Engine Sputtering Intermittently at Idle

D

drew855

Member
Location
NJ
I posted about this in another thread, but figured I would start a separate thread for anyone else who might have this problem in the future and to hopefully get some more insight from members.

My engine has been sputtering while at idle for a few months now. I figured it was because my car is running lean, but not 100% sure on that. The engine mods I had on the car when I first noticed the problem were: Kinetix V+ plenum, LMS intake tube with Stillen CAI, Throttle body spacer, and HKS exhaust with Kakumai Y-Pipe. I took off the throttle body spacer because I read they tend to make our cars run lean, and also took off the LMS tube for good measure. Removing these pieces did not resolve the issue.

I just did the ECU reset, accelerator position learning, throttle valve position learning, and idle air volume learning and the puttering at idle did not go away. I recorded a video below of the puttering while at idle I am talking about. The first time it dips down is at the 10 second mark and then jumps back up at the 14 second mark, then dips down again at 40 seconds and back up at 44 seconds. It is kind of hard to notice in the video, but every time it dips down it makes a sputtering noise and the whole car starts to vibrate a little bit until the idle levels itself again and the sputtering stops. Sometimes it is more extreme than others. Does anyone have any insight on what might be causing this, there is no CEL on.

https://www.youtube.com/watch?v=1nkC6rH-T2w&feature=plcp
 
I think the 60k service requires a TB cleaning. You should definitely have it cleaned if not so.
 
i would clean the tb and also the upper and lower manidfold. My lower manifold was so gunked up it took multiple attempts to clean it. Dont forget to take the metal plate off the top of the lower plenum ( thats where mine was gunked up). buy some throttle body cleaner and rags and go to town with it. clean as much as you can
 
soonster said:
I think the 60k service requires a TB cleaning. You should definitely have it cleaned if not so.
Click to expand...

I doubt this was done as I brought it to a mechanic with a list of services I wanted completed and this was not on the list. I will give this a try as soon as I can.

---------- Post Merged at 09:06 AM ---------- Previous Post was at 09:05 AM ----------

Viperi said:
i would clean the tb and also the upper and lower manidfold. My lower manifold was so gunked up it took multiple attempts to clean it. Dont forget to take the metal plate off the top of the lower plenum ( thats where mine was gunked up). buy some throttle body cleaner and rags and go to town with it. clean as much as you can
Click to expand...

I am sure it is pretty gunked up. Would seafoam help or would I really have to remove the plenum to clean.
 
i would remove it and take your time cleaning it. mine at 62k never cleaned was disgusting. Took like multiple attempts to clean the upper and lower manifold and the tb! Sea foam will help after you clean it and use it regularly.

When cleaning the TB, you can push the flap open to clean it better. Just be gentle when you release it back in position ( its spring loaded). Once everything is cleaned, do all the resets.
 
Viperi said:
i would remove it and take your time cleaning it. mine at 62k never cleaned was disgusting. Took like multiple attempts to clean the upper and lower manifold and the tb! Sea foam will help after you clean it and use it regularly.

When cleaning the TB, you can push the flap open to clean it better. Just be gentle when you release it back in position ( its spring loaded). Once everything is cleaned, do all the resets.
Click to expand...

Okay. Hopefully I can find some time this weekend to do this. Thanks for the tips!
 
If it's a vacuum leak which it could be, you could always hook a gauge up to one of your vacuum lines. I forget what the idle vacuum should be for an FX, but you can look it up. On my old car, it was boosted so I could just look at the boost gauge to see if i had a vacuum leak. Symptons are similar to what you're describing.

Or you could have an issue with the MAF. Just because it's not triggering a code yet doesn't mean it's not on it's way out. Maybe try swapping MAF's to see if that solves it. It's really hard to run lean at idle because of bolt ons, so I don't think your TB spacer was doing it.
 
I actually have a brand new MAF replaced by the dealer under warranty. I haven't had time to clean the TB and plenum, but I think a vacuum leak is a very good possibility. Just the other day I heard a whining noise coming from the engine. I haven't heard it since, but it sounded like a leak. It probably wasn't the spacer, but I didn't notice much difference in performance with that anyway so didn't have a problem taking it off. Thanks for the tip. What kind of gauge would I hook up and where are the different vacuum hoses.
 
I'm not sure if you can just buy a vacuum gauge at an autoparts store, but probably. I've seen some sort of diagnostic gauge on the shelf before. I had a boost gauge so I used that. Really, any small vacuum line will do. They all see the same amount of vacuum. Also, you can spray some soapy water around your plenum to see if the leak is there since you put an aftermarket one on.
 
I had the exact same symptoms a few months ago and cleaned my TB. I assume it had never been cleaned and by the time my FX was sputtering it was over 100k miles. I bought some TB cleaner and cleaned the TB as best I could. I was careful with the butterfly valve but did move it in order to clean it. As others have pointed out, it did cause the idle to act wacky and I had to do the idle reset pedal dance, which was NOT fun. I had to try doing it many, many times before the idle came down to a reasonable level.

Fast forward almost a year and my FX is sputtering again and just kicked a CEL. I am going to clean the TB again, but this time I am going to try and remove it from the engine altogether and NOT mess with the butterfly valve. There's a post on the '09 forum about how to clean the TB and even though our engine is slightly different, alot of the same ideas apply.
 
As a follow up to my post above, I did clean the TB again, this time much more throughly than before. I made sure to to touch the butterfly valve. I also removed the plenum and cleaned it as best I could.

I put everything back together and fired up the FX. The idle went back to normal but the CEL was still on. I tried to do the pedal dance and the CEL would go off but then it came back on. The idle was normal and the engine idle was a little smoother so I figured the ECU would turn off the CEL after a while and sure enough, a couple of days later the CEL turned off.

The idle has been consistent and the engine has never sputtered since.


Sent from my iPhone
 
drew855 said:
I actually have a brand new MAF replaced by the dealer under warranty. I haven't had time to clean the TB and plenum, but I think a vacuum leak is a very good possibility. Just the other day I heard a whining noise coming from the engine. I haven't heard it since, but it sounded like a leak. It probably wasn't the spacer, but I didn't notice much difference in performance with that anyway so didn't have a problem taking it off. Thanks for the tip. What kind of gauge would I hook up and where are the different vacuum hoses.
Click to expand...

Sorry to bring this thread back from the dead but did you find out what the issue was? I am having the same idle issues with my car. I cleaned the TB and Maf sensor but the issue still persists. Let me know. Thanks.
 
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