, the majority of all M70 engines run with these. Bosch ignition coil testing I have posted above. Check original coils for cracks outside.
Check the distributors and rotors again. A bad cap/rotor can cause the sensor not to pick up the spark properly triggering this fault.
1247 , read this https://www.bimmerforums.com/forum/s...odes-1247-1234
and this https://www.bimmerforums.com/forum/s...ondary-Monitor
https://www.bimmerforums.com/forum/s...k-in-limp-mode
Shogun tricks and tips for the E32 series are HERE!
Thanks for the help! I will look over the parts tomorrow.
I just finished reading a thread that Scott started years ago in regard to the 1247 fault. Now I am wondering if the cracked and broken insulation on wiring loom at the block where the CI and CPS plugs fit could be causing the fault? The wiring was not in very good shape when I hung up the loom to reseal manifold gaskets. I did my best to insulate a few very small broken/bare spots using some Locktite liquid insulation.
I have installed so many new ignition and fuel components in the past few months before I ever started the engine and I would be surprised that new parts would be defective but I guess it only takes one! Other than this intermittent fault, engine runs like a scalded cat. It will pull extremely well to red line in all gears, well, except 4th, because I run out of room.
Last edited by JDP530; 02-27-2018 at 12:26 AM.
Starting to think it maybe the same problem causing my issue - https://www.bimmerforums.com/forum/s...-misfire-Help! - unfortunately have never been able to scan or stomp test for faults so very hard to pinpoint the cause. Definitely electrical as symptoms are identical to a faulty cap/rotor but I have replaced all with new. Don't you just love 8ers!!!
I am sorry to report that I have not taken the time to go through all of the electrical connections and compare to the test data that Shogun provided.
I bought a Foxwell scanner several months ago with the idea that it would help diagnose problems with the car and I can use it with my F-250. Looks like it does work with the 850 showing info on about 24 parameters, but I have never used a scanner before so I will need to learn how to use it and interpret info. And, this scanner does provide live data.
So I tried it yesterday and I found one code, 16- Ignition, and then another code showed up but then dropped off scanner, 26- NVA (ti). Not quite sure what they mean.
Then I took out car for a drive today and I do notice a very light 'bump' or hesitation when driving at highway speed and I let off throttle. Then for the first time a code popped up today on the MID, 'trans fail-safe program+', but code when away and hasn't resurfaced again.
Now I am wondering if the torque converter is acting up even though trans and engine perform extremely well most of the time. Its only this slight hesitation at speed that is a problem. Car runs through the gears at red line and shifts fine at low to medium speed around town and high speed driving.
Last edited by JDP530; 03-03-2018 at 07:01 PM.
Trans Fail-safe program puts the transmission into third? gear. Don't worry about it too much. My 95 has had trans fail-safe many times. Mostly due to a low voltage from the batteries but once I had a long term problem with the engine misfiring. Check engine light came on even though car did not seem to have a problem. Code was not found by BMW DIS. It happened again soon after and same result. The third time check engine came on it stayed on and then I started experiencing loss of power which was corrected with a restart of the engine. Later the problem became more problematic and the check engine light started staying on full time and then started flashing even though the engine had full power more often then not. When it had no power it was so slow. DIS showed miss-fire on all cylinders. The intake manifold gaskets and the PCV on the rear of the manifolds were replaced. There was a service bulletin about the PVC part on the M73. If you problem gets worse it might be easier to figure it out.
While this is not exactly the same as your problem. My transmission is as smooth as butter.
[QUOTE=JDP530;29961943]I drove my car around today so now I have put about five hours driving time in it since registering the car a week ago. The car has a quirky response once in a while at highway speeds. I can be running along at 60 or 70 mph just fine but when I want to accelerate engine/trans lose power, like its being strangled, and it hardly picks up any speed. Sometimes it just wants to slow down. But if I let off accelerator pedal for an instant I can resume accelerating at a much fast rate.
Hi,
Engine seems to run very smoothly and it will accelerate hard up to the red line through each gear. Its just odd how it will hardly accelerate from a steady pace once in a while. Most of the time it will accelerate quickly like it should. I did change out the pedal bushings when I r&r'd the GM.
I too had this problem. I noticed that you refurbed your DK's all the way down to the gears. There is a very good chance that your wiper arms are not reinstalled exactly equal. If they are clocked differently the DME's will get conflicting signals, and this may be what is causing your issues. In my case, after pulling the DK's off, and upon inspection under better lighting, and using a small metal ruler I could see about a 60 thousands difference compared to the peg. Once I got the wiper arms as equal as I could see with my old eyes I sprayed CRC electronic cleaner on the variable resistor plate, and the brushes etc. reassembled, and reinstalled. I took the car out, and did three runs up to 5k rpm, coasted down, and parked, let it idle for five minutes, and everything was fixed, yay! Bye the way, I have been running NGK BKR6EK plugs and the newer Bosch coils for over three years with no issues. My car runs like an ape,,love it. Good luck..
I too had trans fail safe program pop up on the display. I used a peake unit, and it showed cam sensor. I ended up replacing caps rotors, wires, and coils. Then got back into the dk's and discovered my mismatch in the wiper arms. I was also chasing a Clunk, and replaced all my drivetrain rubber bushings even those in the rear carrier to body, trailing arms, upper shock mounts, differential, as well as a new driveshaft. The 4 speed automatic does have a bit of a pronounced bump both entering, and exiting torque convertor lockup.
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