slight hiccup in 2nd gear @ 2400rpms

[staticuxo]

i recently noticed when i'm driving in 2nd gear conservatively, around 2400rpm, i get a slight hiccup during the acceleration. i don't know if it's a misfire or not, but it does it in 3rd sometimes as well. it does it with or without the AC on and it doesn't do it at WOT.

i thought i felt it a few times during idle, but the rpms BARELY dropped. could this be a coil pack issue? they haven't been changed for the recall and i have set an appointment to swap them out next saturday. the spark plugs have been replaced about 2k miles ago.

any ideas?

[dparm]

Could be a misfire, but you'd likely throw a code. What if you hold it steady at or around that engine speed?

I'd say if you can hook up a diagnostic tool and drive around, check the sensor readings.

[AndyGs4]

I would change the coilpacks anyways. If you are running pre-recall packs, there is a known weakness.

The main problem with misfire detection is the computer won't always toss a code when it happens. Light/random misfires will typically light the CEL, and a hard misfire (repetitive) with make the CEL flash. But if the misfire only happens once every several thousand engine cycles..the computer may not register it.

I am amazed however, that there is something that happens to the power you can actually feel, without throwing a code. You have no CEL at all? I have also seen a stuck injector cause similar symptoms, but there would most certainly be a CEL with that.

I have also seen bad fuel cause a similar symptom.

[dparm]

OBD2 cars are fickle anyways. I swear, some days my car feels faster than others.

[staticuxo]

It's very weird, no CEL. I did just put in some Mobil 93, but I don't know if that is it either. The coil packs will be replaced next Saturday and I will see what happens next fill up... I usually run Shell 93.

[staticuxo]

update: 8 new coil packs installed and did a throttle body cleaning.. same issue where acceleration is not smooth, it hesitates slightly.

as stated earlier, spark plugs were replaced 2k miles ago as well as fuel filter. any other ideas?

i'm beginning to think it is the tune..

[dparm]

Throw it on a dyno and see what happens. I'd be interested in the HP/torque lines at that RPM, and the AF ratio.

[staticuxo]

john (extremesport3) vag'd the car today.. no codes. i had him drive it and he felt it, too. while the car was idling, it also started to shake a bit an the rpms dropped slightly off and on for about 30 seconds.

[staticuxo]

problem has continued.. i got a CEL and codes read misfire on cylinders 1, 4 and 8. shut the car off and when i started it, it ran fine with the 'normal' slight hesitation.

car ran fine the next day.. then later last night i got a CEL while driving. i pulled over, restarted it and it ran fine with the hesitation issue for the next 20 mins home.

keep in mind, at WOT car pulls hard and very smooth.

my thread on euroaddiction: http://www.euroaddiction.net/forum/s...ead.php?t=1625

[staticuxo]

my problem continues.. flat spot/hesitation/hiccup 2-3k at 1/4 throttle (normal driving) and once in a while a rough idle with or without a CEL. a few times i got a misfire while driving.. the CEL goes away within 30 seconds and the car is back to 'normal' driving with the hesitation.

i got frustrated this weekend.. so i got another set of spark plugs, installed them, checked the coil packs, i cleaned the MAF, cleaned out the intake, and cleaned the k&n air filter. since my last post i've also tried chevron fuel injector cleaner, techron fuel system cleaner and lucas fuel injector cleaner.

the chevron fuel injector cleaner seemed to make the car smooth WHILE it was in the tank. the next tank ran crappy again. maybe i need to get my injectors flushed/cleaned?

previous attempts:
-spark plugs changed 4k miles ago
-fuel filter changed
-coil packs changed 3-4 weeks ago at dealer
-cleaned throttle body
-tightened intake manifold bolts

any other ideas?!

[Gtndirty]

I’m having the same issue in my a6 4.2 c5.... just no codes. Get a bit of a wobbly feeling at idle sometimes then back to normal, but the small hiccup in second gear really throws me off..