Decel fuel delivery, stoich @ 0% tps? WTF!

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Nov 22, 2006 | 09:28 PM
  #1  
So, i just drove to Phoenix from Salt Lake, and noticed that when i am off throttle (0% tps) and the rpms are above 3k, my wb reads stoich (14.7 afr, 1.0 lambda). Once rpms drop below 3k, it goes dead lean (no fuel delivery).

Why?!

Why would it be this way? Shouldn't any 0% tps readings be dead lean, with no fuel delivery? I dont understand why mitsu would do this. Any thoughts?

I'm sure this can be remedied in an open loop table somewhere, but just thought i would bring it up to the crowd, hopefully it hasn't been covered already.
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Nov 22, 2006 | 09:50 PM
  #2  
It's normal to be at 14 to 15 at Idel and pretty much the same a crusing speed!!
If I 'm not mistaken......That's what my wideband reads..
If you want I'll take some video on idel mixture......
Quote: So, i just drove to Phoenix from Salt Lake, and noticed that when i am off throttle (0% tps) and the rpms are above 3k, my wb reads stoich (14.7 afr, 1.0 lambda). Once rpms drop below 3k, it goes dead lean (no fuel delivery).

Why?!

Why would it be this way? Shouldn't any 0% tps readings be dead lean, with no fuel delivery? I dont understand why mitsu would do this. Any thoughts?

I'm sure this can be remedied in an open loop table somewhere, but just thought i would bring it up to the crowd, hopefully it hasn't been covered already.
Reply 0
Nov 22, 2006 | 10:01 PM
  #3  
Quote: It's normal to be at 14 to 15 at Idel and pretty much the same a crusing speed!!
If I 'm not mistaken......That's what my wideband reads..
If you want I'll take some video on idel mixture......
Yeah, thats fine, cruising, whatever. Any time you are in open loop, it should be stoich.

What i'm talking about is Deceleration. Foot off the gas pedal. 0% TPS!
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Nov 22, 2006 | 10:07 PM
  #4  
Mine goes dead lean at 0% TPS regardless of RPM (other than idle). I wonder if this is something new with the IX. Can anyone else verify that this happens in their IX or does not happen in their VIII as in my case?

-Paul
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Nov 22, 2006 | 10:14 PM
  #5  
How lean?
Quote: Yeah, thats fine, cruising, whatever. Any time you are in open loop, it should be stoich.

What i'm talking about is Deceleration. Foot off the gas pedal. 0% TPS!
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Nov 22, 2006 | 10:20 PM
  #6  
mine reads stoich 14.7 under normal conditions but like you said deceleration 0tps it goes up to like 21
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Nov 22, 2006 | 10:27 PM
  #7  
When you let off the gas and the clutch is engaged the motor is being turned by the wheels through the tranny. It is normal for the AFR to go to 20.0. This will not harm the engine in any way because the load on the engine is virtually 0.
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Nov 22, 2006 | 11:39 PM
  #8  
it's normal behavior, probably there for emissions or fuel efficiency.
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Nov 23, 2006 | 05:01 AM
  #9  
Mine also goes lean to 21 or so when I lift. This is normal. The engine is not under load so no harm done.
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Nov 23, 2006 | 07:21 AM
  #10  
He's saying that with the driveline rotating the engine and the rpm's at 3000rpm that his wideband still reads 14.7:1. IE: the injectors are still working when he is coasting in gear.
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Nov 23, 2006 | 07:34 AM
  #11  
is your 9 stock no mods?
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Nov 23, 2006 | 08:24 AM
  #12  
Quote: So, i just drove to Phoenix from Salt Lake, and noticed that when i am off throttle (0% tps) and the rpms are above 3k, my wb reads stoich (14.7 afr, 1.0 lambda). Once rpms drop below 3k, it goes dead lean (no fuel delivery).

Why?!

Why would it be this way? Shouldn't any 0% tps readings be dead lean, with no fuel delivery? I dont understand why mitsu would do this. Any thoughts?

I'm sure this can be remedied in an open loop table somewhere, but just thought i would bring it up to the crowd, hopefully it hasn't been covered already.
I'm having a hard time following what your asking, I understand what it is your describing. But I think we need to know EXACTLY what mods your car has.

There are several things that can contribute to that, there are probably even decel tables that we haven't documented yet that might also contribute to this.
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Nov 23, 2006 | 10:10 AM
  #13  
Mods: TBE, MBC, WGA. Thats it.

Off throttle, in gear and above 3k rpm, fuel is being delivered to the tune of 14.7:1.

I am running my stock mapping with different timing, mivec, all else is stock.

Perhaps a IX thing? I dunno, i know its probly not a ton of fuel (since it isn't actually being burned) but any fuel delivered on decel is a waste imo.
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Nov 23, 2006 | 10:16 AM
  #14  
crusing im at 14.6 and 12.5 at idell
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Nov 23, 2006 | 10:30 AM
  #15  
Quote: crusing im at 14.6 and 12.5 at idell
I'm talking OFF THROTTLE, Deceleration with car in gear, clutch fully engaged, above 3k rpm.
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