EGO oscilation, please help!!

yellowbird911 · Post by **yellowbird911** » Sun Feb 12, 2006 8:48 pm

Am using v3 with EDIS and an LC1 with the 1-5V set up. When I give the EGO say a 10% authority it will oscilate the AFR up and down. It is seems like it is chasing its tale. With the authority turned off the AFR read steady. Have tried everything I can think of to correct but no luck. Biggest problem is that because of this I can not use the Autotune to tune VE and to my understanding the MStweek doesn't work with MS2 or at least it does not work for me. Also I tried VEXME and it gives an error message. I don't want to tune the whole VE manually with pages of datalogs. Help!!!!

naprotejay · Post by **naprotejay** » Mon Feb 13, 2006 1:26 am

are you getting this oscillation @ idle? if so, set ego correction as 'active above rpm' (~200,300+idle) - if your idle is 800rpm, set this as 1000,1100 rpm, etc ...... that way, idle should stay fairly steady AND you can use autotune to adjust the VE table.

yellowbird911 · Post by **yellowbird911** » Mon Feb 13, 2006 3:45 am

I get oscilation everywhere. I have the cut off set at 1200rpm. The higher the authority I give it the higher the oscilation swing. If set high enough it will send the motor from black smoke at the exhaust to poping through the intake?????
Will try to set the autotune to build a VE table without the authority turned on per another thread I saw. Still though, I can't even turn the authority on even 5% without being able to see and feel the swing as you drive down the road.
Thanks

uberbug · Post by **uberbug** » Mon Feb 13, 2006 10:25 am

Make absolutely sure your MS and your MegaTune is set to recognize the wideband sensor and its not thinking it still has a narrow band sensor attached.

Cairb · Post by **Cairb** » Mon Feb 13, 2006 11:38 am

Have you tried reducing the EGO step % or increasing the ignition events per step?

yellowbird911 · Post by **yellowbird911** » Mon Feb 13, 2006 12:45 pm

I have checked in Megatune and the set up file that the lc1 wideband is selected and have adjusted the lc1 to send the 10-20AFR. In megatune, once I select wideband it will not let me change step or event, in fact the only thing I can adjust is % correction and rpm limits. Is something wrong with my software?

Cairb · Post by **Cairb** » Mon Feb 13, 2006 12:59 pm

Looks like they aren't editable with MS2.

Have you seen this thread though?

http://www.msefi.com/viewtopic.php?p=73 ... step#73156

mops · Post by **mops** » Mon Feb 13, 2006 2:17 pm

i'm experiencing similar issues with wideband oscilating form lean to rich. I tracted it doen to misfire/weak spark issues i'm having. however my car will still swing afr's even if i turn off ego correction completly.

you didnt say what car you run it on or whether you are using ms-I or ms-II.
ms-II (what I use) has a choice of ego correctin algorithms with a choice of 3 algorithms and last two have configurable parameters, so you can tune out quick changes and make them slow and steady.

Post by **grippo** » Mon Feb 13, 2006 2:22 pm

If you are using MSII v2.33 or higher you should have two primary user changeable parameters to tune with: the time between corrections and the proportional gain (equivalent to the step size with NB O2). The first is the same as used with NB O2 and determines how fast corrections are made; the second determines the % of the error between measured and actual afr that is used to modify the pulsewidth. The idea of both these is to prevent oscillation. If you set the gain to 0, you will have no oscillation guaranteed, because there will be no correction.

To solve your problem, switch to vsn 2.33 or higher if you are using anything less than that. Second, make sure you can change the time between corrections and the proprotional step gain. You should also be able to change the authority limt. If you can't, let us know what version of code and of MT you are using and we will try to see what's going on.

It should also be remembered that there will always be some oscillation in the afr control - in fact it is built into most algorithms to make the catalytic converter more efficient. Plus it comes about because there is delay in the response of the sensor + conditioner that the signal goes through. This makes it like a loose steering wheel. You have to proceed slowly (don't make corrections too fast or too much) or you will overshoot.

yellowbird911 · Post by **yellowbird911** » Mon Feb 13, 2006 3:15 pm

I am using a MS2 V3 and v2.34 code. I have checked megatune but I can not adjust steps or time interval. I can adjust the lag factor but this does not help. The AFR is quite steady with the correction turned off but as soon as it is turned on it will osculate, higher the correction-worse the osculation. If there is a way to adjust the step or the time interval I bet it would help. It really feels like MS is maybe taking in the AFR info making to big a correction or something.
The car is a 928 Porsche with a Chevy 454 Big Block and a mild cam.
Thanks for the info.