1995 BMW 740i no spark please help!!

[Viktoriis1]

Hi all, I have purchased a 10/95 Bmw 740i that was sitting for about 8 years. The guy got a new car and parked this one. Of course through time it wouldn’t start so he sold it to a friend and that friend discovered there was no power to the fuel pump after replacing the fuel pump. After that the car sat some more. I have acquired the car and got the fuel pump working and installed a new crankshaft sensor as this is normally what will cause no spark. This time it didn’t work. . I’m not really sure where to go from here. I pulled the DME and checked for curosion. This DME is in great shape others then a couple of ears that hold it together have been broke off. The guys who owned it before me knew nothing about cars so I am sure they didn’t open it. So that’s the story! Can anyone help me with my next step? Oh the fuse’s are good for The DME and there is power at the coil packs.

[Mayorchuck]

Did you replace the crank sensor with a Bosch? Fuel pump relay is above the battery, 2nd from the right. You can swap it with the one to the right just to rule out the relay. Power comes from fuses 17 and 57. Fuse 57 is in the row of fuses above the battery. What is the condition of the battery?

Have you tried checking for codes with a stomp test (google)?

[Viktoriis1]

Did you replace the crank sensor with a Bosch? Fuel pump relay is above the battery, 2nd from the right. You can swap it with the one to the right just to rule out the relay. Power comes from fuses 17 and 57. Fuse 57 is in the row of fuses above the battery. What is the condition of the battery?

Have you tried checking for codes with a stomp test (google)?

Thanks for the reply,
The crank sensor is not Bosch but it is German direct. Fuel pump is no longer an issue. Stomp test?

- - - Updated - - -

Battery is new.

[Viktoriis1]

Ok performed stomp test and nothing happens.

[Mayorchuck]

I've never had to use the stomp test but most say it takes several tries to work. Could be there are no codes. I can tell you aftermarket sensors rarely work on these cars. We see it time and time again in the forum. You might look into getting a diagnostic set up to use on the 20 pin port near the ebox under the hood. Plenty of threads on it here or check the Diagnostic forum here as well.

[Viktoriis1]

So my research reveals that Bosch never and still doesn’t make a crankshaft sensor for my car. I feel that after years of sitting with no battery hooked up the diagnosis via the computer will be a waste of time. Could the camshaft sensor cause no spark? Or anything else?

[Timm]

Are you absolutely sure you have no spark? They can be pretty weedy on the M60 engine. How did you check for a spark?

Broken tabs on the DME is normal - the software will have been updated a number of times over the cars lifetime, and the only way the software can be updated is to open the case and replace the EPROM!

Pop a sparkplug out and see if it is wet with fuel - if it is then the CRANKshaft sensor is working fine as the injectors only fire (and the fuel pump run) when the signal is present - the engine will run with the CAMshaft sensor disconnected (but not very well), it will also run with a completely dead CAMshaft sensor, but not one that gives the wrong signal.

The 1995 model has a slightly different wiring scheme to the other models - the circuit diagram is here:

http://www.meeknet.co.uk/E38/BMW_95E...ng_diagram.pdf

[Viktoriis1]

Hi Timm thanks for responding. I checked for spark by pulling the plug and installing it into the coil pack then grounded the plug and turned the car over. When I pull the plugs they are wet. Could the key be an issue? I noticed yesterday that the light doesn’t come on and none of the buttons work.

[Qsilver7]

... Could the key be an issue? I noticed yesterday that the light doesn’t come on and none of the buttons work.

Unfortunately...a dead key battery doesn't affect it's ability to start the car (EWS). The battery in the remote keys is only used to transmit the RF signal for the FZV/DWA (remote central locking & anti-theft alarm siren system).

Which key do you have? If you have the 3 button remote...have you opened the back of the key to see if the EWS transponder is still there? Perhaps someone opened it up and unintentionally lost the transponder chip. :

EWS is powered through induction. A 125 KHz radio frequency is sent from the Transmitter Receiver (or the EWS control module in later models) to the Ring Antenna (located around the ignition cylinder). This powers up the coil inside the transponder chip:

[Timm]

If the plugs are wet with fuel - then the CRANKshaft sensor is working. The next test will be to see if the coils are getting the 12V supply. Each coil has a 12V supply on the GREEN wire:



....and 0V (via a resistor) on the BROWN wires (they all join together in the wiring boxes above the heads). Use a multimeter with sharpened probes and pop through the insulation on the GREEN and BROWN wires and with the ignition in position II you should see 12V or so - do that next before you do anything else!

[Viktoriis1]

Ok I will test the power at the coils again. I had power on one wire at the coil pack plug. Not sure of the color.

[Viktoriis1]

Ok so no power on the brown wire and there is power at the green wire.

[Qsilver7]

Did you respond to the question as to if the EWS transponder is still inside the key? I may have missed it if you did.

[Viktoriis1]

No I didn’t and yes it is still in the key.

[Viktoriis1]

And it is a three button key.

[Timm]

That means that the main DME relay and the unloader relay are both energised and supplying current to the DME and ignition coils. So, we are up a blind alley, if the injectors are firing then the plugs should be firing. You have EWSII on your '95 model:

https://www.meeknet.co.uk/E64/04_Car...ems.pdf#page=6

...and any transponder fault should stop the starter turning, and yours is so that rules out the EWS.

My gut feeling is (as long as you are sure the injectors are firing) is that you actually DO have a spark - and your engine is flooded - they are complete pigs to get going again - here's the procedure:

http://www.meeknet.co.uk/E32/Flooded_M60_Start.htm

[Viktoriis1]

So you said I should have power on both the green and The brown wire right? I don’t have power on the brown wire.

[Mayorchuck]

All your browns are ground wires.

[Viktoriis1]

Ok thank you Mayorchuck. That makes perfect sense.

- - - Updated - - -

Flood process did not work. I have no spark.

- - - Updated - - -

I even tried starting fluid!! Something I hate to do and nothing happened

[Viktoriis1]

So now I’m back to having no fuel as well. I have power at both fuses 17, 57. I have power at the relay and I have switched it with the other relay that fits and nothing. Fuel pump works fine when jumped. So no fuel or spark. I’m I back to this Crankshaft sensor??

[Timm]

You are!

[xboss]

It's always the crankshaft sensor! I though the v8 sensor had to be positioned properly when you bolt it down but no mention of that here yet.

[Viktoriis1]

There is only one way it can go in. The bolt hole is just big enough for the bolt.

[Viktoriis1]

Thanks everyone for your help. It doesn’t run well but it running!!

[Timm]

Was it the crankshaft sensor then?