7/21 update: Help whine/howling at WOT---is it my csb or driveshaft?

[Spitfi-r]

I know sound questions are hard to diagnose over the internet but any help is appreciated--the noise is pretty easy to hear on the vidoes below.

I'm getting a loud howling at WOT between ~5-6k rpm. It's noticeable on the street some, at the track (including the videos), and I just did an autocross event where you can really hear it. FYI, the mic is at the rear bumper.

Seems to be mostly second gear, it goes away after 6k rpm. The check engine light comes on sometimes for 1 or 2 seconds.

Otherwise, car pulls really well, sounds good, and runs smoothly.
**excuse the noob autocross driving**



I've heard that the TRM chips sometimes cause check lights at the higher rpms depending on the exact 3.5" MAF you use, although, I did send them the part number when I was getting my chip. No one mentioned any noise associated with the check light.

Waterpump is new, tensioner is new, belt is new. no AC, no PS, no idler pulley. Ka motors 3.5" intake

Could it be intake noise? Why the check light?

A vacuum leak?

harmonic balance problem?

Ping from my higher compression pistons?

Something with the exhaust?

Details on the car:
rebuilt 1995 M3 S50B30US head on a rebuild and overbored 1999 M3 S52B32US block 11:1 CP Pistons, 21.5# injectors, Turner underdrive pulleys, TRM chip, AC+PS deleted on AKG solid aluminum motor mounts.
Driveline: Stock g260 with 3.73 LSD.
Exhaust: Ebay Supersprint replica header to Magnaflow "y" collector to single Vibrant 2-1/2 High Flow Cat to Vibrant 2-1/2 Ultra Quiet Resonator to Vibrant Streetpower muffler.

[treff-7]

I have an obd I s52 in mine with ka motors 3.5" intake and trm chip and there is an awesome intake "noise" (more like a symphony to me) but nothing like this. To me it sounds like whistling from the exhaust. Try to slowly rev the engine up while the car is parked and see if it does this without WOT. Also try to identify where it's coming from. It seems to be very loud on the onboard camera but not that bad from the side of the track.
Hope this helps.

[brent5631]

What does your intake tract look like? Filter setup and tubes? My friend has this same issue on his s50 with 3.5 maf. I think it's a resonance issue in the intake.

[Spitfi-r]

I have an obd I s52 in mine with ka motors 3.5" intake and trm chip and there is an awesome intake "noise" (more like a symphony to me) but nothing like this. To me it sounds like whistling from the exhaust. Try to slowly rev the engine up while the car is parked and see if it does this without WOT. Also try to identify where it's coming from. It seems to be very loud on the onboard camera but not that bad from the side of the track.
Hope this helps.

Thanks I'll give that a try. Slowly R3v'ing upwards doesn't seem to cause it while driving. In fact, I don't hear it at all on the street with normal driving.

What does your intake tract look like? Filter setup and tubes? My friend has this same issue on his s50 with 3.5 maf. I think it's a resonance issue in the intake.

How does your friend's setup compare? Did he have any success in fixing it?

Most of it is pretty straight and simple. It's definitely tight between the radiator support and the start of intake, but can the engine suck enough air to whistle there?

https://picasaweb.google.com/1148940...eat=directlink

[treff-7]

i don't think it's the intake however you don't have a lot of room between the rad support and the intake of the filter. on mine i cut a piece off the bimmerworld boot and shifted everything back a few inches. also my ka motors filter came with a 45deg elbow that goes over the filter and makes it suck cold air from behind the headlight. but i have no room for shifting the maf away from the filter so i do get the CEL on high RPMs. I'll snap a pic later so you can see it.

my money is still on the exhaust. looks like you only have it on WOT and high RPM when the gas flow is the highest. i think it's way too loud on the video where you have the mic on the bumper for it coming from the front. if it was the intake it would have been much quieter. can you tell where it's coming from? front or back?

Thanks I'll give that a try. Slowly R3v'ing upwards doesn't seem to cause it while driving. In fact, I don't hear it at all on the street with normal driving.




How does your friend's setup compare? Did he have any success in fixing it?

Most of it is pretty straight and simple. It's definitely tight between the radiator support and the start of intake, but can the engine suck enough air to whistle there?

https://picasaweb.google.com/1148940...eat=directlink

[Spitfi-r]

i don't think it's the intake however you don't have a lot of room between the rad support and the intake of the filter. on mine i cut a piece off the bimmerworld boot and shifted everything back a few inches. also my ka motors filter came with a 45deg elbow that goes over the filter and makes it suck cold air from behind the headlight. but i have no room for shifting the maf away from the filter so i do get the CEL on high RPMs. I'll snap a pic later so you can see it.

my money is still on the exhaust. looks like you only have it on WOT and high RPM when the gas flow is the highest. i think it's way too loud on the video where you have the mic on the bumper for it coming from the front. if it was the intake it would have been much quieter. can you tell where it's coming from? front or back?

Update: No whine at all with with the car sitting still and revving. I also don't get the check light with the car sitting still-->coincidence? While driving there is no way to tell where the sound is coming from.

My latest thoughts: If it occurs only under load, then it's unlikely to be intake or exhaust. So is it a driveshaft or CSB problem (doesn't explain the check light that seems to almost always accompany the sound.)
My g260 is pretty loud (worn bearings).

[sweet3]

Im not exactly sure if my whine is the same as yours. But when im going at least 20mph, the whine starts to come and only gets worse/louder. I think my noise is the diff output shafts. I don't get any check light though. Maybe the light is part of something else and not a part of the noise? Just something to think about

[Spitfi-r]

Im not exactly sure if my whine is the same as yours. But when im going at least 20mph, the whine starts to come and only gets worse/louder. I think my noise is the diff output shafts. I don't get any check light though. Maybe the light is part of something else and not a part of the noise? Just something to think about

Thanks, mine is only there with hard acceleration.

[aldur99]

Did you ever figure out what was causing the whine? I have the exact same thing at WOT. Everything is new on my setup except the drive shaft.

[Spitfi-r]

Did you ever figure out what was causing the whine? I have the exact same thing at WOT. Everything is new on my setup except the drive shaft.

I think it was the pilot bearing. It was quite loose when I put it into the crank. When I pulled the trans it basically fell out and there was a lot of metallic residue that made it look like the bearing was spinning in the crank. I did some reading and found some people had a bad run of bearings that had the wrong outer diameter. I think my bearing was FAG from Pelican.

My car is apart and off the road so I have not been able to test it.

PS: I swapped the driveshaft, replaced the CSB and still had the noise