Z3 Throttle Issue and Question

[Nippon Roadster]

Good day to you all! Currently working in Tokyo and I got ahold of a Japanese 2000 Z3 2.0, I believe the code is a GF-CL20. It has the 2.0 straight six. The car was behaving itself just fine up until a month or so ago. When I start it she idles just fine however when you give her any gas the RPM will only go to about 2-3k and she starts to bog down. My first thoughts where fuel filter, MAF sensor, and maybe a sticking throttle body. Today I pulled the airbox out and all the ducting to the throttle body, the engine was decently clean only having 60k kms on it. While doing so I found a badly damaged vacuum line, so I replaced that thinking that may have been the source of my problems but no improvement. While testing the vacuum line I noticed that the throttle body was not opening while my wife was giving it some gas, and I could not get the butterfly to open by hand, the cable and actuator will turn but no movement on the butterfly. All air seems to be getting sucked in by a secondary line off the throttle body (I'm guessing its some sort of Idle bypass?). This is my first BMW so I am a bit new to German engineering. Has anyone else seen this or can point me in the right direction? Should the throttle be opening or am I missing something?

Regards!

 

[kyrix1st]

Greetings. Also from JP

Have you read the error codes with INPA?

Is this particular throttle by wire or electric? I remember my M54B30 Z4 being electric...

 

[Steve Medlock]

https://zroadster.org/threads/idle-control-valve-query.23380/ Post No. 5

 

[jaguartvr]

I had exactly the same symptoms and it was the throttle flap. Remove the air filter, maf and pipework until you can see the throttle flap sitting in the air intake pipe and give it a sharp tap with a bit of wood. Make sure it can open. Hopefully, that will cure the problem.

 

[FRANKIE]

Good day to you all! Currently working in Tokyo and I got ahold of a Japanese 2000 Z3 2.0, I believe the code is a GF-CL20. It has the 2.0 straight six. The car was behaving itself just fine up until a month or so ago. When I start it she idles just fine however when you give her any gas the RPM will only go to about 2-3k and she starts to bog down. My first thoughts where fuel filter, MAF sensor, and maybe a sticking throttle body. Today I pulled the airbox out and all the ducting to the throttle body, the engine was decently clean only having 60k kms on it. While doing so I found a badly damaged vacuum line, so I replaced that thinking that may have been the source of my problems but no improvement. While testing the vacuum line I noticed that the throttle body was not opening while my wife was giving it some gas, and I could not get the butterfly to open by hand, the cable and actuator will turn but no movement on the butterfly. All air seems to be getting sucked in by a secondary line off the throttle body (I'm guessing its some sort of Idle bypass?). This is my first BMW so I am a bit new to German engineering. Has anyone else seen this or can point me in the right direction? Should the throttle be opening or am I missing something?

Regards!

I wish I could give you some information regarding this. I have a '96 1.9L engine and perhaps not the same setup as yours. I never had any problems yet with it and have not had to deal with the throttle body. I am concerned with your saying that you couldn't get the butterfly open by hand. I have worked with throttle bodies on other cars and pick-up trucks. What I can't recall is if you have to disconnect any cable linkage to move the throttle body by hand. I don't know what kind of actuation exists on a throttle body that is electrically operated. However, no matter which type it is, you should be able to disconnect the connection that opens and closes it. I'm not even sure if you need to disconnect anything to move the butterfly. But whatever the case, once the linkage is disconnected you should be able to move the butterfly. This is the only way you can really tell if there is carbon build-up interfering with its movement. On a few occasions, I have been surprised on how relatively clean a throttle body looks from the outside only to find out just how sticky it is from carbon build-up on the inside. There can be a build-up on the wall of the throttle body preventing the butterfly from moving past a ridge of carbon or/and a build-up of carbon on the pivot pins of the butterfly that extend through the wall of the throttle body. You can't really know or see this completely until you physically can move the butterfly by hand without it being attached to anything else. As you may know, there are products available specifically for cleaning the throttle body (labeled "Throttle Body Cleaner" (a spray can)). Sometimes they can be so dirty, you have to remove them completely from the engine to clean them properly.. Let me know how you make out. There are others on this forum that can give you better detains on your car. Perhaps @t-tony will respond to this also. I think he's busy right now showing his boss his now "smiley" shirt he got on his hols or stashing away his goodies (inside joke)......................Frankie

 

[NZ00Z3]

I too have a CL20 Z3. The throttle body is a mix of electronic control and accelerator wire control. The electronic control is master, this means that the accelerator wire control has a loose connection to the butterfly. The electronics have various safety routines e.g. If the electronics does not know were the butterfly is (faulty position sensor), it will not allow it to move. This sets a error code in the engine computer (DME).

The idle control valve (ICV) is as you have suspected a bypass system and controls the rev's up to around 2,500 rpm. The throttle body starts coming in around 2,000 rpm.

Here are a couple of things to look at:
- The butterfly may be stuck in place with carbon/oil. Give it a good spray with carb-cleaner or similar solvent to get it moving.
- You may have a faulty throttle body. Buy another throttle body

The advice about getting a good scanner is a great idea, as there could be throttle body error codes that could guide you in your repairs.

 

[Nippon Roadster]

Wow! Just got home from work. Thank you for all the replies. I suspected the throttle may have an electronic element to it as one side has a big black box connected to it. Should I still be able to move the butterfly by hand or is there a solenoid that prevents this? It's raining at the moment so I probably wont be able to tear back into it until this weekend. Also looks like I need to get a set of Torx sockets if I need to remove the entire throttle assembly. I will update when I make some progress.

 

[jaguartvr]

You should be able to move the butterfly by hand or by using a stick as it's quite hard to get to. Mine wouldn't move at all but a sharp tap with the stick and it broke loose. Quick clean around the edges and the problem was solved.
I didn't remove the whole assembly.

 

[Nippon Roadster]

Update: So I got the throttle butterfly freed up, gave it a little tap and it popped open. I sprayed it with some cleaner and cycled it by hand a few times using the spindle the cable is connected to. I started her up and everything seemed sorted out, got her to rev up around 5k where she was bogging at 2k before. I put everything back together to go for a test drive and as soon as I backed out of the drive way the EML, traction control light came back on and I was back to bogging down around 2k. Seems like I'm back to square one. Any suggestions?

 

[jaguartvr]

Sounds as if it is still sticking. Mine was sticking at the edges. Can you get someone to press the throttle while you have your hand on
the butterfly?