I have VEMS wideband installed and untill first day numbers change in idle or same speed driving as mad... one time is 9, another 29, then 15 etc
here is litle video too
http://www.youtube.com/watch?v=i5Qcvw88HVQ
As u see on full throtle it stays 10.3-10.2 (it's very rich)
I have:
Alldata chip
Straight pipes
one step colder NGK iridium spark plugs

 

I have an innovate lc-1 with a dynotune gauge thats similar. I would recalibrate it if I were you and try it again.. also where did u tap off the wideband?


Suman

 

Also the one step colder plug might be richening you up to much. try a 6 step again


Sm

 

wideband lambda sensor is near first original sensor.
I think it too, that colder plugs riches too much(after changing original->one step colder fuel usage goes up) but I have nitro and I don't want missfire
How can I recalibrate it?

 

hmm this is a wierd situation. Well I would look here and calibrate the wideband. http://www.vems.hu/manual/html/ch09s06.html dont know much about VEMS. Also I would probably put the NGK bkr6E plugs in and wire a boost a pump to the fuel pump with a hob switch to come on, on boost. This will give you the added safety for the nitrous. http://www.kennebell.net/accessories...boostapump.htm


Just my 2 cents.

Suman

 

If the Porsche ECU works like all the others I'm familiar with, it does not maintain a rock steady AFR while you are driving normally. Rather, the AFR will jump back and forth quickly between rich and lean. It's the *average* value that stays very close to 14.7:1. If my assumption is true, then your wideband AFR meter is telling the truth and your car is behaving as it should.

I'm sure if my assumption is in error, someone will promptly correct me.

Jeff

 

At part throttle, your ECU will run closed loop so it will fluctuate high/low readings. At full throttle, it will run open loop so this is the time you want to take the readings. The AFR reading will then stabilize.

 

I dont get crazy fluctuation and I have an innovate lc-1 and dynotune square gauge......

 

Your tune may lock the ECU in open loop rather than relying on the O2 sensors for feedback. I'm still trying to learn if the factory O2 sensors are true wideband or the far more common narrowband type. If they are wideband sensors, then I'd expect stable AFR readings. If they are narrowband, then I'd expect the readings to swing back and forth past 14.7 unless your ECU has been programmed to essentially ignore them (open loop)

Jeff

 

I didnt use the factory sensor. I drilled pre cat into my exhaust and put a sensor there. I dont trust OEM wideband R u kidding!

 

I didn't mean that your aftermarket AFR meter was using the factory wideband, rather I'm wondering exactly what kind of sensor the factory uses.

If the factory uses a true wideband, then I'd expect the AFR to be pretty stable under all conditions. If the factory uses a narrowband, or treats a wideband as if it was a narrowband, then I'd expect the AFR to swing back and forth around 14.7.

Jeff

 

Factory sensors are narrowband

 

OEM is wide band. I believe it is the same Bosch 02 sensor you get when you purchase an AFR gauge /w sensor.

 

Everything I've been told and read says that the 996TT O2 sensors are not. Only the GT3 is. That's why everyone welds in extra bungs for wideband sensors like I just did.

Can any of the tuners confirm this? It would be nice to be wrong on this one to make it easier to monitor both banks.

 

jimmer,

I just installed an AFR meter utilizing the OEM wideband 02 sensors. It works through the OBD2 port. I used it yesterday and today and read both banks of AFR without any problem.

Brockway confirms the Porsche 996 cars have wideband 02 sensors. If my car didn't have WB - I would not be getting AFR readings. Here is the information - see the section highlighted in RED below:



EGT (Exhaust Gas Temperature) °F or °C (only available when the EGT1 is connected)

MPG/KPL (Economy) Miles Per Gallon or Kilometers Per Liter

FR (Fuel Rate) lbs/hr or cc/min

• One custom screen mode that allows the user to select the data displayed.
• Speed and Temperature can be displayed in Metric or English units.
• Reads and clears diagnostic trouble codes (DTC's) and turns off check engine light (CEL).
• Displays boost on vehicles equipped with a MAP sensor or the AP1.
• Calculates and displays fuel economy in MPG or KPL.
• Calculates and displays fuel rate in lbs/hr or cc/min.
• Adjustable vehicle speed correction.
• Displays A/F ratio on vehicles equipped with an OEM wideband O2 sensor or an external wideband sensor.
• A/F ratio conversion for early Honda/Acura K-series engines.
• External sensor input from a wideband O2 sensor, AP1 MAP sensor or EGT1 exhaust gas temperature sensor.
• Programmable shift light output. Can also be used to control the AT1 Auto Timer module.
• Acceleration timer. (with optional AM1)
• Adjustable ECT alarm.
• Simple Plug and Play installation with included Data Link cable.
• Premium automotive grade reverse contrast green LCD.
• Case dimensions: 6.5"x2.75"x1".
• Single DIN mounting kit (MK1) available.

Shift Light - adjustable from 3,000 rpm to 9,900 rpm in 100 rpm increments. Output can drive an LED shift light such as the IND1 or SL3.
Acceleration Timer - completely automatic and no calibration required. It resets when the vehicle speed is 0 and starts counting as soon as the vehicle starts moving. Once the vehicle reaches either 60 mph or 100 km/h, it freezes the elapsed time. This result will remain on the screen until the vehicle comes to a complete stop. With the aid of an internal accelerometer to detect vehicle motion, the R920 achieves exceptional accuracy. Once triggered, the R920 tracks the VSS to determine vehicle speed. It is very repeatable and excellent for checking the affect of a vehicle modification.
External Sensor - one external sensor input which may be used with a wideband O2 sensor such as the LC-1 from Innovate or SM-AFR from PLX, an AP1 MAP sensor or an EGT1 exhaust gas temperature sensor. Vehicles not factory equipped with a wideband O2 sensor can plug in a wideband O2 sensor and have A/F ratio along with other sensor data. Vehicles not factory equipped with a MAP sensor may want to use the external MAP sensor to monitor boost pressure.