Guest djm Posted December 15, 2005 Share Posted December 15, 2005 Took my '84T in to be smogged today (northern virginia) and failed. my readings were: 15MPH - 1564 RPM (Limit/Measured) HC: (92/79 PPM) Passed CO: (.37/.55 %) Failed NOx: (1200/1665 PPM) Failed 25MPH - 1734 RPM (Limit/Measured) HC: (167/52 PPM) Passed CO: (.53/.29 %) Passed NOx: (1167/1251 PPM) Failed So my guess is the EGR system, but I really have no idea, as I've only owned this car 1 week. It has 102k miles is a manual, and seems to be well cared for. The other and potentially much more worrisome problem is that my car overheated in its 5min on the dyno. normally the temp gauge runs in the lower 1/4 of the travel, so it didn't seem to be a big deal that it inched up to just above the halfway point on the gauge during the test, but when the car was shut down, there was what sounded like boiling (never heard that from this car before today). So, I'm hoping for emissions help, but of more concern is what to do about the overheating problem. are these gages really so far off that over heating is at 1/2 guage travel? as an fyi the previous owner claimed to have replaced the waterpump and heater core recently and it seems to have plenty of coolant. it cooled down almost immediately once I drove it back on the road. Quote Link to comment Share on other sites More sharing options...
PeterZ Posted December 15, 2005 Share Posted December 15, 2005 Excessive heat, too-advanced ignition timing and a faulty EGR systen can all cause excessive NOx emissions. Good luck. Quote Link to comment Share on other sites More sharing options...
BrandonsZ Posted December 15, 2005 Share Posted December 15, 2005 I chassed that squirrel with my prelude for 3 months... nevert really got it. My NO was 950, cutoff was 850, previous cycle my NO was 990 and the cutoff was 1150. Those BASTARDS! After... New cat New O2 Cleaned and checked EGR I got 980. so I adjusted the exhaust cam one notch on the belt increasing the exhaust gas that was left in the cylindar, then it got 840. and passed. then I donated it to charity just before the next cycle, was burning lots of oil by then anyway. HATE SMOG REGS! It's just unfair to smaller cars that's all. Quote Link to comment Share on other sites More sharing options...
george.bryant Posted December 29, 2005 Share Posted December 29, 2005 Can someone please explain to me how this system works? Here in NZ we dont have any emission controls (yet *gulp*) Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted December 30, 2005 Share Posted December 30, 2005 high nox is created by high combution chamber temps.the overheating didnt help it.it is usually the lack of egr flow that causes high nox.check by using a hand vacuem pump on egr valve at idle.engine should run rough or stall-indicating exhaust gas leaned out the engine.if the engine stumbled i connect a vacuem gauge with a t to egr valve and test drive-watch for vacuem at a steady speed.it might not be 15 or 30 mph though-the egr solonoid is ran by the ecm.sometimes doing a combustion chamber decarbonizing and getting the cooling system working properly will work-this is usually done on cars with no egr system.so make sure the egr system is operating as it was designed to when car was new and get the overheating fixed.egr is exhaust gas recirculation for non smog members..some countries are more concerned about unburnt hc and some about nox.nox is what makes a brown sky in southern california.every body should be concerned about unbunrt hc-its gas that didnt get burned-but you payed for it.proper tuning of your efi system will help. Quote Link to comment Share on other sites More sharing options...
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