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Caveit77777
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She Lives!!

Post by Caveit77777 » Fri Dec 28, 2012 10:43 am

Finally the KA is running again and boosted for the first time ever!!!!!! Built block with a T3/T4 running 8 psi. I should still technically be breaking in the clutch but I've had a few quick pulls already and boy does it pull! Just found out the cheap bov I have is stuck shut an is causing some nasty flutter. I actually popped a coupler off last night while driving cause of it haha.

Anyways though I have the AEM UEGO wideband and I know all the sensors are in the correct sections of the DP. But my gauge likes to bounce from 13 to about 17 and then --- yet everything is still running perfect. Idle is great and evens out to about 14.7 once warmed up. Any ideas on whats causing my gauge to go wacko?
1996 Zenki: Arias 8.8:1 Forged Pistons, AMS Sportsman Series Rods, Tial 38mm, 370cc, Fel-pro Gaskets, New Stock Crank, Nismo Thermo, Nismo Mounts, Dual Canister Exhaust, Walbro 255, T3/T4 Turbo, Mishimoto Rad, Isis Fans, HKS SSQV, SPL Tension Rods, GAB Revo Sport II Coilovers, Enthalpy Tuned... more to come

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RyanFSH
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Post by RyanFSH » Fri Dec 28, 2012 12:12 pm

I have the same gauge and out of boost mine does this same thing, I've always thought it was because I'm just running an safc on stock Ecu (low boost). But maybe its just the way the Nissan Ecu controls fuel... it reads a narrow band o2 so it should bounce around but mine does more than I would think at idle and very low load and throttle.


Another thought, my idle will start off around Stoic and be OK then creep to 12-13:1 and stay there then I pop the throttle and it gets a lil better then creeps again, it doesn't really bother me cuz it runs very well.
1992 240sx Ka24DeT
1998 Durango

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supakat
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Post by supakat » Fri Dec 28, 2012 1:13 pm

When you are in full boost or cruising and let go of gas, decel mode turns on and shutdowns fuel. It is perfectly normal.
12.96 @ 116.36 - 2.1 60ft - 11/2011
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RyanFSH
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Post by RyanFSH » Fri Dec 28, 2012 1:43 pm

Mine does this at idle and maintaining low speeds, doesn't make it run crappy just idles real rich every once n a while mostly.
1992 240sx Ka24DeT
1998 Durango

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supakat
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Post by supakat » Fri Dec 28, 2012 2:01 pm

10.0 is rich 11.0 is ideal for boost on pump still rich for idle/cruise 14.7 is stoich great for idle/cruise 15.0 is lean 17.0 is leaner ---- is beyond lean and should be diagnosed. Check for vac leaks if you are getting 16.0 or higher afr's at idle.
12.96 @ 116.36 - 2.1 60ft - 11/2011
13.1 @ 114 - 2.3 60ft - 8/2012
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nismoautoxr
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Post by nismoautoxr » Fri Dec 28, 2012 7:49 pm

caveit. What method of ECU tuning are you using?
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95 SE ,LS1 N/A and T56, 230/232 @.050 cam, MS3 with MS3X,GC coilovers,17x8.5 Enkei RPF1 on 255 40 17 RS3 Hankooks, 377HP/351TQ , megasquirt3 fully sequential

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RyanFSH
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Post by RyanFSH » Fri Dec 28, 2012 9:31 pm

Mine does this at idle and maintaining low speeds, doesn't make it run crappy just idles real rich every once n a while mostly.
1992 240sx Ka24DeT
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nismoautoxr
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Post by nismoautoxr » Fri Dec 28, 2012 10:02 pm

RyanFSH wrote:Mine does this at idle and maintaining low speeds, doesn't make it run crappy just idles real rich every once n a while mostly.
real rich being ????? 10-11-12????
Ricky Ragan,
95 SE ,LS1 N/A and T56, 230/232 @.050 cam, MS3 with MS3X,GC coilovers,17x8.5 Enkei RPF1 on 255 40 17 RS3 Hankooks, 377HP/351TQ , megasquirt3 fully sequential

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Caveit77777
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Post by Caveit77777 » Sat Dec 29, 2012 12:19 am

nismoautoxr wrote:caveit. What method of ECU tuning are you using?
Enthalpy tuned. Also where my downpipe meets up with the exhaust doesn't exactly match up. There's two studs down there so just picture 1 stud bolted on basically leaving a triangle gap when viewed from above. AKA a fatass exhaust leak. One of the 02 sensors is near the bottom flat part of the downpipe and im wondering could it be the exhaust leak making it read funny?
1996 Zenki: Arias 8.8:1 Forged Pistons, AMS Sportsman Series Rods, Tial 38mm, 370cc, Fel-pro Gaskets, New Stock Crank, Nismo Thermo, Nismo Mounts, Dual Canister Exhaust, Walbro 255, T3/T4 Turbo, Mishimoto Rad, Isis Fans, HKS SSQV, SPL Tension Rods, GAB Revo Sport II Coilovers, Enthalpy Tuned... more to come

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Post by Freise » Sat Dec 29, 2012 3:46 am

exhaust leak near the sensor will definitely mess up your afr reading. When my car normally idles at 15, it was reading 18-19 even with a relatively small leak after the sensor, and very spastic. I'd recommend sorting that leak out, you want that wideband reading as accurately as possible if you are interested in reliability
95 240sx KA24DE-T
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