Inspection/emission problem

mirage83 · 02-27-2010, 12:03 AM

For the high HC check plugs, EGR, vacuum lines, stuff like that. Even your timing being off some can raise HC.

For CO, check your O2 sensors/wires, air filter. The TPS, coolant temp sensor and/or the AFM could also be responsible.

cre · 02-27-2010, 12:49 AM

EGR will cause high NOx, I don't think it's suspect here.

HC and CO are both due to running excessively rich. I would start with checking for diagnostic error codes, then check plugs, air filter and timing... then we'll move on to bigger things.

Check codes: http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx

Look in the MKIII FAQ for info on setting timing; You probably don't need to worry about the mechanical timing, just the spark advance.

mirage83 · 02-27-2010, 01:21 AM

I knew a bad EGR can create high NOx, but for some reason I was thinking that a leaking or bad EGR might be causing a rise in HC under some conditions.

cre · 02-27-2010, 03:22 AM

Nah, a leaking EGR shouldn't cause any changes in your engine's emissions as the gasses are inert. A clogged or otherwise nonfunctional EGR will contribute to greater amounts of ping or knock which would result in the ECU pulling timing and adding fuel but it would also result in a big increase in NOx.

02-27-2010, 12:49 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	EGR will cause high NOx, I don't think it's suspect here. HC and CO are both due to running excessively rich. I would start with checking for diagnostic error codes, then check plugs, air filter and timing... then we'll move on to bigger things. Check codes: http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx Look in the MKIII FAQ for info on setting timing; You probably don't need to worry about the mechanical timing, just the spark advance. __________________ 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 --->

02-27-2010, 03:22 AM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Nah, a leaking EGR shouldn't cause any changes in your engine's emissions as the gasses are inert. A clogged or otherwise nonfunctional EGR will contribute to greater amounts of ping or knock which would result in the ECU pulling timing and adding fuel but it would also result in a big increase in NOx. __________________ 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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02-27-2010, 12:03 AM	#1
mirage83 12psi boost Join Date: Feb 2007 Location: Georgia Posts: 359	For the high HC check plugs, EGR, vacuum lines, stuff like that. Even your timing being off some can raise HC. For CO, check your O2 sensors/wires, air filter. The TPS, coolant temp sensor and/or the AFM could also be responsible.

02-27-2010, 01:21 AM	#3
mirage83 12psi boost Join Date: Feb 2007 Location: Georgia Posts: 359	I knew a bad EGR can create high NOx, but for some reason I was thinking that a leaking or bad EGR might be causing a rise in HC under some conditions.