950 commander tuning help

[farmerz24]

hello all, i am running a holley commander 950 in my 00 cav, controlling a 3100. anyways, the problem is this:

i think the 02 is not giving a good reading, its a KEM aftermarket GM equivilent, but it doesnt seem to read right. on decelleration, it shows super lean, but increasing my fuel to 100ms or more does nothing. also, at idle if running closed loop it always thinks my mixture is rich and starts subtracting fuel until the engine goes lean and dies. i dont know what to think, and i havent been able to find the standard ignition SG2 o2 sensor which is reccomended from holley. running the gm 1 wire right now.

also, the plugs are prety black and the gas guage goes down fast so thats my other reasoning for thinking the o2 is not giving a good reading or soemthing else is wrong. please help.;

[Guest]

RE: 950 commander tuning help

The car will go real lean on decel. It doesnt' need any fuel with the TB closed.

If your plugs are black then you are too rich. Lean it out.

Are you using a wideband to check your a/f ratio or one of those crappy autometer gauges?

[eliteweapons]

Did you setup the voltage conversion for the o2 sensor you are using? That could easilly be the problem. I am running the 950 throttlebody setup on my truck but I am using the holley wide band controller with the supplied bosh o2 sensor. Also verify that all your sensors are working correctly, eg. throttle position, map sensor, iat.

[sharkey]

it will always go super lean on decel, its called decell fuel cut. its for fuel economy. and at idle i wouldnt run closed loop. most motors will idle rich, and thats the way they need to idle. id turn off closed loop till after 1200rpm if you are able to.

[timg]

One wire O2 sensors are notoriously inaccurate. Even standard narrowbands aren't good for tuning an aftermarket EMS. If you really want to know what is going on, spend $250 and get a wideband. They REALLY help.

Tim

[91BerettaGT]

Not to boost a old thread, But if you look under the Engine Parameters, you can enable a Decel Fuel RPM at which fuel comes on. If you set that RPM at your max, fuel is cut whenever you let off the gas no matter what. This helps prevent bucking in a manual trans vehicle...

Just thought i'd spread my knowledge.