Trying to diagnose rattling during acceleration (and a coolant issue)

[alexandre]

Hey guys!

I noticed some quite important rattling when accelerating (pedal to the floor) in 3rd to 6th gears between 2,000 and 3,000 rpm, at various speeds. There's hesitation and then past 3k it accelerates properly. I know VANOS seals were done recently (Dr Vanos kit) so we can rule this off. Oil is 6k old, I want to do 7.5 on each change. Only mods are a CAI and a 3.46 diff.

The car also starts a bit roughly when I let it sit for more than 24h, as if it would stall (it starts, then alternates between 1100 and 900 rpm 2-3x until it idles at like 1000). Could there be a link ?

I'll record some audio tomorrow to post here to help you guys out.

And finally, my radiator/coolant indicator lights up randomly for no apparent reason. Temperature gauge is right in the middle so I doubt it's a level issue... What else could it be ?

Thanks!

[Oli77]

Your DISA may be responsible for the rattle. Easy DIY, air box out and then the dreaded intake air boots.

Faulty sensor on the coolant temp? (there are several)

More experienced brothers/sisters will chime in.

[WOLFN8TR]

X2 on the DISA Valve. If its rattling bad I would check it ASAP. If it comes apart the metal pin will get sucked into the intake. G.A.S makes a rebuild kit and offer the Gold valve. did mine and what a difference, quality parts also.

Germanautosolutions.com


Bayerische-Motoren-Werke

[llll1l1ll]

Mine makes a ticking sound on acceleration. I have new VANOS seals and rattle kit as well as a new DISA. I'm going to keep my eye on this thread.

Also, no need to remove the airbox and intake boots to do the DISA! Just undo the upper boot from the airbox and mush it out of the way while you work on the DISA screws.

[alexandre]

Okay so this is what happens when I start the car:

https://www.dropbox.com/s/sxo21j5kqgdml3u/IMG_0885.MOV

I can't run the car until Friday so I'll post a video of the acceleration then.

[alexandre]

I got caught up with work on Friday so I couldn't leave with the car. However I ran a full code scan with my BMW Scanner. Here are the results:

# ERRORS DETAILS - DTC(hex)/PARAM(hex)
---------------------------------------------------------------------------------------------------------------------------
DME* -> 28B6/81 - Inlet-camshaft bank1: mechanically
28DD/84 - Air mass system
28BC/81 - Exhaust camshaft bank1: stiff
28B8/81 - Exhaust camshaft bank1: mechanical
2747/82 - Mis-fire cylinder 4

EWS -> 13/02 - Toleration of changing code increased, key 1
0F/3F - Power on reset
03/0A - Toleration of changing code increased, key 0

LEW -> 09/65 - No CAN message (ASC)

A/C -> 20/02 - AUC heating

SRS -> Shadow-memory:
50/20 - Power supply, undervoltage

IKE -> BE/68 - Data-filing difference to central light module (LCM)

ZKE -> 6B/04 - No answer passenger mirror
6C/03 - No answer driver mirror


# SCAN END

Something tells me air mass or cylinder 4 could be the culprits. Can anyone chime in ?

Codes were all cleared 2 weeks ago and I did around 300 mi of 50/50 hwy/city driving since then. CEL lit up for a few minutes once during hwy driving and disappeared soon after.

I also found this (http://forums.bimmerforums.com/forum/showthread.php?t=1597163). Trying to find a DIY to see if that might solve my issues.

[alexandre]

DISA checks out. No funky noises, no excessive wear. One of the PO's probably replaced it at some point. [edit: they actually did - my car has the updated version, part #11617544805]

DME upgrade is being done in 2 weeks, so we'll see what's going on. I noticed the jumping idle was only on a cold start, so I think it's either DME or 200k+ mi wear.

Do bad intake boots throw CEL's or make weird noises ? I don't have access to a garage/tools often right now so it's really hard to take things apart.

[echo46]

I think bad intake boots could throw a code if there is a significant vacuum leak. Check the boots closely for any cracks. I went ahead and replaced my intake boots with the Stett silicon boots. Vacuum leaks can also come from the dreaded CCV and all it's associates hoses etc. Did you check your Mass Air Filter?

[alexandre]

I think bad intake boots could throw a code if there is a significant vacuum leak. Check the boots closely for any cracks. I went ahead and replaced my intake boots with the Stett silicon boots. Vacuum leaks can also come from the dreaded CCV and all it's associates hoses etc. Did you check your Mass Air Filter?

You mean the MAF sensor ? It was replaced at 155k. Probably needs a cleanup. I'll see if I can check out the boots later this week.

[danewilson77]

You mean the MAF sensor ? It was replaced at 155k. Probably needs a cleanup. I'll see if I can check out the boots later this week.

Yes....the sensor.

[telijah]

Did you ever find out whats up with your coolant level sensor? I would try to replace it. It is cheap and easy to replace at the bottom of the expansion tank.

However, do not let the coolant temp be your indicator. Once it reaches normal temp, it is sort of padded from there until "OMG I am overheating" temperature. If you;re actually checking your level and it is fine, could either need a bleed or faulty level sensor.

[alexandre]

Nope I didn't yet. It's not a huge priority for now since the whole cooling system is only 30k old, but I'll try that asap. It seems to be a pretty common failure on E46's.

On the other hand, the rattling/hesitation seems to be much less present since today's oil change - I drove 75 mi home back from the dealer and acceleration seemed much smoother. The oil was only 4k old (it's my first change since I bought the car) but maybe PO's mechanic used oil that wasn't on BMW's LL01 list...

With a DME update I'll probably be good to go hopefully!

[BRGcoopahS]

I hate to get off topic but I feel like this issue has been beaten around the bush and I dont want to make a new topic.

My fathers ZHP has been a little sluggish so he gave it to me for the day. I noticed the car will "hiccup" once or twice during decent acceleration (around 3,750-4,000 RPM). It was most prominent in 2nd gear but also would happen in 3rd gear. 4th-6th I didnt notice anything. I also noticed in a small alleyway a rattle noise driving around 4kish in first gear.

From what I've heard around here, Im assuming thats the 4k power dip and it could need a DME tune, and/or a new disa valve. Any ideas?

[Hornung418]

Remove DISA and inspect for damage.

Horney...via TT.

[BRGcoopahS]

Remove DISA and inspect for damage.

Horney...via TT.

thanks!

[alexandre]

I forgot to follow up on this.

A bottle of Techron and an ICV cleanup improved all these issues. Still waiting for DME.

I bleeded the cooling system and changed the sensor - no more funky lights. Car is running great!

[NorCalZman]

I noticed a rattling in my car last night as well. Was in first gear going down a small street into my parking structure. Around 2-2.5k rpm or so I heard the rattling. Would go away if I fed it more gas