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SN95 Cobras
Low RPM stumble/miss
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<blockquote data-quote="ZeroDCX" data-source="post: 15620074" data-attributes="member: 91953"><p>The code you're posted P1131 is due to a detected lean condition on bank 1 during closed loop operation. This is pre-catalytic converters, so installing an OR-X will have no effect on alleviating the code versus the stock H-Pipe. In all actuality, installing an OR-X w/o a tune or MIL eliminators would result in the following codes P0420 and P0430, nothing more. Signifying that the downstream O2 sensors are reading high values (rich), since the catalytic converters are not there to burn off post combustion fuel. Upstream O2 sensors are not effected either way stock H-Pipe w/ cats or catless OR-X.</p><p></p><p>Strictly regarding the posted code: The system either has a faulty MAF, vacuum leak, exhaust leak (pre mid pipe), fuel delivery (faulty injector) or faulty O2 sensor issue affecting bank 1. If you were to datalog this, you would see that system's STFT's on bank one relatively high (more than 0% and closer to 25% - meaning ECM is commanding more fuel as its detecting a lean condition on bank 1), it should try to correct the lean issue by bringing LTFT's higher in value (adding more fuel), to bring STFT's back to zero. Both STFT's and LTFT's should be "near" 0% in engine burning fuel stoichiometrically (14.7:1).</p><p></p><p>More than likely, I would be looking towards an exhaust leak. If the mid-pipe is not tightly secured, it could pull fresh air between the manifold and mid-pipe, bypassing the engine and read by the upstream O2 sensor. This would result in a lean condition detected by the ECM. Also make sure your O2 sensors are tightened properly and all connections are secured. A faulty MAF "should" read lean on both banks 1 & 2, but things can happen to prevent such an occurence. Under the right conditions a vacuum leak could present it self on only one bank or be worse on one bank versus the other.</p><p></p><p>If the coil packs were an issue, then there would be a rich condition from fuel failing to be ignited. The ECM "should" throw a misfire or rich code. You could also data log to verify this by watching STFTs/LTFTs. A rich condition would result in the ECM commanding negative fuel trim values (ECM pulling fuel) to compensate.</p><p></p><p>Either way, good luck and let us know how it goes.</p></blockquote><p></p>
[QUOTE="ZeroDCX, post: 15620074, member: 91953"] The code you're posted P1131 is due to a detected lean condition on bank 1 during closed loop operation. This is pre-catalytic converters, so installing an OR-X will have no effect on alleviating the code versus the stock H-Pipe. In all actuality, installing an OR-X w/o a tune or MIL eliminators would result in the following codes P0420 and P0430, nothing more. Signifying that the downstream O2 sensors are reading high values (rich), since the catalytic converters are not there to burn off post combustion fuel. Upstream O2 sensors are not effected either way stock H-Pipe w/ cats or catless OR-X. Strictly regarding the posted code: The system either has a faulty MAF, vacuum leak, exhaust leak (pre mid pipe), fuel delivery (faulty injector) or faulty O2 sensor issue affecting bank 1. If you were to datalog this, you would see that system's STFT's on bank one relatively high (more than 0% and closer to 25% - meaning ECM is commanding more fuel as its detecting a lean condition on bank 1), it should try to correct the lean issue by bringing LTFT's higher in value (adding more fuel), to bring STFT's back to zero. Both STFT's and LTFT's should be "near" 0% in engine burning fuel stoichiometrically (14.7:1). More than likely, I would be looking towards an exhaust leak. If the mid-pipe is not tightly secured, it could pull fresh air between the manifold and mid-pipe, bypassing the engine and read by the upstream O2 sensor. This would result in a lean condition detected by the ECM. Also make sure your O2 sensors are tightened properly and all connections are secured. A faulty MAF "should" read lean on both banks 1 & 2, but things can happen to prevent such an occurence. Under the right conditions a vacuum leak could present it self on only one bank or be worse on one bank versus the other. If the coil packs were an issue, then there would be a rich condition from fuel failing to be ignited. The ECM "should" throw a misfire or rich code. You could also data log to verify this by watching STFTs/LTFTs. A rich condition would result in the ECM commanding negative fuel trim values (ECM pulling fuel) to compensate. Either way, good luck and let us know how it goes. [/QUOTE]
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