Odd richness problem... - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

sunnys14 · 02-13-2008, 10:25 PM

Built KA-T
AFR's are fine while cruising while engine isnt totally warmed up (13.6-14.5). After it reached operating temperature, cruising AFR's go from 11.5-13.9 up and down. At WOT its 11.5 no matter if the engine is cold or warmed up all the way, so it cant be a boost leak. Checked for boost leaks and nothing. Changed the O2 sensor, new CTS, plugs, wires, cap and rotor. Wideband sensor is also fairly new.

Not sure what the problem is... is the the TPS going bad? Car thinks that its WOT sometimes when its not (hence afr's dropping to 11.5 sometimes). But the problem only happens after ive been driving for about 10 minutes. Happens ONLY during cruising and out of boost, WOT is fine (AFR's 11.5 and no bucking). No power loss either...

Kouki · 02-14-2008, 07:44 AM

Maybe you need to tune for cruising load and rpm, instead of just full throttle tune.

sunnys14 · 02-14-2008, 12:33 PM

its an enthalpy tuned ecu...

Koopa Troopa · 02-14-2008, 01:05 PM

Quote:

Originally Posted by sunnys14

Built KA-T
AFR's are fine while cruising while engine isnt totally warmed up (13.6-14.5). After it reached operating temperature, cruising AFR's go from 11.5-13.9 up and down. At WOT its 11.5 no matter if the engine is cold or warmed up all the way, so it cant be a boost leak. Checked for boost leaks and nothing. Changed the O2 sensor, new CTS, plugs, wires, cap and rotor. Wideband sensor is also fairly new.

Not sure what the problem is... is the the TPS going bad? Car thinks that its WOT sometimes when its not (hence afr's dropping to 11.5 sometimes). But the problem only happens after ive been driving for about 10 minutes. Happens ONLY during cruising and out of boost, WOT is fine (AFR's 11.5 and no bucking). No power loss either...

Once the engine warms up the AFR's will go up as there is less fuel being given because the ECU will dump fuel to help the motor warm up. When you're just driving AFR's will go all over the place because the slightest touch of the throttle will have the TPS send a voltage signal to the ECU to tell it how much fuel to give. 13.9 is pretty rich for just cruising though...

When I'm just driving I usually see numbers from 14.6 - 17.8.. Once I get back those numbers will change though. Remember that the lower that number the more fuel you're wasting...

Your tune is fine.. The only problem with it is it's a ROM tune and they obviously went rich to be safe.

sunnys14 · 02-14-2008, 01:23 PM

there has to be something wrong, at 15% throttle on the freeway doing a constant 70mph, the afrs go from 13.9 to 11.5, back and forth slowly, in a matter of seconds...

Koopa Troopa · 02-14-2008, 01:34 PM

Yeah, it's suppose to do that. I'd worry if it did that during boost though. If you're not rolling in boost then don't worry about it..

sunnys14 · 02-14-2008, 02:11 PM

The problem is i've been getting about 17mpg now due to unstable AFRs. This hasnt happened before. Usually i get about 23mpg on the freeway with constant stable AFR's.

Z U L8R · 02-14-2008, 02:20 PM

i'd say get an safc2 and get it on a dyno that can put load on it.

Dave

02-13-2008, 10:25 PM	#1
sunnys14 Zilvia FREAK! Join Date: Mar 2006 Location: a land far far away... Posts: 1,549 Trader Rating: (19) Feedback Score: 19 reviews	Odd richness problem... Built KA-T AFR's are fine while cruising while engine isnt totally warmed up (13.6-14.5). After it reached operating temperature, cruising AFR's go from 11.5-13.9 up and down. At WOT its 11.5 no matter if the engine is cold or warmed up all the way, so it cant be a boost leak. Checked for boost leaks and nothing. Changed the O2 sensor, new CTS, plugs, wires, cap and rotor. Wideband sensor is also fairly new. Not sure what the problem is... is the the TPS going bad? Car thinks that its WOT sometimes when its not (hence afr's dropping to 11.5 sometimes). But the problem only happens after ive been driving for about 10 minutes. Happens ONLY during cruising and out of boost, WOT is fine (AFR's 11.5 and no bucking). No power loss either...

02-14-2008, 01:34 PM	#6
Koopa Troopa Post Whore! Join Date: Sep 2006 Location: 北谷著, 沖縄県、日本 Posts: 2,565 Trader Rating: (3) Feedback Score: 3 reviews	Yeah, it's suppose to do that. I'd worry if it did that during boost though. If you're not rolling in boost then don't worry about it.. __________________ Buy my Stillway shifter!

02-14-2008, 02:20 PM	#8
Z U L8R Zilvia FREAK! Join Date: Jan 2007 Location: Georgia Age: 43 Posts: 1,194 Trader Rating: (0) Feedback Score: 0 reviews	i'd say get an safc2 and get it on a dyno that can put load on it. Dave __________________ RB25 280z GT30/76R 441hp/381tq 11.9@125

02-14-2008, 07:44 AM	#2
Kouki Zilvia Addict Join Date: Feb 2005 Location: Nebraska Age: 40 Posts: 727 Trader Rating: (3) Feedback Score: 3 reviews	Maybe you need to tune for cruising load and rpm, instead of just full throttle tune.

02-14-2008, 12:33 PM	#3
sunnys14 Zilvia FREAK! Join Date: Mar 2006 Location: a land far far away... Posts: 1,549 Trader Rating: (19) Feedback Score: 19 reviews	its an enthalpy tuned ecu...

02-14-2008, 01:23 PM	#5
sunnys14 Zilvia FREAK! Join Date: Mar 2006 Location: a land far far away... Posts: 1,549 Trader Rating: (19) Feedback Score: 19 reviews	there has to be something wrong, at 15% throttle on the freeway doing a constant 70mph, the afrs go from 13.9 to 11.5, back and forth slowly, in a matter of seconds...

02-14-2008, 02:11 PM	#7
sunnys14 Zilvia FREAK! Join Date: Mar 2006 Location: a land far far away... Posts: 1,549 Trader Rating: (19) Feedback Score: 19 reviews	The problem is i've been getting about 17mpg now due to unstable AFRs. This hasnt happened before. Usually i get about 23mpg on the freeway with constant stable AFR's.