No Spark

[franan]

My 1987 BMW was running perfectly, now it does not even start. The spark plugs are not sparking. Can someone tell me what the issue is? If I changed the rotor and wires as well as the spark plugs, what would the next step be? I do not want to throw money on parts I want to get straight to the problem.

[faber]

I am currently in the same boat as you. Posted a couple weeks ago and only got crickets in response.

I will do my very best to try and help you though.

First of all check the fusible link in the trunk it is located about 10 inches from the positive post of the battery. Grab a meter and check that you have continuity through it.

Check that you are hearing your fuel pumps when you start cranking the car over. if you don't hear the pumps then check your fuel pump relay and main relay. these are located in a box under the hood on the drivers side of the engine compartment. There are three relays there. Make sure they are working.

If that doesn't resolve the issue then you will want to check your crankshaft position and reference sensors. the ECU (or DME) located in your glove box takes timing signal from your crankshaft position sensor and grounds pin 1 at intervals relevant to the signals coming from the sensors. This pin is connected to the negative post on your coil. Pull the negative coil wire and test that it has continuity to pin 1 on the DME harness, and that it does not have continuity to ground.

Since the engine is timed by grounding pin 1 of the dme which causes the coil to be energized and fire it is important that you do not have voltage floating on the ground rail of your car. Another wire shorting to ground can cause this signal to be interrupted which will cause the coil to not fire.

Another thing you can do is clip a test light between the positive and negative posts of the coil and see if it flashes when you turn the car over. If it does and you still dont have spark I would replace the coil.

I hope some of this helps you!

[RobDog]

Since you already checked for spark, I would also check for fuel to confirm that it is a no spark/fuel problem and we could rule out the ignition side of things. Get the return fuel line from the Fuel pressure regulator, disconnect it, and set it aside. Then attach a short piece of fuel line to the FPR, put the fuel line from the FPR into a bottle, then crank the engine. If you have no fuel and no spark than try these things:

1) Swap Crank Shaft Position sensors. I engines have the sensor on the front/passenger side of the engine and it reads off the harmonic balancer. The harmonic balancer can separate into 2 pieces causing no spark. The Eta engines have 2 sensors in the trans bell housing on the drivers side. They read off the flywheel. There is a metal weight that one sensors reads on the flywheel that can fall off causing no spark. Look through the sensor hole with a flashlight while someone slowly turns the engine over. Ensure that the weight is there.

2) Main relay: under the hood on the drivers side near the strut tower will be 3 relays. They may be under a cover. The forward/lowest relay will be the main relay. The main relay is not your standard relay because it has two 87 outputs. This relay turns on 2 outputs and does not switch between outputs like your standard relay. Makes sure you have the correct relay and that it is working.

3) OBC lockout: The OBC code function can cause random no spark/fuel. Under the drivers kick panel, behind the abs computer(big shinny silver box), is a small black box with 2 green connectors. The connectors look like the door chime plugs but green. In those 2 green connectors are about 6 wires. The 2 largest wires are green and green/red. Splice the green and green/red wires together to bypass the obc relay. This will ensure that your engine is getting full voltage since this is the voltage supply to the main relay.

4) Check the fusible link in the trunk, Located on the smaller wire that runs parallel with the main battery cable in the trunk, about 10 inches back from the positive terminal.

5) Try swapping computers with a known working one just incase you are having ECU problems.

[franan]

I thank everyone for their time. I am going to sell the car I can not deal with the headache anymore.

Since you already checked for spark, I would also check for fuel to confirm that it is a no spark/fuel problem and we could rule out the ignition side of things. Get the return fuel line from the Fuel pressure regulator, disconnect it, and set it aside. Then attach a short piece of fuel line to the FPR, put the fuel line from the FPR into a bottle, then crank the engine. If you have no fuel and no spark than try these things:

1) Swap Crank Shaft Position sensors. I engines have the sensor on the front/passenger side of the engine and it reads off the harmonic balancer. The harmonic balancer can separate into 2 pieces causing no spark. The Eta engines have 2 sensors in the trans bell housing on the drivers side. They read off the flywheel. There is a metal weight that one sensors reads on the flywheel that can fall off causing no spark. Look through the sensor hole with a flashlight while someone slowly turns the engine over. Ensure that the weight is there.

2) Main relay: under the hood on the drivers side near the strut tower will be 3 relays. They may be under a cover. The forward/lowest relay will be the main relay. The main relay is not your standard relay because it has two 87 outputs. This relay turns on 2 outputs and does not switch between outputs like your standard relay. Makes sure you have the correct relay and that it is working.

3) OBC lockout: The OBC code function can cause random no spark/fuel. Under the drivers kick panel, behind the abs computer(big shinny silver box), is a small black box with 2 green connectors. The connectors look like the door chime plugs but green. In those 2 green connectors are about 6 wires. The 2 largest wires are green and green/red. Splice the green and green/red wires together to bypass the obc relay. This will ensure that your engine is getting full voltage since this is the voltage supply to the main relay.

4) Check the fusible link in the trunk, Located on the smaller wire that runs parallel with the main battery cable in the trunk, about 10 inches back from the positive terminal.

5) Try swapping computers with a known working one just incase you are having ECU problems.

[redlightpete]

Before you throw in the towel, you might try getting the Bentley manual. I’m guessing from your initial post that you don’t already have one. That would help you solve a majority of problems without having to rely on instructions from forum members.
I think people are more willing to lend assistance when the person asking seems to have gone through all the appropriate troubleshooting items. The manual would get you to that point if it doesn’t get you to the solution.

[franan]

I have 2 other E30s and 2 Bentley books and a CD copy.