'bouncing' idle

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rossparkman

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I've got a problem with my '96 a4 1.8t idling. When i am slowly rolling in traffic (with clutch in or in neutral), say 5mph, my idle 'bounces' between 300rpm and 800/900rpm. once i have stopped it levels out to a steady 800/900rpm idle. at higher speeds with the clutch in there is not a problem - only at that 5-10mph mark(!).

the only other time i get this problem is sometimes when i blip the throttle the revs drop to around the 300rpm mark again before stabilising.

the car never stalls but gets very close to it.

does anyone have any ideas what could be causing this? /ubbthreads/images/graemlins/confused.gif
 
When was it last serviced?

Mine did that quite often in traffic whilst idling. Then I had it serviced with new air filters and plugs etc, and now seems fine. Mine bounced between 800-900 revs, but felt lumpy.

Also, i found it better now that the air is cooler (due to winter) - i.e. morning and evening driving home from work...
Performs a little better in the cold - maybe it's just me?

Other solution is get the idling speed checked/changed...

There's my £0.02. Hope someone has more of a clue than me.

 
it has done this during the year i've had the car, even after servicing. i have changed plugs, filters etc and nothing seems to make a difference.

the overall drive is very smooth and not lumpy at all - only at rolling speeds is there a problem.

just had temp sensor replaced and a cleaner put through to remove build up. garage said it was filthy so i'm hoping it has solved problem - i'll find out tonight!
 
Hey Stiffnipples,

What kind of cleaner did you use to flush your engine? Oh yeah, nice name by the way /ubbthreads/images/graemlins/laugh_roll.gif /ubbthreads/images/graemlins/laugh_roll.gif /ubbthreads/images/graemlins/laugh_roll.gif
 
mines just piped up with a similar problem...... can anyone advise ????
start car, tick over fine, as you pull off, revs drop pretty low.... it dosent stall but its close...
once you get goining, its fine ??
although i have noticed on tick over, there is the slightest of murmers every 30 seconds or so ?????

any advise would be appreciated.....
 
audi upgrades
to answer you guys in order....

it's done 130,000 miles. full audi dealer history.

i wish i knew what type of cleaner got put through the engine but all i can tell you is it is listed as 'carb cleaner' on the bill.

all i know is it was the best £5 i've ever spent on a car! made a huge difference and the odd high idling has now sorted itself out after 100 miles today. very happy!

myzeneye, i would recommend you do the same thing and flush the system through. it sounds like i had the same thing as you exactly.

p.s. thanks for the name appreciation K212!
 
that is what mine was doing myzeneye, little murmers the it progressed to stalling every now and then.
 
i think simon is right on this one as i have found out that the cleaner put through my engine was for the throttle bodies.

the specialst also thinks that the slightly higher revving (intermittant - and blip throttle and it's fine again) at idle since the clean is due to the temp not being reported correctly. the sender has been replaced and the thermostat is getting replaced this week.
 
stiffnipp's...
what was the cleaner they used and does it just go in the fuel ???
simon, thanks for the info, ill try that if the cleaner does'nt work.... (easy option) as a heating engineer/plumber, this is a busy time for me.... infact... the phone's ringing now !!
it never stops!!!
ill do as you instruct if i get chanc some time over chrimmy...
mind you, if anyone calls me out on xmas day, their bill should just about pay for a new car! /ubbthreads/images/graemlins/lol.gif /ubbthreads/images/graemlins/lol.gif /ubbthreads/images/graemlins/lol.gif
 
Matty - if you'd have seen the amount of carbon that came off the throttle body, I'd be very surprised if a spray in cleaner shifted it - I had to scrub it off!!
The job only takes an hour - especially for a practical guy like yourself!
Mine is going markedly better.
 
i guess it depends how clogged the throttle body is as to what is needed to clean it.

it wasn't a fuel additive as far as i'm aware, more of a flush through directly. i will find out from the specialist on wednesday when the car goes in again for the temp problem.

for the £3 it cost me and zero effort it's worth a shot as a first try(!)
 
Sorry to steal Stiffnips glory but if it's the car I'm thinking of, it's the Dogs Boll*x of an Audi. The Autumn/Winter Audi magazine for 2003 has it on page 20.
It's an Audi "concept car" - Le Mans Quattro unveiled last year at the Frankfurt motor show:
2 seater, 5 litre Mid Engined bi-turbo V10 (40 valve).
610ps
750Nm torgue from 1750rpm to 5800rpm, Peak power arrives at 6800rpm
Top speed 214 mph
Theoretical 0-62mph = 3.7secs
0-124mph = 10.8 secs
6 speed Sequential gearbox
Alluminium and carbon fibre plastic body

If you get chance to look closer at the headlights - do so.
 
My A3 does this... but only when i've been giving it some and come to a quick stop... I reckon in my case its because im running rich so its kind of flooding the engine a bit.

Rich
 
[ QUOTE ]
simon_golf_tt said:
Matty - if you'd have seen the amount of carbon that came off the throttle body, I'd be very surprised if a spray in cleaner shifted it - I had to scrub it off!!
The job only takes an hour - especially for a practical guy like yourself!
Mine is going markedly better.

[/ QUOTE ]

ill do it. no point messin about.
cheers mate. i ushally need a foot up the @rse to do anything for myself.... if it was for anyone else, a friend, family or even a complete stranger who is a freind of a freind, i'd do it in the dark at midnight in a hail storm, immediatly..... but when its for yourself ?????
ill do it.
cheers. /ubbthreads/images/graemlins/beerchug.gif
 
[ QUOTE ]
HopA4TSport said:
Sorry to steal Stiffnips glory but if it's the car I'm thinking of, it's the Dogs Boll*x of an Audi. The Autumn/Winter Audi magazine for 2003 has it on page 20.
It's an Audi "concept car" - Le Mans Quattro unveiled last year at the Frankfurt motor show:
2 seater, 5 litre Mid Engined bi-turbo V10 (40 valve).
610ps
750Nm torgue from 1750rpm to 5800rpm, Peak power arrives at 6800rpm
Top speed 214 mph
Theoretical 0-62mph = 3.7secs
0-124mph = 10.8 secs
6 speed Sequential gearbox
Alluminium and carbon fibre plastic body

If you get chance to look closer at the headlights - do so.


[/ QUOTE ]

WOW that thing is amazing and HAS to be built....i swear i saw that in one of those ropey UFO footages (so quick you couldnt make out what it was) /ubbthreads/images/graemlins/laugh_roll.gif That car is fantastic if it comes out i think i'll and see if i can pick it up cheap on Autotrader secondhand! /ubbthreads/images/graemlins/laugh_roll.gif /ubbthreads/images/graemlins/laugh_roll.gif It just blows away any other car on looks alone never mind performance! Phew /ubbthreads/images/graemlins/jawdrop.gif
 
HopA4TSport is right, it is the car he is thinking of.

I saw the car at the Audi stand at Le Mans this year and that's where i took the photo. It is absolutley gorgeous in real life and the photo doesn't do it justice!

they HAVE to make it! /ubbthreads/images/graemlins/cool.gif
 
hey guys, im having the same problem but i thought it may be the catalytic convertor as its been rattling. When i slow down and let go of the accelerator, the revs bounce between 400-700 and then stabilize at 900. Also, when the car is idle, i keep getting these very very slight jerky noises like the exhaust is spitting out something. To top it up, in the morning the car wouldn't start, I had to giv it a good revving to start it.

u reckon this is the same problem?
 
Right,

So tuesday night i removed the throttle body from the car and took it inside intonthe warmth. Used vast amounts of brake cleaner to clean the inside of it and remove ALL deposits that have built up over the last 6 years. I then took the cover off the side and cleaned all the potentiometer contacts and made sure everything was working correctly...

Put it back on the car, plugged in VAG-COM and checked there were no errors which there werent. After driving it yesterday i can say it worked better than i thought! idle is now completely stable and doesnt fluctuate at all!

Since i had the car mapped for the big turbo, it would never idle properly...I was thinking that the car was running rich, but in fact it was just a coincidence that it happened at this time. Anyway, thanks for the info! Made me so much happier with the car! Was really p*ssing me off before...Mine would actually stall if you werent careful!

Rich
 
any chance of a photo of the offending throt bod ***'...
if i know what im dealing with, i can do it no probs. but i havent even looked yet...
point me in the right direction and ill take the thing completly to peices....
are you talking about the carb ? s#it, i dont even know if it has carbs ?? ha ha ha
give me a bike or a boiler any day...
i think its just the wording " throttle body ***" thats confusing me... could mean anything.

cheers simon.
milky bars are on me. /ubbthreads/images/graemlins/smile_smoking.gif /ubbthreads/images/graemlins/smile_smoking.gif /ubbthreads/images/graemlins/beerchug.gif
 
Matty - didn't have time to take a pic - but borrowed one off KingD's sig (cheers!). It's the little casting between the inlet manifold and the intercooler output hose. The throttle cable goes to it. See the red arrow!
 
hey guys my car does exactly the same thing, and it also starts up and then the revs just die quite a lot recently too. I do however run on with less fuel than i should a lot of the time, but the idling thing happened today in a que and the revs were at about 50, thought it was going to stall!!

Is this thing easy to take out as i don't know anything about engines at all,

Thanks /ubbthreads/images/graemlins/smile.gif
 
this is my engine... not sure which bit i need to be cleaning, could somebody please advice, thanks.
 
Just done mine today it was black as anything and being a 4 year old car i would not have thought it would have been that bad.
Cheers Simon for the advice. It has worked a treat.
Scared me thought when i started the car up and the revs were jumping more that a playboy porn star on a space hopper.
But turned it of and there was a high squeek coming from the DBW bit and then it went, restared the car and it was fine.
I even took the time to replace some of the boost vacumm hoses with some clear ones that i had which look cool.
 
a.p.courtenay - not sure about the 1.6 mate - all I can suggest is that you follow the throttle cable (if it is non drive by wire).

Markey - glad it had the desired effect - and a DBW too! Excellent.
 
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