Up-Pipe has no hardware to install sensor.....what now?

[f85stealth]

I just installled the crucial racing up pipe and discoered it has no where to installt the sensor into it. What has eeryone been doing with the sensor. Id assume i can get rid of the CEL with the AP i have purchased but what do i do with the sensor? Doi i just leave it hanging in the engine bay ? Do i disconnect it from the car completely? If so wont corrosion start to occur on the now exposed connectors? Not sure what the design intent of removing this to begin with was anyway.

[NewScooby]

Disconnect the sensor from the car and zip tie the cord back. If you are using a Cobb Accessport you are fine. If you do not have a way to program the ECU by way of an AccessPort or OPEN ECU software then you need to put a resistor in the plug that is remaining.

Search for Uppipe resistor if you need to know which one you need.

Also, if you are worried about the connector corroding, cover it with electical tape.

[fweasel]

2nd ^^^. The stock EGT sensor is useless in a catless UP.

[twisted]

CObb AP ECU Flash solves the Check engine....otherwise u need to put that resistor in. I think a quick solder will do it.

[f85stealth]

just finished the install and no CEL weird but thats good. Ok i will ziptie it back i just didnt want it tangling and ugly lookin was wonderin if anyone made liek a black cover so i could just remove the sensor and cap it off.

[legacy_y_tu]

just finished the install and no CEL weird but thats good. Ok i will ziptie it back i just didnt want it tangling and ugly lookin was wonderin if anyone made liek a black cover so i could just remove the sensor and cap it off.


I unplugged mine at the box above the turbo. Then I wrapped the plug with black electrical tape to keep sand and crap out of the plug in case I want to use it again for some reason.

[Crucial Racing]

This is explained in our installation instructions and it's the reason we include a resistor w/ every uppipe :p

The reason we absolutely positively DO NOT have a bung in our uppipe for the EGT probe is... actually, there's a couple, but bottom line is that we DO NOT want people to even think about putting an EGT probe -- stock or otherwise -- into their uppipe!!! Why? This is why:

1) the stock probe's sole function is to monitor the internal temperature of the catalytic converter in the stock uppipe. If the cat got too hot it would break apart and destroy your turbo, so the EGT probe is a trigger that trips at a specific temperature and tells the ECU to essentially shut the car down (puts you into "limp home mode"). No cat, no purpose for the probe. The STi uppipe and other OEM catless Subaru uppipes do not have EGT probes.

2) The OEM EGT probe is incapable of providing accurate readings. You cannot look at ECU logs and determine from the EGT temps it shows what your actual EGTs are. The oem probe is nothing more than a high/low trigger that trips at a certain temp.... its readings of temperatures below that temp are completely innaccurate and if you tuned based off of them you'd be in a world of hurt.

3) without the catalytic converter surround the EGT probe, it is exposed to higher temperatures, more vibration, and a generally harsher environment. The OEM probe tips ARE absolutely known to break off. If this happens, it destroys your turbo. It's simply unsafe to put the stock probe back in

4) the useless probe sticking into your exhaust stream is causing tubulence for no reason. Just the bung itself causes turbulence, even if you plugged it w/ a bolt or something.

5) ...and here's the kicker... the uppipe is too far from the exhaust ports in the cylinder heads to provide accurate EGT readings, PERIOD. Even if you have a really nice aftermarket EGT gauge, you want the probe 2" to 4" from the cylinder heads for the most accurate readings. Moving it all the way into the uppipe gives the exhaust enough time to cool down and it legitimately makes more than large enough of a difference to make your temp readings totally off by enough to be dangerous if you're tuning for a specific EGT. There's also an added delay to the readings because of the distance from the exhaust ports.


Soooooo... we don't include a bung on the uppipe. There is NO circumstance in which it makes sense for somebody to want or need one.

The EGT probe simply unplugs (follow the wire back to the harness near the passenger strut tower where it's plugged in). If you have tuning, it will take care of the CEL. I still recommend sticking the resistor into the car-side plug half though just to make sure. It is foolproof, whereas occasionally the tuning fix doesn't always work and you can still get an errant CEL for EGT probe or O2 sensor or whatever. You don't even need to solder, you can quite literally just stick the resistor into the plug (the car-side of the plug is female, so you just stick one end of the resistor into one side of the plug and the other into the other. Voila. Tape over with electrical tape to hold the resistor on there and you're good to go.)

Jeremy

[PhilT]

This is explained in our installation instructions and it's the reason we include a resistor w/ every uppipe :p

The reason we absolutely positively DO NOT have a bung in our uppipe for the EGT probe is... actually, there's a couple, but bottom line is that we DO NOT want people to even think about putting an EGT probe -- stock or otherwise -- into their uppipe!!! Why? This is why:

1) the stock probe's sole function is to monitor the internal temperature of the catalytic converter in the stock uppipe. If the cat got too hot it would break apart and destroy your turbo, so the EGT probe is a trigger that trips at a specific temperature and tells the ECU to essentially shut the car down (puts you into "limp home mode"). No cat, no purpose for the probe. The STi uppipe and other OEM catless Subaru uppipes do not have EGT probes.

2) The OEM EGT probe is incapable of providing accurate readings. You cannot look at ECU logs and determine from the EGT temps it shows what your actual EGTs are. The oem probe is nothing more than a high/low trigger that trips at a certain temp.... its readings of temperatures below that temp are completely innaccurate and if you tuned based off of them you'd be in a world of hurt.

3) without the catalytic converter surround the EGT probe, it is exposed to higher temperatures, more vibration, and a generally harsher environment. The OEM probe tips ARE absolutely known to break off. If this happens, it destroys your turbo. It's simply unsafe to put the stock probe back in

4) the useless probe sticking into your exhaust stream is causing tubulence for no reason. Just the bung itself causes turbulence, even if you plugged it w/ a bolt or something.

5) ...and here's the kicker... the uppipe is too far from the exhaust ports in the cylinder heads to provide accurate EGT readings, PERIOD. Even if you have a really nice aftermarket EGT gauge, you want the probe 2" to 4" from the cylinder heads for the most accurate readings. Moving it all the way into the uppipe gives the exhaust enough time to cool down and it legitimately makes more than large enough of a difference to make your temp readings totally off by enough to be dangerous if you're tuning for a specific EGT. There's also an added delay to the readings because of the distance from the exhaust ports.


Soooooo... we don't include a bung on the uppipe. There is NO circumstance in which it makes sense for somebody to want or need one.

The EGT probe simply unplugs (follow the wire back to the harness near the passenger strut tower where it's plugged in). If you have tuning, it will take care of the CEL. I still recommend sticking the resistor into the car-side plug half though just to make sure. It is foolproof, whereas occasionally the tuning fix doesn't always work and you can still get an errant CEL for EGT probe or O2 sensor or whatever. You don't even need to solder, you can quite literally just stick the resistor into the plug (the car-side of the plug is female, so you just stick one end of the resistor into one side of the plug and the other into the other. Voila. Tape over with electrical tape to hold the resistor on there and you're good to go.)

Jeremy

All good reasons not to have the EGT sensor in, but not all accurate.

The EGT sensor gives accurate readings from ambient up to 1,800 F, these are not going to be the same as measured on the header, but not going to be far out either.

The cat does not surround the sensor, the sensor is before the cat and the temps it sees are exactly the same whether the cat is there or not.

Not sure how the vibration is going to increase without the cat, but nevermind.

The sensor is so small, the turbulence is negligible, no more than a poor weld.

I haven't heard of any sensors breaking off, I had mine in for over 30,000 miles, granted it failed in that it stopped giving any readings, but it didn't break off.

Now, I agree that is useless as a tuning tool, and pretty pointless to leave it in there, but to say it's dangerous and unsafe is just scare mongering.

[toshiba2.5]

thanks for clearing it up PhilT i left mine in there but im taking it out tomorrow

[Crucial Racing]

I haven't heard of any sensors breaking off, I had mine in for over 30,000 miles, granted it failed in that it stopped giving any readings, but it didn't break off.

Now, I agree that is useless as a tuning tool, and pretty pointless to leave it in there, but to say it's dangerous and unsafe is just scare mongering.
It's most definitely not fear mongering. EGT probes fail all of the time, stock and aftermarket (K type thermocouples simply tend to fail over time. They are a wear-and-tear item. Now that doesn't mean they physically break but it DOES happen). There are any number of accounts on NASIOC of it happening to Subarus, sometimes damaging the turbine, sometimes not, and plenty of other accounts on the internet in general of probe tips separating, breaking, and damaging the turbine. A dense metallic particle has a good chance of damaging your turbo and it truly does happen. I have nothing to gain by letting people know that an EGT probe can be dangerous. If you want to purchase an uppipe with a bung, $1 and a 12mm 1.25 thread bolt can plug it... shouldn't sway your decision.

From Unabomber's uppipe FAQ even:

"My uppipe has an EGT bung, should I plug it or reinstall the stock EGT sensor? There is a chance down the road that EGT probe could burn up and pieces of it could be ingested by the turbo. Plugging it is the best option."

I promise, it happens.


The EGT sensor gives accurate readings from ambient up to 1,800 F, these are not going to be the same as measured on the header, but not going to be far out either.

If you care to trust the EGT temperature readings that the ECU gets from the OEM EGT probe that's cool. I've seen too many accounts from various tuners testing aftermarket thermocouples right along side the OEM one and showing variances in the readings more than large enough to cause engine damage were you to tune based on the stock probe readings. I really don't believe it to give accurate readings and would never trust it to do so.

Additionally, you might be surprised how quickly the exhaust actually cools off, especially if you have a stainless header. The exhaust manifold on the Subaru is probably the longest OEM turbo manifold of practically any car. It's ridiculous. Exhaust leaving the ports at 1500* can be 700* leaving the turbo. If it's 1500* at the ports and 1250* where the probe is in the uppipe, you have a massive problem if you're tuning based on that.



The cat does not surround the sensor, the sensor is before the cat and the temps it sees are exactly the same whether the cat is there or not.
Weird... for some reason I thought I recalled the tip of the probe actually being in the cat. I honestly haven't played with a stock [catted] uppipe in a REALLY long time though :lol:... BUT... I can say with 100% certainty that the probe is NOT before the cat as you claim. As you can clearly see in this picture, it is, in fact, after the cat. With the angle of the bolt I still wouldn't be surprised if the tip went into the cat but I'm sure it could just be hovering barely above it.

http://i19.photobucket.com/albums/b166/lx89stang05/100_0488.jpg

Additionally, the temps are most certainly not the same... especially knowing the probe is after the cat, not before, but it would still be higher were it before. The cat is a restriction in the system and removing it in this case increases volumetric efficiency of the engine, which raises EGT's. Obviously with it after the cat, the removal of said cat is going to noticeably change the EGT probe's environment.

The sensor is so small, the turbulence is negligible, no more than a poor weld.
Yeah, it's small. But if you were going to choose one place to reduce turbulence as much as you could, anywhere close to the turbine inlet is a wonderful place to choose. It makes a noticeable difference smoothing out exhaust flow close to the inlet and it doesn't take much to cause truly non-negligible turbulence.

Additionally, there's a very good reason why a smooth, nice uppipe like ours makes easily verifiable power gains of ~6+ whp over the oem catless uppipes (and quicker spool and more torque) even though we use a diameter nearly identical to stock. It's 90% turbulence. It's not negligible. We've shown more power from our uppipe vs. aftermarket ones w/ flex sections that actually have larger diameters... that is definitely due to turbulence because all other things equal, the larger diameter would shift the powerband to the right, leading to a couple more ponies up top at the expense of spool and therefore low end power. Turns out we usually make more power (that's a turbulence thing) AND have significantly quicker spool (a diameter thing, and, granted, the coating does help too).

Not sure how the vibration is going to increase without the cat, but nevermind.
Yeah maybe vibration wasn't the right thing to say (although with the cat out of the way I think it's likely that the probe is hit with harder exhaust pulses, and with many thousands of those every minute I'd probably call that vibration) but, as the probe is clearly after the cat, it's darn sure to see a harsher environment as mentioned. More unburned fuel will be hitting it. More pieces of carbon from the combustion chambers and manifolds will hit it. Temps will be higher. Exhaust velocity will be higher.




So............. if you have an uppipe with a bung for an EGT probe, get a 12mm with 1.25 thread pitch bolt (often can be found as an oil drain plug) and plug it $0.02. Costs you almost nothing and I don't sell them so I'm not pushing bolts for my own benefit :lol:

Jeremy

[Crucial Racing]

I haven't heard of any sensors breaking off, I had mine in for over 30,000 miles, granted it failed in that it stopped giving any readings, but it didn't break off.

Now, I agree that is useless as a tuning tool, and pretty pointless to leave it in there, but to say it's dangerous and unsafe is just scare mongering.
It's most definitely not fear mongering. EGT probes fail all of the time, stock and aftermarket (K type thermocouples simply tend to fail over time. They are a wear-and-tear item. Now that doesn't mean they physically break but it DOES happen). There are any number of accounts on NASIOC of it happening to Subarus, sometimes damaging the turbine, sometimes not, and plenty of other accounts on the internet in general of probe tips separating, breaking, and damaging the turbine. A dense metallic particle has a good chance of damaging your turbo and it truly does happen. I have nothing to gain by letting people know that an EGT probe can be dangerous. If you want to purchase an uppipe with a bung, $1 and a 12mm 1.25 thread bolt can plug it... shouldn't sway your decision.

From Unabomber's uppipe FAQ even:

"My uppipe has an EGT bung, should I plug it or reinstall the stock EGT sensor? There is a chance down the road that EGT probe could burn up and pieces of it could be ingested by the turbo. Plugging it is the best option."

Even Cummins, stating "in the event of failure," recommends EGT probe placement specifically after the turbo on their truck engines because of how extremely expensive those turbos and engines are. On specific setups like that, which the owners do not modify, they know the exact temperature drop pre- and post-turbo so they can correct for that and factor it into the ECU and whatnot. That done, they put the probe post-turbo for safety reasons.

I promise, it happens.


The EGT sensor gives accurate readings from ambient up to 1,800 F, these are not going to be the same as measured on the header, but not going to be far out either.

If you care to trust the EGT temperature readings that the ECU gets from the OEM EGT probe that's cool. I've seen too many accounts from various tuners testing aftermarket thermocouples right along side the OEM one and showing variances in the readings more than large enough to cause engine damage were you to tune based on the stock probe readings. I really don't believe it to give accurate readings and would never trust it to do so.

Additionally, you might be surprised how quickly the exhaust actually cools off, especially if you have a stainless header. The exhaust manifold on the Subaru is probably the longest OEM turbo manifold of practically any car. It's ridiculous. Exhaust leaving the ports at 1500* can be 700* leaving the turbo. If it's 1500* at the ports and 1250* where the probe is in the uppipe, you have a massive problem if you're tuning based on that.



The cat does not surround the sensor, the sensor is before the cat and the temps it sees are exactly the same whether the cat is there or not.
Weird... for some reason I thought I recalled the tip of the probe actually being in the cat. I honestly haven't played with a stock [catted] uppipe in a REALLY long time though :lol:... BUT... I can say with 100% certainty that the probe is NOT before the cat as you claim. As you can clearly see in this picture, it is, in fact, after the cat. With the angle of the bolt I still wouldn't be surprised if the tip went into the cat but I'm sure it could just be hovering barely above it.

http://i19.photobucket.com/albums/b166/lx89stang05/100_0488.jpg

Additionally, the temps are most certainly not the same... especially knowing the probe is after the cat, not before, but it would still be higher were it before. The cat is a restriction in the system and removing it in this case increases volumetric efficiency of the engine, which raises EGT's. Obviously with it after the cat, the removal of said cat is going to noticeably change the EGT probe's environment.

The sensor is so small, the turbulence is negligible, no more than a poor weld.
Yeah, it's small. But if you were going to choose one place to reduce turbulence as much as you could, anywhere close to the turbine inlet is a wonderful place to choose. It makes a noticeable difference smoothing out exhaust flow close to the inlet and it doesn't take much to cause truly non-negligible turbulence.

Additionally, there's a very good reason why a smooth, nice uppipe like ours makes easily verifiable power gains of ~6+ whp over the oem catless uppipes (and quicker spool and more torque) even though we use a diameter nearly identical to stock. It's 90% turbulence. It's not negligible. We've shown more power from our uppipe vs. aftermarket ones w/ flex sections that actually have larger diameters... that is definitely due to turbulence because all other things equal, the larger diameter would shift the powerband to the right, leading to a couple more ponies up top at the expense of spool and therefore low end power. Turns out we usually make more power (that's a turbulence thing) AND have significantly quicker spool (a diameter thing, and, granted, the coating does help too).

Not sure how the vibration is going to increase without the cat, but nevermind.
Yeah maybe vibration wasn't the right thing to say (although with the cat out of the way I think it's likely that the probe is hit with harder exhaust pulses, and with many thousands of those every minute I'd probably call that vibration) but, as the probe is clearly after the cat, it's darn sure to see a harsher environment as mentioned. More unburned fuel will be hitting it. More pieces of carbon from the combustion chambers and manifolds will hit it. Temps will be higher. Exhaust velocity will be higher.




So............. if you have an uppipe with a bung for an EGT probe, get a 12mm with 1.25 thread pitch bolt (often can be found as an oil drain plug) and plug it $0.02. Costs you almost nothing and I don't sell them so I'm not pushing bolts for my own benefit :lol:

Jeremy

[mwiener2]

If the EGT was ONLY there for cat protection.....why is there a table in the ECU for closed loop fueling based on EGT?

[qikslvr]

I don't kow much, but I would think that the EGT reading is what determines when the ECU switches from closed to open loop. Basically, it runs closed loop until the Header/UP/Exhaust Gas reach proper operating temp and then allows for the open loop fueling. Again, I don't know much about it, but it seems to make sense.
Anyone know what temp the resistor mod is supposed to simulate?

[mwiener2]

I just messed with all this last night


2.2k resistor sims ~1292 degrees F

Stock Closed Loop EGT setpoints: Enter below 1634 F Exit Above 1670 F

[qikslvr]

So how does the closed/open loop work when we either have the EGT sensor zip tied to a hose or removed all together and resistored?
Do Cobb/TDC/PDX or other maps compensate for this?

[Crucial Racing]

If the EGT was ONLY there for cat protection.....why is there a table in the ECU for closed loop fueling based on EGT?
Well if that weren't the case, the probe would be completely functionless. OF COURSE it has the ability in the ECU to affect closed loop fueling. That's how it saves the cat and therefore the turbo. EGT is capable of taking the car out of closed loop if temps get too high in order to prevent the cat from breaking apart. It is there for the cat. In order for high EGTs to be able to trigger the car to go into "limp home mode" or to prevent EGT's from getting to that point in the first place it has to have a table in the ECU for doing that. This shouldn't be a surprise.

Again, there is NO EGT PROBE in the STI or any other Subaru with a catless uppipe. It is not used by the Subaru ECU for anything other than making sure the cat isn't damaged by heat. Whether or not you might be able to use the EGT table for some positive effect during custom tuning is inconsequential in this question of what its factory purpose is.

I don't kow much, but I would think that the EGT reading is what determines when the ECU switches from closed to open loop.
What determines, during normal driving with a stock ECU, when your ECU goes between open and closed loop is throttle position. Typically when you get a tune this is switched so boost pressure controls the switch between open and closed.

EGT's DO NOT control open or closed. This is very easy to prove on a stock-ECU car with a manual boost controller. This setup has blown many engines because, unlike w/ stock boost control that only gives you full boost above a specific throttle position, an MBC will give you full boost at very light throttle. This means the ECU is still in open loop and does not provide the necessary fuel to keep up with full boost airflow rates. The car goes lean and EGT's skyrocket. Many an engine has been blown because of this. If the EGT readings were quick or accurate enough, the engine would be shut down when they got too high OR, better, the higher EGT's would switch the ECU over the closed loop but it just doesn't happen.

This is why an MBC with a tuned ECU fixes the partial throttle full boost issue. You still get full boost at partial throttle, but since the open/closed switch is now boost controlled, the ECU switches over and you actually get the fuel you're supposed to.



A resistor tricks the ECU into seeing a constant EGT reading from the sensor. Therefore, no problems and no limp home mode.

Tuning takes the parameters for the EGT range that the ECU considers "okay" and basically makes the acceptable range from negative to positive infinity... that way no matter what reading the probe is sending to the ECU, the ECU has no problem with it. This is how tuning takes care of O2 sensor CEL's as well... just makes the acceptable range as huge as possible so any readings will always be within that range.

Hope it helps.

Jeremy