Wesmaster

I don't really have any questions or anything really interest to tell everyone, I just wanted to discuss my tinkering with this feature over the last day.

Ever since I got the car back it stalls on occasion. My shop said it was the lightweight flywheel, and based on when it stalls (occasionally when I let the engine free fall) I believe them. I decided to play with the eManage Anti Engine Stall feature to see if it could help with the problem. This feature works by clamping the low end of the voltage from the MAP sensor during certain RPMs. The AEM EMS has a similar feature but I'm sure it works better. The Anti Engine Stall screen has a box for entering a throttle position, then a grid for entering 8 points of voltage clamping. The percentage is supposed to allow you to say that anything at or under X% throttle should be treated like 0% throttle, and therefore use your clamp settings at that % throttle.

When I first started playing with this feature, putting any value in the % throttle would kill the car. I did some looking around and noticed that my throttle position at idle was 4% on the eManage. I recalibrated and was able to enter values into the Anti Engine Stall screen without the car dying. At idle the e-01 was telling me that the MAP sensor voltage was .60-.65 or so. I set the values on the clamp map to .60 from 500 RPM up to 3K RPM. At .60 the car would die at idle. When I increased the clamp to .80 the car ran fine. But, this caused the idle to run at .80, and it ran a little rich. The car ran OK but if I let the car idle for too long (1 minute or so) the car would die out of nowhere. I figure the ECU is trying to correct slowly and it ends up killing itself.

After talking to cjb80 about how the AEM EMS's feature works I set the clamping to only be from 1K to 3K so that it would not affect idle at all. He explained that if the car swung to 800 RPM before the injectors kicked back in it was too late. The problem is, if I don't have a setting at 800 RPM (idle) the car dies after the revs go up and down a few times. I've played with setting the % throttle position from 5% down to 1% but the idle still has problems then dies. On the EMS it is able to keep the injectors flowing while the car swings down which would prevent my problem. In theory I can't really explain to myself how telling the ECU that more air is flowing into the motor than really is is going to make it easier for the motor to catch itself. I would really like to get rid of my swing down stall problem...I may just go back to the stock flywheel.

modifry

It sounds like you're saying the ECM cuts fuel (zero injector duration) when revs are significantly above idle and dropping during a closed-throttle event. Right?

It would be interesting to stick a scope on one of the injectors and watch injector duration during these conditions. If you made one test with no "anti-stall" settings you should see at which rpm the injectors cut out and when they kick back in, and then compare that to a test with the feature applied. If the injectors do indeed cut completely off during free-fall, you may be able to put a 12v light or LED tester in parallel with the injector and actually see when they cut out. The advantage of the scope is that you can plot rpm and injector duration at the same time and review it in detail later.

I wonder what MAP voltage a stock car reads at idle? The voltage you measured corresponds to a manifold pressure of about 3 psi, which should be a vacuum reading of about 24" (I think). If I had mine I'd measure it, but instead I have a '94 Grand AM as a substitute, and a VERY poor substitute it is.

Wesmaster

Based on the A/F readings the injectors seem to cut out no matter what I put in the map. Ideally if I could make them stay on that would be the best, but this feature has no way of telling the ECU/ECM to do that. So, I'm still not sure if it will really do anything for my problem.

modifry

Ahh, I see now. During closed-throttle free-fall the ECM probably cuts the injectors based on rpm, and there's no way to fudge that. So no matter how you do the programming it can only affect mixture when the injectors are firing, when they're off - they're off.

I can see where the lighter flywheel will cause rpm to drop quicker but I'm surprised it doesn't make it easier to "catch" it too.

In the old days auto makers used dashpots to solve problems like this on carburetted engines. I don't know if that idea would help here but it may be worth looking into before you give up and pull out the flywheel.

The changes you tried fooled the engine into thinking there was more air available than there really was, maybe by actually providing that air (with a dashpot) you can reap some improvement.

S2000_Europe

Wes you are worry me, I bought a lighter Flywheel for my Sc S2000.... i have only the SC and the Stock ECU no Emanage , no AEM...

Dees anyone has the same problem? WEs which flywheel do you have?

Wesmaster

It's the Comptech flywheel. I think a rich idle could be the cause as well. I'm going to do some looking into my maps to see if anything is out of whack. I don't want to make any changes without a wideband so I might have to keep it like this for a while.

arsie

Yes I do. It will be on my list when I return to the tuner in a few weeks. It might just have been my seat position and failing to floor the clutch completely when I slow to a stop at junctions after spinning along at a fair lick. We will see.

Also I do still get that nasty bogging on light throttle at low speeds. I am not convinced it isn't just the bouncy ground and throttle pedal flex - or so it feels to me. It rarely gets out of control on smooth roads.

Rog

SsamJang

i have the exedy clutch and flywheel and i notice it happens sometimes.

Turtle

The Mugen ECU often drops past idle to 600rpm or so before picking back up on an N/A car. Using it with the extra drag of the supercharger could exasperate this. Also, the Mugen ECU (unlike stock) doesn't compensation for electrical drain, or the air con being on. So it's more prone to this drop when the air con is on. Doesn't stall on an N/A car. Might be something you can tune with the Greddy but the base setup isn't ideal to begin with.

-Brian.

arsie

Brian,

Spot on; that sounds like the explanation. I road tested using the AirCon button Strange that this has to go all the way to San Diego and back (12,000 miles or so) to get 150 miles from Yorkshire to Norfolk

Thanks,
Rog

ps. Wes, I noticed that the live .GSC on the Macamobile does not have the anti stall feature ticked. Whereas the earlier MAPS do have anti stall ticked. When I go back to the tuner in a couple of weeks I will ask why. I know Maca (Cameron) started out with stock ECU but then switched to the Mugen ECU - I will find and TTT the thread with more on this.