Split hose search advice

P

Phil-E30

Active member
Afternoon all,

Going out to have a hunt for the issue causing my secondary air flow error code and acceleration hesitation.

I've checked that the black pump works on cold start, and it does, coming on after a few seconds. Therefore I want to check for split hoses and vacuum leaks.

It'd be great if anyone had any suggestions on which hoses to check as good starting points. Just tell me where they are in the engine bay and I'll have a good look!

Thanks
 
take iit you alreadychecked for the main air intake manifold from the air box right through to the throttle body?
that hose part from the MAF to the TB is notorious for splitting at the Y section.....
 
Chris_D said:
take iit you alreadychecked for the main air intake manifold from the air box right through to the throttle body?
that hose part from the MAF to the TB is notorious for splitting at the Y section.....
Click to expand...
Not like that on the S54 Chris.

Phil,
There's only one pipe really from the secondary air pump (circled in blue), so obviously check that. It's been some time since I've fiddled with it but from recollection it connects to a valve (circled in red). Pull it off from there and check the pump is actually doing anything would be my first starting point.
BMW_S54B32_Engine_Ink_LI.jpg

What is the acceleration hesitation you are referring to? When cold, all the time, etc?
 
Thanks Tom, I'll take that hose off and check the pump is doing its job. I also wondered if the valve may be faulty but was unsure how I'd know if this was the case. I really need to get the BMW diagnostic software for the car laptop.

As for the acceleration hesitation, it's pretty much all the time. I plant my foot, it takes a couple of seconds to react and then I can feel the car come to life. It's possibly more pronounced when cold.

Only error codes I've got from my generic reader point to secondary air system.
 
Phil-E30 said:
Thanks Tom, I'll take that hose off and check the pump is doing its job. I also wondered if the valve may be faulty but was unsure how I'd know if this was the case. I really need to get the BMW diagnostic software for the car laptop.

As for the acceleration hesitation, it's pretty much all the time. I plant my foot, it takes a couple of seconds to react and then I can feel the car come to life. It's possibly more pronounced when cold.

Only error codes I've got from my generic reader point to secondary air system.
Click to expand...


Hmmm, that's pretty odd. Not really heard of that symptom before, sounds quite severe :( .
Secondary air pump does nothing after a couple of minutes really so perhaps it's a red herring :?
I think you can check if the valve is working or not by blowing through the hole (where the secondary air pump would blow through) on cold start up, from recollection it alters the revs but I've had a couple of beers and may not be thinking straight :D
 
This explains it all better Phil... It could be that the check valve has gone bad leaving it open all the time?
http://www.bavauto.com/newsletter/2008_n408_newsletter.pdf#page=6
 
A hose had split on my z4 causing air ingress it was the small rubber one at the back on the intake side.
 
goon said:
A hose had split on my z4 causing air ingress it was the small rubber one at the back on the intake side.
Click to expand...

Mine too, with consequent misfire.
 
TomK said:
This explains it all better Phil... It could be that the check valve has gone bad leaving it open all the time?
http://www.bavauto.com/newsletter/2008_n408_newsletter.pdf#page=6
Click to expand...

Thanks Tom, that's really useful actually. I will do a bit of diagnostics today if I have time. I also need to try and get the BMW diag software downloaded. I hope you enjoyed the beers last night :thumbsup:

Cheers Goon & Z4MC, I will double check a few more hoses. I did a quick check spraying water onto potentially problematic hoses yesterday and didn't find anything alarming.
 
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