In the OBD I diagnostics, running "test pipes" would throw what DTC's?
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In the OBD I diagnostics, running "test pipes" would throw what DTC's?
Thinking about installing test pipes to enhance stock exhaust flow while maintaining near stock appearances. My car is a 1994, thus OBD I. Just wondering if the sub-O2 sensors after the cats just sense heating in the ECM like most OBD I vs. OBD II cars. If so, then test pipes could be installed without triggering a MIL. However, Lexus was kind of advanced for its time in the 90's, so I was wondering if the post cat O2 sensors sniff for change in oxygen content from the pre-cat O2 sensors. Also, if so, then would a simple mechanical fix taking the sensors out of the mainstream a little suffice? TIA for anyone who knows.
Last edited by Rex Ruthor; 06-14-08 at 07:30 PM.
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running test pipes most likely would set a CEL, for codes 27 and 29 (sub oxygen sensors, left and right banks). they function in much the same way as the main o2 sensors, like you mentioned.
also, you can find and o2 simulator/defouler to help eliminate the CEL, which like you also mentioned, removes the o2 sensor out of the exhaust stream.
also, you can find and o2 simulator/defouler to help eliminate the CEL, which like you also mentioned, removes the o2 sensor out of the exhaust stream.
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running test pipes most likely would set a CEL, for codes 27 and 29 (sub oxygen sensors, left and right banks). they function in much the same way as the main o2 sensors, like you mentioned.
also, you can find and o2 simulator/defouler to help eliminate the CEL, which like you also mentioned, removes the o2 sensor out of the exhaust stream.
also, you can find and o2 simulator/defouler to help eliminate the CEL, which like you also mentioned, removes the o2 sensor out of the exhaust stream.
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Good point. I want to hear that wonderfully designed 4.0 L a bit more. Perhaps custom muffler replacement out back is the best option.
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The weakest link in the exhaust setup is the header. One quick look and you'll see why they are hindering your performance. I dont have an LS400, but the 4.0 V8 gained about 15whp and 20ftlbs almost throughout the revband on the GS400 and SC430. Gobs of midrange torque available. Of course, they dont come cheap and it (S&S headers) might not fit the first gen LS400.
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