VEMS Community Forum

VEMS => Calibration & Mapping => Topic started by: dnb on February 03, 2015, 09:41:44 pm

Title: Car with bipolar disorder?
Post by: dnb on February 03, 2015, 09:41:44 pm

I found an interesting feature with my new car engine.  It's done less than 50 miles so is not even close to run in or tuned (so I know there's loads of work left to do, including finding the 10% bias in fuelling between the banks) but I did expect it to behave the same way on two occasions on the same day.

Run 1 - half past 7 at night, air temperature around 3 degrees C.
https://dl.dropboxusercontent.com/u/8968424/vems/v3.3_u004371-2015.02.02-19.26.23.vemslog (https://dl.dropboxusercontent.com/u/8968424/vems/v3.3_u004371-2015.02.02-19.26.23.vemslog)

Run 1 - quarter past 9 at night, air temperature around 1 degrees C.
https://dl.dropboxusercontent.com/u/8968424/vems/v3.3_u004371-2015.02.02-21.14.52.vemslog (https://dl.dropboxusercontent.com/u/8968424/vems/v3.3_u004371-2015.02.02-21.14.52.vemslog)

in run 1 the car ran quite rich (as I wanted it to do when running in) such that the average EGO correction across both banks was around 95%.  Idle was high for some reason, and the IAC couldn't reach target.  EGO correction maintained good mixture throughout the drive and didn't appear to be biassed by air or coolant temperature.

In run 2, the car ran quite lean such that EGO correction averaged 103%.   This is much less good!  Again, there looks to be no obvious bias from anything the ECU is measuring.

You should be able to see that no tables were changed between the two runs - so why is the car behaviour inconsistent?  What am I not measuring or seeing?

My first thought is that the cam sensor is not working right and the engine synchronised differently, however the cam sensor looked to be reliable when I tested it during installation.

My second thought is that fuel temperature has a much bigger effect than I thought - the car was warm for the couple of hours between runs, so the fuel would have become hotter, and there would have been less fuel for the same injected volume.

Any thoughts?
Thanks

Title: Re: Car with bipolar disorder?
Post by: jeanno on February 04, 2015, 08:03:21 am

MAT is higher on run 2.  ;)

Title: Re: Car with bipolar disorder?
Post by: dnb on February 04, 2015, 09:50:07 am

Initially yes, but it drops off over the run.  In the first run mat increases.

Title: Re: Car with bipolar disorder?
Post by: fphil on February 04, 2015, 10:47:20 pm

I had only quote that the battery voltage is about 14V+ in one run , 13.65V in the other. However with your injector settings this could not make a difference more than 3% in case that setting is  unecessary

Title: Re: Car with bipolar disorder?
Post by: dnb on February 05, 2015, 12:25:08 am

Looking like I have an ADC problem on that ECU.  I can't get any life out of the analog inputs. :(

Title: Re: Car with bipolar disorder?
Post by: fphil on February 05, 2015, 08:30:18 am

I would also have a look at the wbo2 sensors. Have you already swapped the two of them by banks?

Title: Re: Car with bipolar disorder?
Post by: dnb on February 05, 2015, 01:49:19 pm

Yes.  Done the bank swapping thing.  It makes no difference.

Title: Re: Car with bipolar disorder?
Post by: dnb on February 07, 2015, 02:10:01 am

ADC chip replaced.  I now have proper ADC signals again on all channels.  Hopefully this will make a difference to some of the funnies and I'll be able to monitor fuel temperature too.