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Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1667
Experience:  GM Grand Master Technician 2007. 14 year experience.
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Help, please! Vehicle failed emissions. Otherwise purring

Customer Question

Hello - help, please! Vehicle failed emissions for NoX. Otherwise purring like a kitten. Replaced EGR Valve now rough idle, lowered RPM, not as much "punch," and Service Engine light flashing. Had diagnostic = only understood words: manifold, throttle, vacume, and missing on one cylinder (also just had "spider" replaced and spark plugs etc replaced). any advice for the neighbor who's been working on it. Oh yeah, it's a 95 GMC Jimmy
Submitted: 8 months ago.
Category: GMC
Expert:  Amedee replied 8 months ago.

Hello and welcome! My name is ***** ***** I can assist you with your question. A high NOX reading is caused by the internal cylinder tempature is too high. Now if the engine is running rough, this needs to be addressed first before going any further. Once the engine is running good and if the NOX numbers remain high, then we need to dig a bit further.

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