Weird Problem - E46 BMW 318i N42

[Wolverine]

Hard to say, my car never used to switch off but had trouble starting.
Wouldn't hurt to change the DME relay, it's only R180 from BMW and about R160 after the discount.

The DME seems to supply parts of the car with 'power' so to say...

Like, my alarm used to never re-code for some time, after I changed the DME relay, it re-codes and you hear the computer box clicking and doors locking..

The fuel pump primes everytime the key is turned on and the car has been working fine since then.

The other thing you should test is the relay for the valvetronic motor. This should be located on teh VVT module. If this is on it's way out, the VVT motor won't get it's required power.

Just be carefull when you guys take your cars to workshops guy, half the time these guys don't know their ars from their elbow's!

I don't beleive I actually wasted money on teh valvetronic when the DME realy was actually the fault on my car

 

[Syl]

Sorry bro,

You were right, the fuel pump relay is under the glove compartment.
The blue relay is the one under the hood.

The primary circuit within the relay control
unit carries a very small amount of voltage
and amperage, which runs through a small
coil. This secondary
current is then used to switch on the fuel
pump.
The DME relay is a small cube of about 1
inch that may be located under the hood in
the engine compartment, inside the fuse and
relay box under the driver's seat or inside a
fuse box, hidden under the dashboard. The
relay itself may be marked with the legend
DME-relais on top.
Problems starting your car, the engine dying while driving down the road (but able to start
after it has cooled down) are common
problems associated with the DME relay,
which may be reaching the end of its life.
This may be due to breaking solder joints
inside the unit--the most common cause--or
an internal diode failure.
What Is a DME Relay?
The Digital Motor
Electronics
(DME) relay unit
is used on many
Porsche and
some BMW
models. This is
actually a double
-relay-in-one
component. The
main relay is
used to fire the
DME control unit
(computer), while the secondary relay gives power to the
fuel pump and heater element inside the oxygen sensor.
Failure in the injection system is usually related to the
DME relay, but some technicians seem to have found a
solution for it.

Thanks for the info man!! I'm going to replace mine tonight, and we'll see what happens!

BTW I replaced the vvt motor, Leonard calibrated it for me (Thanks again man!:thumbs, but the symptoms did not go away.:bangdesk::bangdesk:


Just out of interest, I tested the relay last night.
Except for the fuel pump not always switching on, my car goes into this rapid repetitive clicking after I try starting it sometimes. It goes on even after I take out the key from the ignition. And when this happens the fuel pump does not switch on, and it seems to affect different systems at different times. Sometimes there would be clicking from the gear lever, other times it would just be a thump from in front of the car somewhere, and sometimes it actually opens and closes the throttlebody constantly.
I've had a few occasions now where I had to disconect the battery for it to stop.

So last night it did this again, and when I removed that specific relay it seemed to stop. I also cooled down the relay with an ice pack and put it back in, and the car started. Took it out, left it on the engine to warm up from the residual heat for a few minutes, put it back in and the car didnt start again. Not a very high-tech test and I might have just been lucky. But interesting none the less.

Hard to say, my car never used to switch off but had trouble starting.
Wouldn't hurt to change the DME relay, it's only R180 from BMW and about R160 after the discount.

The DME seems to supply parts of the car with 'power' so to say...

Like, my alarm used to never re-code for some time, after I changed the DME relay, it re-codes and you hear the computer box clicking and doors locking..

The fuel pump primes everytime the key is turned on and the car has been working fine since then.

The other thing you should test is the relay for the valvetronic motor. This should be located on teh VVT module. If this is on it's way out, the VVT motor won't get it's required power.

Just be carefull when you guys take your cars to workshops guy, half the time these guys don't know their ars from their elbow's!

I don't beleive I actually wasted money on teh valvetronic when the DME realy was actually the fault on my car

Interesting that you mention the not re-coding and the key not working. Mine is not working at the moment either. Even after I replaced the control box for central locking, windows etc. It worked for a month, and slowly deteriorated into nothing.

 

[Wolverine]

It's very hard to pin point problems on these cars. The DME relay (digital motor electronics relay) seems to control a number on things. Like for example, if you remove the relay and try to start the car, it would never start but your electric fan will come on...

I know a way of testing the relay by bridging it but haven't tried it out.
This basically closes the circuit so power will flow to componets..

This seems to work in theory but not sure if it would practically

 

[Syl]

It's very hard to pin point problems on these cars. The DME relay (digital motor electronics relay) seems to control a number on things. Like for example, if you remove the relay and try to start the car, it would never start but your electric fan will come on...

I know a way of testing the relay by bridging it but haven't tried it out.
This basically closes the circuit so power will flow to componets..

This seems to work in theory but not sure if it would practically

Yip! Electric fan also comes on after I removed the relay. And actually also did even when the relay was still in. Meaning that the relay did not work properly... we might be on the right track now...

I got the relay, R170 bucks, now just have to wait till tonight to put it in.

 

[Wolverine]

Yes, the only time that fan will go off again is if you put teh relay back and turn on the ignition..What symptoms is you car giving SLY?

 

[Syl]

Yes, the only time that fan will go off again is if you put teh relay back and turn on the ignition..What symptoms is you car giving SLY?

Wow there are quite a few and I'm not sure if it's related to only one problem or a few.

Heres a short list:

1) Trouble starting. Car would sputter and die, then on the second try it would sputter but then 'find itself' and idle, yet it idles a bit rough.
When the car is warmed up though, it doesnt seem to have trouble starting.

2) Sometimes after the car is running, it would just cut out suddenly. But I expect thats related to no.1 as its not starting correctly, and therefore might not activate or adjust everything correctly.

3) Sometimes after the car is running there is a 'dead spot' in accelleration where the car misfires until you are over about 2500rpm.
Then it's smooth.

4) The newest symptom though is as I mentioned earlier. The petrol pump does not switch on, and the car makes this repetitive clicking sound like a relay thats stuck or something. Sometimes you just hear constant clicking, sometimes the clicking comes from the gear lever (Auto), and sometimes it opens and closes the throttlebody with every click. Then you wait a couple of minutes until it stops, turn the key again and if your lucky and it does not start clicking again, the fuel pump is activated and the car starts.
BTW The clicking carries on even after you remove the key.

5) Key fob does not work anymore. But I'm not sure thats related. I replaced the controller box. Reprogrammed the key, and it worked for a month. I might try putting back in the old controller box...


Stuff I've replaced:

- Battery.
- Spark plugs.
- Cam and crank sensors.
- Oil seperator pipe top of engine.
- Air intake resonator box.
- Fuel filter.
- Oil filter + Oil change.
- Valvetronic motor.

All within the last 5 months.


Stuff I've checked:

- Checked coils. All working.
- Vacuum leak check. With carb cleaner. And removing oil cap while car is running. All fine.
- I have swapped the fuel pump relay with the horn relay.
- I've checked all fuses, as well as the fuses in the front in that little black box.

There was more, I just cant remember now...

 

[Wolverine]

Yes, the only time that fan will go off again is if you put teh relay back and turn on the ignition..What symptoms is you car giving SLY?

Wow there are quite a few and I'm not sure if it's related to only one problem or a few.

Heres a short list:

1) Trouble starting. Car would sputter and die, then on the second try it would sputter but then 'find itself' and idle, yet it idles a bit rough.
When the car is warmed up though, it doesnt seem to have trouble starting.

2) Sometimes after the car is running, it would just cut out suddenly. But I expect thats related to no.1 as its not starting correctly, and therefore might not activate or adjust everything correctly.

3) Sometimes after the car is running there is a 'dead spot' in accelleration where the car misfires until you are over about 2500rpm.
Then it's smooth.

4) The newest symptom though is as I mentioned earlier. The petrol pump does not switch on, and the car makes this repetitive clicking sound like a relay thats stuck or something. Sometimes you just hear constant clicking, sometimes the clicking comes from the gear lever (Auto), and sometimes it opens and closes the throttlebody with every click. Then you wait a couple of minutes until it stops, turn the key again and if your lucky and it does not start clicking again, the fuel pump is activated and the car starts.
BTW The clicking carries on even after you remove the key.

5) Key fob does not work anymore. But I'm not sure thats related. I replaced the controller box. Reprogrammed the key, and it worked for a month. I might try putting back in the old controller box...


Stuff I've replaced:

- Battery.
- Spark plugs.
- Cam and crank sensors.
- Oil seperator pipe top of engine.
- Air intake resonator box.
- Fuel filter.
- Oil filter + Oil change.
- Valvetronic motor.

All within the last 5 months.


Stuff I've checked:

- Checked coils. All working.
- Vacuum leak check. With carb cleaner. And removing oil cap while car is running. All fine.
- I have swapped the fuel pump relay with the horn relay.
- I've checked all fuses, as well as the fuses in the front in that little black box.

There was more, I just cant remember now...

---

Shew! That sounds hectic.

1.) That sounds like the engine isn't getting fuel. Check the DME relay (which you are doing tonight) and fuel pump.

2.) This definitely sounds like a fuel supply problem.

3.) Dead spot seems like there is either no fuel or air going into the cylinders and no combustion is occuring at that specific moment..no combustion means no power, ie: your dead spot.

4.) If you can't hear your fuel pump prime up that means theres no power going to it. It's either the relay is not working (supplying power to the pump or the pump isn't working itself)
Lets start by changing the relay and see, if that doesnt work, I will show you how to test the pump.

I'm sure that the DME relay has a lot to do with your problems but don't hold me to that.

Just remember that the DME relay is the blue relay under the hood and the fuel pump relay is found under the dash.

One more thing that you can check for me is your air mass meter. This thing can also cause the car to behave very strangely!

When the car is idleing, pull out the air mass meter sensor, if the engine sounds liek its going to die off, the your meter is working fine. If it has no effect on the idle, the its cooked.

Where are you based SLY, maybe I can give you my contact detials and help you out if you like?

 

[Syl]

Shew! That sounds hectic.

1.) That sounds like the engine isn't getting fuel. Check the DME relay (which you are doing tonight) and fuel pump.

2.) This definitely sounds like a fuel supply problem.

3.) Dead spot seems like there is either no fuel or air going into the cylinders and no combustion is occuring at that specific moment..no combustion means no power, ie: your dead spot.

4.) If you can't hear your fuel pump prime up that means theres no power going to it. It's either the relay is not working (supplying power to the pump or the pump isn't working itself)
Lets start by changing the relay and see, if that doesnt work, I will show you how to test the pump.

I'm sure that the DME relay has a lot to do with your problems but don't hold me to that.

Just remember that the DME relay is the blue relay under the hood and the fuel pump relay is found under the dash.

One more thing that you can check for me is your air mass meter. This thing can also cause the car to behave very strangely!

When the car is idleing, pull out the air mass meter sensor, if the engine sounds liek its going to die off, the your meter is working fine. If it has no effect on the idle, the its cooked.

Where are you based SLY, maybe I can give you my contact detials and help you out if you like?

This kinda has DME written all over it hey! But we will see...
I'm sure I've checked the MAF but I'm gonna check it again tonight to make sure. Any idea how much the MAF sensor costs?

I'm in Gauteng hey, I see you are in Durbs! So it's a bit far. But thanks anyway man!!:thumbs:

 

[Wolverine]

Shew! That sounds hectic.

1.) That sounds like the engine isn't getting fuel. Check the DME relay (which you are doing tonight) and fuel pump.

2.) This definitely sounds like a fuel supply problem.

3.) Dead spot seems like there is either no fuel or air going into the cylinders and no combustion is occuring at that specific moment..no combustion means no power, ie: your dead spot.

4.) If you can't hear your fuel pump prime up that means theres no power going to it. It's either the relay is not working (supplying power to the pump or the pump isn't working itself)
Lets start by changing the relay and see, if that doesnt work, I will show you how to test the pump.

I'm sure that the DME relay has a lot to do with your problems but don't hold me to that.

Just remember that the DME relay is the blue relay under the hood and the fuel pump relay is found under the dash.

One more thing that you can check for me is your air mass meter. This thing can also cause the car to behave very strangely!

When the car is idleing, pull out the air mass meter sensor, if the engine sounds liek its going to die off, the your meter is working fine. If it has no effect on the idle, the its cooked.

Where are you based SLY, maybe I can give you my contact detials and help you out if you like?

This kinda has DME written all over it hey! But we will see...
I'm sure I've checked the MAF but I'm gonna check it again tonight to make sure. Any idea how much the MAF sensor costs?

I'm in Gauteng hey, I see you are in Durbs! So it's a bit far. But thanks anyway man!!:thumbs:

 

[tai88]

Yes, the only time that fan will go off again is if you put teh relay back and turn on the ignition..What symptoms is you car giving SLY?

@Wolverine do you have the part number for the DME? N42 engine aswell.

 

[Wolverine]

Hold on to you seat...MAF sensor is about R5 000 from BMW:bangdesk:
Don't even think of buying the after market part (about R1 500)

It won't even start the car, I learnt that the hard way! I got a sensor from the scrap yard, took it off an E90 320i (R800)..they have the same engines in them.

Let me know if your car comes right, will be interesting to find out:idea:

 

[Syl]

So... It didnt work.
Symptoms remain unchanged after I replaced the relay.
:argh::argh::bangdesk::bangdesk:

I did check the MAF though and the car dips when I pull it out. So thats fine.
Next step is to take the car to the dealer I suppose...

---

Yes, the only time that fan will go off again is if you put teh relay back and turn on the ignition..What symptoms is you car giving SLY?

@Wolverine do you have the part number for the DME? N42 engine aswell.

B61366915327
Sky blue relay.

Hope you have better luck then me bro!! Seriously.

 

[tai88]

So... It didnt work.
Symptoms remain unchanged after I replaced the relay.
:argh::argh::bangdesk::bangdesk:

I did check the MAF though and the car dips when I pull it out. So thats fine.
Next step is to take the car to the dealer I suppose...

---

Yes, the only time that fan will go off again is if you put teh relay back and turn on the ignition..What symptoms is you car giving SLY?

@Wolverine do you have the part number for the DME? N42 engine aswell.

B61366915327
Sky blue relay.

Hope you have better luck then me bro!! Seriously.

---

When someone sorts out this ghost in the N42, hell will freeze over!

 

[Wolverine]

So... It didnt work.
Symptoms remain unchanged after I replaced the relay.
:argh::argh::bangdesk::bangdesk:

I did check the MAF though and the car dips when I pull it out. So thats fine.
Next step is to take the car to the dealer I suppose...

---

Yes, the only time that fan will go off again is if you put teh relay back and turn on the ignition..What symptoms is you car giving SLY?

@Wolverine do you have the part number for the DME? N42 engine aswell.

B61366915327
Sky blue relay.

Hope you have better luck then me bro!! Seriously.

---

---

There's nothing seriously wrong with your car bro...follow the below link and see what's happening to your car:=):

http://www.m3forum.net/m3forum/archive/index.php/t-370805.html

 

[Syl]

So... It didnt work.
Symptoms remain unchanged after I replaced the relay.
:argh::argh::bangdesk::bangdesk:

I did check the MAF though and the car dips when I pull it out. So thats fine.
Next step is to take the car to the dealer I suppose...

---

Yes, the only time that fan will go off again is if you put teh relay back and turn on the ignition..What symptoms is you car giving SLY?

@Wolverine do you have the part number for the DME? N42 engine aswell.

B61366915327
Sky blue relay.

Hope you have better luck then me bro!! Seriously.

---

---

There's nothing seriously wrong with your car bro...follow the below link and see what's happening to your car:=):

http://www.m3forum.net/m3forum/archive/index.php/t-370805.html

---

---

Really interesting read!!

Some difference in symptoms though:

He doesn't mention anything about his car going into a frantic clicking spree.
And his car does not run for more than 10 minutes.
My car, IF I get it started runs fine until I switch it off again. I drove for an hour and a half the other day without issues...

But the symptoms do sound really familiar to some of the random things that has gone on with my car, and the car is getting worse with time which means something is deterioating, which means that it must be mechanical and not computer related. So I suppose the DME box is out of the equation.

So I'm gonna check it out tonight, and will see what it does. Here we go again!!

You mentioned something about testing or priming the fuel pump manually?
Could you share how to do this so I can try it out as well please.

Thanks for trying to help man!!:thumbs:

 

[Wolverine]

So... It didnt work.
Symptoms remain unchanged after I replaced the relay.
:argh::argh::bangdesk::bangdesk:

I did check the MAF though and the car dips when I pull it out. So thats fine.
Next step is to take the car to the dealer I suppose...

---

Yes, the only time that fan will go off again is if you put teh relay back and turn on the ignition..What symptoms is you car giving SLY?

@Wolverine do you have the part number for the DME? N42 engine aswell.

B61366915327
Sky blue relay.

Hope you have better luck then me bro!! Seriously.

---

---

There's nothing seriously wrong with your car bro...follow the below link and see what's happening to your car:=):

http://www.m3forum.net/m3forum/archive/index.php/t-370805.html

---

---

Really interesting read!!

Some difference in symptoms though:

He doesn't mention anything about his car going into a frantic clicking spree.
And his car does not run for more than 10 minutes.
My car, IF I get it started runs fine until I switch it off again. I drove for an hour and a half the other day without issues...

But the symptoms do sound really familiar to some of the random things that has gone on with my car, and the car is getting worse with time which means something is deterioating, which means that it must be mechanical and not computer related.

So I'm gonna check it out tonight, and will see what it does. Here we go again!!

You mentioned something about testing or priming the fuel pump manually?
Could you share how to do this so I can try it out as well please.

Thanks for trying to help man!!:thumbs:

---

---

---

You will need:

a.) Size 8 spanner to open fuel pump housing.
b.) 12 volt power supply (similar to the one found in electric driveway gates) OR 2 pieces of long cord which yo ucan connect directly to the battery.

Step 1Remove the 'arse rest' or the back seat

Step 2Unbolt the fuel pump cover with the size 8 spanner (pump is on the RHS..behind driver)

Step 3Switch on key and using a multi meter, test if power is going to the pump.

Step 4Open the back door and look at the pins on the pump. There will be 2 pins on the RHS. These are the pins you will use.
Connect cord to the battery and plug to pins on the pump.
Your pump should prime...

(No worry if you use the wrong pins, you'll just hear the pump making an odd noise - the noise you will be listening for is the buzzing noise)

Best way to do this is to run the car and when it doesnt start or if you do not hear the pump priming, do this test.

Make sure you don't get any sparks when testing the pump, you have a whole tank of fuel below.

Prime the pump (you will hear the buzzing noise) and try starting the car...
If it starts you know what your problem is, the pump is most probably not getting power supply and some stages.

This test sounds silly but that's how I found the problem to my car...

 

[Syl]

So after testing a few things, including some relays that had nothing to do with the fuel pump(accidently), I've come to the conclusion that the fuel pump seems fine.
The problem seems to not only affect the fuel pump, but other systems as well. Such as the throttlebody at some stages, the gear lever (lock), and some other relays as well. Something is trying to get a signal through or trying to switch on but it's not happening. So ... Clickclickclickclickclick......

So next up, temp sensors! Who can tell me more about the car temp sensors? I know about the one near the radiator ( which is slowly leaking water BTW. But thats easy to fix.)
Is this where the cluster gets the temp from? Or is it there for the soul purpose of switching the fan on and off?
Is there another temp sensor that I could unplug and check somewhere? Perhaps near the waterpump or thermostat? Does the thermostat perhaps send readings to the DME?

What do you guys think?


P.S. I booked the car in at the dealer for next Wednesday. If I cant get this sorted hopefully they can. Will keep you guys updated!!!

 

[Wolverine]

So after testing a few things, including some relays that had nothing to do with the fuel pump(accidently), I've come to the conclusion that the fuel pump seems fine.
The problem seems to not only affect the fuel pump, but other systems as well. Such as the throttlebody at some stages, the gear lever (lock), and some other relays as well. Something is trying to get a signal through or trying to switch on but it's not happening. So ... Clickclickclickclickclick......

So next up, temp sensors! Who can tell me more about the car temp sensors? I know about the one near the radiator ( which is slowly leaking water BTW. But thats easy to fix.)
Is this where the cluster gets the temp from? Or is it there for the soul purpose of switching the fan on and off?
Is there another temp sensor that I could unplug and check somewhere? Perhaps near the waterpump or thermostat? Does the thermostat perhaps send readings to the DME?

What do you guys think?


P.S. I booked the car in at the dealer for next Wednesday. If I cant get this sorted hopefully they can. Will keep you guys updated!!!

 

[Syl]

Okay, the car went in this morning to BMW, and they phoned me with a quote.
Apparently it's the DME itself thats not behaving so they want to replace it.

It's gonna cost around R15300 just for the unit alone!!!:yikes::bangdesk:


I'm gonna go lie down a bit....:facepalm:

 

[tai88]

That thing that controls the electronics! mine f'd out a year ago, had it replaced with a second hand one for R1500.

I'd go the second hand route. Mine is behaving itself since.. 15000 is a raping

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the symptoms I had were windows not winding, not unlocking doors with remote. not starting sometimes.