'17 with really lumpy idle running AC

AVC

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'17 CX-5 Select
Has anyone else noticed that their idle is really lumpy when the A/C compressor is running? And, I don't mean a steady vibration because of the extra load, but irregular mild shuddering vibration. When the compressor cycles off, the idle is lumpy coming back down to 600 RPM and then is more smooth until the compressor kick back in and RPM goes back to a lumpy 750. I've check MAF, MAP, cleaned PCV, the throttle body is squeaky clean , fuel trims OK, no cylinder misses detected by PCM.
 
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2019 CX5 Reserve AWD
Man this brings back bad memories of our CR-V. There was always a bad shudder when the A/C was on and the car was at idle.

I've noticed a minor fluctuation (don't want to say shudder) in our 19. At idle the tach settles around 600rpm and when the compressor kicks on it moves up to around 750 then settles back down to 600.
It's not abrupt but it's noticeable if you're watching the tach.
 

AVC

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'17 CX-5 Select
Yeah, I suspect your '19 is how it ought to be. Mine isn't rhythmic vibration like a bad motor mount would cause, but irregular vibration, and only when compressor is running. I'm thinking a slight power imbalance, like from carbon buildup on intake ports, or an injector with slightly less flow than others. Not enough for the PCM to register a miss, but certainly felt in the seat. Before I tear into that, am canvasing the crowd here for experiences. This issue might be related to an occasional off-idle stumble, with or without AC on.
 
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2013 Mazda CX-5 Sport FWD Auto
My 2.0L did that to a certain extent as the miles crept up. How many miles on your ‘17, and how’s your mix of city vs highway driving?

I changed my spark plugs a little early, that seemed to smooth things out slightly. Possibly placebo. Plugs looked fine but I have no idea what the electric specs were like at 7 years of age/68k miles. I cleaned my MAF and throttle body (both looked fairly clean). Took off the intake manifold and cleaned the intake valves with B12 ChemTool. Deposits were easily removed with that solvent. Didn’t get them spotless but got at least 75-90% of the gunk off. Replaced manifold and throttle body gaskets when reassembling. Did a bottle of Gumout Regane in the gas tank. Changed the oil after the fuel treatment.

Idles like new 68k to 78k. I’ll likely do a follow up of CRC intake cleaner soon and repeat every 10k miles. Id hazard a guess that an equilibrium of normal carbon buildup is reached. My intake valves looked just like FelixD’s in hisYouTube video. He had much lower but harsher stop and go city mileage. Mine was mainly highway. My slightly “lumpy” idle could simply have been due to dirty injectors. I’ve been using Top Tier ever since *shrug*
 
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2019 CX-5 Signature Soul Red Crystal Metallic
My '19 does this - I think I even posted here about it.

It's annoying and it makes me feel like my car is older than it is. It's probably just my own brain, but it feels like a car that's about 4-5 years old and its barely 1 year old.

I have 24,000 km on my car.. I'm going to mention it to the dealer next time I'm in.
 

AVC

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'17 CX-5 Select
B12 is an effective solvent. I've used a can of it twice in about 1/3 tank of gas. No detectable change in idle quality.

My next task is probably to pull the intake and look at carbon buildup. Not sure I want to mess with the injectors, as it appears the teflon seals are one time use, and installing new seals is a pain.
 
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2013 Mazda CX-5 Sport FWD Auto
I wouldn’t mess with the injectors either. Good luck if you pull the manifold to inspect. My mother in laws ‘17 2.5L has a lot more vibration than my ‘13 2.0L but it but I never felt that stumble you describe on her CX5. Feeling that on my ‘13 through the seat drove me to take the actions listed lol
 

AVC

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'17 CX-5 Select
The intake manifold removal actually looks quick. Is that your experience?
There is a YouTube that covers it specifically.
 
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2013 Mazda CX-5 Sport FWD Auto
The intake manifold removal actually looks quick. Is that your experience?
There is a YouTube that covers it specifically.

It was pretty quick and painless. Getting the car up, removing the passenger wheel, and turning the crank to close the valves as needed was more cumbersome. Actually cleaning the valves was tedious and time consuming. And messy lol.

I worked from disassembling the air box and then the throttle body from the intake, so that’s why I cleaned the MAF and throttle body as I went.
 

erhayes

Contributor
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CX5 Reserve
My 2014 with 60,000 miles seems to idle smoother after a good highway run with a few WOT to ~ 4,500 rpm. Maybe cleans out some carbon. I always use a Top Tier fuel also. Ed