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Discussion Starter #1
Hi all

My A3 1.8T has a really annoying intermittent misfire problem (feels like a little 'hiccup' when you go to accelerate sometimes). It's also very hesitant for the first couple of minutes from a cold start, and sometimes the idle starts bouncing anywhere between 500rpm (nearly stalls) and 1,100rpm.

The misfire feels electrical, like HT breakdown, rather than a fuelling problem, but I could be wrong. I've replaced the coils, plugs and MAF but the problem is still there.

I guess the next possible culprit could be a faulty lambda sensor. I just wondered if anyone else has seen these symptoms, or whether they sound like a possible lambda issue?
 

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did you recently change your battery?
 

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Discussion Starter #3
no, I've had the car about a year and the problem was there when I bought it. (it's a 2001 model). Just never been able to get to the bottom of it, it's driving me nuts.
 

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Have you had the car serviced by Audi lately?
They should be able to plug it into vag com for fault codes on engine running if your totally stuck in fixing it yourself.
Or you could try one of those techno home tune guys for about £40 as they are quite experienced in misfires etc and plug your car into a pc.

Let us know how you get on.

ps. I hope its not your ECU module on its way out.
 

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Discussion Starter #5
yeah I guess I need to bite the bullet really and pay someone to investigate it properly. I really hope it's not the ECU too, otherwise that's a pretty good reason to sell the car before it dies completely
 

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Discussion Starter #7
yeah it does feel like an HT problem, the thing is they were replaced last year with brand new ones, and the problem was still there immediately afterwards.

Unless one of the new coils was faulty from the word go......I guess it's possible?
 

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did your car go in for new coil packs last year cos it was misfiring then?
Was it Audi that diagnosed coil pack failure?
 

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Discussion Starter #9
Yeah I just took it to a local guy as the car was out of warranty, and he replaced all 4 coils, and the plugs. I had these replaced specifically because of the misfire/lumpy idle problem.

Originally he was gonna replace only 2 coils to begin with, but the problem is there's no way of telling which coil is at fault (if any), so I said we might as well do all four.

The car seemed better for a few days but then the problem just came back again ....so I suppose it is possible that another coil has died in its infancy.
 

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if you put it on Vag Com it tells you which cylinder is misfiring..

I have the same issue and replaced one coil pack and it was ok..(i then replaced all 4 to make sure for future issues...

do you have the old coil packs??? is this guy some one you can trust?? coil packs are around £25 each.. is that what you paid??

its eash to change the coil packs... just unclip remove and replace re-clip...

i have 3 spare used coil packs from mine here if you need to try them??

If you can tell me what the part number of yours are i will confirm and you can have it for a fiver plus postage..say £2.00.. to try and resolve it if required, then you can remove one and drive... remove the second and drive and so on... its upto you...
(i think they are all the same)

cheers..
 

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Had same problem with my 1.8 T quattro, throttle body dirty with carbon, had it cleaned and throttle body reset by vag.com now rock solid and no hiccups cost £75 by my local independent Audi specialist. As a footnote had DV replaced with Miltek Hyperboost DV £120, it transformed acceleration worth every penny. Hope this helps you.
 

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Discussion Starter #12
sorry for the late reply guys, I had to get away for a few days, too many stresses at the moment!

RickT, thanks very much for the offer of the coils, I will check the p/n tomorrow provided we actually get a day where it doesn't rain. I did indeed pay about £25 per coil (bit less I think), I don't know the guy all that well but he seemed pretty genuine, I don't have the old coils though unfortunately.

Audimac, cheers for the suggestion mate, gives me something else to check. I'm wary of touching the throttle body though, as my old 156 had fly-by-wire throttle and you could bugger up the calibration by messing with the throttle body - anyone know if the A3 is similar, or is it good old fashioned cables?
 

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Mine is a fly by wire but if you get a reputable specialist not stealers they can reset using vag.com a simple process i am told in the right hands.
 

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hi Rick do you stil have those coil packs,

I've got a similar problem on my A4 SE and the mechanic told me its the air flow meter but i've got a feeling it's not.
 

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you will probley find its the motor in the throttle body had one go on a polo. beacuse it is the bosch one it controls the idle as well the motor inside gets a little notch on it and it sticks then moves then sticks which makes the miss fire.
 

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Audi A4 Erratic Idle Issue

Hello,

My 2001 Audi A4 1.8T Quattro with 95,000 miles is idling rough while at stops. There are no check engine lights on. It seems to surge up and down as the RPM’s fluctuate. At times it will stabilize but then the surging returns a bit later. It also seems to happen when shifting in reverse and is triggered when turning the heat or AC fan off & on again. When accelerating from a stop it seems to miss a bit too…. but it seems to run just fine at higher speeds, etc.

I have replaced the Spark Plugs, Oxygen Sensors and Mass Air Flow meter (MAF) to no avail. It’s frustrating and I don’t want to dump any more money into it and NOT FIX it.

Were you ever able to find, diagnose and fix this problem? If so, PLEASE let me know….

You can contact me directly if you wish:

Jason

Denver, CO USA

[email protected]

Cheers!
 

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I've now sold my vehicle but i did manage to iron out the problem before that here's how:

I took it to a local garage for a service he notices on of the rubber pipes needed replacing this fixed things for about two weeks but no totally.

However I notice putting in ultimate fuel (from BP) stopped the idling problem so just continued putting premium fuel in.
 

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newuser said:
I've now sold my vehicle but i did manage to iron out the problem before that here's how:

I took it to a local garage for a service he notices on of the rubber pipes needed replacing this fixed things for about two weeks but no totally.

However I notice putting in ultimate fuel (from BP) stopped the idling problem so just continued putting premium fuel in.
Thats not really a solution
 

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Hi folks

I'm new here so I hope you don't mind me digging up this old thread?

I have a similar problem with the 2003 Audi S3 I've just bought.. Mine ticks over nicely but is always lumpy and hesitant from cold - even if I sit for 5 minutes with the engine running to warm her up.. After a couple of minutes on the road it runs just fine.

I thought maybe a cold start sensor or something along those lines? It was given a major Audi service a few thousand miles ago (cambelt, plugs, haldex oil... in all about £2500 worth!) so I'm not sure if they missed this problem or it's new. Either way I'd appreciate some guidance from anyone who's had similar.

Thanks, Spen
 

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i have the same problem, one minute it drives fine and then all of a sudden it starts jumping like im letting the clutch off all the time, thats what it feels like.

when at traffic lights the rev gauge goes all the way down just above zero and eventually cuts out, always annoys me as it looks like ive stalled lol

it seems fine on short trips but anything past about ten miles then it seems to go, strange but i also took it the garage where i bought it from (under warranty) and they said the computer showed no problems.
 
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