Lambda long term trim

[pmc_3]

I've been trying to put some miles on the Chim, running in the new cam. I plugged in Roverguage the other day and noticed the long term trim hasn't set so I let it idle hot and let it do and initial set.

I took the car to work today and thought I'd plug it in just to see how it had settled down as I've driven about 150 miles since before and I noticed it had gone back to 0 which was odd as the battery hasn't been disconnected. I let it set itself again and a bit later went out to drop something off to a colleague, when I got back I plugged it in and it was at 0 again.

What would cause it to not be saving the long term trim data?

[blaze_away]

pmc_3 said:

I've been trying to put some miles on the Chim, running in the new cam. I plugged in Roverguage the other day and noticed the long term trim hasn't set so I let it idle hot and let it do and initial set.

I took the car to work today and thought I'd plug it in just to see how it had settled down as I've driven about 150 miles since before and I noticed it had gone back to 0 which was odd as the battery hasn't been disconnected. I let it set itself again and a bit later went out to drop something off to a colleague, when I got back I plugged it in and it was at 0 again.

What would cause it to not be saving the long term trim data?

Have you select it to be logged in RG settings ?

[pmc_3]

blaze_away said:

Have you select it to be logged in RG settings ?

I don't mean in the logs, just when you connect and go to the long term trim in the software. I thought it would display the last long term trim values unless you did an ECU reset, or am I incorrect?

Edited by pmc_3 on Friday 11th April 14:48

[blaze_away]

If its not ticked in OPTIONS-EDIT SETTINGS it won't show on the main screen. Does it show short term trims ?

[pmc_3]

Short terms show and fluctuate as normal with the engine running. What I am saying is every time I have plugged in recently and gone on to long term it's at 0 like it has reset itself. I can get it to set the long term by letting it hot idle for a few minutes but the next time I go out in the car if I plug in Roverguage long term has gone back to 0 again.

[blaze_away]

Thats odd. Is it normal ? I'd say no but would need to check mine to see it too does it.

Do you have some sort of device that disconeects the battery when you lock n leave the car ?

[pmc_3]

Nope, nothing like that fitted.

[pmc_3]

I unplugged the ECU to do a reset before I drove home from work and it's set a long term trim and seems to be remembering it now. Hopefully just needed a reset.

[pmc_3]

Long term trim was back on 0 when I plugged it in after a drive out yesterday. So either I have a problem or it just doesn't display the last saved values, I'll have to get someone else to test.

[Belle427]

What are the short terms doing?

[pmc_3]

Short terms are both cycling normally around the mid point

[Belle427]

Mark (blitzracing) is your man for this, he may pop up soon.
If short terms are cycling around the mid point does the long term move much if the engine is running well?

[pmc_3]

The long term when I let it set was quite negative, which is why I was keeping an eye on it as I wanted to see if it improved. I don't think I'm lucky enough for it to just be that the long term trim is perfect!

I think there is an issue with the ECU causing it to not save the long term trim. I found a post with someone with a similar issue and I messaged the OP to find out the end result and he said swapping out the ECU resolved it. One of the replies also mentions someone else who had the same problem and it was an ECU fault.

https://www.pistonheads.com/gassing/topic.asp?h=0&...

I'm going to try and get hold of a used ECU and see if it resolves it, I can always sell it on if it doesn't solve the issue.

Edited by pmc_3 on Thursday 17th April 10:17