NA Header

907mge · 03-07-2010, 01:08 AM

I know this has been talked about before but I can’t seem to find an answer. I got a pacesetter header, which besides some minor modification seems to be half decent for the money. My question is with the 02 sensor location which is far back by the cat. Is there any reason to have it moved up further towards the engine?

cre · 03-07-2010, 04:41 AM

The lower location has its ups and downs, just as is the case with a higher location. It ensures a broader sample of gasses by placing the sensor after the collector so that the exhaust from all cylinders will pass the sensor. With some more delicate sensors such as aftermarket wideband sensors the added distance is needed to prevent damage from excessive heat. In some exhausts the lower sensor location may put a non heated O2 sensor in a position where it is operating below the desired operating temperature resulting in an inaccurate reading. In this case installing a heated sensor (such as is used in the 7M-GTE) will resolve the issue. I don't know if anyone's had trouble with the added distance causing issues... I don't think it'll be a problem.

The graph below shows (somewhat) that as the temperature increases the range seen as stoichiometric gets smaller. But, get too hot or too cold or too erratic and the ECU will not receive what it views as a valid signal and an error code will be stored.

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907mge · 03-07-2010, 05:35 PM

I was planning on putting exaust wrap up top by the block on it. Do you think that will help to keep the sensor hotter down the pipe? Also what do you think a realistic gain is with the header?

cre · 03-07-2010, 09:57 PM

Insulation is a good idea, but unless you live in a very dry area I'd get it ceramic coated instead of wrapping it. The pacesetter is mild steel and from what I've read and seen it doesn't hold up to the condensation which collects in the wrap.

I really don't think you need to worry about the exhaust being too cool. Given how much faster the gasses are going to be moving the temp will probably not vary much and N/A exhaust is pretty hot as it is (hence the unheated sensor). If you want to really dig in you could install a portable EGT in the bung and go for a drive. Optimum temp is around 400*C.

03-07-2010, 01:08 AM	#1
907mge 20psi boost Join Date: Dec 2009 Location: Harrisburg Posts: 759	NA Header I know this has been talked about before but I can’t seem to find an answer. I got a pacesetter header, which besides some minor modification seems to be half decent for the money. My question is with the 02 sensor location which is far back by the cat. Is there any reason to have it moved up further towards the engine?

03-07-2010, 04:41 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	The lower location has its ups and downs, just as is the case with a higher location. It ensures a broader sample of gasses by placing the sensor after the collector so that the exhaust from all cylinders will pass the sensor. With some more delicate sensors such as aftermarket wideband sensors the added distance is needed to prevent damage from excessive heat. In some exhausts the lower sensor location may put a non heated O2 sensor in a position where it is operating below the desired operating temperature resulting in an inaccurate reading. In this case installing a heated sensor (such as is used in the 7M-GTE) will resolve the issue. I don't know if anyone's had trouble with the added distance causing issues... I don't think it'll be a problem. The graph below shows (somewhat) that as the temperature increases the range seen as stoichiometric gets smaller. But, get too hot or too cold or too erratic and the ECU will not receive what it views as a valid signal and an error code will be stored. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar ---> Last edited by cre; 03-07-2010 at 05:07 AM.

03-07-2010, 09:57 PM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Insulation is a good idea, but unless you live in a very dry area I'd get it ceramic coated instead of wrapping it. The pacesetter is mild steel and from what I've read and seen it doesn't hold up to the condensation which collects in the wrap. I really don't think you need to worry about the exhaust being too cool. Given how much faster the gasses are going to be moving the temp will probably not vary much and N/A exhaust is pretty hot as it is (hence the unheated sensor). If you want to really dig in you could install a portable EGT in the bung and go for a drive. Optimum temp is around 400*C. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

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03-07-2010, 05:35 PM	#3
907mge 20psi boost Join Date: Dec 2009 Location: Harrisburg Posts: 759	I was planning on putting exaust wrap up top by the block on it. Do you think that will help to keep the sensor hotter down the pipe? Also what do you think a realistic gain is with the header?