zammobhoy
|
| posted on 15/7/18 at 02:10 PM |
|
|
Megaquirt variable AFR
Hi Folks,
I've built a Westfield kit car with a 1800cc Blacktop Zetec and Megasquirt EFI. Car runs well even though I've mapped it myself using the
autotune feature in TunerStudio. The issue I have is that the AFR is variable at idle, the car doesn't stall but the difference in in running is
clear and the AFR can wander from 13 - 16 without anything obviously changing during a drive. Anybody experienced this or have any ideas what could be
causing it. I have noticed a difference when the cooling fan cuts in so I was thinking Voltage Compensation?
Any help appreciated.
Cheers,
Paul.
|
|
|
|
|
MikeRJ
|
| posted on 15/7/18 at 03:58 PM |
|
|
If you record a log during idle while this is happening, can you see the injector pulse width changing and do you see any of the input parameters
changing (e.g. TPS, MAF/MAP, CLT, IAT, system voltage etc.)?
|
|
|
40inches
|
| posted on 15/7/18 at 06:20 PM |
|
|
Try using autotune with the car idling for about 20 mins. Worked for me 
You will need to drop the lower threshold to around 500rpm.
[Edited on 15-7-18 by 40inches]
|
|
|
wombat258
|
| posted on 16/7/18 at 10:16 AM |
|
|
I second that you should log with TunerStudio to see what is happening to cause the AFR swings. Also make sure that your VE numbers around idle are
the same, so that the ECU is not chasing wildly different VE values with small RPM and MAP changes.
|
|
|
zammobhoy
|
| posted on 16/7/18 at 10:45 AM |
|
|
Thanks for the replies guys,
I'll take some logs when I get a chance. Inputs seem pretty stable but I suppose I'll need to log over an extended period and do some
closer analysis.
Cheers,
Paul
|
|
|
SPYDER
|
| posted on 16/7/18 at 10:53 AM |
|
|
Hi Paul. Widebands aren't always accurate at tickover. It could be running weaker than the reading suggests. Try commanding for a lower AFR and
see if it settles down. My 3SGE engine is best at 12.5 at tickover. It may, or may not, actually be 12.5 but who cares? Give the engine what it
likes. This all supposes that you are running "closed loop" at idle. If you are not then you would need to increase the idle bins in the
VE table to richen up the AFR.
As already suggested, the VE numbers around the tickover bin should be the same. Many people arrange a square of four bins, all the same, with your
tickover spot sitting right in the middle. You could try a similar arrangement in your ignition table.
[Edited on 16/7/18 by SPYDER]
|
|
|
chris
|
| posted on 16/7/18 at 11:42 AM |
|
|
I found having a weak mixture at tickover causes wot you are experiencing
|
|
|
