does anybody elses exhaust pop and burble?

M

mad_mackem

Member
 bristol
evening all,

just wondered does anybody elses exhaust pop and burble when revved at a standstill ? i think this might be linked to my misfire?
i recently carried out the vanos fix and all was well for 300 miles and the burble and popping dissapeared with the misfire between 1500 and 3000rpm, now after 300 miles and filling up with a new tank, the popping and burble is back as is the misfire, i couldnt believe it as i thought id fixed the problem with the vanos but it would appear not!
 
I have a 3.0 litre 2003 Z4

Are you sure you had a problem with the Vanos, i thought i did but i am not sure now. I did the vanos repair back at the start of the summer, i didnt notice a huge difference after i finished the work. I still get the burble when i accelerate and take my foot of the pedal, I think this is normal though and not anything i would worry about.

In trying to resolve my intermitant hesitation i replaced the following:

Changed Vanos oil seals
Spark Plugs
Ignition Coils
Disa valve
Cleaned the MAF with CRC cleaner
44K cleaner
DME software update at the dealer

If i am honest i would say i do still have off days with the car when it just doesnt feel quick enough (could be i am used to it now), it no longer hesitates to be honest since the software update. I think the software update evened out the acceleration throughout the range giving a more stable delivery of power than a surge, i used to like the surge but i didnt like the erratic hesitation i used to get. I have read that some people have had problems with their CCV following the vanos procedure which is making me want to swap that out also, i am thinking i will leave it alone for now.
 
i think the vanos probably needed doing anyway when i took it apart the pistons were relatively loose fit, but this misfire is starting to wind me up. before i did the vanos i took it to a local indy who stuck it on the diagnostics and it said the car was missing on 4 5 and 6 , so we cleared the faults and he said take it up in a weeks time which i did, it misfired on the way there but when on the diagnostics no faults came up which made me think it was the vanos seals. the popping doesnt bother me i quite like it, it just seems that the popping and the misfire are linked. i lifted out each individual coil pack while the engine was running and the engine note deteriorated each time i lifted off a coil pack, which makes me think all of them were fine, iv not done anything with the disa or the maf though and these may be places to investigate, how much was the software update by the way?? and sorry for the ignorance what does DME stand for?
iv also heard things that it could be down to poor fuel and that i should run it on high octane for a short while, and that it could also be a clogged fuel filter, im not sure as this is a lifetime part.
 
I believe our cars pop and burble when letting off the accelerator after revving it. Even in early reviews of the 2003 3.0i Z4 they mentioned the nice burbling which they liked.
 
The initial diagnostic of 4 5 6 misfire may be the key to your problem, it could be faulty ignition coils. You are best to let the indy take a look if he has aleady seen the car, ignition coils can act up in a number of ways. Do you have the bosch coils or the Bremi ones, i think the bremi ones had issues and were replaced by BMW under warranty. i would get the coils looked at, they may only be acting up when they are hot but they can be unpredictable.

Regarding the Disa, you can inspect it relatively easily see link below:
http://www.z4-forum.com/forum/viewtopic.php?f=30&t=12150

If you want to clean the MAF then i would use a CRC cleaner rather than anything else, also ensure that you allow it to dry before reconnecting it and starting the car.

DME is Digital Motor Electronic (basically the main ecu), I paid around £90 to get the software updated at the dealer. Incidentally i now only run my car on Super Unleaded as part of me wondered if there were some knock adaptations stored in the DME prior to the update due to crap fuel, I am now scared to go back to regular unleaded incase i get my hesitation back. When the DME is updated the knock adaptations are cleared assuming the software update was successful. I dont think the fuel filter is a lifetime part, i believe they usually need changed every 30K miles.

Lastly, you haven't said what engine you have. I know its a 6 pot but is it a 2.5 or 3.0? I never at any time got any fault codes with my car, i just didn't feel like it was running right. You problem is related to the 4 5 6 misfire, you need to get that looked at for sure. Let us know how you get on and if you get it sorted.
 
sorry iv got a 2.5i M54 engine, im going to try the few bits you ve recommended that i can do myself, ie clean the MAF and the DISA and the ICV, and run it on superunleaded for a bit see if that changes anything and then if not take it back to the indy or dealer for the update
 
Heres a link to a good you tube video for how to clean the ICV if your interested:
http://www.z4-forum.com/forum/viewtopic.php?f=34&t=20128

I dont think the MAF, DISA and ICV are the cause though, I would be happy to be wrong at least you can check em on your own before spending £££'s.
 
It readily pops back if the throttle is opened then rapidly closed with a hot engine and exhaust, whether under load or stationary. In fact, when I heard it popping and burbling at the end of the test drive, I knew I wasn't going home without it... :D
 
Oh yes :D

[youtube]cH9KsajKYks[/youtube]

Even with the standard setup I was constantly driving in lower gears around town and letting off the throttle suddenly.
 
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