Missfire S3 8L

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himself26

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Hi Guy's n Girl's.

I'm looking for some help / advice Please.
Around 2 weeks ago my S3 lost its servo assistance at the same time it also started to splutter & caugh.
So i put it on my diagnostic & it cam up with codes - P0300. P0301. P0302. Which equates to a multitude of issues from faulty wireing to internal engine damage. Well i know the engine is fine as ive pretty much re-built it.
So started off with new plugs. Then a set of coil packs. Still no better.
So other common issue is a vacuum leak & when i had a good look the was a badly perished pipe in the 06A133789 pipe set-up. So i took it out & replace everything but the T-piece (i did put a new standard rubber one in) with silicone upgrades.
Car ran & idled very smooth but seemed to be lacking the umph it used to have.
Anyway took it for a run today & it was nowhere near as quick as before & now its spluttering worse.
Any help would be much appreciated
 
Have you fixed the issue with the servo? as I'd put money on these issues being related

<tuffty/>
 
<tuffty/> said:
Have you fixed the issue with the servo? as I'd put money on these issues being related

<tuffty/>
Click to expand...

Hi tuffty.
Yeah that was a simple fix the hard pipe from the plenum chamber was loosing air simply put a jubilee clip on & job done. However its niw been replaced with a silicone hose.
Eleanor has been running fine for a while until recently & on checking i found this.
 
Pix
 

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brake servo pipe? well that explains your car losing boost and the servo not working, it probably failed because of the clamp you put, they like to break thin pipes if overtightened
 
Zans said:
brake servo pipe? well that explains your car losing boost and the servo not working, it probably failed because of the clamp you put, they like to break thin pipes if overtightened
Click to expand...

Its been running fine with the clip on it for months ;)
 
I had a similar issue to this on my old UR Quattro ended up being the air flow sensor in the metering head basically a MAF Sensor.
It it possible it could be the MAF on my S3 thats causing the issue ?
 
O.K. tried the car yesterday & if I build up the revs gradually it goes & boost fine. However if I put the right foot down fast it coughs & splutters like crazy you can feel it wanting to take off but its like its being choked !!!

Anyone have any idea's please as I've just treat myself to an A5 but I want the S3 running properly before I let Her go.
 
himself26 said:
I had a similar issue to this on my old UR Quattro ended up being the air flow sensor in the metering head basically a MAF Sensor.
It it possible it could be the MAF on my S3 thats causing the issue ?
Click to expand...
Plug in a Vagcom and read the fault codes
 
Im gonna fix the issue & she will be 3250 if any1 wants he as is id take 2700quid that 550quid to sort it yourself. She's a good clean car hpi clear rebuilt engine & furking quick when running right
 

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bought a VCDS this is what it says.

4 Faults Found:
17608 - Boost Pressure Control Valve (N249)
P1200 - 35-00 - Mechanical Malfunction
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 -
16685 - Cylinder 1
P0301 - 35-00 - Misfire Detected
16686 - Cylinder 2
P0302 - 35-00 - Misfire Detected
Readiness: 0110 0101

What I cant fathom out is how this all started from a split pipe ?
 
i did a delete on the 249 and whilst rebuilding the entire engine, i stripped off all the connecting pipework that ran to it, half the stuff was broken and brittle causing a lot of leaks and to be fair, half the issues i couldn't see until they broke in my fingers. theres a guide in the stickies how to do it, but you need to keep the main part connected or it will throw faults up.
as you prob know well, these engines are pretty anal about the right boost and can go down in power and pefrormance thro the slightest leak, and theres plenty of little brittle connectors in that system to fail.

my thoughts would be to consider doing the delete and seeing how it runs, with respect to the missfire i'm not too sure if thats connected to the n249 fault. plugs, coil pack, poss timing.
 
Cheers for the reply Danny.

N249 on my S3 has been bypassed for over a year m8.
Ive replaced allthe vacuum pipes under the inlet with upgraded silicone ones also done the servo pipe & the small servo pipe that seemed to be the cause of this issue.
Its also had new bkr 7es plus & a new set of coil packs & all of this in the last 2 weeks.
Ive just ordered a new cam position sensor. As to me (being an old skhool mechanic) missfires were usually cause by the timing being out. So fingers crossed....lol
 
i was gonna mention timing tbh, but the faults for the missfire seemed to point towards a vac/boost leak or coils/plugs.

that pic of the brakes booster pipe with the jubilee clip on; is it the one that runs up to the top left side of the bulkhead, just off the timing belt? mine had split there under heat and was causing little probs for me. just a thought altho you said its been running fine.

be interesting to actually find out whats causing this as theres a few things i think it could be but not being a mechanic, i wouldn't be too sure about. [ divertor valve and puck can be a sod too]
 
It just a prosses of elimination at the min m8.
I started with cheapest fix first i.e. Plugs. Then Coil Packs. Then Vacuum pipes & so on.
Ive also changed the N75 valve.
So only other things i can think of are the MAF or in my mind & more probible the cam position sensor as that would have a direct influence on the timing. Which again to me would be the most probible cause of a misfire ?
I have a good Foxwell diagnostic tool but even went to the extent of buying the latest VCDS just incase my Foxwell was missing something.
Anyway im getting sick of thoughing money at it & ive bought an A5 now so its going to be sold either way m8. I'd just prefer it to be as close to 100% as pos for its new owner.
 
O.K. so here's an update.
I've now fitted.
New Plugs NGK - BKR7ES
New Coil Packs all 4 of them
New Silicone Vacuum Pipes
New N75 Valve
I've checked the timing as i read a post on an Audi forum about belts stretching. Even though this belt hasnt done a 1000 miles yet.
Can anyone on here though any light on the problem PLEASE
 
The N249 code is because the ECU tried to use the DV to dump boost... most likely saw more boost than it thinks it should have and as the pressure didn't drop in time then it assumes that the N249 'circuit' is not working

As your N249 is bypassed this is just symptomatic of that and on its own is nothing to be concerned about but in combo with your current issue it almost suggests an over boost issue...

Ideally you want to log a few things to see what the ECU is seeing at the point it misfires... it could be one of a number of issues here (N249 could also be a red herring)

If its over boosting it could just be down to it pulling back and the misfire is from the overshoot of fuel... it could be indicating a worn out fuel pump as your part throttle seems fine but on boost its where its gets its knickers in a twist

So... need to log, see what is actually happening... blocks 001, 001 and 115 together would be a fair place to start

<tuffty/>
 
Cheers <tuffty/>

Im not too familiar with VCDS yet
 
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Possible injector failure had one go on me but for 2 injectors to go together would be strange, could try move the injector and see if the misfire follows by logging it on vcds.
 
hharry100 said:
Possible injector failure had one go on me but for 2 injectors to go together would be strange, could try move the injector and see if the misfire follows by logging it on vcds.
Click to expand...
did this when buying the coil packs m8. put new plugs in & deliberately put old coil pack in different positions. original misfire was on 1 & 2 after changing plugs it went to 1 & 3 so I bought new packs.
Either way I've had my fill of it. It's probs an easy fix if you know how to used VCDS but unfortunately I don't.
So im just gonna stick it up for sale cheap or maybe break it which would be a shame as its a weapon when its running right but ive bought an A5 now so it needs to go
 
why have you not asked if theres anyone local thats got vcds and knows how to use it? [might have missed if you did ;) ] but i asked when i was stuck n TJ sorted me out with multiple scans and logs so i could sort mine out.
we are all here to help eachother out at the end of the day, these things are a hobby and a passion and a royal pain in the **** but worth it :D and usually the fixes are easy once you are on the right track.

are you simply after selling the car on or wanting it right to sell, coz if its just a sell thing, put it up cheap and be done with it, let someone else pick up a potential bargain and they will enjoy knowing they did the work and sorted it themselves.

i am looking for a newer s3/rs3 atm and saw your post to sell in the classifieds from a few months back so im assuming you wanna get it right as i wouldn't wanna sell a problem on without trying to sort it first so i totally get that.

where are you located btw, you might be close to peeps that can help.
 
is that ****** little earth strap making a good connection on the cam cover outta curiosity as i have read sometimes that can be a culprit of bad things.
 
danny_dj3 said:
is that ****** little earth strap making a good connection on the cam cover outta curiosity as i have read sometimes that can be a culprit of bad things.
Click to expand...

Danny I appreciate yours & everyone elses input but I'm too old & tired for to be messing about with it & tbh have lost interest m8. It's going in the Classified for £2k as is which as far as I can see is the cheapest MOT'd & HPI Clear S3 8L in the country at the moment.
 
little outta the manchester area, but im sure theres peeps around there that have and know vcds well. dont we have a map for users?
 
Maybe a silly question but !!!
is the ( G28 ENGINE SPEED SENSOR ) Actually the Crankshaft sensor ?

as this is the only thing coming up on VCDS.

17748 - Camshaft Position Sensor (G40) / Engine Speed Sensor (G28)
P1340 - 35-00 - Incor. Correlation
Readiness: 0110 0001​
 
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