Dumb question about sensors....but i gotta know

rohan_fonseca · 12th April 2007, 18:54

Have k&n & free flow on a zen. What would be the effect of disconnecting the
i. Oxygen sensor in the exhaust manifold
ii. AIT sensor
iii. TB position sensor
iv. MAP sensor

nextlevel350z · 13th April 2007, 19:28

In some cases, such as with the AIT and MAT (and sometimes o2) sensors, your car would probably just run in "limp" mode and you would get trouble codes and a check engine light. Performance would go down.

In others, such as the MAP, MAF, TPS, and most likely o2 sensors, your car wouldn't be driveable, it would spit and sputter, possibly smoke, and you would have a mess on your hands.

You need all of these sensors for your car to operate properly. Many piggybacks modify MAF, MAT, IAT, and MAP signals to create power or fuel economy gains, but it is absolutely necessary for the ECU to get a reading from each of these sensors.

Some companies also make o2 sensor simulators...in case you have a bad o2 sensor, or you have altered your car in a way (exhaust mods, etc.), so that you have terrible emissions. The o2 simulator will send an immitated signal to your ECU showing it that everything is OK with the exhaust, when in reality, it is not.

rohan_fonseca · 13th April 2007, 22:35

Actually posted that question because i had a weird situation. The oxygen sensor wire to the exhaust was cut( probably the wire was hanging close to the fan due to my negligence). Probably was that way for months. There was no drop in fuel economy or mileage. Also no engine warning light. Was wondering why. Have also seen an OHC with disconnected sensors(i.e. O2 sensor and IAT sensor). It is a well tuned car with no ECU upgrade!!! Is that possible?

rdkarthik · 14th April 2007, 09:01

O2-
It depends on what car you have. Euro 2 suzukis run perfectly fine without an 02 sensor, but the Euro3 version through an error. Most of the newer cars may have issues with drivability in closed-loop mode (everywhere but full throttle )

AIT/IAT - Almost all cars run fine without this. Checklight will turn on. You can be sure you are not getting the best fuel mixtures and ignition timing

ECT - Same as IAT, but usuakll causes high idle and switches on radiatior fan.

TB and MAP - You can still use the car with either of them working,at the cost of drivability. On most cars you will not have any significant drop in performance in full throttle conditions .

rdkarthik · 14th April 2007, 09:02

Quote:

Originally Posted by rohan_fonseca

Have also seen an OHC with disconnected sensors(i.e. O2 sensor and IAT sensor). It is a well tuned car with no ECU upgrade!!! Is that possible?

I guess possible if disconnected, but not so if sensor is connected but screwed.

rohan_fonseca · 16th April 2007, 15:41

To satisfy my curiosity, disconnected the O2 & AIT sensors. Car ran ok but with a small drop in performance.....(as measured by my b-Dyno

)

chetanhanda · 19th April 2007, 03:38

Quote:

Originally Posted by rohan_fonseca

To satisfy my curiosity, disconnected the O2 & AIT sensors. Car ran ok but with a small drop in performance.....(as measured by my b-Dyno

)

hahah you are an interesting RnD type of the guy ..
now try this out for me.. remove the TP sensor and measure the performance ..

12th April 2007, 18:54	#1
rohan_fonseca BHPian Join Date: Jan 2006 Location: Panaji Posts: 984 Thanked: 8 Times View My Garage	Dumb question about sensors....but i gotta know Have k&n & free flow on a zen. What would be the effect of disconnecting the i. Oxygen sensor in the exhaust manifold ii. AIT sensor iii. TB position sensor iv. MAP sensor
	() Thanks

13th April 2007, 19:28	#2
nextlevel350z Newbie Join Date: Apr 2006 Location: Bloomsburg, Pennsylvania, USA Posts: 20 Thanked: 0 Times	In some cases, such as with the AIT and MAT (and sometimes o2) sensors, your car would probably just run in "limp" mode and you would get trouble codes and a check engine light. Performance would go down. In others, such as the MAP, MAF, TPS, and most likely o2 sensors, your car wouldn't be driveable, it would spit and sputter, possibly smoke, and you would have a mess on your hands. You need all of these sensors for your car to operate properly. Many piggybacks modify MAF, MAT, IAT, and MAP signals to create power or fuel economy gains, but it is absolutely necessary for the ECU to get a reading from each of these sensors. Some companies also make o2 sensor simulators...in case you have a bad o2 sensor, or you have altered your car in a way (exhaust mods, etc.), so that you have terrible emissions. The o2 simulator will send an immitated signal to your ECU showing it that everything is OK with the exhaust, when in reality, it is not.
	() Thanks

13th April 2007, 22:35	#3
rohan_fonseca BHPian Join Date: Jan 2006 Location: Panaji Posts: 984 Thanked: 8 Times View My Garage	Actually posted that question because i had a weird situation. The oxygen sensor wire to the exhaust was cut( probably the wire was hanging close to the fan due to my negligence). Probably was that way for months. There was no drop in fuel economy or mileage. Also no engine warning light. Was wondering why. Have also seen an OHC with disconnected sensors(i.e. O2 sensor and IAT sensor). It is a well tuned car with no ECU upgrade!!! Is that possible?
	() Thanks

14th April 2007, 09:01	#4
rdkarthik BHPian Join Date: Sep 2005 Location: bangalore Posts: 206 Thanked: 13 Times	O2- It depends on what car you have. Euro 2 suzukis run perfectly fine without an 02 sensor, but the Euro3 version through an error. Most of the newer cars may have issues with drivability in closed-loop mode (everywhere but full throttle ) AIT/IAT - Almost all cars run fine without this. Checklight will turn on. You can be sure you are not getting the best fuel mixtures and ignition timing ECT - Same as IAT, but usuakll causes high idle and switches on radiatior fan. TB and MAP - You can still use the car with either of them working,at the cost of drivability. On most cars you will not have any significant drop in performance in full throttle conditions .
	() Thanks

16th April 2007, 15:41	#6
rohan_fonseca BHPian Join Date: Jan 2006 Location: Panaji Posts: 984 Thanked: 8 Times View My Garage	To satisfy my curiosity, disconnected the O2 & AIT sensors. Car ran ok but with a small drop in performance.....(as measured by my b-Dyno )
	() Thanks