89 525i cutting out/off

[jiminEcricket]

maybe someone has had this problem. my 89 525i manual has started to shut off during driving. it always seems to happen right around 3000rpm after the car has reached operating temp. it does not do it all the time ,but it is always around 3000rpm, mostly in 3-4-5 gears. i do not think it is fuel as when it cuts out it is as if the ignition is disconnected. usually fuel has a gradual "dying" or loss of power before it actually stalls out. i have thought of many possible faults, but the part that puzzles me is that none of these faults would be occuring only at the 3k rpm mark. bad coil,wires,plugs,etc would be bad at any/all rpms. any help is appreciated. sorry if i left anything out

[genphreak]

You need to read the fault codes form the ECU, they will help. Do the instruments do anything strange? If they are alive, I think it means the ECU is still responding, so in that case the issue is more likley to be in the ignition components liket you already know. I think coil is easily diagnosed (a special code is triggered) when it starts misbehaving. Look also for corroiseon in connectors on the coil- it could be just that!

[shogun]

Advanced BMW ABS hints and tips
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.
SOLUTION: Replace the ASC control unit. no further diagnosis of the ABS/ASC system should be
necessary.
http://www.bba-reman.com/bmwabsfaults.htm

[Tiger]

Splash cold water on your CPS to see if that solves the problem. If so, CPS is bad.

[jiminEcricket]

there are no fault codes stored - did the stomp test.
- shogun this may be a silly question , but what exactly does ASC stand for? if it is for automatic speed control - my car is a grey market with no options whatsoever- cloth interior, manual sunroof,manual rear windows,no cruise or a/c
- if i put cold water on the cps, it will most likely be evaporated/gone by the time i drive the car long enough to get it to act up.
-all of these sound plausible and i will check all of them, thank you all for the help.

[jiminEcricket]

[QUOTE=genphreak;329250]You need to read the fault codes form the ECU, they will help. Do the instruments do anything strange? If they are alive, I think it means the ECU is still responding, so in that case the issue is more likley to be in the ignition components liket you already know. I think coil is easily diagnosed (a special code is triggered) when it starts misbehaving. Look also for corroiseon in connectors on the coil- it could be just that



I will check for corrosion in/on the coil thanks

[shogun]

ASC = automatic stability control
Automatic Stability Control (ASC).
On uneven or slippery road surfaces the Automatic Stability Control (ASC) system ensures you can accelerate out of each bend safely and with maximum traction.

Automatic Stability Control (ASC) is an element of the Dynamic Stability Control (DSC) system. It prevents loss of traction on the drive wheels when setting off, when accelerating out of curves and in other critical moments. When one wheel has good traction but the other is on a slippery patch of road, the wheel with less traction is braked until it is again able to gain a grip on the road surface.
If both wheels lose traction, the engine management system also intervenes and reduces the power output, which significantly reduces the danger of the rear of the vehicle skidding out. The entire process takes place in milliseconds.
Thus ASC quickly brings the vehicle back to stability and restores traction. Drivers wishing to attain a degree of wheel slip, for example when aiming to have a certain amount of "drift", can disengage ASC if desired.
http://www.bmw.com/com/en/insights/t...y_control.html

http://www.318ti.org/notebook/asc/index.html
http://www.usautoparts.net/bmw/technology/dsc.htm
The ASC + T system will reduce engine output until the vehicle can move or or until acceleration can occur without the wheels spinning. If this reduction is insufficient, each drive wheel is braked individually until both wheels have optimum traction.

[Tiger]

When your car dies, splash the cold water on the CPS and if car starts up and runs no problem until it get hot again, you know it is the CPS. On BMW it is very common for CPS to die... usually of old age.

Only use OE BMW CPS... aftermarket is junk. Also check if your CPS is mounted correctly and not loose... some folks find their CPS loose and grinding

ASC is traction control... if you have a switch by the gear selector under the ashtray... you got ASC.

[jiminEcricket]

[QUOTE=Tiger;329273]When your car dies, splash the cold water on the CPS and if car starts up and runs no problem until it get hot again, you know it is the CPS. On BMW it is very common for CPS to die... usually of old age.

Only use OE BMW CPS... aftermarket is junk. Also check if your CPS is mounted correctly and not loose... some folks find their CPS loose and grinding

ASC is traction control... if you have a switch by the gear selector under the ashtray... you got ASC.



the car idles o.k. - only seems to cut off while driving, though i have not tried to rev it in nuetral in the driveway. i will try that and check for play in the sensor. i also seem to not have ASC (no switch). thanks for the info