Acceptable AFRS?
 

What are acceptable AFRS under engine break in? I am seeing around 14.3-15.2:1 while driving in the 2-3krpm range, is that bad? If so I guess I should prolly hook up the SAFC sooner then...

They were a bit lower, but I had adjusted the idle fuel mixture screw, because at idle I would see it around the 11.3-12:1 range. I had adjusted the idle up to about 13:1 which then caused a little leaner 2-3K range by about .5-.8:1 ...

N/A or turbo

if you are talking about cruising that is different than AFR's at WOT. AFRs at WOT are what people "tune" for IIRC cruising AFR goes to "stoich" which means it goes lean.

you shouldn't be adjusting the mixture idle screw as well.

The solenoid resistor does not effect the afr at anytime other than idle. Period. The figures you stated seem ok to me for just tooling around at two or three grand. Not WOT. Which you wern't doing.

Oh sorry a TII.

Whats IIRC? So stocih (14.7:1) is alright for crusing? I had just installed my WB with my new engine so I am not sure what it was running before, or what accpetable cruisung AFRS are good.

If I am not mistaken when you would tune with a SAFC, wouldn't the AFRS saty at whatever you set it to? For example 13:1 at 3k or 12.5:1 at 6K would be the same for both WOT and crusing right?

Why not? Because when ever I would give it any throttle input the car would bog down (when Idle was in the 11.3-12.1:1 range). Now that it is up to the 13:1 it doesn't bog NEARLY as much. Besides, everytime I would remove the spark plus they would be cover in gasoline! I had to constantly pull the plugs and blow them off to get the engine to restart.

I know its going to run rich because of the low compression with it being a new engine...

HAILERS, you say that the switch only effects idle, but why would I get slight leaner readings from the WB then?

IIRC=if i remember/recall correctly

The resistor is ok to adjust..The idle mixture screw is set at factory and should not be touched.

The S-AFC does not know shit about AFRs to my knowledge. It alters the input signal to the ECU comming from the AFM. This inturn changes the amount of fuel added to the engine. Fuel and AFR are not even close to being the same thing. they are related though. The more fuel per amount of air the richer you will run the same thing is said for the oposite the less fuel you have for a given amount of air the leaner you will be. AFR at cruising has nothing to do with AFR at WOT.

Wait I am lost now. Where is the resistor? I adjusted what ever the little screw is on the passenger fender with a R and L on it, which I assume stand for rich and lean....

The idle misture screw, are you talking about the screw on teh AFM?

I'm talking about the Variable Resistor. The outfit with a screw reccessed in it with a L and a R embossed on the side/top of it.

But you know what? If I had to prove to you that it only effects idle mixtures, I'd be hard put to do so. It really does not say that in the 87FSM. Try repeatability. Turn it rich and see if it effects the afr just the opposite of what you said above ......then lean again to see if it effects the afr.

Nope. I can't backup what I said. It ain't in the FSM (87fsm).

Yeah, the L and R is the resistor.

What I was trying to say is if I set the SAFC like plus 10% at 4Krpm (say it gives me a 13:1) the SAFC is RPM dependent, so it would not give a damn if the engine is under WOT or crusing.

Now I know I under cruising the boost would rpolly be at or below zero, so in theory the AFRS would be richer crusing at 4K than engine speen at 4k under WOT...


Thats under standable, I am not trying to prove you wrong, but thats what I saw the AFR readings. Although I didn't want to expirement with the screw to see if there is a difference when not idling...

IIRC the only AFC that is RPM dependant is the oldschool one like the one I had on my N/a. Is that what you have? If you have the S-AFC II I beleive it is TPS dependant. :p which would mean that if you are cruising it doesn't do shit. ;)

Hmmmm interesting! Yeah I have the SAFC II, well if that is the case I like that even better! I know it needs tps/boost sensor input, so that would make sense... I haven't had time to read the manual yet, so I was just basing it of what I heard on the forums... Thanks!

So stocih is ok for crusing then?

I said *solenoid resistor* in an earlier post when I meant variable resistor.

The SAFC is rpm and throttle dependent. It has a Low Throttle and a High Throttle setting. You can adjust the low throttle settings at 1000rpms increments and the High Throttle settings at 1000 rpms increments. If not hard on the throttle the low settings will be in effect and if hard on the throttle the high settings will be in effect. High and Low throttle points can be set by the user.

If I were you I'd note where the variable resistor screw is right now......and play with it to see if it really does effect the mixture at higher levels than idle. That's before installing the safc that you mention.

I'm curious. What are you using to look at the afr? A wideband or ....other?

Sure I guess I could check that out for you. Yeah I got the Innovate LM-1 Wideband, That thing is great!