Random misfire/ hesitation.

[unlimitedMIKE]

Ive done a good bit of forum searching and cant pinpoint my problem.

Please keep in mind this is my first turbo car so my familiarities with some of the quirks of the engines noises, habits are ever changing.

that being said I've noticed a slight random misfire/hesitation,a small occasional stumble. there are no engine codes or any other notable symptoms. The car does this cold and warmed up. Hard driving conditions doesn't seem to bring it out anymore than around town driving. I can say i only notice it at idle, it doesn't seem to affect my acceleration/WOT.

My first and only thought is new Coils and plugs. before i do so i figured id get some experienced opinions and suggestions as to what i might be experiencing. if it is plugs, what type of plugs do you run? (should i step down one colder?) <--- i have no software upgrades and my car is completely stock. should i do anything at all/ is it just "NATURE OF THE BEAST?"

i appreciate any help,
-MIKE

 

[Alexiscoolbitches]

Maybe need a new fuel filter?

My first thought was cam follower but when mine failed it was most noticeable between 3-5k rpms. Mostly in 3rd or 4th gear. I never noticed any issues at idle so it doesnt sound that similar. It still couldn't hurt to check it.

 

[The Fed]

Pull your dipstick, does it get worse? If not, replace your PCV valve.

I have the same issues, it's probably dirty valves. I replaced the plugs and coils, no improvement. Ran 6 cans of fuel injector cleaner though the gas, no improvement.

 

[shaunraney]

Have you done a code check or do you assume you have no codes because of no CEL?

Also, check your hoses and connections on the intake side. You might have a small leak causing this issue with no codes.

 

[nhbubba]

The section titled ROUND 4 LOGGING: Misfire-Specific Diagnosis on this guide from APR helped me. If you are able to reproduce the misfire(s) while logging, it should tell you which cylinder(s) are misfiring. Then you can decide what to do.

I had misfires, threw a P0304 code, indicating misfire on #4. Per some suggestions from folks here, I sapped my #3 and #4 coils. Misfire then showed up on #3 when logging. This proved to me fairly conclusively that my coils were the issue.

Four new coils from a discount dealer on the interwebz and I've been fine since. <knocks on wood>

Fuel filters are a good item to do periodically anyway. I do mine every 40k miles.

 

[alphabits]

Could also be carbon build-up.

 

[The Fed]

^^^^^^ This.

 

[SRTthis]

Coils should be free. just had mine replaced under the recall with 105k on the clock

 

[silversleeper]

-carbon
-flapper intake
-coils/plugs
-bad intector(s)

 

[nhbubba]

Coils should be free.

They weren't on my '09. Is the OP a TSI or FSI?

Although plugs & coils seem like the least expensive, least evasive place to start.

 

[unlimitedMIKE]

- ive got a broad range of suggestions here, all seem to be helpful places to start though. carbon build up and the PCV system failure both seem to make a good bit of sense. i can run a catch can for the PCV, what do you suggest for the carbon build up? for the PCV is there any surefire way to determine if blow-by is getting to be to much

- the car doesnt seem to be replicating a intake or vacuum leak (only my opinion) but i've experienced idle surges and sputtering from leaks and this is nowhere near constant or often enough to lead me down that path.

- i have hooked up my personal scan tool and have found no current codes stored in the car, the only code Ive ever thrown was after starting the car without the MAF connector plugged in.

- I have not looked into the fuel filter.... i am coming up on my 30k very soon its something ill definantly consider.

- as for the rest of the responses, i was under the impression (correct me if im wrong) that if the flappers in the intake or bad injectors where a problem then they would throw one of any number of codes. also i would imagine my problem being more persistent/ noticeable? also after reading other threads the cam followers do not seem to be my problem (although it is something i need to to take car of soon)

- if im to vague in my description then im sorry, it is only a slight stumble/misfire and not reliably persistent also as stated before i only notice it at idle..... it doesn't seem to affect the overall performance of the car. i am aware it is a frustrating question to diagnose but i willing to receive any knowledgeable advice warmly and appreciate any point in the right direction.

again this might be more of a "NATURE OF THE BEAST" sort of thing and im going on a tangent :iono:

-MIKE