S3 misfire/stutter

doctor46goat

Registered User
I've recently noticed my '08 s3 will "miss a couple of beats" at about 2500rpm just as the turbo is spooling up, under load. It doesn't do it all the time, and only seems to be at this point in the rev range then clears. May be my imagination, but tickover seems a bit lumpy lately too.
anyone got any ideas to what this could be?
 

fouryoghurts

Registered User
Praps coil/s dropping a spark when the environment inside the cylinder becomes more hostile.
Can u run misfire detection via diagnostics?
 

doctor46goat

Registered User
forgot to mention, no fault lights/codes present.
how would I run a check? vcds or is it possible on an obd2?
 

doctor46goat

Registered User
plugs were going to be my first thing to check, but was wondering if there was any other common faults.
car is standard on 58,000, don't know if/when plugs were last changed.
thanks for the info lads!
 

S3Alex

Rarely neutral
Gold Supporter
plugs were going to be my first thing to check, but was wondering if there was any other common faults.
car is standard on 58,000, don't know if/when plugs were last changed.
thanks for the info lads!

Those would be my first things to swap out.

Audi's service intervals on oil and plugs are IMHO way too long.
 

s3_trev

Northern Ireland
Pretty common issue on the s3 dude so dont panic, should be a simple enough fix. Id say coils / plugs also. Erratic at idle could also be PCV valve which is cheap fix.
 

audismart

YOU ARE JUDGED BY THE CAR YOU DRIVE.
Wouldn't do the car any harm by whacking in some R8 coil packs as they do start to pack up around that sort of mileage so I've been told and mine is at 57k now and I had a misfire when on full boost the other night and my plugs were changed about 4k ago.
So you can guess my next purchase.
 

Y111_PJL

Registered User
Would this be the same issue I'm seeing... even with a stutter and drop in power between 5000-6000rpm?

If so, what would be the better choice... NGK or Bosch plugs?
 

S3Alex

Rarely neutral
Gold Supporter
Would this be the same issue I'm seeing... even with a stutter and drop in power between 5000-6000rpm?

If so, what would be the better choice... NGK or Bosch plugs?

Possibly,yes,and it's the easiest/cheapest thing to try.

Use whichever plug is the stock option of choice right now,as mine runs on stock plugs.
 

audismart

YOU ARE JUDGED BY THE CAR YOU DRIVE.
The R8 coilpacks make no difference to performance,so other than for planned replacement etc,there is no benefit,but they do look better.
The R8 coil packs are more reliable I though Alex? especially on mapped cars?
 

S3Alex

Rarely neutral
Gold Supporter
The R8 coil packs are more reliable I though Alex? especially on mapped cars?

Urban myth I think.

Like how much better the Okada coilpacks are and how you need them for big turbo cars.

I still have the original set of coilpacks on mine.....
 

Y111_PJL

Registered User
Possibly,yes,and it's the easiest/cheapest thing to try.

Use whichever plug is the stock option of choice right now,as mine runs on stock plugs.

Cheers mate.
Worth changing the coil packs too then I take it, from the above comments?
 

fouryoghurts

Registered User
I'd swap the plugs out first and see if that cures it,before spending on coilpacks too.
Agreed. Although your mechanic/technician will be able to inspect/test them to confirm if renewing the plugs is worthwhile. If there's any doubt about their serviceability, then yes, renewing plugs is first step...My earlier comment assumed plugs were renewed inline with service requirement (40k/ 6 years).
Let us know how it goes.
 

Y111_PJL

Registered User
Yeah, mine were changed on time at around 40k. Since then though, I've had the car mapped to stage 2. Only recently have I been seeing the stutter. If and when Audi actually decide to answer their phones I may be able to get it sorted... may take a while though.
 

S3Alex

Rarely neutral
Gold Supporter
Yeah, mine were changed on time at around 40k. Since then though, I've had the car mapped to stage 2. Only recently have I been seeing the stutter. If and when Audi actually decide to answer their phones I may be able to get it sorted... may take a while though.

My car had a Stg1 remp at 10k miles,and Stg2/2+ soon after.

What I found was the plugs seemed to last for about 10k miles at best,before the occasional misfire would start,and that was always the sign to replace them.
Now,the car gets serviced at about 6k mile intervals.
 

audismart

YOU ARE JUDGED BY THE CAR YOU DRIVE.
Urban myth I think.

Like how much better the Okada coilpacks are and how you need them for big turbo cars.

I still have the original set of coilpacks on mine.....
Heard bad things about Okada packs, Isn't there a stronger spark with the R8 packs?
 

S3Alex

Rarely neutral
Gold Supporter
Heard bad things about Okada packs, Isn't there a stronger spark with the R8 packs?

No...in terms of spark current, voltage and duration,the Okada packs are the best,and at around £700 they should be.

The problem is that the power gains amount to a few bhp at peak rpm on very high power engines.

If you have an engine turning out 500-600bhp,the money could be spent on something else that would provide bigger gains.

The R8 and S3 packs are pretty much equal and the stock S3 packs work perfectly on mine.
 

s3_trev

Northern Ireland
Another option for those experiencing mid rev range stutter or drop, is the RS4 fuel pressure valve. Depending on who you ask this may be a myth or very useful upgrade. I found it a very useful upgrade and def noticed the difference.
 

doctor46goat

Registered User
only just noticed all the replies to this!

plugged an obd2 bluetooth adapter in and ran a misfire check. don't know how accurate the information is, but logged a few misses on 3 out of the 4 cylinders, only single figures though.
Decided to try a set of plugs before coils and the old ones I took out look like they have never been changed and are a different part no. to OEM (old-bkr8eix new-pfr7s8eg) maybe they are an outdated plug now?
the old plugs seemed to have a massive gap compared to the new ones, possibly very worn?
seems a lot smoother, and not missing at moment, but fault was intermittent so I'll see how it goes over next few days before splashing out on coils!
 

S3Alex

Rarely neutral
Gold Supporter
only just noticed all the replies to this!

plugged an obd2 bluetooth adapter in and ran a misfire check. don't know how accurate the information is, but logged a few misses on 3 out of the 4 cylinders, only single figures though.
Decided to try a set of plugs before coils and the old ones I took out look like they have never been changed and are a different part no. to OEM (old-bkr8eix new-pfr7s8eg) maybe they are an outdated plug now?
the old plugs seemed to have a massive gap compared to the new ones, possibly very worn?
seems a lot smoother, and not missing at moment, but fault was intermittent so I'll see how it goes over next few days before splashing out on coils!

Usually the plugs are the first things to go,and if so,it's saved you spending out on a new set of coils.
 

doctor46goat

Registered User
yeah, they looked like they had done the full 58k miles the car has done, massive gap and a bit of rust staining on the white ceramic part!
 

audis3UK

Audi s3 8p 2009 st 2
Which app did you run to get the misfire check?
only just noticed all the replies to this!

plugged an obd2 bluetooth adapter in and ran a misfire check. don't know how accurate the information is, but logged a few misses on 3 out of the 4 cylinders, only single figures though.
Decided to try a set of plugs before coils and the old ones I took out look like they have never been changed and are a different part no. to OEM (old-bkr8eix new-pfr7s8eg) maybe they are an outdated plug now?
the old plugs seemed to have a massive gap compared to the new ones, possibly very worn?
seems a lot smoother, and not missing at moment, but fault was intermittent so I'll see how it goes over next few days before splashing out on coils!
 

samuelh_888

Registered User
Carista, OBDEleven or VCDS
 

ron burgandy

Registered User
Mine does the same but only on long trips and records nothing on vcds. Even tried running the car with vcds connected
 
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