Hi all.

I have just bought an s5 that was sold as lumpy on cold start, But once warm its fine.

It arrives tomorrow , but have seen many video's from the owner on start up and idle etc once warm.

I plan to do a carbon clean on it. and as far as i know its had the plugs done. But i cannot verify this.

I have seen a video where its rough on starting, very rough lol. spluttering and misfires 

But after 2 - 5 mins its ok. But still slightly spluttery as it hasnt been used in a while.

No smoke or anything from the exhaust / engine

If the carbon clean dosnt solve this issue. What would be any ones next point of action please.

The carbon guy will be reading the codes etc tomorrow , may have a better idea then.

But seeing as it gets better once warm, I wondered if anyone might know what that might points to or suggest.

Many thanks in advance.

Mark

Edited July 15, 2025Jul 15 by AudidoThat
missing information

Welcome to the forum you'll find the members on here are a friendly and helpful bunch 🙂 

Sounds an interesting project. You'll definitely have a better idea after you've got fault codes. How much service history is with the vehicle? 

Can the seller give you any idea of what work they've done to resolve the issue? 

Could it be a cam sensor, crank sensor, maf sensor or a fuel delivery issue?.

Thanks steve,

The car is 2009 with 84,000 miles. Says it has lots of history with it, and apart from possibly doing the spark plugs, I dont think the seller has done much as it was a px for them. and they cant throw any more money at it, so i got it a bit cheaper. it hasnt been driven for nearly a year as its been sat in their yard as its the lower end of cars they usually deal with. But the issue was present before it sat for a year,

Maybe best is to report here the fault codes in a day or so once done,  and go from there. 

The carbon clean is being done on thurs, so i will know more after that

Thanks for the reply tho

Edited July 15, 2025Jul 15 by AudidoThat
spelling error

I hope the service history gives you an idea of what parts have recently been changed. My worry, is that the cars been px'd because of the issue either because the previous owner found it was going to be an expensive repair, or they had enough chasing the issue and spending money on various parts to fix it. 

Welcome Mark,

I fear you are about to throw your money away by engaging in this ‘carbon clean’ - a bit like putting on your best designer gear, when you haven’t changed your underpants for a week! 
If it were mine:- 

Check how much fuel is in it - hopefully not much - and add 2 gallons of E5 to which you have added a fair dose of Redex. (See this morning’s response to a similar issue with an aging convertible).

Get it plugged in and find what codes are showing.

It seems you have been told it has service history, but you have not seen the evidence before committing to buy. Bit of a chance taken there, but….

I would certainly keep my ‘carbon clean’ funds as far down in my pocket to render it inaccessible. 
Please let us know how you get on Mark.

Regards,

Gareth. 

It’s Thursday tomorrow Mark. 
Any further thoughts on your Carbon clean? 

I had the carbon clean guy booked in,  Its not overly expensive, £90, and for that he is going to also scan it delete codes and rescan etc and let me know what comes up. 

Currently although i have the car, The dealer has let me take it with no charge, to see if i can fix the issue, The dealer has been fair in this regard. I figured for £90 it was worth the gamble with the clean, whilst also having the codes looked at as i dont have a scanner myself. So he is due tomorrow morning. and i will know more then.

Im hoping his scan can tell me what the issue is, fingers crossed.

I did find a bill in the glove box for 8 spark plugs, and 1 coil pack.

Also when i looked under the bonnet, there is a mixture of coil packs, a mixture of black and red coil packs,

Is this normal ? maybe different brands etc are conflicting with each other, and im wondering why they only bought 1.

well lets hope tomorrow brings good news lol

also the fuel said 20 miles left, and i topped it up today before seeing this with £8 worth of premium unleaded.

As because the car has been sat for a year hardly used i thought it best to get some fresh fuel in it.

Different coil packs could imply the previous owner has been trying to fix this issue for a while. 

Make sure the guy deleting any codes saves notes them down first. 

Please keep us posted on how you get on 

well, The carbon clean was done today using hydrogen,

Time will tell if this makes a difference as im still not really driving it.

Although i think it may sound a bit better, 

The code reading date found lots of misfire codes etc, 

Upon reading the live data, The air mass meter was going crazy, 

So i ordered a new 1 today which comes on Monday,

Im also going to probably replace the 8 coil packs, as it was showing a few codes for that.

And somebody has changed a few as there is a mixture of red and black coils currently. 

What colour are oem meant to be , red or black ?

The injectors all looked ok apparently, which is good

Hopefully the air mass will solve it, with a combination of coil packs also.

The plugs have been done so i wont change those for now unless the other bits dont work.

If the air mass meter and coils solve it ill be happy.

At least his not told me its 8 injectors  lol

The air mass sensor was a hard thing to get,

GSF, euro car parts and others all listed it but nobody had it. 

Now has to come from Germany 

Roll on Monday 

 

just seen on google mine should have red oil packs, at least i can now se how many have been changed

Small update,

I changed the air mass sensor and 1 coil pack on cylinder 1,  i thought it had cured it, As i thought it sounded better upon 1st start up.  But in the morning on cold start it was miss firing again the same as usual. 

I have ordered another 7 coipacks and will fit them tomorrow so i have 8 new 1s,

IS there anything that jumps out to anyone, the fact that its bad on cold start up for 5 -10 mins, then it seems perfectly fine after it warms up, or gets a lot better . Would this point towards something in particular ?

Latest update, ive now changed all 7 coil packs, and the issue is not resolved 🤔

Sorry to hear the issue isn't resolved. Could it be a crank sensor? 

Or an issue with the air intake system. I appreciate give changed the mass air sensor, but maybe something isn't sealing right? 

Could it be a fueling issue? Is it worth changing the fuel filter? 

Thanks for the reply, I honestly dont know.

Im not much of a mechanic tbh, i just drive them lol. So im not sure how much of an impact those things you suggested would have or make if replaced.

It just seems strange to me that it improves as it gets warmer, almost like its a choke issue on cold start up, or something like that with my minimal knowledge lol.

13 minutes ago, AudidoThat said:

Definitely worth checking. Also worth seeing if the high pressure fuel pump is working correctly. 

Mark.

You could waste huge amounts of money fitting new parts at random in the hope it will solve your problem. You have already bought coil packs, a carbon clean, and a mass flow sensor to no avail. How much more money and time are you prepared to throw away? The key to an economical repair is diagnosis on a VCDS or similar quality machine.

Yes mate i think your right,  you mean a code reader plugged into the OBD port ?

If sop im am aiming to get this done this week before spending anymore.

That was done by the carbon clean guy also. But im not sure how knowledgeable he was tbh.

I have some pictures of some of the screens he looked at i will post now

This may give somebody an idea.

not sure if this will mean anything to anyone, and im not sure if these were all still active after he cleared them.

 

 

just googled audi p130a hide cylinder, and it says this,   does this mean something has to be reactivated to work properly ?? and until its reactivated it will keep misfiring even with the new parts ?

Just to clarify, the car is misfiring, But the ecp light did come on after the battery went flat on collection and after starting it after a long time. but now that ecp light or engine lights are no longer on currently, so not sure if the P130a was a code present prior to fixing the coilpacks and airmass, and now they have been replaced the light is out. or if that p130a code is still present even though the lights are not showing.  I guess a fresh code read will be the only way to tell. The reason i changed the air mass was because on 1 of his screens on the live date, the air mass apparently was all over the place outside of whatever the parameters it was meant to be. And upon me changing that the old 1 was all ripped inside on the wire mesh, not sure how that effects it or not but i changed it anyway. and the coil packs were a mixture of old and new, so i changed all 8 to eliminate them all as i weant to keep the car longer term so may aswell do them all in my not very knowledgeable mind mechanical wise lol.

Edited July 26, 2025Jul 26 by AudidoThat
more info added

48 minutes ago, AudidoThat said:

Yes mate i think your right,  you mean a code reader plugged into the OBD port ?

Yes I mean a code reader, but not the cheap ones available from Ebay and the like. You need a professional quality scanner which can read the full range of codes. VCDS is one commonly recommended on the forum, and there are a couple of others whose names I don't recall.

3 hours ago, cliffcoggin said:

Yes I mean a code reader, but not the cheap ones available from Ebay and the like. You need a professional quality scanner which can read the full range of codes. VCDS is one commonly recommended on the forum, and there are a couple of others whose names I don't recall.

Thanks Cliff, will get that read next week,    did the codes i posted here from the carbon clean guy tell you anything by any chance ?  or not really 

12 hours ago, AudidoThat said:

 did the codes i posted here from the carbon clean guy tell you anything by any chance ?  or not really 

No, such things mean nothing to me.