strange hickups from 1500-2100rpm?PROBLEM SOLVED

[Timmo6]

Hi all,
I recently had some hickups during acceleration between 1500rpm and 2100rpm. The problem seems to become worse now.
I have a datalog and msq file here:
http://www.box.net/shared/aryby8jk0g
http://www.box.net/shared/rxegnc88w4
The car bogs and doesn't want to accelerate as it should. Its like there is not enough fuel or like spark is not strong enough. I replaced plugs, plugwires,rotorcap but nothing changes. I can't really find something in the datalog that could be the problem but I am not so technical in this matter.

The car is a 4cyl bmw 518i from 1987 (e28)
I use a Hall sensor with two triggers 180° apart
I have firmware 1.0.53

Thanks for any help.
Tim

[rob@vems.co.uk]

Looks a bit odd, the fuelling seems to stay pretty good which suggests to me that theres not a misfire as we'd start to see strange readings in the lambda field (either very rich or very lean), lambda remains 0.9x to 1.0x all the way through.
Are you getting any trigger errors reported?
How is the clearance between the sensor and the trigger wheel?  Is there any swarf/rust build-up on the sensors?

[Timmo6]

I will check if there are trigger errors and there may be some rust build upon as well.
thanks

[Timmo6]

I have no trigger errors, so that should be OK.
Its like something is missing at that moment, spark or air or fuel but the datalog looks OK???

However in the datalog(near the hickups) I sometimes see the Accel button down the screen highlighted while the TPS is the same before and after?

[rob@vems.co.uk]

Its not looking like the Accel is putting significant amounts of fuel in there.  What are you Accel enrichment figures?

[Timmo6]

These are my accel enr settings
http://www.box.net/shared/2lyeu4eg40

[rob@vems.co.uk]

Okay, first off, dont use the Wizard.
In the Settings->Accel Enrichment screen set the dv/dt values to

• =1, [1]=5, [2]=20, [3]=40

then in the enrichment values use your 0.3, 0.6, 1.2 and 2.4 values - you'll probably find that you need to re tune these.

This will help with tuning but I am not sure if it will help cure the RPM issue.

Rob

[Timmo6]

Someone pointed me in the datalog that at 1500rpm the spark advance suddenly jumped from 20 to 24 without any reason? According to my sparkmap its not possible at that rpm with that kPa.
How can this be??
thanks for your help!
Tim

[rob@vems.co.uk]

as the next cell is 2000rpm VEMS will be interpolating between the 1500 and 2000 cells.

[Jorgen]

In some rare cases you can experience a bad lookup at 1499rpm if you have a loadsite at 1500. This is fixed in the next release (1.0.73). It is unlikely that your hickup is caused by this.

Jörgen Karlsson
Gothenburg, Sweden.

[Timmo6]

Hi,
I upgraded to 1.0.73 and made a datalog with the sparkadvance fixed at 25° to eliminate a timing issue.
The engine still bogs even more. There was also a little problem with the tempsensor. I needed to recalibrate these.
I can see in the datalog a few things that go up and down together with the hickups which I don't fully understand: Its the Gammae and Gair data?
Someone have any insight in this behaviour?
http://www.box.net/shared/0lm040zgg8
Thanks

[Timmo6]

PROBLEM SOLVED
Due to a loose bolt off the distributor it moved a bit by time and was a few degrees off.
I changed the TDCtrigger value and everything worked as before!
Thanks for the help!
Tim