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1,150+ rwhp club
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Discussion Starter · #1 ·
New install of AEM on a 93 TT.
Version 1.19
AEM wideband all in one guage thingy. It is calibrated to the AEM.

I've got the car idling perfectly at 14:1 (big cams). If I turn on 02 FB, it instantly jumps to 18:1!!! If I try and correct the idle fuel cells, a very small RAW change will send 02 FB Value from one extreme limit to the other (+/-12%). I changed the Accel Max to 20 from 50 and the Update Rate from 58 to 100 thinking 02 FB was getting ahead of itself.... did not fix it.

I'm stumped. Any ideas?
 

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I take it the WB has always been working then it suddenly malfunctioned? If so, have you checked your wiring? Tried a new 02 Sensor?

I also use the AEM WB non-guage version. It's been fine for 2 years but I never ran leaded gas.
 

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1,150+ rwhp club
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Discussion Starter · #4 ·
mike91t said:
What's your O2 FB target map set at? Also your O2 FB gain, options etc?

At idle, 14:1.
<see pic>


MK4UMHA - The sensor and setup is brand new. the guage and aem o2#1 both show the same AFR.
 

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just a question.. do people normally run O2 FB in boost? I have mine turn off at 4 psi right now...
 

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Discussion Starter · #10 ·
mk4umha said:
I dont know how big that is, it depends on your fuel injector size too.

I checked my personal map... it's at 35. I'll try lowering that and see what happens.
 

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JamesN1830 said:
I checked my personal map... it's at 35. I'll try lowering that and see what happens.

You can't just change it. you have to basically highlight then copy the fuel map in DUTY CYCLE view, then change the M/sec bit, then paste it into the Fuel Map again.
I think 75 is a very large value.

http://forum.aempower.com/forum/index.php?topic=11494.0
 

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What's your O2 proportional gain table look like? If the gain is too high (and I mean really high), the FB circuit will become unstable and actually diverge from your target (versus converge).

It also requires a non-zero integral setting to force constant offsets (due to the proportional gain) to zero, too.

-scott
 

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Discussion Starter · #13 ·
motorheaddown said:
What's your O2 proportional gain table look like? If the gain is too high (and I mean really high), the FB circuit will become unstable and actually diverge from your target (versus converge).

It also requires a non-zero integral setting to force constant offsets (due to the proportional gain) to zero, too.

-scott

you can see both pro and int in the pic above. They are on the right side of the pic.
 

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JamesN1830 said:
you can see both pro and int in the pic above. They are on the right side of the pic.
Doh! Sorry... I didn't see it.

Here's a pic of my O2 FB settings. It works like a champ for me.

I should mention that my fuel is close, anway. I use a combination of boost comp (boosted section) and cell-by-cell in the vacuum section of the map. The throttle mod table is zero. O2 FB is only +-3%

-scott
 
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There are a few things more than likely that need adjusted.

1) You need to copy the fuel map in Pulse width...change MSBP to 30, then paste the map back. Also double your engine start fuel.
2) What injectors are you running? You may need an injector driver
3) How close is the actual fuel map, once you have the above fixed.

Jason.
 

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Discussion Starter · #18 ·
Jason S. said:
There are a few things more than likely that need adjusted.

1) You need to copy the fuel map in Pulse width...change MSBP to 30, then paste the map back. Also double your engine start fuel.
2) What injectors are you running? You may need an injector driver
3) How close is the actual fuel map, once you have the above fixed.

Jason.

precision 880's
at idle, the fuel map was right on.


UPDATE - The car in question had its 2 day old th400 fail on it. I won't be tuning it until it's fixed. I'll bring this thread back from the dead once I can have some running car time again.
 
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