2004 Z4 3.0i Intermittent no Start

[Dynamics99]

Hi,

I bought an '04 Z4 3.0i with around 92k miles. Cosmetically good. Mechanically it needs maintenance like belts, pulleys, ofhg.No biggie since I do it myself. This is my 2nd Z4 also. Last week the car started but after 20 mins that it was turned off the engine would not start.All the lights, radio, climate, headlights worked. I had to wait close to 10-15 mins for it to finally start. I figured it would be the ignition switch so I took the one from my first Z4 and swapped it over since my first Z4 always started and it's sitting at 135k miles. Now the same occurrence is happening where sometimes it likes to start and sometimes I get nothing. Of all the times I hear the fuel pump priming so I doubt its the pump. The battery has been tested and its good to go. Now I'm thinking if it isn't the ignition switch can it be the starter? Today the car started in the morning and evening. Now its night time and it wont start. How would I go about diagnosing her? Shame my first Z4 put me through issues but she never left me stranded.

Also I have the Z4 trifecta lights: TPMS, Brake, and traction with the triangle icon which are all lit as yellow. I did get a fault for steering angle sensor not plausible and lateral acceleration sensor which reads 2.04 when the car is turned off. Believe its supposed to read 0 G's. I think INPA won't let me calibrate the SAS unless the engine is started since I do not see an option to calibrate with just ignition on. Any ideas?

[Clearancediver]

Check your cold battery voltage and also when running. Rule out battery/voltage regulator.

Check to see that your battery cables are properly tightened etc. Check to see if the BST has blown and is only making a partial connection.

Then check your engine grounding strap.... if it's deteriorated it may not be allowing sufficient voltage to start... although it will power your headlights etc....

When it doesn't start add an addition ground (google how to do it) and see what happens.

At this point you should have ruled out an electrical reason for your intermittent starting problem.

[Dynamics99]

Originally Posted by Clearancediver

Check your cold battery voltage and also when running. Rule out battery/voltage regulator.

Check to see that your battery cables are properly tightened etc. Check to see if the BST has blown and is only making a partial connection.

Then check your engine grounding strap.... if it's deteriorated it may not be allowing sufficient voltage to start... although it will power your headlights etc....

When it doesn't start add an addition ground (google how to do it) and see what happens.

At this point you should have ruled out an electrical reason for your intermittent starting problem.

Okay, So I checked the cold battery voltage and its pumping out 12.7. If it cranks/starts the voltage rises to 14.3-14.33. Battery cables are tightened and they won't wiggle free. I looked at the starter today and saw the positive power cables nut 12mm was loose and allowed a lot fo play for the cables. Tightened it and still have the intermittent no start issue. Checked the BST and it's not fired so the cable is fine. Replaced the ignition switch with a new one today. I'm leaning towards a failing starter. What do you think?

[Cuervo1416]

Sounds like a similar issue I had not long ago. I would turn the key and only hear 1 click, it would happen sporadically. I looked into similar things and the issue still continued. Finally, I got stranded at Target where my wife and I had to push start the car. I changed the starter the next day and haven't had an issue since..My car only has 29K miles...

[Clearancediver]

Outside of the grounding strap being ...so so.... which you haven't checked, changing the starter would be my next step. Doing it yourself is relatively inexpensive.

I changed mine without removing anything except the air intake stuff from the air filter back to the engine/idle control valve... It was relatively easy. I have normal sized hands and you already have said you were in there tightening starter cabling.

Out of curiosity I googled starter failure symptoms here....

https://www.google.ca/amp/s/repairpal.com/starter.amp

Just for info on common starter issues.

[Dynamics99]

Hi everyone,

Got stranded at the supermarket. I got frustrated so my friend drove me home and I grabbed the replacement starter and replaced in 1 hour. Easy to take out and easy to put back in. Starter cost me $60 and it fired right up. Happy days

Now I have to diagnose the Z4 trifecta lights: tpms, traction, and brake light. Getting steering angle sensor inplausible, lateral sensor accelartion electrical faulty.

How do I do about diagnosing this from INPA?

[Clearancediver]

I have INPA software as well but it's been awhile since I used it.

It's not that difficult to drill down to where you read and clear error codes. I would do so and clear the error codes and then take your ride for a drive to confirm no further starting issues and see if error codes reappear.

Those particular error lights/codes have a tendency to show up with low voltage... or when you disconnect something and battery wasn't disconnected. So first step is to clear codes and see what pops up... if anything....during your drive.

Diagnose from that point onwards.

[Dynamics99]

Originally Posted by Clearancediver

I have INPA software as well but it's been awhile since I used it.

It's not that difficult to drill down to where you read and clear error codes. I would do so and clear the error codes and then take your ride for a drive to confirm no further starting issues and see if error codes reappear.

Those particular error lights/codes have a tendency to show up with low voltage... or when you disconnect something and battery wasn't disconnected. So first step is to clear codes and see what pops up... if anything....during your drive.

Diagnose from that point onwards.

Hi Clearancediver,

I tried to recalibrate my steering angle sensor. Now when I read the lateral acceleration sensor it is showing 2.04G's when the car is not moving. How would I go about diagnosing it or recalibrating it? Should I swap the sensors? I have another Z4 that's collecting dust but no sensor issues.

[tomjonesBT33]

Sounds like your lateral acceleration sensor is bad. Sometimes folks call it a yaw sensor. It’s located in front of the passenger seat on the floor under the carpet. The sensor went bad in my ‘04 E85. I replaced it with a used one, reset the errors and it solved the trifecta light problem. Also sounds like your steering angle sensor may be bad. Can you communicate With and get a Reading from your steering angle sensor? If not then it’s probably bad too.

[Clearancediver]

I'm going to go with what TomJones suggests.... but start with switching yaw sensors between current/other Z4 to see if that makes a difference in readings.

Just disconnect batteries prior to disconnecting sensor(s) so you don't induce error codes.

I can't help you with steering angle sensor issue as I've not dealt with that issue personally.

[Dynamics99]

Well,

Swapped the sensor from my other Z and before swapping it the yaw sensor on the trifecta Z was covered in white substance. Most likely water damaged. The trifecta lights went away after swapping the sensor. The part numbers are the same. I drove around and I felt the vehicle drive and decel better Will look into ordering a used sensor so both the Z's work. Will probably dive into the steering angle sensor issue as I havent scanned the codes after swapping the sensors.

[Clearancediver]

Clear the codes and see if anything comes back...only the codes that reappear..if any ...are valid.

[Dynamics99]

Originally Posted by Clearancediver

Clear the codes and see if anything comes back...only the codes that reappear..if any ...are valid.

Thanks, ClearanceDiver! I have a question. I got an LCM module with the rear fog light button. In addition to recoding the LCM(Vin, algorithm match) what else do I have to do to fully activate the rear fog lights? Whenever I turn the ignition on I see the yellow is for rear fogs.

[Clearancediver]

That is best answered by someone more versed with coding.

However if you have the rear fogs wired up and functional with the error light coming on for the rear fogs.... you may be able to code the error light to stay off.

You will need to read up on NCS Expert and the use of NCS Dummy to change the file associated with the light module ....

Best download the pdf files associated with their use and read...

I would also start a google search on the rear fogs...

Try something like.... code z4 rear fog warning light off....

https://www.google.ca/search?q=code+...;client=safari

Lots of info there....

[Dynamics99]

Originally Posted by Clearancediver

That is best answered by someone more versed with coding.

However if you have the rear fogs wired up and functional with the error light coming on for the rear fogs.... you may be able to code the error light to stay off.

You will need to read up on NCS Expert and the use of NCS Dummy to change the file associated with the light module ....

Best download the pdf files associated with their use and read...

I would also start a google search on the rear fogs...

Try something like.... code z4 rear fog warning light off....

https://www.google.ca/search?q=code+...&client=safari

Lots of info there....

I took a leap of faith and swapped over to the Euro LCM unit. I changed the algorithm to the partial match since it was the closest to my US LCM unit. Coded in the VIN and mileage. Tamper dot did not exist after that. Did give me errors for rear fogs electrical faulty. Will open her up this weekend to see if the rear taillights are wired up for the rear fogs. Although the Euro LCM did activate my front headlights and foglights my rear lights and side markers failed to turn on. Interesting. For now I swapped back to my US LCM so I can drive in the night if needed.

[Clearancediver]

When I got my INPA software some years ago... there were a number of other programs that came with it... one was for coding of the LCM module... was able to turn on/off daylight running lights etc as well as code out error light activation by selecting if I wanted them active or not.

You might do a google search for current existing stand alone programs for coding.

The gentleman (UK Z4 Site)who provided me the software etc went dark about 5 years ago. Think he got some sort of cease and desist order.

[Dynamics99]

Originally Posted by Clearancediver

When I got my INPA software some years ago... there were a number of other programs that came with it... one was for coding of the LCM module... was able to turn on/off daylight running lights etc as well as code out error light activation by selecting if I wanted them active or not.

You might do a google search for current existing stand alone programs for coding.

The gentleman (UK Z4 Site)who provided me the software etc went dark about 5 years ago. Think he got some sort of cease and desist order.

Dang, rip software dude. Ordered an M cluster because I want to swap out the non-M. Got a good price on it. Will see how much work I need to put in to make it work although im expecting one or two features to not work. Barely see posts about upgrading to the Z4M cluster. There is a video on youtube but the guy disabled comments lol.