HELP?! PLEASE!! (E30 in DANGER!!)

[mbdt7]

My newly acquired 88' 325is that I use for a DD is having 2 major problems.

First of all when I am driving, the car randomly turns off (by turn off i mean: i feel a stop in power and when i press the gas to give it some juice nothing happens and my engine doesn't even rev) however i don't think the car is completely off because my lights are on and I am still able to move the steering wheel freely and use the brakes.

Second when I push my AC button on, to turn my Air Condition on my engine starts to rev up on its own (while im just idle-ing around 800/900 rpm it jumps to 2000 rpm and when I turn off the AC it drops back down).

Im tired of thinking my car is gonna stop randomly on the freeway and tired of being in the SoCal heat without Air Conditioning . So if anyone can help, i would appreciate it.

[Isostar13]

AC could be the kickdown switch in the glove box. Mine wasn't plugged in completely and it caused some idle issues when the AC was engaged.

[hfabricius]

Second when I push my AC button on, to turn my Air Condition on my engine starts to rev up on its own (while im just idle-ing around 800/900 rpm it jumps to 2000 rpm and when I turn off the AC it drops back down).

Im tired of thinking my car is gonna stop randomly on the freeway and tired of being in the SoCal heat without Air Conditioning . So if anyone can help, i would appreciate it.

The second "problem" isnt actually a problem. When you press your a/c button, the compressor is turned on and engages the compressor clutch. To compensate for the extra load that the compressor takes, the engine revs up to keep from stalling out. Every car does it, some cars are more noticeable than others.

[TurboJake]

The AC kicking it up to 2k is definitely a problem. Just not one that's putting the car in any danger.

[quikveedb2]

First of all when I am driving, the car randomly turns off (by turn off i mean: i feel a stop in power and when i press the gas to give it some juice nothing happens and my engine doesn't even rev) however i don't think the car is completely off because my lights are on and I am still able to move the steering wheel freely and use the brakes.

Main relay is my bet.

[mbdt7]

Well if you're moving the car you wouldn't feel a difference at all in the steering. Does the RPM drop to 0 when this happens?

Ya thats exactly what happens. It just suddenly drops to 0.

[Pl3wA]

there is fuel in the device?

[scottinAZ]

check all grounds and the main relay. Mine did the same damn thing just after my motor swap. Turns out I put a shitty main relay in. swapped out the craptastic relay, and all is well

[Xat1cZ]

The first problem also points somewhat to a bad alternator... either the alternator being bad or it might not be grounded properly....

[iSOregon]

crank sensor? sounds exactly like what happened to me

[bmw325_num99]

First of all when I am driving, the car randomly turns off (by turn off i mean: i feel a stop in power and when i press the gas to give it some juice nothing happens and my engine doesn't even rev) however i don't think the car is completely off because my lights are on and I am still able to move the steering wheel freely and use the brakes.

I'd like to know for sure whether your engine is turning off completely or just sputtering and hesitating. Next time it happens put the car in neutral and see if the tach drops to 0. If "lights" mean the alternator/battery/oilpressure etc lights come on and stay on, the engine is stopped. If you mean headlights then it doesnt matter - move on to the next symptom.

Like another has said, my 1990 325i would stop periodically for a while. I replaced the main/fuelinjector relay with a used one from a junk yard and it has worked fine ever since. I would get one or two just in case as a spare anyway for long trips.

[quikveedb2]

I replaced the main/fuelinjector relay with a used one from a junk yard and it has worked fine ever since. I would get one or two just in case as a spare anyway for long trips.

Or you could just buy a new one and not worry about it for another 25 years. Just sayin.

[mbdt7]

I'd like to know for sure whether your engine is turning off completely or just sputtering and hesitating. Next time it happens put the car in neutral and see if the tach drops to 0. If "lights" mean the alternator/battery/oilpressure etc lights come on and stay on, the engine is stopped. If you mean headlights then it doesnt matter - move on to the next symptom.

Like another has said, my 1990 325i would stop periodically for a while. I replaced the main/fuelinjector relay with a used one from a junk yard and it has worked fine ever since. I would get one or two just in case as a spare anyway for long trips.

Ya when i said "lights" i meant the headlights, but since you said that doest matter i moved on. The car recently just stopped again and it dropped to 0. and I had to pull over, stop, and restart the car to get moving again. What should I do?? or replace??

[AndrewBird]

What should I do?? or replace??

Uh...

Main relay is my bet.

check all grounds and the main relay. Mine did the same damn thing just after my motor swap. Turns out I put a shitty main relay in. swapped out the craptastic relay, and all is well

Like another has said, my 1990 325i would stop periodically for a while. I replaced the main/fuelinjector relay with a used one from a junk yard and it has worked fine ever since. I would get one or two just in case as a spare anyway for long trips.

[quikveedb2]

*sigh* Since you obviously haven't seen the answer here in this thread let me suggest you use the search. Here's some light reading coutesey of jlevie;

For the engine to run the following conditions must be met:

Power on DME pins:
27 Start Input
18 Un-switched Power input
37 Power Input from Main Relay

Ground on DME pins 2, 14, 19, 24

Timing data from the CPS on DME pins 47 & 48 from a rotating engine

To have spark power must be present at the coil positive and ground pulses
from the DME's pin 1 must reach the coil negative. Power to the coil is
controlled by the ignition switch via C101. When checking for spark, use the
output lead from the coil to eliminate the distributor, rotor and plug wires.

To have injector firing power must be present at each injector and ground
pulses from the DME's pin 16 (Bank1) and pin 17 (Bank2) must reach the
respective injector bank. Note that the injectors are wired as two banks of
three. With cylinder 1,3,5 being bank 1 and 2,4,6 being bank 2. Power to the
injectors is controlled by the main relay. Injector firing is best checked
with a noid light.

The fuel pump relay must have power on pin 86 (relay coil) from the main relay
output (pin 87) and power on pin 30. The DME will ground pin 85 to turn on the
relay and power the pump(s) via pin 87. Of the above, only the fuel pump power
is fused. So if the there's power at pin 87, but not at the pump, check fuse
11.

The main relay and DME pin 18 receive power from the smaller of the two wires
that connect to the battery's positive terminal. That wire incorporates an
in-line fuse. When the DME is presented with a start signal, it grounds the
main relay pin 85 and furnishes power to the fuel pump relay, injectors, and
DME.

Troubleshooting:

Disconnect the battery and the DME cable. Then:

1) Disconnect the coil negative and check continuity from that connector to
DME pin 1. Also verify that from DME pin 1 to ground is an open circuit.

2) Check the resistance across DME 47 & 48, which should be 500-560 ohms. If
the CPS is dismounted, the resistance can be seen to change from about 500 to
540-560 ohms when a ferrous object is brought to the face of the
sensor. Neither pin should be grounded.

3) Check for continuity from DME 36 to main relay 85 and from DME 3 to fuel
pump relay 85.

Reconnect the coil, remount the CPS (air gap should be 1mm), plug the
relays back in, reconnect the DME, and connect the battery. Then do the
following checks:

1) With the key off, verify that power is present at DME pin 18 and main relay
86 & 30.

2) With the key on, verify that power is present at DME pin 27 and pin
18. Power to pin 18 is from the main relay and there should be power to the
injectors and fuel pump relay.

3) With the key on, verify that no voltage is present at the DME grounds (2,
14, 19, 24).

4) Verify that power is present at the coil positive and at fuel pump relay
pin 30. Those get switched power from the ignition switch via C101.

The engine will start and run (if poorly) with only those connections to the
DME in place. The other signals from Cylinder ID, AFM, temp sensor, etc., are
necessary for proper operation. But they won't prevent the engine from firing.

IMPORTANT:

A power check means seeing a voltage within about a tenth of a volt of what
you measure across the battery terminals, which should be at least 12.6v on a
charged battery.

A continuity check means seeing less that 1 ohm of resistance.

An open circuit means seeing a resistance of at least 100k ohms.

A good quality auto-ranging digital multimeter will make these tests much
easier.

But based on experience, I'd just buy a new main relay, shit get the fuel pump one too if you're feeling froggy!