1990 c4 elecricity cuts of to engine.

[meichelmann]

My 1990 C4 started to st-udder and act as if out of gas stall but will always start up again the tach would momentarily dip none of the warning lights go on unless engine stalls. I thought it was the fuel/dme relay but I replaced it and problem the same.
I further checked and found the power to the coils stops while the fault is happening, it's only momentary, if revs are up it only shutters if at idle it dies.
I now believe it could be the alternator voltage regulator. Any Ideas please?

[bazar01]

If the coil power supply is getting interrupted, it could be the ignition switch.
Try to put the ignition switch to ON but do not start the car.
Then hook up the analog or digital meter to the coil and ground.
Then jiggle the ignition switch with the key and see if you loose the 12V to the coil.

[meichelmann]

electricity to the coils happens only when engine is running, the switch is good power also gets cut of to fuel pump even though i jump relay 41(pump/dme).
from my reading help books it seems as it could be the voltage regulator spiking or the dme control module having a fault. Both of which I hope are not.
Hope for more Ideas.

[bazar01]

If you have or can get access to a digital meter with data logging or trending capability, you can monitor power supply at the cigarette lighter while driving.
If the voltage regulator is spiking, you should also see the gauges/instrument lighting and headlights change intensity or flicker when driving at night.

[meichelmann]

I have paid attention to the lights and don't see a brightening as you say, when the engine stalls I do see them dimming as the alternator is no longer generating. Its as if something tells the fuel pump and ignition system to turn of momentarily. it happens about every three to ten seconds apart.
Thanks, Any more Ideas?

[ischmitz]

If you have replaced the DME relay the next things I would look into are the engine speed sensor, connectors under the seat, and eventually the DME itself. What year is your car? Does it have a CEL. If so you should check whether there are any fault codes stored in the DME.

Good luck and keep us posted,
Ingo

[unclebilly]

I'd start by cleaning your battery connections.

[Lorenfb]

"dme control module having a fault"

The DME unit doesn't control the power to the coils.
It only momentarily switches the coils to ground via the ignition modules.

If it's really a loss of power to the coils, then run a direct 12 volts to them for testing.

[bigchillcar]

similar symptoms in my '90 C4 turned out to be sensor issues- disconnect your cht and maf sensor connectors and check for light corrosion..clean them if you find any. fixed my car like magic..

[bazar01]

Originally Posted by bigchillcar

similar symptoms in my '90 C4 turned out to be sensor issues- disconnect your cht and maf sensor connectors and check for light corrosion..clean them if you find any. fixed my car like magic..

bigchillcar, did you get your car running?
So was it the cht sensor connector or the AFM connector? and not the sensor itself?

[bigchillcar]

Originally Posted by bazar01

bigchillcar, did you get your car running?
So was it the cht sensor connector or the AFM connector? and not the sensor itself?

yes i did. sorry for not posting..work and home life has been underestimated as hellish of late. the cht sensor was replaced, but didn't solve the problem. the maf sensor connection was checked and light corrosion found on the pins. cleaned them, reseated my aftermarket k&n filter back into place (wrench i know hates 'em) and voila - no more black smoke, rich running, stalling, etc. like pure magic..