mahoney944

So I finished my wideband install today and the car read right on, i also did a full throttle body restoration, new seals, deleted the brass port..welded shut, reset idle as described on LR. When i jumped the isv I noticed something, my car idled perfectly but the car was rich. It seems the car has been running rich and the isv has been compensating making it run at normal figures, anyways I was wondering what's the best way to lean it out some? Still using AFM so I hear there's an adjustment there as well as the DME fqs. Not sure which is a better option for leaning. And I haven't really checked the fqs to see where it is, assuming stock position.

Also on a side note, if you're using the isv still and have wideband and this is an awesome idle tunning check! Maybe this will help others fix annoying idles

mahoney944

Checked the DME it was in stock location, I set it at position 2 (-3%) and it maybe helped a little but not enough. Anyone?

fejjj

What are your AFR's at idle?

mahoney944

With the isv jumped and idle set normal I was getting 13:1. Remove the jumper and it would raise the idle and get 14:7. So I changed the fqs to -3% and repeated above, when jumped it read 13:8. Better but not ideal. So I set the fqs back to the stock position and adjusted the AFM and now when its jumped it reads 14:7 and when removing the jumper I get 14:7. That I'm happy with, the only thing I notice is when the car is fully hot and you jump the isv the idle drops closer to 800 a little low and idles a little rough too, when you remove the jumper it raises to 940 but seems to be a smooth idle. I attempted to turn the idle adjustment screw a little past the recommended 1/2 turn from seated but that causes the idle to be correct when jumped but is raised a tad high (1000 to 1050) when you remove the jumper. So I set it back at a half turn from seated. I'm getting good readings with the wideband but the idle is a tad high if going by 840 rpm. Not sure what else to adjust or if I need to. I would think when the isv is jumped the Afr should be 14.7 and removed it should be 14.7.....don't know if I should be concerned about the slight idle raise, as it seems to idle smoother at 940.......thoughts?

mahoney944

Anyone?

fejjj

My car idles at 940 with M tune.

mahoney944

I think I'll play with it more tonight. When adjusting the Allen head bolt on the AFM, what is this actually doing? Is it allowing more air to the manifold or telling the DME to adjust the fuel? Both would result in leaning or riching. But depending on which way its adjusting its either adding more air to a rich condition or removing fuel.

CBR944

Loosening the idle air/fuel mixture valve on the AFM allows more air to bypass the vane ("flapper"). Obviously, as more air bypasses the vane there is more air entering the intake than the DME thinks, so the mixture is leaner. Tightening the valve reduces the amount of air bypassing the vane. The effect is apparently only noticeable at idle (that is, as the throttle opens the amount of air bypassing the vane doesn't change, so its effect is minor compared to the greater volume of air moving through the AFM above idle speed.)

mahoney944

This makes sense , what is the stock position of the adjustment?

CBR944

Sorry, don't know. Mine was mostly closed before I adjusted it, but have no way of knowing if it was set that way at the factory. I loosened mine out as chips and a 3 bar FPR seemed to be causing a rich idle.

Paulyy

Half turn open.

mahoney944

Just to clarify because the throttle body is a half turn up as well. So both the throttle body and AFM adjustment screws are a half turn up?…………..…....

Also I noticed that when I set the throttle body a half turn from seated it idles too low for comfort, barely 800, and this causes the volt gauge to be low, I had to turn it an extra half turn to maybe a full turn for it to hold the volts normal and to have an idle around 900 to 950 which works well for the mods I have.

Another thing to add is that tuning the mixture at the AFM really isn't effective if you're using the stock O2 sensor and isv as they self correct the issue if there's one. This tuning just sets the adjustment to as close as possible to a 14:7 ratio, which makes less work for the O2 sensor and isv making a smoother idle. Ideally the idle screw on the throttle body, needs to be set as close as possible to when the isv is jumped or not jumped before tuning the afm