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Lean is bad

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Old Apr 22, 2003 | 08:50 AM
  #1  
XSTransAm's Avatar
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From: Gaithersburg, MD / WVU
Lean is bad

Im finally making the power on the dyno... but im afraid it might be at the cost of my engine if im not careful... its running what I think is extremely lean... any ideas?

http://www.azezial.freewebpages.org/afr.jpg
http://www.azezial.freewebpages.org/boost.jpg

this is before and after sequential conversion. and their was a horrible vacuume hose job in between
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Old Apr 22, 2003 | 09:19 AM
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your links are not working, just throwing pop-ups at me. Yuk!
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Old Apr 22, 2003 | 09:25 AM
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You might want to tell people what the lines on the AFR chart represent. The red plot looks like trouble to me.

The green plot looks good-11.3 at 10 psi should be safe. Probably even a little rich at high rpm. Remember there is a bit of lag before an AFR sensor can provide a reading.

Cut out the link and paste into a new window to avoid the popups.
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Old Apr 22, 2003 | 09:33 AM
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the red is what its running now.. the green is what it was before I messed with the car.. but as you can see my boost was way low.
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Old Apr 22, 2003 | 09:35 AM
  #5  
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http://www.turboxs.com/RX7AFR.htm
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Old Apr 22, 2003 | 10:07 AM
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At 4K you're at 10 psi, but your AFR is nearly 13. Also, you're at 14+ AFR at 2 psi. I'd say you're out of the safe zone. The entire map needs to be richened up. Is this on a stock ECU? What other mods do you have?
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Old Apr 22, 2003 | 10:27 AM
  #7  
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thats a stock ecu, my mods are a dp and a intake... is their anything i can do so i dont have the factory vacuum mess controlling fuel pressure?
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Old Apr 22, 2003 | 10:40 AM
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There is a solenoid that the fpr vac line goes to, you can disconnect it then run the vac line straight from the fpr to a uim nipple.

If your on the stock computer, what are you doing to change your fuel settings? You running some kind of piggy back or what? I have a bad feeling about your set up.

I'm lookin at your graphs but all I see is the a/f and rpm. What boost are your running at each rpms point?

What are the graphs based on? A dyno? A Gtech or something? Do you know for sure they are absolutly accurate? It says your tq is at flywheel which means its very low.....in both the green and red....if they are in fact flywheel.

STEPHEN
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Old Apr 22, 2003 | 10:47 AM
  #9  
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im not doing anything currently to change my fuel settings, i have a haltech in the mail but i was told that as long as i dont go past an intake and dp that i would be ok long as i didnt do any serious 4th gear pulls. and that is on a dyno... very accurate readings imo. and that is wheel torque, i dont know why it says flywheel.


and their is a boost to rpm chart at the top of the thread.... someone said not to click on it but to copy it into your browser to make it work
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Old Apr 22, 2003 | 10:54 AM
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My first thought is that the AFR is probably inaccurate. Where was the sensor mounted? It should be mounted before any cat converters. If it is mounted properly and known to be a good sensor, then I'd verify fuel pressure. There aren't many things that can go wrong no an RX-7 to make it run lean.

Wade
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Old Apr 22, 2003 | 10:57 AM
  #11  
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its taken from the tailpipe... the same place and sensor that showed my car as in the green graph. if i put my regulator to the uim how will that affect my fueling at low rpm?
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Old Apr 22, 2003 | 11:18 AM
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Ok, your a/f readings really are not accurate cuase they were taken from the tail pipe on a car with cats still in place.

Here is the deal, after 4500rpms when trans would normally occure there is no difference between your car non seq or seq, its the same flow either way so your ok there. Prior to tran however you are flowing more air. As an example at 6psi of boost and below tran the stock computer says to use a certain amount of fuel. It doesnt realize that now your flowing 2 turbos instead of one so your flowing a lot more cfm thru the engine at 6psi but not getting any extra fuel.

If I were you I would go back to the dyno, pull your stock O2 sensor and put thier wideband in there. Then make some runs to get a better idea of your true a/f from 3000-4500.

You might be a little lean but there is a little more room for being lean when your at real low boost like you are before 4500rpms so you might be ok.

STEPHEN
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