Rough idle, worse with A/C off - Page 2 - BMW M5 Forum and M6 Forums
E39 M5 and E52 Z8 Discussion 1998-2003 Advertiser's Forum

Reply
 
LinkBack Thread Tools Rate Thread Display Modes
post #11 of 18 Old 3rd July 2019, 02:14 AM
Sailor24
M5 Expert (>4000)
 
Sailor24's Avatar
 
Join Date: Oct 2010
Location: Cobourg Ont
Age: 57
Posts: 9,751
Thanks: 986
Thanked 1,968 Times in 1,652 Posts
Dude, why did you not mention that before. 8 out of 10 times when the ebox fan fails people get no symptoms because it can fail in many ways. There is one failure that causes your exact symptoms, and that is when it locks up solid.


Clear those codes and see if they come back is step one. Those other two codes are very telling but could be a result of too much power beiig sucked up by the Ebox circuit.
Sailor24 is offline  
Sponsored Links
Advertisement
 
post #12 of 18 Old 3rd July 2019, 06:32 AM Thread Starter
smithr
Member, Sport: Off DSC: On (>50 posts)
 
smithr's Avatar
 
Join Date: Jan 2016
Location: Dresden, Germany
Posts: 98
Thanks: 2
Thanked 6 Times in 6 Posts
Quote:
Originally Posted by Sailor24 View Post
Dude, why did you not mention that before
I ruled out the E Box fan code because it's been there forever and I've both replaced the E Box fan and tested the complete circuit related to the E Box fan and it all checks out.

The weird thing with the fan is that my car has the 'old' 3 pin E Box fan but BMW list the 'new' 2 pin fan for my build date. Makes me wonder whether the DME software is expecting and testing for the newer 2 pin fan.

Quote:
Originally Posted by curtissp321
Have you ever replaced your fuel pump / fuel filter? If not - how many miles / Km on the car?
Fuel pump and filter were replaced ~10000km ago ('Preventative maintenance') I did notice that the pump is quite audible when I was under the car a few weeks back but not sure if that's normal or not. Testing the fuel pressure is on my agenda.


I think I need to go back and systematically check some of the basics again. With hindsight I think the dealer was not really motivated to diagnose a 20yo car so that was probably a waste of time. Probably should improve my German language skills and fond some local enthusiasts to help out.
smithr is offline  
post #13 of 18 Old 3rd July 2019, 05:41 PM
Sailor24
M5 Expert (>4000)
 
Sailor24's Avatar
 
Join Date: Oct 2010
Location: Cobourg Ont
Age: 57
Posts: 9,751
Thanks: 986
Thanked 1,968 Times in 1,652 Posts
I will take your word for that, but I would check the Ebox fan again just to be sure it is still running. Just in case you did all these tests last year and are assuming it still works.
One or both those codes say you are having voltage issue. It might be simplest to replace the unloader relay than try and test that system but I would also replace the main relay, seems cheap compared to your next test which might be to swap out DME, or have to go to a dealer where they will do a virtual swap.
Which fan did you put in the 3 or 2? has your car had updated software in it?

Last edited by Sailor24; 3rd July 2019 at 05:43 PM.
Sailor24 is offline  
 
post #14 of 18 Old 4th July 2019, 10:18 AM Thread Starter
smithr
Member, Sport: Off DSC: On (>50 posts)
 
smithr's Avatar
 
Join Date: Jan 2016
Location: Dresden, Germany
Posts: 98
Thanks: 2
Thanked 6 Times in 6 Posts
I'll check the fan again but I'm not expecting much, would be a nice surprise if it was that simple though. Note that I never got rid of the 8F code even with the new fan which I confirmed working at the time (old fan was also actually fine).

On the subject of the Ebox fan - the WDS diagrams show the 2Pin fan arrangement as being introduced in Sept'99, Mine is a June car, so I guess my car's not the anomaly and BMW made an error with their ETK.

Afte reading your comments in this thread Sailor (https://www.m5board.com/vbulletin/e3...ain-relay.html) I'll check battery connections again - battery was out of the car until a month ago while I was on holiday. but this new behaviour doesn't seem to relate to bumps specifically. I took a different route to work yesterday but experienced the same behaviour and codes after about the same amount of driving time and it cleared up around the same time too. Thinking that must be temperature dependent if it's occurring in such a well defined window after cold start. Didn't do it on the way home after sitting for 6 hours. Interested to see what happens today.
smithr is offline  
post #15 of 18 Old 4th July 2019, 09:15 PM Thread Starter
smithr
Member, Sport: Off DSC: On (>50 posts)
 
smithr's Avatar
 
Join Date: Jan 2016
Location: Dresden, Germany
Posts: 98
Thanks: 2
Thanked 6 Times in 6 Posts
Quote:
Originally Posted by Sailor24 View Post
I would also replace the main relay
Which relay is this exactly? The DME relay? I've seen the 'Main relay' referred to frequently online but I can't find anything in the ETK or WDS that mentions anything by this name.
smithr is offline  
post #16 of 18 Old 5th July 2019, 03:55 PM
Sailor24
M5 Expert (>4000)
 
Sailor24's Avatar
 
Join Date: Oct 2010
Location: Cobourg Ont
Age: 57
Posts: 9,751
Thanks: 986
Thanked 1,968 Times in 1,652 Posts
Crud my failing memory is going to bite me again. Pretty sure it is most often refereed to as terminal 30, but maybe it is terminal 15, which my memory says is the unloader relay. It is one of the two but the best place to find it is on this page way down at the bottom.
https://www.realoem.com/bmw/enUS/par...9-BMW-M5&mg=61
Not going to guess for you because you have a 99 and they are different. Your next question will be is it the DME relay or the one called motor. Take the numbers and reference the wiring diagram the one that feeds the other is term 30 or the main relay refereed by your code.
Sailor24 is offline  
post #17 of 18 Old 5th July 2019, 08:09 PM Thread Starter
smithr
Member, Sport: Off DSC: On (>50 posts)
 
smithr's Avatar
 
Join Date: Jan 2016
Location: Dresden, Germany
Posts: 98
Thanks: 2
Thanked 6 Times in 6 Posts
I guess it can't hurt to check the relays since they're cheap.

Car was running much worse today the whole way to work and back, bad enough on the way home that I won't be driving it until I sort this.

The 2D and 36 errors keep coming back, INPA had a bit more information but I forgot to get a screen grab, will do tomorrow. Interestingly, 'Input voltage' was mid-11V to high-12V for the 2D error and ~5V for the 36 error. Assuming this would be the power to the DME.

Something that was odd though was that the 'battery voltage' reported by INPA fluxtuated between ~ 11.8V and 14V at idle. I though this was strange because test Nr 9 in the 'secret menu' shows a pretty constant 13.8V, I'd expected them to be the same. The Torque android app via bluetooth ODB2 adapter shows a constant 14V. Definitely something fishy going on with the electrics.
smithr is offline  
post #18 of 18 Old 6th July 2019, 06:21 AM
Sailor24
M5 Expert (>4000)
 
Sailor24's Avatar
 
Join Date: Oct 2010
Location: Cobourg Ont
Age: 57
Posts: 9,751
Thanks: 986
Thanked 1,968 Times in 1,652 Posts
I wrote all below, then checked it to see if my memory was tricking me and it seems it was not, but I did find an interesting set of notes on a car with a single failed diode in the alt. Then a second failed and he had the car towed to me. I replaced the alt, and it was a beast again. That is the opposite of what I said below, don't know what to tell you, the notes are similar to your car. I have no recollection of the car at all.


It has been a while, I hope my memory holds up. Basically a car has two electrical systems or maybe better described as two sides. That is how the idiot light works, it shows the balance between the two systems. The OBC basically reports the ALT voltage 90% of the time, not really the battery voltage. Yes they are connected, but.... Sorry all I can really say is but.
Without a 5 page essay explaining how things work, take my best guess as you definitely seem to have a bad connection or a shorted battery, something wrong on the battery side of the two systems.



Step one clean your terminals on the battery. Disconnect it and charge it, then read the volts after you remove the surface charge. Easiest would be to connect it again turn the lights on for 30 seconds or so, then disconnect and read the volts. Perfect battery would be 12.9 good battery 12.8, usable battery 12.6 - 12.7. 12.5 might need another charge or charged at a higher rate but likely is not really very good any more.


That is your battery test if it tests good then you need to test voltage at different locations to help find where a connection is not so good. You can't use a volt meter alone because it does not draw enough, you need something that draws power and a volt meter together.


But maybe you just need a short cut, I have lots of them. If you have never noticed any issue starting the car and it turns over strong, we can likely rule out the battery and all the wiring to the starter. But there is a connection in the right side trunk compartment when looking at the battery. That is not ruled out so loosen the red and look at it clean it bolt it back up.


Next you have to get to the starter, even though we have power to the starter there is a second wire that sits on the same bolt, that might be where the problem is. It is not uncommon place for corrosion.Then after that spot you need to check the booster terminal that is where the ALT side of the power joins to the battery side of the power.

Last edited by Sailor24; 6th July 2019 at 06:24 AM.
Sailor24 is offline  
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the BMW M5 Forum and M6 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes Rate This Thread
Linear Mode Linear Mode
Rate This Thread:



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome