Smoke machine vac leak diagnosis?

[Russianblue]

My current M54 runs perfectly other than an annoyingly low idle. I've had it checked for vacuum leaks but not sure they caught them.

It's not really throwing any codes, it just idles like 100-150 rpms lower than normal, probably around 600, at least compared to my previous M54, and there is a slight vibration with it that causes every manner of RATTLE inside the cabin. Door panel rattle, sunroof panel rattle, dash rattle. The rattles are small and irregular. Not everything rattles at the same time. And not all the time. The vibration is really pretty slight.

If I hold the brake and press the gas and get the idle up by 100rpms, the rattles disappear completely. There are ZERO rattles in neutral and park.

I do have a smoke machine but have never used it. What would be the best procedure to check for vac leaks with a smoke machine which would cover all potential problem spots?

[EODguy]

Don't forget that rattling at lower RPMs can also be worn motor, transmission mounts or in some engines (can't remember which) harmonic balancer issues.

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[andrewwynn]

Adjust your idle up. I used my foxwell 510. Usually boost of 60-80 is enough to get rid of the red light in drive shakes. Car idled perfectly fine in neutral but shook enough I would put in neutral pretty regularly at red lights.

[timmyc]

I use a rubber glove over the oil filler hole. Cut a tip of a finger off and tape the hose onto it, then rubber band the glove to the filler neck. Good luck!

[workingonit]

Originally Posted by andrewwynn

Adjust your idle up. I used my foxwell 510. Usually boost of 60-80 is enough to get rid of the red light in drive shakes. Car idled perfectly fine in neutral but shook enough I would put in neutral pretty regularly at red lights.

+1...
from another thread

Originally Posted by workingonit

I used my Foxwell NT510 Elite scan tool to change my idle speed, raising it by 50 rpm. I had thought that a little more rpms in the hottest weather would help with the A/C temperature inside, while sitting stopped at a light, but discovered that I didn't have the center vent setting to full cold, so that adjustmentt wasn't needed. I returned the idle to normal. Easy peasy.

Since then, a year ago, I've noticed an interior rattle, when sitting at a light, occasionally. It's to be expected on a 23-y.o. vehicle. But, I'm going to raise the idle again, anyway, just to see if the infrequent rattle goes away. It might just work.

Re: Smoke machine vac leak diagnosis?
I've got a decent smoke machine, but the rubber glove trick (over the intake tube, in my test) didn't work, as my gloves kept tearing (medium size, 4 mil thickness) and leaked all the smoke out at that point. So, last week, I bought an AutoLine Pro Universal Bladder Adapter for $25, from Amazon, and will use that device to test with next time. It should do the trick. I may or may not have a vacuum leak, which so far, I've been hunting since October 2021.

[Effduration]

I would measure your short and long term fuel trims first... to see if you have a lean condition.

You can do it in INPA while the car is running and driving, but I use OBDfusion (phone app) with a wifi OBD2 reader...I learned this all over at E46fanatics...
Here is one of several good threads over there:
https://www.e46fanatics.com/threads/obd-fusion.1240733/

Once I determine I am running lean - which means more than +10% (-10% would indicate it is running rich) on long term fuel trims I will break out the smoke tester - stinger model that I use with an air compressor.

I am not quite expert on smoke testing, but I am trying... I remove MAF and cover the rubber intake boot with a 7 or 8ML rubber glove and introduce smoke for at least 10 minutes in several areas including intake hose, oil fill, dipstick, and brake booster.

[Russianblue]

Originally Posted by andrewwynn

Adjust your idle up. I used my foxwell 510. Usually boost of 60-80 is enough to get rid of the red light in drive shakes. Car idled perfectly fine in neutral but shook enough I would put in neutral pretty regularly at red lights.

Sweet! Just ordered the Foxwell. Been meaning to do that for years. Keeping a laptop updated is just unsustainable.

I'll try with the smoke machine trick as well. Really curious to see if I can find anything.

[andrewwynn]

It's never a bad idea and idle has the most vacuum but I don't think I'd mess with idle much. I just know I needed to bump both our e53 up a bit before idle waa smooth in drive not moving.

[Russianblue]

does the NT510 really take like 5 minutes to "Quick Scan" all the modules? Looked that way on Youtube....and I thought BMW Scanner was slow. I haven't opened mine yet and would consider returning it for an upgraded model if the scan speed is faster.

Are some scanners faster than others based on the power of the Scanner itself or is everything limited by the early 2000s processing inside the OE BMW modules ?

[EODguy]

Originally Posted by Russianblue

does the NT510 really take like 5 minutes to "Quick Scan" all the modules? Looked that way on Youtube....and I thought BMW Scanner was slow. I haven't opened mine yet and would consider returning it for an upgraded model if the scan speed is faster.



Are some scanners faster than others based on the power of the Scanner itself or is everything limited by the early 2000s processing inside the OE BMW modules ?

It does take a little while but to be fair almost all the "fast" scanners aren't bidirectional and if you consider the startup and loading of your laptop it's the same. The only real difference is that you can keep the Foxwell in your X5 no matter the weather, unlike laptop based systems.

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