Ok so I have a 1990 760 turbo with the b230ft. It's not starting because it have no spark but I cant figure out why. I replace the plugs, wires, and got a used coil and ignition amplifier. I pulled the distributor cap and rotor off to check them and they seemed ok. I check for resistance across the rotor and that checked out fine. The cap didn't have an o-ring which it is supposed to have??? Not sure about that.

Just for reference the car also has a brand new in tank fuel pump and filter, a replacement used chassis mounted pump and new crank position sensor, a new fuel pump relay and a replacement used Air Mass Meter. I know it has a bad O2 sensor.

The car seems to be getting fuel fine just no spark at all.

I've been trying to get this car going for months now but no luck so far. Any ideas? Maybe the computer??? Any help would be greatly appreciated.

 

Of course it could be the ecu, but I'd check a few things first. Do you have a repair manual and a digital volt meter? Are you getting power TO the coil? I ask because if the ecu does not see a crank/rpm signal, it will not energize the coil. I know you have replaced it, but the signal may not be making it to the ecu so perhaps check there. Also, your car has OBD...have you checked the codes? Of course, if the car hasn't run in months the codes may be worthless but somewhere to start. Do you know if your injectors are firing? The radio suppression relay will cause a no start as well...it's located on the coolant overflow bottle bracket. Two identical relays, one is a fan relay and the other is the RSR which actually oversees the injectors.

 

Ok so I tested to see if the coil was getting power yesterday. It is however the battery is completly dead so the car must be jumped and the coil was getting between 5.2 and 6.5 volt. It was fluctuating.

I tried swapping the two relays to see if it made a difference but nothing changed. Which I guess could mean that both relays are working or it could mean they are both dead.

As for codes, you are correct in saying that after sitting for months there are non. But this also makes me think it may be the ecu because there is a diagnostic light under the hood that will blink codes. It should blink constantly if there no codes when the button is pressed but its not getting a signal.

Now what?

Thanks for the help

 

ok first thing with any vehicle, did the car ever run before you got it? 2nd did you do a motor swap.3rd it may be your hall sensor in dizzy. Reply back so can further assist you..