Car died while driving now no spark.

[Skoobeesnak]

OK guys I am really scratching my head on this one and I am about to breakdown and take it to a garage to fix I am hoping the collective braintrust can point me in the right direction.

I was driving my car just out running errands and upon shifting from 2 to 3 after leaving a stoplight my car just died. Shut off and wouldn't restart, it would stumble a little bit but wouldn't catch and run.

At first I thought fuel pump since the stock in tank unit had never been replaced and it was at 252K miles. Needless to say I replaced that then realized I didn't have a spark. I have gone through some troubleshooting steps I found online and have verified that even when connected directly to the coil there is no spark. I have verified power at the DME.

So far here is all I have replaced:

- In tank fuel pump. Tested the external fuel pump and it works fine.
- CPS I replaced it after reading and mistakenly tested the wrong direction with my multipmeter.
- Main relay
- DME I got a replacement and popped it in. Still no change. On a side note the "stomp test" reads no error codes so everything from that end seems fine.
- Coil even though the stock unit passed the ohm test I remember reading that someone had one that passed the tests but wouldn't fire.

Any other ideas?

[spdracrm3]

are you getting power to coil ? if you have a test light check for power at coil terminals with key on , the check for a pulsing/flashing signal on coil neg terminal while cranking .

does car have a 13 button OBC? if so there is a relay box that controls power to coil (part of the code set security feature) that is known to have issues with connector corroding and relay failing

[mr.vang]

It's time to pop the distributor cap and peek inside.

[///M42 sport]

where is that relay box you speak of?

[spdracrm3]

where is that relay box you speak of?

up above the ABS controller ,behind headlamp switch in drivers dash area

[Skoobeesnak]

It's time to pop the distributor cap and peek inside.

I should mention that I did take the distributor off and checked out the rotor and cap which are less than 1 year old. They looked fine. I had a replacement timing belt and tensioner that I had been dragging my feet on putting in and replaced that while I was there everything looked good. while I was swapping it.

[Skoobeesnak]

are you getting power to coil ? if you have a test light check for power at coil terminals with key on , the check for a pulsing/flashing signal on coil neg terminal while cranking .

does car have a 13 button OBC? if so there is a relay box that controls power to coil (part of the code set security feature) that is known to have issues with connector corroding and relay failing

Just tested and I am not getting any power to the coil with the key on or while cranking. Seems like something I should have done before but I am not very good at electrical troubleshooting.

Yes it is a 13 button OBC. So I am just looking for a bad connection to that box? I am looking at my Bentley manual and it saying to check for a short between the coil and terminal 15. I am not sure what they mean by terminal 15. Do they mean fuse 15 or pin 15 to the DME?

One other thing I forgot to mention is that this is on a 1987 325iS.

Thanks in advance for your replies.

[jlevie]

The coil power comes from the ignition switch, optionally through the OBC code relay, and then to the coil. Start tracing from the coil back to the ignition switch to find the problem.

[spdracrm3]

there are two terminals on the coil label 15+ (power supply) and 1-(ECU control) power is supplied to coil at terminal 15+ thru the relay box ,so yes find that box above the ABS controller and find the two large green wires (one might be green/red) at pins 3 ,4 and check voltage at each if you have power at one an not the other disconnect and jumper them together and see if you now have power at coil and engine starts/runs .if it does you either have a problem in the relay box or a codes is set in the OBC not allowing engine to run (or a wiring issue between the obc/relay box)

if no power at either green wire at relay box the the issue is between ignition switch and relay box or ignition switch itself

[Skoobeesnak]

What am I looking for here?

Hey guys thanks again for getting me on the right track. I dropped the ABS module (at least I think I did) it was the big metal box with a huge amount of cables going into it held on by 2 10mm screws. Anyway I am not sure what to look for here or if I am looking at the right place. Looking at this picture can you tell me which set of wires I need to look at for this relay?


http://imgur.com/2ac0weA


http://imgur.com/vB2SZ23

[spdracrm3]

second picture ,see the two green connectors (one has a sticker with "12" on it) on the right end of that connector i see the green and green/red wires in pin 3 &4

[Skoobeesnak]

second picture ,see the two green connectors (one has a sticker with "12" on it) on the right end of that connector i see the green and green/red wires in pin 3 &4

OK here is what I got. I get 12volts on the solid green wire and I get no voltage on the green and red wire. with the key on. I jumpered them between the two pins and I get voltage at the coil. I am by myself right now so I can't tell if I am getting a spark but the car won't start.

I swapped my original DME in to see if that could be the case and same result. I can't help but think that relay is bad but shouldn't it start with the green wires jumpered?

[spdracrm3]

well were at least making progress ,now that you have power at coil you can put test light or voltmeter on neg control side of coil and you should have power key on and a flashing test light or fluctuating voltage reading (DVOM) while cranking if ECU is working to control coil. if you can get a helper check for spark out coil tower wire and at a plug while they crank engine.

the plugs might be fouled if you have been cranking while so you might have to do a WOT clear flood ...

[Skoobeesnak]

well were at least making progress ,now that you have power at coil you can put test light or voltmeter on neg control side of coil and you should have power key on and a flashing test light or fluctuating voltage reading (DVOM) while cranking if ECU is working to control coil. if you can get a helper check for spark out coil tower wire and at a plug while they crank engine.

the plugs might be fouled if you have been cranking while so you might have to do a WOT clear flood ...

OK I finally got a helping hand and I plugged the connector with the 12 sticker on it into the relay. I do get voltage to the coil on the negative side at roughly -12 volts with the key on. When the starter is engaged the voltage drops to about -10.8 or so but it does not fluctuate. Still no spark. So....is it the relay that is bad?

Thanks again for your help you have saved me many more hours of frustration.

[spdracrm3]

10.8 would be close enough to normal while cranking (it will also average reading if the ECU is controlling on/off time so might be seeing some of that effect too),what kind of voltmeter are you using ? it can be hard to tell with many as the the voltage changes so fast the meter can catch it (if a fluke meter look at the bar graph on bottom to see voltage fluctuations ) if not a very good meter try a test light as you can visually see it flash .