my 2009 Honda fit sport 5A/T extremely well taken care of the problem I’m having is after the car heats up after a normal drive and I have my AC on it has A stutter or sputter randomly every 30 seconds or so I shut the air off it’s a little less noticeable what sensors or possible problems can I take a look at?

(NO CODES NO IDIOT LIGHTS ON)

all fluids checked at level and clean.
compressing the brake harder does not help.

I have done the following
a full tuneup spark plugs coil packs oil change valve adjustment new belt all done by the dealership.
new tranny fluid/filter was done 15kmiles ago as requested by dealer (still pink and no burnt smell.) Oil is also always clear no milky or metallic no weird noises neither.

The car also experiences the same stutter in park and neutral I never experience any acceleration loss or sputters as long as the motor is under throttle it acts normal.

thank you for anything you can come up with too help!

 

Thoughts on this are to check old work and verify that all air hoses are properly installed. Engines run much off of vacuum at idle, so's my understanding. Something stupid like the boot going onto the intake air box being left untightened. no codes for that. could pitch other ideas, but that seems most likely tonight!

 

honda reinstalled all the intake itself. Still there.

I also swapped the intake out for a short ram everything is tight and right it did it with the stock box also. Still there.

ill tripple check but what else ya got in the bag? Lol

 

I've been doing stuff with wood lately so my head's been elsewhere!

Ramp for our two 10 year old dogs

Toolbox that I definitely should have designed with solid 5ply sides and a full back panel (and the soft close drawer slides. Those springs would have kept me from needing to put a strap around the drawers). Was trying to use scrap n save wood for the ramp.

Was slightly proud.

Uh. Air leaks/issues ain't fully off the table! Could go over and inspect all the intake vent lines, even add a fuel soluble rubber grease. I've used stuff branded as O-ring grease sold at motorcycle dealership parts centers because I was screwing with a Keihin FCR carburetor for 2 years before throwing in the towel. Wound up using it for all kinds of rubber seals (not brake boots, amazon's Red Rubber Grease works for that)
Here's a link to some overpriced molykote: I havent used this specific one yet but molykote does put out OEM honda lubes, and aviation mechs seem to love this one for all things o-ring.
My idea here was to take off vent lines, lube the tubes they go on to (including intake air boot) and reassemble with hopes of getting a leak-free seal. The lubes disappear into the rubber where they cause a little swelling.

With a slew of work done on your end my first thought is to recheck said work no matter who dunnit. If memory serves, the black intake plenum on top of the engine has hose hook-ups that I've forgotten once or twice. I'll look into the manual to see if I can spark a memory because I'm spacing.

Oh, here's a fun suggestion! I've just replaced an o2 sensor on our 2nd gen tacoma after getting a code for it and am now being told it's running better than it did pre-code Supposedly, those sensors can underperform before actually failing! As for the reason of failure, could be the leaky exhaust (post cat) courtesy of a local welder, coulda been the short term leak at the exhaust manifold caused by my swapping out rusty hardware for high grade new stuff that required re-torquing, or age, or all three!

Didn't notice power loss (or rough noise) while in motion, but the idle had some minor roughness even pre-code.
EDIT: HERE is a fuel safe rubber lube. Some say you can just use vasoline.

 

Okay. Maximum effort!

Q: Are short ram intakes bad for engines?
"Now this isn't a problem unless the coolant gets hot enough to damage fittings, gaskets, or other engine parts. But since the Short Ram Intake is more likely to add extra heat to the engine than a Cold Air Intake or even the stock airbox, it's more likely to cause a Heatsoak." -some google result from a forum

Causes For Rough Idle:

• Intake/vacuum air leak
• Clogged/obstructed fuel filter screen
• Clogged/obstructed fuel injector
• Thrashed throttle position sensor
• Clogged PCV valve (I've never seen this affect idle, but been told it does)
• Dirty/loose spark plugs
• Worn out/damaged plug wires/ignition coils
• Dirty/faulty MAF/MAP sensor (or improperly sealed MAF in your new intake?)
• Exhaust leak (pre or post o2 sensor, potentially)
• Dirty/worn out O2 sensor/s
• Valves not operating within proper range/dirty valve seat resulting in poor seal
• Binding of something on the serpentine belt/excessive engine load (hey, it could happen)
• Idle Air Control Valve? Do we have one of those?
• Computer buggery
• Rat chewed wires/CEL for unrelated issue affecting above systems

That's.. all I've got for now.
EDIT: The coolest person on here put up some info a while back (and it's so easy to read!):
10. GENERAL INTAKE CLEANING & MAINTENANCE
Prior owner changed air filter and oil filter April 2018. Additional maintenance:

- Clean throttle body & IAC valve (caution as don't want to spray off moly lubrication at butterfly valve)
- Clean MAF (only special MAF sensor cleaner, don't touch internals)
- Clean EGR valve and passages (very easy access on Fit and common issue apparently)
- Replace PCV valve

https://www.fitfreak.net/forums/2nd-...-question.html
"www.youtube.com/watch?v=e-PzkoGhv0M" Honda EGR Valve Cleaning DIY VIDEO
"www.youtube.com/watch?v=v1xdHMWSFNM" Cleaning 2008 Honda Fit EGR Passages VIDEO
"www.youtube.com/watch?v=h1cHn_ld2C8" HONDA CITY/JAZZ Cara Membersihkan Throttle Body dan IACV VIDEO
"www.youtube.com/watch?v=cwo1Hs_0aSI" Honda Idle Air ControlValve, PCV and Throttle Body Cleaning VIDEO

Quote:
Originally Posted by JerrySFL
Replaced pcv valve on 2012 Fit woth 92k, valve was getting sticky,
Tools needed, 10mm socket to pull harness bolts, long needle nose piliers to pull clampand hose , 17mm socket for valve and a ratchet . This only took less tham 15 minutes,

- Fiting