'03 3.0 Lumpy Idle & Sucking Noise (CCV Been Replaced) HELP!

[dazparki]

Hey all,

Really need some help trying to figure out what to do next on our Z4...

I've had the car a month or so. It has been stood for the best part of 2 years and we are trying to get it up and running and roadworthy.

The Fault

When the car fires up, it has a rough idle and has a SUCKING NOISE. Sounds like the car is struggling to breathe. Occasionally, when revved, it may cut out before it has chance to return to idle. It is hesitant around 3,000 rpm.

So far we have...

[*]Replaced the CCV and every hose that goes with it - All new and genuine parts
[*]Replaced temp sensor while inlet was off
[*]Had a full diagnosis by an auto electrician and has confirmed MAF is working fine and all fuel pressures are okay
[*]Visual check of DISA valve as well as auto electrician confirming operation

Video



Next Move?

[*]DISA Valve
[*]Throttle Body
[*]CAT

Has anyone had this problem before? It's the removing of the oil cap which is confusing us the most.

Thanks,

Darren

 

[parky]

Anyone any ideas on this?

 

[simonlpearce]

Spray some carb cleaner around the intake tubes and listen for changes to the engine note. Sounds very much like you have a vacuum leak, most likely from a split intake boot between the MAF and TB. Would also be worth taking out the ICV and giving it a good clean to rule that out.

 

[dazparki]

All pipes have been checked, replaced and ICV has been thoroughly cleaned with carb cleaner

 

[simonlpearce]

Did you remove the pipes to check? If not then do it again.

Have you checked all the breather pipes into and out of the intake manifold are attached properly? Also have you checked all the plugs are properly tight?

 

[parky]

Its been full stripped down and all put back together with brand new parts, a full ccv pipe kit from bmw. Iv sprayed carb cleaner all over and it makes no difference...there is definitely no air leaks and all pipes and hoses are new

 

[toolmanchris]

Daft question but I take it you have checked the air filter box is on properly and that the intake pipe and air filter are not blocked?

 

[parky]

I have yes. There all spot on. Its got to be something or nothing. It seems to be throttle related. I say that because when you press the throttle a little bit it struggles and sometimes cuts out but if you floor the throttle it revs up although hesitant at first...driving me mad lol

 

[parky]

Im thinking next, lambdas, throttle body, disa valve. Iv done the test on the disa valve how it shows on line and its working fine although wether the electrical side of it is i dont know.. is thete a throttle switch at the pedal?

 

[parky]

Also need to bare in mind thats its rich as the plugs are getting black soot on them. Theres no smoke from the exhaust andniv had a fuel pressure test and comoression test done..the only codes were po171 and po174. ..running lean on bank 1 and 2

 

[toolmanchris]

Might be worth cleaning the MAF sensor (make sure you use the proper stuff not brake cleaner as its easly damaged)

I follow this guy on YouTube and like his style, take a look at this page for Idle issues, it may help

http://www.ericthecarguy.com/faq/solving-automotive-idle-problems?start=2

Chris

 

[parky]

Ill have a look...cheers

 

[Z4M-2006]

Is there still vacuum in the crankcase?

 

[maxman]

If the car was running ok before it stood for a while, it could be linked to fuel.
Old petrol, fault in fuel line or tank, petrol cap?

 

[parky]

Is there still vacuum in the crankcase?

How do i test this ?

 

[Smartbear]

pull open the oil filler cap whilst the enging is running, the vacuum will try & keep the cap from being pulled open-if you cant open it with 2 fingers it points to excessive vacuum & possible breather/ccv issues
regards

 

[parky]

If the car was running ok before it stood for a while, it could be linked to fuel.
Old petrol, fault in fuel line or tank, petrol cap?

Its had fresh fuel in and a pressue test but iv not checked the fuel cap so i will look at that tomorrow.

I dont know if the car was faulty before it was parked up, the woman i bought it from said it was fine but who knows :-/

 

[parky]

pull open the oil filler cap whilst the enging is running, the vacuum will try & keep the cap from being pulled open-if you cant open it with 2 fingers it points to excessive vacuum & possible breather/ccv issues
regards

no thers no suction when the cap is removed..all the ccv pipes are new and just been replaced

 

[Smartbear]

Sounds like your problem then, there should be a vacuum withing the engine that you can feel whilst opening the filler cap-you mention new pipes, what about the valve itself?

 

[parky]

Sounds like your problem then, there should be a vacuum withing the engine that you can feel whilst opening the filler cap-you mention new pipes, what about the valve itself?

There was a valve in the kit. Its a black thing with 3 pipe connectors on it? Is that the valve?