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Gauges Question

andy95'R33GTR

By andy95'R33GTR,
in Engines & Forced Induction

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**RB2530** Proficient

**RB2530**

Posted
Posted
A/F just runs of the 02 sensor wire going to your computer. Not completely accurate but gives you good idea, only accurate if you run a wide band 02 sensor.

EGT ?

Not what your definition of accuracy is?

Factory O2 sensors are very accurate when it comes to measurement around stoichiometric A/F ratios (14.7:1)...Their accuracy falls rights away when you deviate too far from stoich, but for their intended purpose as a 'narrow band' sensor that is only used for fine adjustment of fueling during cruise when the ECU is closed loop, they are good.

'Wide band' sensors on the other hand have a much wider measurment range and will give reasonble indication at much higher and lower A/F ratios, right down or up to the extremes where the engine runs poorly or goes bang...

Your stock rb26 would not have an EGT sensor I dont think...With the rb25 there is a temp sensor in the stock cat but the intent of this is to indicate a blocked cat. The best place to put and EGT sensor is in the exhaust manifold. The further away form the cyl head you get, the less accurate and more lag you get in your measurement...But the down side is if it breaks in the manifold, the bits go through the turbine...Although, I have been using a 1.6mm K-type sensor mounted in a manifold for about 3 years now and it still is in one piece and works well...

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andy95'R33GTR Rising Star

andy95'R33GTR

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Not what your definition of accuracy is?

Factory O2 sensors are very accurate when it comes to measurement around stoichiometric A/F ratios (14.7:1)...Their accuracy falls rights away when you deviate too far from stoich, but for their intended purpose as a 'narrow band' sensor that is only used for fine adjustment of fueling during cruise when the ECU is closed loop, they are good.

'Wide band' sensors on the other hand have a much wider measurment range and will give reasonble indication at much higher and lower A/F ratios, right down or up to the extremes where the engine runs poorly or goes bang...

Your stock rb26 would not have an EGT sensor I dont think...With the rb25 there is a temp sensor in the stock cat but the intent of this is to indicate a blocked cat. The best place to put and EGT sensor is in the exhaust manifold. The further away form the cyl head you get, the less accurate and more lag you get in your measurement...But the down side is if it breaks in the manifold, the bits go through the turbine...Although, I have been using a 1.6mm K-type sensor mounted in a manifold for about 3 years now and it still is in one piece and works well...

so for the A/F, i only need to buy a gauge only and attach it on the wiring on my a/f on my ecu, and the EGT, i need to buy the complete set, so .. where exactly i need to install my egt sensor?

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**RB2530** Proficient

**RB2530**

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so for the A/F, i only need to buy a gauge only and attach it on the wiring on my a/f on my ecu, and the EGT, i need to buy the complete set, so .. where exactly i need to install my egt sensor?

Yes and no about the O2 sensor...The factory O2 sensor will only give you an accurate reading when your A/F ratio is close to stoichiometric which is around 14.7:1..You should only be running this type of A/F at light engine loads ie when you are on the freeway and just cruising...

Gauges fitted to factory O2 sensors don't tell you enough info for power tuning...ie Safe A/F ratio for power is around 11-12:1. At this A/F ratio, the factory O2 sensor wont even give a reading let alone an accurate one...Its like trying to measure 20v on a 0 to 5v meter...The gauge will either tell you that the A/F ratio is RICH or LEAN 'but not' by how much...search Wikipedia for more info...

If you are interested in tuning, the factory o2 sensor is useless. Get a good wideband sensor setup..be prepared to fork out some cash too...Also any extra gauge that you connect to the factory o2 sensor may skew the sensors reading...It never good practise to connect too many gauges to the one sensor..If you are really keen installa another sensor..

The best place to install the EGT is in the exhaust manifold BUT on a turbo car don't do it unless you understand what can go wrong (sensor breaking off and damaging turbine)...Mounted in the dump pipe is good from a safety point of view but no so much from a measurement point of view. Be appreciative of the fact that the dump pipe EGT will be lower than the exhaust manifold internal temp...If you do put it in the dump pipe, make sure it is as close to the turbo as possible..

If however you dyno the car with a good tune and get a baseline dump pipe EGT value at the same time, you can assume that this temp is safe and normal...Any significant increase in this temp later will indicate that something in the tune has changed and there is a problem...And before you ask, the dump pipe EGT will differ from car to car so dont ask what it should be...It will be a function of things like size/type of your exhaust, turbo etc..

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andy95'R33GTR Rising Star

andy95'R33GTR

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Yes and no about the O2 sensor...The factory O2 sensor will only give you an accurate reading when your A/F ratio is close to stoichiometric which is around 14.7:1..You should only be running this type of A/F at light engine loads ie when you are on the freeway and just cruising...

Gauges fitted to factory O2 sensors don't tell you enough info for power tuning...ie Safe A/F ratio for power is around 11-12:1. At this A/F ratio, the factory O2 sensor wont even give a reading let alone an accurate one...Its like trying to measure 20v on a 0 to 5v meter...The gauge will either tell you that the A/F ratio is RICH or LEAN 'but not' by how much...search Wikipedia for more info...

If you are interested in tuning, the factory o2 sensor is useless. Get a good wideband sensor setup..be prepared to fork out some cash too...Also any extra gauge that you connect to the factory o2 sensor may skew the sensors reading...It never good practise to connect too many gauges to the one sensor..If you are really keen installa another sensor..

The best place to install the EGT is in the exhaust manifold BUT on a turbo car don't do it unless you understand what can go wrong (sensor breaking off and damaging turbine)...Mounted in the dump pipe is good from a safety point of view but no so much from a measurement point of view. Be appreciative of the fact that the dump pipe EGT will be lower than the exhaust manifold internal temp...If you do put it in the dump pipe, make sure it is as close to the turbo as possible..

If however you dyno the car with a good tune and get a baseline dump pipe EGT value at the same time, you can assume that this temp is safe and normal...Any significant increase in this temp later will indicate that something in the tune has changed and there is a problem...And before you ask, the dump pipe EGT will differ from car to car so dont ask what it should be...It will be a function of things like size/type of your exhaust, turbo etc..

so what is the best and brand of a/f gauges and EGT gauges with sensors to use?

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paulr33 Grand Master

paulr33

Posted
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for wideband go for the techedge wb02 and get a bosch wideband 02 sensor - dont even bother using the stock 02 sensors, they are NOT suitable for A/F guages, dont even bother

should be around $250 ish

for EGT any reputable brand is good (hks, apexi, autometer) should be around $300 ish

both are expensive as they contain and use expensive sensor technology

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  • 3 weeks later...
parkie Contributor

parkie

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The best place to install the EGT is in the exhaust manifold BUT on a turbo car don't do it unless you understand what can go wrong (sensor breaking off and damaging turbine)...Mounted in the dump pipe is good from a safety point of view but no so much from a measurement point of view. Be appreciative of the fact that the dump pipe EGT will be lower than the exhaust manifold internal temp...If you do put it in the dump pipe, make sure it is as close to the turbo as possible..

If however you dyno the car with a good tune and get a baseline dump pipe EGT value at the same time, you can assume that this temp is safe and normal...Any significant increase in this temp later will indicate that something in the tune has changed and there is a problem...And before you ask, the dump pipe EGT will differ from car to car so dont ask what it should be...It will be a function of things like size/type of your exhaust, turbo etc..

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paulr33 Grand Master

paulr33

Posted
Posted

the 02 sensor must be mounted in the correct orientation and as close to the exhaust outlets as possible, after the turbocharger

look where your factory 02 sensors are and aim around there. be sure to note the specific installation instructions for the 02 sensor when you buy it

wideband 02 sensors are very sensitive and can die easily if you just go ahead and install it and don't read it properly

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