Annoying Misfire / Erratic Idle

dannyboy29 · 05-16-2006, 10:25 AM

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?

**kazyee** · 05-16-2006, 10:27 AM

did you recently change your battery?

dannyboy29 · 05-16-2006, 10:32 AM

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.

**T-sport** · 05-16-2006, 12:07 PM

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.

dannyboy29 · 05-16-2006, 05:20 PM

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

**AllWheelGrip** · 05-17-2006, 05:06 AM

i bet its your coil packs

dannyboy29 · 05-17-2006, 06:41 AM

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?

**T-sport** · 05-17-2006, 12:34 PM

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

dannyboy29 · 05-18-2006, 04:50 AM

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.

**RickT** · 05-18-2006, 11:07 AM

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..

05-16-2006, 10:27 AM	#2 (permalink)
kazyee Moderator Join Date: Jan 2006 Posts: 532 Gallery: (0)	did you recently change your battery? __________________ when you wake up in the morning, ask yaself, who are you? if you dont know.... how could ya dreams come true?

05-16-2006, 12:07 PM	#4 (permalink)
T-sport Super Moderator Join Date: Sep 2005 Location: Devon,uk Posts: 1,568 Gallery: (0)	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. __________________ 2002 1.8 T Avant 18" TT Quattro Replicas Forge Motorsport DV

05-17-2006, 05:06 AM	#6 (permalink)
AllWheelGrip Super Moderator Join Date: Jun 2005 Posts: 1,725 Gallery: (0)	i bet its your coil packs __________________ There are many paths to the top of the mountain but the view will always be the same

05-17-2006, 12:34 PM	#8 (permalink)
T-sport Super Moderator Join Date: Sep 2005 Location: Devon,uk Posts: 1,568 Gallery: (0)	did your car go in for new coil packs last year cos it was misfiring then? Was it Audi that diagnosed coil pack failure? __________________ 2002 1.8 T Avant 18" TT Quattro Replicas Forge Motorsport DV

05-18-2006, 11:07 AM	#10 (permalink)
RickT Super Moderator Join Date: Feb 2005 Location: West Yorkshire, UK Posts: 1,640 Gallery: (0)	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.. __________________

05-16-2006, 10:25 AM	#1 (permalink)
dannyboy29 Member Join Date: Oct 2005 Posts: 45 Gallery: (0)	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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05-16-2006, 10:32 AM	#3 (permalink)
dannyboy29 Member Join Date: Oct 2005 Posts: 45 Gallery: (0)	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.

05-16-2006, 05:20 PM	#5 (permalink)
dannyboy29 Member Join Date: Oct 2005 Posts: 45 Gallery: (0)	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

05-17-2006, 06:41 AM	#7 (permalink)
dannyboy29 Member Join Date: Oct 2005 Posts: 45 Gallery: (0)	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?

05-18-2006, 04:50 AM	#9 (permalink)
dannyboy29 Member Join Date: Oct 2005 Posts: 45 Gallery: (0)	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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