I don't like the new MAP sampling routine

UnaClocker · Post by **UnaClocker** » Thu Aug 02, 2007 11:09 am

Ever since the new map sampling was added, I've had a real strange issue. It's random, doesn't happen most of the time. What happens is sometimes, the engine will start choking, like it's suddenly getting WAY too much fuel. It only happens on sudden throttle movement, usually when pulling away from a stop. Sometimes happens when I just punch it while cruising along. Only seems to happen when fully warmed up. All accell enrichments are turned off.
With the old map sampling, my map lag was 25. I've been able to turn it up to 60, any higher and the map numbers in MT are just a blur they are moving around so fast. I've tried getting map signal in several different places on my intake without much change.
When the bogging problem starts, if I nail the throttle to the floor, and wait about 2 seconds, it clears up and away I go. But I usually let off the throttle for a second and try again. It's kind of dangerous the way it is, because I'll pull out into traffic expecting to get up to speed immediately, and it doesn't...
I suppose you'll want a datalog showing it happenning, and my latest MSQ? I'll try to catch it sometime soon.

Post by **muythaibxr** » Thu Aug 02, 2007 11:28 am

Yep, I'll need both, as I, and several others have used the code as it is now with no problems, and so far, nearly all of the feedback has been saying how much better things are with the new MAP sampling.

Just looking at it, are you using normal AE or EAE? It almost sounds like there's something mistuned with AE.. The new method's way of calculating MAPdot is more accurate now, and that might be causing your problem.

Ken

rb26dett · Post by **rb26dett** » Thu Aug 02, 2007 11:51 am

perhaps shift the sampling back a bit towards what it was?

Post by **muythaibxr** » Thu Aug 02, 2007 12:06 pm

Not sure what you mean by that. It was every 10 ms before, now it's on every tach event until they get closer together than 10 ms, at which point it switches to every 10 ms.

There's no way to "go back a bit," and even if there was, I wouldn't want to do that because most of the people using the new sampling method have said it makes their MAP signals a lot more stable, and they have been able to remove mechanical filtering devices (restrictors, etc...) and set their MAP lag factors higher (me included).

If there's a bug somewhere causing undesired behavior, and I can duplicate it, I'll gladly fix it.

Ken

rb26dett · Post by **rb26dett** » Thu Aug 02, 2007 12:10 pm

my map lag was 25. I've been able to turn it up to 60,

thats what i meant

lag, lag on sampling, samping averaging, etc

sorry for being unclear.

fred.

Post by **muythaibxr** » Thu Aug 02, 2007 12:20 pm

ahh ok, that makes more sense. Thanks.

Ken

krisr · Post by **krisr** » Thu Aug 02, 2007 4:05 pm

Not sure with the Extra code as i'm running the B&G latest beta but with the new map sampling rate I found that the lower vacuum/low RPM area of the VE table actually get used now so I had to lower my AE values - I had a similar problem, the engine would go pig rich (dash mount WBo2 gauge) then clear itself up and take off.

Once I fixed that up the car drives better than an OEM interms of throttle response and no lean tip in whatsoever.

UnaClocker · Post by **UnaClocker** » Thu Aug 02, 2007 4:08 pm

That could be it. It's really hard to tune that area. It's also very hard to catch this problem in a datalog. I can't seem to reproduce it at will.. It may take me a couple more days to either catch it, or whatever. ;)