missfiring a3 1.8t

[jed1kn1ght2000]

hello everyone,

i've had my 2001 a3 1.8t (44k miles) for nearly a week now, it looks great and can really shift when you want to :D, whilst being a comfy cruiser. getting about 38mpg on average which is pretty good i think!

i have a slight concern; under gentle acceleration between 1500- 2000rpm the engine is very lumpy, sometimes jerky even. there is not a large loss of power but it feels very flat in that area. the engine seems fine at higher rev's, although, i'm not quite sure how quick it should feel.

i've been looking round the forums and have condisered replacing core packs and investigating the dump valve as i hear they plastic (or rubber).

i'm taking it back to the VW dealer so hopefully they'll sort it but i'd like to have some input into the diagnosis.

cheers

[jed1kn1ght2000]

hi, i just wanted to update evryone on the symptoms of my slightly poorly a3 1.8t.

sometimes there is a chirupping noise when backing of the throttle (like rally car tyres squealing on hot tarmac, not as loud obviously!) and a noise kind hard to describe, like air coming from somewhere in the engine (not high pressure sound like a dump valve though, 1.8t dump-valves dump internally anyway, i think, so you don't get the hiss)

i think the turbo is sometimes shutting off prematurely, it comes in quite early then i feel a flat spot where the boost stops about 500rpm later.
it seems intermittent as this morning i got a long bout of boost in first gear. it really pulled hard and made me realise that the true boost is not always present.

been looking around and will suggest to mechanic that a MAF fault has these symtoms.

can anyone confirm that these symptoms / diagnosis are correct?
thanks

[S2AVANT]

Vag-Com the car and see what issues that shows up.
The S3 dump recirculating valve is made of rubber / plastic. They are £20 or less from GSF for the OEM part.
I wouuld change this if you are hearing any whistling noises.

[jed1kn1ght2000]

cheers for that. i had heard that dump valves could fail. luckily it's still under warranty so i'll request the full check.

i've been having a look under the bonnet and there's a fast ticking noise present - is that normal?

[jed1kn1ght2000]

Hi,

My 1.8t went into the vw dealers on Saturday and wouldn’t perform the fault for the mechanics. Anyway, they hooked it up to the computers and the verdict was new dump-valve.

Although it is running better, the jerkiness is still there. It feels to me as if the turbo is shutting off soon after coming in, although this all happens between 1000 and 2000 rpm, so I guess this probably isn’t the turbo. It does at higher revs / speeds sometimes feel as though the turbo isn’t always there, it sounds quite throaty too.

Any suggestions?:confused:

[jed1kn1ght2000]

hi,

the car was running fine for about a week.

today the engine management light came on, the engine temp falls dramatically and at idle revs fall.

i thought audis were supposed to be reliable.

2001 44000miles immaculate surely can't be going wrong already?

any ideas?

[seraph]

this is starting to look like a monologue!!

No car is completely reliable - they all go wrong, in fact, in a recent insurance poll, the VAG family of cars had one of the highest warranty claims per 100 cars....

Get that error read out, and go from there...


ps. its not a dump valve on the 20vt, its a recirculating valve!

[jed1kn1ght2000]

just a note on those reliability claims....

beware of them. take the following example.

there's an audi a4 with a faulty water pump.

there's a vauxhall vectra with a faulty water pump.

both cars have the same fault but the audi is deemed more 'unreliable' as the repair costs are higher!

90% of all stat's are useless.

p.s. i am a statistician

[sharc]

Hey
I have a related problem with my 2000 A3 1.8T so I am interested in the result of this thread. Unfortunately it seems that there's not been much help for you so far.
My A3 misfires and judders at all rev ranges, but it doesn't do it all the time. It ONLY does it after you have accelerated hard. By that I mean put the pedal to the metal. Doesn't even need to be high revs, just opening the throttle.
The car will then misfire for the remainder of the journey and indeed the whole day. The next day it returns to normal.
I have had new spark plugs at the last service, I have had a cleaned throttle body, a full coil pack set, a new fuel filter and VAGCOM diagnostics clear a few faults, but the fault is still there. Interestingly I also have the same temperature problem that you have. the car rarely hits 90 degrees any more, and when it does, it will quite quickly drop, usually to around 80 but sometimes as low as 60.
My local dealer told me that they thought the misfire was due to this temperature problem because the car could be getting the wrong fuel/air mixture. They weren't all that sure, though, but wanted to charge me £250 to change the thermostat and temperature sender. I declined and have since gone to an independent specialist who as yet have not found the source but suspect the air meter, as they say that is a common cause of misfires.
I don't suppose this post has been much help to you, but I hope it has.
I'd be very interested to hear of any developments with your car.

Andy.

[jed1kn1ght2000]

Hi,

thanks for your post. your symptoms seem considerably worse than mine. annoying isn't it!

i really think replacing the MAF sensor is the best option.

my car has had the maf (air mass) and temperature sensors replaced.
plus, dump (recirculating) valve replacement and throttle body cleaned and adjusted.

all under warranty thankfully and it's lovely now. i don't think replacing maf is costly (under 100) so rather than spend money on diagnostics i'd just go for replacing (or cleaning) the maf.

i have a question for you; whats the suspension like in your car? i feel knocks through the steering wheel on all road surfaces. i don't think this is normal.

good luck with the car. when they're running well they're a pleasure to drive :biglaugh:

[sharc]

Hi

I have no problems with the suspension at all. Any knocking is a bad thing! I once had a knocking when going over bumps but that turned out to be the centre exhaust section wobbling because the clamp which holds it to the body had sheared. It's a common fault, but doesn't sound like your problem if you can feel something in the steering. Get it checked out as it's still under warranty.
Things are so much easier when it's under warranty. The dealer can change everything without worrying about the cost, or if they are overdoing it. That way you don't know which one of the parts they changed was faulty. So it doesn't help me at all :( I think a new temperature sender is in order, though, as they are only about a tenner if I can fit it myself.
I think I'll look into cleaning the MAF next.

Andy

[jed1kn1ght2000]

the maf is pretty easy too if you're happy to get your hands dirty.

search in google and there'll be a guide for sure.

you can also disconnect it, drive the car and if the problems have gone then there's your answer.

please research this before jumping in though.

good luck

[sharc]

Disconnected the MAF last night and the car performs so much better.
It's as smooth as silk and it's actually faster with the MAF disconnected, I had forgotten what it's like to be pushed into the seat :) I can't wait to get this fixed now.
I'm going to try cleaning it first, and if that fails, I'll replace it.
Andy

[jed1kn1ght2000]

hi Andy , that's great news!

removing the maf means that the turbo is not regulated and will therefore generate maximum boost at all times (this is my understanding at least!)

i'm not sure how it would effect the car long term but it sounds like you're enjoying it!

i'm tempted to have mine remapped to around 180bhp - anyone have any experience of this? £cost?

[Kmist]

Hi Andy,

I have just my A3 (1998 model) back from the garage, coils changed, actually thought the problem was fixed, then as you can understand the same symptoms apppeared.. frustrating more than anything .. let me know the MAF option goes ..

Kmist




Disconnected the MAF last night and the car performs so much better.
It's as smooth as silk and it's actually faster with the MAF disconnected, I had forgotten what it's like to be pushed into the seat :) I can't wait to get this fixed now.
I'm going to try cleaning it first, and if that fails, I'll replace it.
Andy

[Easy_Tiger]

Hi ya all heres my 2p worth

1st up clean the MAF with some carb cleaner (remember not to touch the wire with your bare fingers) this can only do good and free up some gee gees and at only costs about a £10 from any motor factor

2nd I'm really concerened about the temp gauge dropping this would cause the ECU to run the "start up map" ie extra fuel and less boost - extra fuel means extra wear on the cylinders and rings in okay for a week or two bad in the long run:(. IMHO the likley cause of this is the sticky themostat - might be worth pulling this out and giving it the boil test to check its operation. - this can also be damaged by mixing anti freeze types.

Is it the case the the faster you go the colder the water temp gets but sat in traffic you're fine ??

3rd cause could be a dodgy oxygen sensor on the exhaust which might confuse the ecu.

Good luck with the probelms there is light at the end of tunnel then ---- whoose you go

[sharc]

Hi again
After cleaning the MAF, the problems didn't go away. No problem, it cost me nothing to try it.....So, I replaced the MAF myself - bought the part from an Audi dealer so I knew I was getting a good one.
I also reset the ECU by disconnecting the battery. Apparently that clears any changes the computer has made to engine management caused by a mis-performing MAF. Only 4 days have passed and so far, so good. No misfiring and the temperature problem seems to have gone away as well! I really don't understand how the 2 symptoms can both be caused by a dodgy MAF, but there you go!
To answer a previous question, yes, going faster did seem to cool the engine down a little, but then at other times, the temperature would drop for no apparent reason.

Andy

[jed1kn1ght2000]

hi all,
thought i'd follow up my problems. back in feb/march time i had a new maf installed and the throttle body cleaned. all has been fine until recently where i can feel the symptoms returning.

i decided to have a go at cleaning the maf myself. i removed the unit and then the sensor (about 3 inch long thin thing, can it be disassembled any further??) from the unit and have sprayed it with carb cleaner. i can't really see these wires that people warn against touching??

it's drying off at the moment so i'll report back - i looked really clean - like new in fact, i suppose it is only about 4 months old. could it get dirty so quickly?

on another subject; i see remapping the 1.8t can up the power by about 40 ish bhp and torque by quite a lot. has anyone done this and how does it affect reliability and economy. obviously TTs run at 225 bhp from basically the same engine - plus intercoolers etc. really just wondering if it's worth the expense. i don't really push my car hard at all but the idea of all that torque is nice!

[Space Cadet]

The TT 225 engine is not the same as the 1.8T; it has various internal upgrades and exhaust manifold etc. I had the 1.8T in an old Golf GTI, it’s a wicked engine and can easily take the re-map upto close to 200bhp (I don’t think any of them are actually 150bhp to start with - more closer to 160bhp). After that you have to think about larger intercoolers, pipes and a hybrid turbo, which I did, took it up to circa 240bhp. After that you need a bigger turbo which means a new exhaust manifold to accept it, prices have really come down for these two. But anyway, definitely get it re-mapped, just make sure you use 99 Ron petrol, get it mapped properly for this and stick an uprated non-oiled panel filter in (Pipercross/Green).

[engineermk]

I had a 150BHP 1.8T Golf, I had it chipped by Superchips to approx 185BHP (according to thier rolling road data). I ran it for 30,000mile / 2.5yrs before selling it. The driveability was much better than the standard car and fuel consumption increased by just 1mpg for the extra performance. I was a fantastic drive and my current A3 2.0TFSI doesn't feel significantly better.

I'd recommend doing it.

[jed1kn1ght2000]

hi all,
thanks for all the responses.

the symptoms have come back i'm afraid to say. i cleaned the MAF myslef which removewd the problem again temporarily - but sure enought the issues returned shortly after. there's no drop in performance

i decided i'd clean the throttle body but didn't have a new gasket for it and the haynes manual didn't really help too much. is it easy and is it worth replacing it?

cheers

[sharc]

You said that you had previously had a new MAF fitted, so I don't see why you are bothering cleaning it already, the problem obviously isn't MAF related, unless you got a dodgy replacement MAF. I guess you could try disconnecting it like I did and see if that cures it.
I don't envy you, good luck!

Apart from my previous experience which I have laid out on these pages, I can't help any further I'm afraid!

Andy

[paul b]

It would be very odd if the MAF has gone again already. Has the oil for turbo etc been replaced every 10k? If that isn't done then it increases reliability problems. As mentioned, disconnect MAF and see if it is cured for a bit.
Paul

[HermanZeGerman]

hi all,

a remap is a good way of getting some serious power from the 150bhp... i drive the 1.8T quattro with 180bhp and it's pretty rapid! the only difference between these is the boost pressure, by installing a manual boost controller and a boost gauge you can hit 180bhp for less than £50 if you shop around

i believe the 150bhp is 9psi and the 180bhp is 12psi

hope this is of help