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ArminF2021

Black Smoke & Stalling: Infiniti M Engine Crisis

Car won't start

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Loss of engine power

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Unsteady engine

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Shaking while idling

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Black smoke from exhaust on acceleration

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Engine shuts off by itself

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Check engine light on

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Stalling while idling

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Jerking on acceleration

Hey everyone, my 2003 Infiniti M is acting up pretty badly. The engine's super unstable black smoke when I accelerate, constant jerking, and it keeps stalling both while driving and idling. The check engine light is on, and sometimes the car won't even start. When it does run, there's a lot of shaking and the power feels really weak. I'm suspecting it might be the idle control valve, but I'd like to hear from anyone who's dealt with similar symptoms. Has anyone here had this fixed? What was the actual problem and how did your mechanic resolve it? Thanks in advance!

4 comment(s)


SophieFrank19

Hey there! I had a similar issue with my 2005 Infiniti G35 last year (I'd say I have some experience working on cars). Those symptoms sound really familiar my car was doing almost the exact same thing. Turned out it was indeed the idle control valve cable that was giving me grief. Took it to my regular mechanic who diagnosed it pretty quickly. The fix involved replacing the cable and plug assembly on the idle control valve cost me around 155€ (remember this was in Europe). Car's been running smooth as silk since then. What's the mileage on your M? Also, have you noticed if these symptoms get worse when the engine's cold or after it warms up? This info could help confirm if we're dealing with the same problem. BTW, my uncle actually had a similar issue with his Q45 too, so it seems to be something that pops up in Infinitis from time to time.

ArminF2021 (Author)

Hey, thanks for the detailed response! My M's got 39458 KM on the clock, and I just had it serviced last month. The symptoms definitely seem worse when the engine is cold, especially in the morning. It takes a few tries to get it started, and the shaking is really bad until it warms up a bit. That's interesting about the idle control valve the price seems reasonable too. Did you notice any warning signs before it completely went bad? Also, how long did the repair take? I'm trying to figure out if I should plan for leaving it at the shop for a day or longer. Really appreciate the help, especially from someone who's dealt with the same issue!

SophieFrank19

Hey again! Glad to help out more with this. Yeah, looking back at my G35's situation, I definitely noticed some warning signs before it completely went south. Started with occasional rough idles, especially on cold mornings just like what you're describing. Then it gradually got worse over about a month or so. My mechanic had my car for about half a day around 4-5 hours total. He knew exactly what he was doing since he'd seen it before. But yeah, I'd plan for a full day just to be safe. Better to give them enough time to do it right, you know? And since you mentioned your car's at 39458 KM, that's actually pretty similar to when mine started acting up (was around 42000 KM). Honestly, considering your symptoms match mine almost exactly especially that cold morning behavior I'm even more convinced it's the idle control valve. Quick tip from my experience: while you're waiting to get it fixed, try to let the engine warm up for a minute or two before driving off. It won't fix the problem, but it helped make my morning commute a bit less stressful until I could get it to the shop. Let me know how it goes when you get it checked out!

ArminF2021 (Author)

this is super helpful! The similarity in mileage and symptoms really makes me feel better about getting this checked out. I'll definitely follow your advice about warming up the engine I've actually noticed it runs a bit smoother when I do that anyway. I just called my mechanic and booked it in for next Tuesday. They said they'd keep it for the full day, just to be thorough. The quote they gave me was pretty close to what you paid too, which is a relief. I was worried it might be something way more serious! Thanks again for all the detailed info and tips really helped me understand what I'm dealing with. I'll update you once it's fixed to let you know if it was indeed the idle control valve. Really appreciate you taking the time to share your experience!

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