2013 GSR w/ 75k miles. As title says, I'm having stutters at idle and low RPMs while accelerating with very light load (makes stop and go traffic horrible). This is only at low RPMs, once my car is at 3k+ it runs perfectly. At WOT I also have no issues, car pulls hard with perfect AFRs as its tuned (basic bolt on car w/ tune)

This first happened a month or 2 ago - I cleaned the MAF sensor and my car ran perfectly again for about 2 weeks. Symptoms began again so I cleaned MAF however this time it didn't fix anything. I figured it was clear my MAF was on its way out so I got a new one, but the symptoms are still there.. My ETS intake filter was also very dirty so I cleaned it but that didn't help. With how dirty it was I'm considering buying a new one as the cleaning may not have done enough

Another thing I've noticed is the car runs much better when it's cold out. On hot & humid days it's at it its worst (which is again leading me to question my dirty intake filter). Wondering what else I should be looking at/replacing here... MAF didn't solve it. All other maintenance is up to date with spark plugs changed roughly 18k miles ago. Any suggestions?

 

Any codes?

 

No codes..

Should also mention I replaced the MAF yesterday and was still experiencing hiccups after. However today the car has been been fine, though the weather is cooler. We'll see how it drives after work

Wondering if car needed to relearn fuel trims? I'm not sure if that would apply when replacing an OEM MAF with an OEM MAF...

 

Whats your mod list and what fuel were you tuned on? If the fuel trim changed it would throw a code.

 

Basic boltons tuned on 93 octane:

ETS UICP
ETS Intake
Grimspeed 3 port EBC
Speed Circuit test pipe
Invidia N1 catback

Was tuned over 3 years ago and haven't changed anything on the car since

 

You have a wideband? Maybe you got a bad batch of gas.

Also check your relays. If you don't have the updated version I recommend you get those.

 

Wish it was a bad batch but I've been through multiple gas tanks at this point.

I replaced my relay to the upgraded one a couple years ago, probably wouldn't hurt to replace again. But I would imagine that a bad fuel pump relay would affect my car at WOT and other instances, whereas my case is specifically idle + low load/low RPM issues.

And I do have a wideband. As I mentioned AFRs are normal at WOT and even when experiencing the stutters at idle I don't see AFRs doing anything wonky.

I briefly experienced the issue again after work yesterday. Was in 2nd roughly sub 2k RPMs going over speed bumps and car stuttered once I got back on the gas. This morning no issues while driving but a few stutters at idle. Seems to be extremely random. Car will run fine, experience hesitation, and go back to normal

 

Recorded video of the idle issue at lunch break:
https://drive.google.com/file/d/1vKPqRGLtA0q2lIq801PjkN-aspk-bUWd/view

Also want to mention it was a hotter day when I recorded this compared to the prior 2 days and issues were significantly more prevalent. Colder weather they were almost nonexistent. Temperature is definitely affecting how the car runs

 

I'm still having this issue however it went away on its own for a few weeks then came back. I guess something's on its way out but I don't know what... So far I replaced MAF sensor and put in a new ETS intake filter since the old one was filthy

What confuses me is that it's an intermittent issue. IE if it was a bad spark plug would the issue go away and come back? In my head that doesn't make sense. Wish my car would throw a code to direct me somewhere

 

Changing spark plugs tomorrow morning in hopes that fixes the issue. If that doesn't work I'll likely take it to local evo shop before I continue spending money on parts that aren't causing the issue

What I've noticed from driving it recently, it only stutters/hesitates (misfires?) in the following scenarios:
- idle
- starting in 1st, if I lightly apply gas to roll off slowly (IE when in traffic) it will stutter. If I start in 1st and throttle it more it drives normally. Low load is the issue
- reapplication of throttle. For example, if cruising in 3rd and come off gas to decel, if I get back on the gas it stutters. However if I keep my foot on the gas when I decel to point where injectors are still fueling, when I apply more gas it's fine. So it's only the initial throttling when injectors add fuel that is the issue

This leads me to wonder if there's a fueling issue somewhere with injectors or fuel pump

 

Ended up being my spark plugs. In hindsight I should've thought to replace these earlier but was thrown off by the initial MAF cleaning temporarily "fixing" the issue along with never throwing a code to direct me somewhere. Just glad the issue is fixed.. and maybe this thread will help someone in the future

Attached is a pic of my spark plugs with ~20k miles on them. Nothing glaringly obvious stands out to my untrained eye, but maybe someone else can see an issue