Strange idle vibrations

So I've already had my local indy shop look at my car to see if these vibrations were a big issue and they told me I shouldn't have any problems and that I should come back if it gets any worse. It only happens when I'm braking at a red light or a stop sign in drive or reverse. So it doesn't happen when I'm in neutral or park.

Basically there are two areas I will feel vibrations depending on what the idle speed is. My e46 will idle around 800-900 rpm @ cold start and the vibration can be felt from the steering wheel and center of the car.

When my engine warms up, the idle speed goes down to ~550-600 then I start feeling the vibrations along my drivers side door panel (Im assuming that the vibrations are propagating along the outer edge of my e46 at this point).

It's really strange, and my local indy couldn't tell me what it was. They looked at the exhaust, brakes area, felt the engine, looked under the engine, and couldn't give me an answer.

Any ideas?

Check vac lines and check your state of 'tune'--plugs, filters, oil...check pulleys/belts...lower intake boot. Read jfoj's sig file on 'misfires' and look around for other vac lines/hoses--especially the line from brake booster.

Maybe clean icv and tb...replace 0-rings/gaskets/grommet (for icv) while the getting is good.

Get under your cabin air filter housing in back of intake manifold to find some of the hoses that might be of issue. I'm feeling the brake booster, but it could be any number of things.

hth

Also check your engine mounts.

Originally Posted by dmax

Check vac lines and check your state of 'tune'--plugs, filters, oil...check pulleys/belts...lower intake boot. Read jfoj's sig file on 'misfires' and look around for other vac lines/hoses--especially the line from brake booster.

Maybe clean icv and tb...replace 0-rings/gaskets/grommet (for icv) while the getting is good.

Get under your cabin air filter housing in back of intake manifold to find some of the hoses that might be of issue. I'm feeling the brake booster, but it could be any number of things.

hth

Thanks guys, I will check these things out. I really wish my BMW was smart enough to tell me what the cause was on its own, guess you can't have a sensor for everything.

Sounds like an engine mount is bad to me.

Originally Posted by WDE46

Sounds like an engine mount is bad to me.

Actually I asked BMW of Anchorage if they've heard of common or similar issues to mine. He said that because "we" lived in Anchorage, Alaska the highest octane offered is 90 (I already knew this). Apparently, not all 90 octanes are the same quality. I fill up my e46 on Costco premium 90 octane and I guess that's the worst here. The BMW technician recommended that I fill up on Chevron 90 octane fuel. I will try that on my next fill up.

Originally Posted by chickenalfredo

Actually I asked BMW of Anchorage if they've heard of common or similar issues to mine. He said that because "we" lived in Anchorage, Alaska the highest octane offered is 90 (I already knew this). Apparently, not all 90 octanes are the same quality. I fill up my e46 on Costco premium 90 octane and I guess that's the worst here. The BMW technician recommended that I fill up on Chevron 90 octane fuel. I will try that on my next fill up.

I'm not sure if they are a gimmick or not, but you can buy octane booster. Add some of that and see if it smooths things out. I think they might be a legitimate product. 90 octane should be fine anyway though. The engine will just change the valve timing to compensate for lower/higher octanes.

Unfortunately you like in a VERY severe climate at times.

It sounds like your idle my be a bit low?

Rubber shrinks and gets very hard in the low temps you probably live in.

Also suggest if you can find someone with scan tool to check your fuel trims to see what is going on this my yield some clues?

Suggest you check the first link below in my signature for more info and since you live in a very cold location at times, I would be very careful with the "orange sludge" and the CCV system.

So I know I asked about this awhile ago, and I tried looking for the cause by myself but I still am not sure. I should mention again that the vibrations vary either felt from the center front of the car (center console/steering wheel/dashboard) or the front drivers door and front passenger door.

The vibrations are mostly felt only when the car is in drive or reverse when braking. When i'm in neutral or park, the vibrations are 1/10 of whats mentioned above, very insignificant, where I can barely feel it.

I would describe the drive/reverse vibrations as the "low" setting on a back massager, maybe even less than that. I'm thinking its the motor mounts as Solidjake has mentioned. I'm thinking about paying BMW $120 to diagnose the vibrations. Do you guys think it would be better to just pay the $320 at my local indy to just have the motor mounts replaced without getting a diagnostics by BMW?

Again, thanks for all the advice and help guys! Appreciate it.

Originally Posted by Solidjake

Also check your engine mounts.

I have experienced exactly what you are talking about, OP. Also, the same thing in 2 other e46s that I know. All of them were fixed with new OEM motor mounts. In fact, the worst e46 had his motor mounts completely broken in half! My idle went from back massager at stop lights to silk again. For around $80 and 2 hours of your day, you can't go wrong! Don't forget new nuts!

No codes?

Don't you have to pull out the engine to replace the two mounts? By the way, because my BMW is an xi (automatic) just the parts alone are ~120-130 online.

@heechkass Nope! Car runs great in every other area. The vibrations are annoying at worst.

You don't have to pull engine out to change mounts. There are plenty of how to on the web.

Originally Posted by chickenalfredo

Don't you have to pull out the engine to replace the two mounts? By the way, because my BMW is an xi (automatic) just the parts alone are ~120-130 online.

@heechkass Nope! Car runs great in every other area. The vibrations are annoying at worst.

Sorry. I overlooked that. Yes, the parts are a little higher but will still be worth it. Just as heechkass said, there are many. Just look up RWD ones and follow those. Just the passenger side will be a bit different but you will see how it's done once you're in there. This will give you a chance to check your pulleys and water pump since you will have the fan off already. Good luck!

Originally Posted by ClaytonL

Sorry. I overlooked that. Yes, the parts are a little higher but will still be worth it. Just as heechkass said, there are many. Just look up RWD ones and follow those. Just the passenger side will be a bit different but you will see how it's done once you're in there. This will give you a chance to check your pulleys and water pump since you will have the fan off already. Good luck!

Will it require more steps if I decide to change out the transmission mount as well? Should I replace the transmission mount?

Thanks ClaytonL

I believe the transmission mount will have to be cut out. Not a simple swap like the RWD. Not 100% sure on this one. Maybe someone with an xi can help out more.
If this were me, I would just replace the motor mounts with OEM and see where you are at from there.

A couple of tips I remembered, don't skimp on removing the radiator fan or cabin air filter. The engine WILL be lifted a couple of inches. Do passenger side first.

Originally Posted by ClaytonL

I believe the transmission mount will have to be cut out. Not a simple swap like the RWD. Not 100% sure on this one. Maybe someone with an xi can help out more.
If this were me, I would just replace the motor mounts with OEM and see where you are at from there.

A couple of tips I remembered, don't skimp on removing the radiator fan or cabin air filter. The engine WILL be lifted a couple of inches. Do passenger side first.

Cool! Thanks. I guess when I first thought about this DIY, I thought about the chance of getting smushed by my engine and didn't want to do it. I'll look more into it.

I'm still stuck on your low idle...500rpm is low!! You may have other things going on as well.

So although. given the age of the car, you may need new bushings all around (Motor mounts, tranny, and differential)....your car may need other things. Just give it a good look when you're in there next time. This is the main reason I work on my own cars... To be able to check other parts and PM it.

Originally Posted by heechkass

I'm still stuck on your low idle...500rpm is low!! You may have other things going on as well.

So although. given the age of the car, you may need new bushings all around (Motor mounts, tranny, and differential)....your car may need other things. Just give it a good look when you're in there next time. This is the main reason I work on my own cars... To be able to check other parts and PM it.

Well it's sometimes at 500 rpm idle and sometimes around 800 rpm idle. Just whatever the car feels is most efficient? Remember my car is in Anchorage, Alaska.

coils