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Discussion Starter · #1 ·
Newbie to tuning here, 94 single w/stock fuel, map ecu. A friend of mine plans on tuning my car and I would like to go over some target a/f ratios. As far as I know, wot should be around 11.1 - 11.5, cruising around 15.1, and idle around 11.5 - 12.1 Do these numbers sound about right for daily driving?
 

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I aim for WOT 11.5

Cruising is currently set at 14.7, but I have seen people go as low as 16.1-16.5 for fuel economy.

Idle stock is 14.7, which is what mine is set at. Some people idle there cars as rich as 13.5. I would go as lean as you can while still maintaining a smooth idle w/no knocking.

HTH,
 

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Discussion Starter · #3 ·
I heard anything over 12.1 high rpm is bad?
 

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REVTECHRACING.COM
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i shoot for 11.5 range at wot on my aem and my low settings are wacky still. idel it fluxs from 5 minutes at 10.7 and a few minutes later itll stay around 11.8 or so. need some more tuning done.
 

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Idle and cruise should both cycle around 14.7. If not, the stock ecu will drive you nuts. If you don't feed it the proper signal from the map ecu to be at 14.7 it will constantly be trying to fix it and tuning will be a pain. The only way around it is use an AEM and not use O2 feedback. Then you can set idle and cruise to whatever you want.

As far as wot, the stock ecu isn't trying to correct to any specific A/F like it does at idle and cruise. I tune for the 11s.
 

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supra400hptt said:
Idle and cruise should both cycle around 14.7. If not, the stock ecu will drive you nuts. If you don't feed it the proper signal from the map ecu to be at 14.7 it will constantly be trying to fix it and tuning will be a pain. The only way around it is use an AEM and not use O2 feedback. Then you can set idle and cruise to whatever you want.

I know exacltly what he means. At idle the ecu hates what the mapecu wants to do and its a constant struggle to keep it where I want it. Damn Stock ECU.
 
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Feedback only works well if open loop is close... I.E. if your 25% off in the map, and the o2 correction has to work hard to get you there, by the time it does, you in another part of the map that is 25% off the other way. Get it right in open loop first, then turn on closed loop. With the AEM if you are still getting a "hunting" affect, you need to move the proportional table closer to zero at that rpm in the O2 feedback screen.
 

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Willjs7 said:
I know exacltly what he means. At idle the ecu hates what the mapecu wants to do and its a constant struggle to keep it where I want it. Damn Stock ECU.
Right, the OE ECU is a piece of shit.
 

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What A/F ratios do you get from when you let off the gas at say 50mph until you stop? I know you should run very lean when you let off. At what point while you're slowing down should it start moving back towards 14.7 for idle?
 
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