Bosch LSU 4.9 sensors dropping like flies

dr_jones
Posts: 162
Joined: Wed Jun 08, 2016 2:24 pm

Re: Bosch LSU 4.9 sensors dropping like flies

Post by dr_jones »

No - I wasn't capturing it at the time - will include it in the ongoing troubleshooting exercise.

-Ed.

dr_jones
Posts: 162
Joined: Wed Jun 08, 2016 2:24 pm

Re: Bosch LSU 4.9 sensors dropping like flies

Post by dr_jones »

Attached is the log (inc duty cycle) of the observed heater voltages with varying output d/c's withthe engine stopped

Full description and notes are in the comments. There seems to be some unexpected behavior (?) on LSUFeedback_U03 at one point and the duty cycle on the output seems to do the inverse of what I'd expected - I imagine there is a reason for that that I'm not aware of.

Next stop - switching to Lambda #2 and seeing if the behaviour is the same.
Attachments
2017-02-02 09-29-25 plus 0h00m00s S6#1628.SD
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TimH
JT Innovations
Posts: 627
Joined: Wed Sep 01, 2010 2:51 pm

Re: Bosch LSU 4.9 sensors dropping like flies

Post by TimH »

Someone linked to this article on FB, regarding premature LSU failures. Thought it might be of interest.

dr_jones
Posts: 162
Joined: Wed Jun 08, 2016 2:24 pm

Re: Bosch LSU 4.9 sensors dropping like flies

Post by dr_jones »

Thanks Tim - that's useful - it pretty much consolidates all the various points made several different sources onto one place!

Ryan.g
Syvecs Staff - Caretaker
Posts: 282
Joined: Fri May 30, 2008 3:05 pm

Re: Bosch LSU 4.9 sensors dropping like flies

Post by Ryan.g »

Gents,

We have done further updates to the Bosch CJ125 Controller based on some new Bosch infomation. If you are using the LSU4.9 on a S6Plus Ecu purchased before 02/18 then please email support@Syvecs.com and will get an update file out to you which flashes via USB for the updates.

Support@Syvecs.com

rac
Posts: 17
Joined: Tue Aug 14, 2018 5:06 am

Re: Bosch LSU 4.9 sensors dropping like flies

Post by rac »

Ed,

How has this ended for you?
Looks like I've done this twice now, first time on an ADV and just now on 2x 4.9's. I wasn’t logging all the Lambda info because I thought I’d moved past this issue but the only thing I can think of that relates my first failure with my second is that I had the ignition on for a period of time prior to starting the car because I needed accessory power for whatever reason. so that makes me suspect that something is up with the heating strategy when the car is not running that is the beginning of the sequence of events. unfortunately not logged. after failure, the sensors behaves like yours did (this time I had two installed side by side), and they respond exactly the same give or take a small time lag - goes leaner and leaner until I go open loop then they rapidly go ultra-lean. It doesn't appear reasonable for me to think a wire continuity issue or the like would affect two separate sensors identically at the same time but I will check it out all the same.

I've got quite a few things to check before drawing any conclusions but was interested if there was a positive conclusion to this thread from your experience.

thanks,
R.

rac
Posts: 17
Joined: Tue Aug 14, 2018 5:06 am

Re: Bosch LSU 4.9 sensors dropping like flies

Post by rac »

I spoke to soon, I lost three injectors and prematurely blamed these guys. oops.

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