e30 m40 batuk batuk

[rockonla]

hello, my m40 e30 seems to be choking abit lately, prolly the AFM punya kerja. rev goes up and then down again sometimes, engine idle also tak stabil. anyways, is there anything i could do to manage this? im planning to see if i could do it myself before sending it to the workshop. thanks!

 

[evilnickwong]

The times my M40 had the coughs, it was either:
1. AFM sticky/dirty - remove and clean the insides with throttle body cleaner.. make sure the flap swings in its full range smoothly
2. ICV sticky/dirty - remove and clean with TB cleaner as well. some sources said don't clean with WD40 or anything else with lubricating properties as the flap is supposed to have a certain amount of resistance
3. Vacuum leak - this one should be fun i guess check all rubber hoses, especially the big one from AFM to TB, make sure nothing is unplugged where it shouldn't be also

 

[rockonla]

thanks dude, but do u know where i can view to help me do this DIY? thanks. been looking online but to no avail. sigh

 

[evilnickwong]

For AFM, it's quite simple:

1. Unclip the 4 catches on the airbox
2. Loosen the metal clip on the AFM, then disconnect the electrical connector (unscrew and pull out)
3. Pull AFM + upper airbox together out of the rubber bellow (that leads to the TB)
4. Inside the upper airbox, you'll see 4 nuts holding the airbox to the AFM, remove these
5. With the AFM on its own, you can see the flap inside. The flap might be dirty, or the chamber itself is dirty causing the flap movement to be sticky. Clean it up with TB cleaner.
* Watch out for the sensor in the front entry of the AFM, avoid spraying it with the cleaner if possible
6. Installation is the reverse


For the ICV, I haven't done it myself, but it's a T-shaped valve with hoses connected to it. For M40, I think it's between the manifold and firewall, abit hard to reach. If you can get it out, just clean it with toothbrush and TB cleaner.

This is what it looks like:

Plenty of ICV DIY guides to give you an idea, altho none are for M40, so the hoses arrangement and location are diff:
http://www.google.com.sg/search?q=b...s=org.mozilla:en-US:official&client=firefox-a


For vacuum leaks, I'd just visually inspect everything closely for leaks. You can spray carb cleaner on places you think might be leaking and if the engine settles down, that place is probably leaking. But I haven't tried this before, sounds messy.