BMW M3 Forum
BMW M3 Forum BMW M3 Gallery BMW M3 Reviews BMW M3 Social Groups BMW M3 Chat M3Forum Sponsors >>
Loading


Mobile M3forum
Go Back   BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X) > BMW M3 Discussions > E46 M3 (2001-2006)
Tire Rack Buy Winter Tires Now!
Not a member? Register Now!
Register Gallery All Albums Garage Search Today's Posts Mark Forums Read Calendar FAQ

E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


Reply
 
Thread Tools Display Modes
Old Sun, Sep-16-2018, 02:09:29 AM   #1
I_M_FAN
Registered User
 
Join Date: Jan 2016
Posts: 4
In the garage:
Reputation: 0 I_M_FAN is on a distinguished road

United States




Default Diagnosing a false knock reading

I'll start from the beginning. I recently picked up my dream car, the E46 M3. I had a little money left over from what I saved up to buy the car so I decided to buy an exhaust and a tune for it. Took me about 15 hours to install the exhaust. The exhaust can be seen here:

After flashing the BuildJournal tune on my car I thought I'd take it to the dyno to see if it made any more power than stock. Stock it came in at 285WHP, and with the exhaust and tune it picked up 3WHP and 4 ft-lbs torque, so, basically no change. It does sound amazing but I started to wonder why the supersprint stepped headers that everyone on the forum raved about and the buildjournal tune made no difference. After taking it to my local shop they told me I was getting a knock reading which was causing the DME to pull timing. So we decided to do a test. Put 100 octane fuel in it to see if it's actually knocking or not. I bought BMWLogger and got to logging.

Here it is on 93 Octane and stock tune


93 Octane BSpec Tune


100 Octane BSpec Tune


My mechanic tells me that timing advance at WOT in 3rd gear should get up to 30 at least, and the fact that it's at ~22 tells us there's a problem. The good news is, the fact that it's still pulling timing on 100 Octane tells us that it's probably a false knock reading. I can send data log files as well if anyone is interested.

Also another thing I'm curious about, my TPS seems to consistently be above 100% when logging, is that normal? Doesn't seem normal.

Where would you look to start diagnosing this seemingly false knock reading from the sensors? Thanks!
Jump to top I_M_FAN is offline   Reply With Quote
Sponsored Links
Register now and remove these ads
Old Sun, Sep-16-2018, 02:19:34 AM   #2
Drewster
Registered User
 
Drewster's Avatar
 
Join Date: Aug 2014
Posts: 2,908
In the garage:
Reputation: 0 Drewster is on a distinguished road

United States




Default Re: Diagnosing a false knock reading

"Definitely false knock" .. unless you have a mechanical problem :P

If you can log the knock sensors, I would replace the one that's faulty

TPS at 100% definitely sounds amiss as long as that logged value is correct. Have you checked for DTC's?
Jump to top Drewster is online now   Reply With Quote
Old Sun, Sep-16-2018, 02:56:14 AM   #3
I_M_FAN
Registered User
 
Join Date: Jan 2016
Posts: 4
In the garage:
Reputation: 0 I_M_FAN is on a distinguished road

United States




Default Re: Diagnosing a false knock reading

Quote:
Originally Posted by Drewster View Post
"Definitely false knock" .. unless you have a mechanical problem :P

If you can log the knock sensors, I would replace the one that's faulty

TPS at 100% definitely sounds amiss as long as that logged value is correct. Have you checked for DTC's?
I'm not sure how to log the knock sensors, how can I do that? There's no CEL and I scanned the car for faults with torque pro and didn't find anything.

Here are the INPA and BMWLogger DME Errors

https://i.imgur.com/Ood1Fwh.png

https://i.imgur.com/ySlLOQJ.png

Last edited by I_M_FAN; Sun, Sep-16-2018 at 06:51:50 AM.
Jump to top I_M_FAN is offline   Reply With Quote
Old Sun, Sep-16-2018, 12:02:20 PM   #4
Obioban
Moderator
 
Obioban's Avatar
 
Join Date: Jul 2003
Posts: 36,011
In the garage:
Reputation: 54 Obioban has a spectacular aura about
Location: SE PA

United States




Default Re: Diagnosing a false knock reading

I just replaced all 3 sensors. They’re pretty cheap iirc.
__________________

Current Cars: 2005 IR/IR M3, 2001 LMB/blk M5, 03 530i, 04 M3 wagon, and some boring stuff
Past cars: 04 M3, 96 M3, S50B32 e36 M3 CM race car
Jump to top Obioban is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



All times are GMT. The time now is 06:34:40 PM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
M3Forum.com and M3forum.net is in no way sponsored, endorsed or affiliated by or with BMW NA / BMW AG or any of it's subsidiaries or vendors.
BMW and M3 (E90 M3 | E92 M3 | E93 M3 | E46 M3 | E36 M3 | E30 M3) are registered trademarks of BMW AG.
M3Forum Terms of Service
Copyright 1999-2017 M3Forum.com
Discussing Diagnosing a false knock reading in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)