Megasquirt Support Forum (MSEXTRA)

So what WAS screwing with your idle control and MPG?

Ken

muythaibxr wrote:So what WAS screwing with your idle control and MPG?

Ken

Mileage was the same with either EAE or standard AE. Probably my right foot was the problem. It's a big car and old motor and 17mpg around town is not unusual. I was just hoping for more.

Idle is still unkown. Part is the fact that I have a 2 wire idle valve. I think 3 wire valve are insensitive to battery voltage but I don't believe 2 wire valves are. My alternator doesn't quite reach regulated voltage at idle so it rides a pretty steep voltage curve above idle rpm. Decreasing injector battery compensation amount evened out the AFR as it hunted but it would still tend to hunt with more even AFR's

I would be nice to have some voltage compensation but for now I'll just live with it.

I still want to do some more datalogging on the variables, but I've had a lot of other stuff going on which is wrapping up. I also want to verify the rpm/idle valve range of my valve/motor to be sure the PID is linear above and below setpoint.

I have started to tune my EAE curves and I have have some questions that needs clarification.
My engine is Cosworth 2.0l 4cyl and I'm running full sequential.

I think I understand how the ATW and SOW tables work and I have started the tuning setting the RPM and CLT curves to 100% and then making some load changes at 3000rpm. I have then made the nessessary changes to ATW and SOW curves to make the AFR look good.

First question is that right after the load change there is 200-400ms long rich or lean spot depending the on the load change direction. After that time I have gotten the AFR quite good. So should I ignore this for now and tune this later with AE?

Next question is moving to the RPM correction curves, as I started by setting the curves to 100% all round should I leave the 3000rpm spot to 100% and make lover and higher rpm like this 90% 2000rpm 100% 3000rpm 110% 4000rpm, I thing you get the idea. Or should I use the original RPM curves that crosses the 3000rpm at 90% and start from there?

Thank you.

Your assumptions are correct. Use regular AE to get past the brief lean/rich spots and keep your rpm curves 100% at 3000 rpm.

Ken

muythaibxr wrote:Your assumptions are correct. Use regular AE to get past the brief lean/rich spots and keep your rpm curves 100% at 3000 rpm.

Ken

Thank you for confirming this.

After reading through this thread I realized something that I had not tried which was switching from 2 squirts per cycle alternating to 4. This actually made a day and night difference on off idle response which everyone knows is the holy grail of ITB engine response. Manifold pressure dropped to 38-39 kPA at idle and was also lower during cruising which made it very refreshing to not have to step on the gas as much to maintain speed. Unfortunately over the course of the day (I was driving around autotuning (AFRs were only slightly off)) the response kept getting worse. During low load condition across the rpm range the AFRs were unstable to the point that you could feel the hesitation during constant load cruising. The next morning the car would not stay on without holding the throttle and even so, the revs would bounce and oscillate almost like a bad vacuum leak. I tried changing the injector dead time but that didn't help. The next day I changed back to 2 squirts per cycle and everything was fine again (just back to the higher 40-43 kPA idle MAP and not as good response). It has actually deteriorated slightly since in the same ways but not too bad.

Has anyone else experienced this phenomena? I hope that changing to 4 squirts per cycle alternating didn't damage the injectors. I did allot of research it doesn't seem to be something that would happen.

I have a 90 Miata, 1.8 BP with AE111 ITBs and toyota COPs.