Jerky Ride

[FlyingBy]

An observation I've made, and I don't know if it should be like this or if somethings faulty.
Most noticeable on the freeway, stuck in traffic, either in 1st gear or 2nd, when I take my foot off the petrol, the car jerks quite violently,and its not that its about to stall either, spead is about 20km/h, revs between 1500 and 2000rpm. The same applies if I apply the petrol again, its not a smooth power take up like you would expect, doesn't matter how gentle I am on the petrol. I had the engine mountings checked by Audi, they say everything is fine, so its not that, they also told me that there is a "throttle closing delay" arrangement on the throttle itself to prevent this lunging.

Has anyone else experienced this? What could I look for to rectify? I spend the better part of 3 hours every day in stop/start traffic, so it gets VERY annoying when the car lurches all the time, and your whole body jerks forward and back too, looks worse than a learner driver....

 

[dultanur]

dunno what the problem is, but it sure isn't normal!

 

[Buster]

My Audi 80 does this and its the air flow meter, don't know if it would be the same with yours

 

[Vman]

My S3 was doing something similar to what you have described (although not as bad) replaced the Air Flow Meter now runs like a dream (touch wood).

 

[FlyingBy]

Thanks, guy's,
At least I'm pointed in the right direction. Funny thing, it doesn't always do it either, sometimes its silky smooth, sometimes not.
But, there's times when if it does, it charges forward like a bat out of hell, then jerks back as quickly and as harsh.
Do you think the TPS could be a suspect too?
And, would it show up as a dodgy "something" on the VAG?

 

[dultanur]

the maf wouldn't. don't know if the TPS would...

 

[mikeoh]

Sorry to resurect this old thread for my first post but i have something similar. No problems on acceleration so i don't think it's the MAF (what's a TPS?), it's just the easing off the throttle at lowish revs where it jerks.

I don't know whether or not the two are linked but i also have an intermittent idling problem where it will idle erraticly between 1000 and 1200rpm before settling down at 1000 after a few seconds. When it's behaving as it should it idles at 800rpm quite nicely.

I should probably mention it's a 1.6 Sport 2000reg. The idling problem only seemed to occur after I had another problem with the car stalling at idle (gunked up throttle body which i had sorted months ago). Recently the throttle body has been thoroughly cleaned and i also fitted a new air hose (the one that goes from filter to throttle body) as the oil breather bit(?!) of the hose was split.

I've been told this could be a coolant temp sensor problem. This weekend i flushed the whole coolant system as it was a bit gunky (blumin radweld!) so hoping that might clear the sensor if that got gooed!

Any help/advice on either of these would be quite useful and very much appreciated.

Great forum btw, have already found out some useful info!

 

[markyp2002]

i had a similar problem not too long ago. mines car is a turbo so the pipe work is obviously different, but i constantly thought it was the MAF causing me problems, but found it was a split pipe leading into the inlet manifold.

your car may/may not have one there but it could possibly a pipe split or loose elsewhere.

get ur car running and listen under the bonnet for any irregular hissing, or over-normal hissing anyway. you might find ur cause is a £10 bit of hosing!

 

[RichA3Turbo]

My A3 has done this for ages... Doesn't worry me but am pretty certain that it is the TPS which means having to buy a whole new throttle body.... I will do this when it finally packs up!

Rich

 

[mikeoh]

i had a similar problem not too long ago. mines car is a turbo so the pipe work is obviously different, but i constantly thought it was the MAF causing me problems, but found it was a split pipe leading into the inlet manifold.

your car may/may not have one there but it could possibly a pipe split or loose elsewhere.

get ur car running and listen under the bonnet for any irregular hissing, or over-normal hissing anyway. you might find ur cause is a £10 bit of hosing!

I changed the one hose mentioned in my original post (30 somat quid) and can't seem to find any other problems with any other hoses. Sadly that didn't fix the problem. My local garage did suggest it could be a temperature sensor that's gone (presumably coolant but i'm not sure). Does anyone have any thoughts on that?

Oh and one other local mechanic did fit a new throttle body but that all went tits up and threw up all sorts of error codes so he put the original one back in. He didn't charge me a penny thankfully (£280 for a new one!!1!!eleventy!!). But I do doubt his ability as a mechanic sometimes so he probably messed up somewhere.

Cheers,

Mike

 

[rodenal]

My 1.6 does this too occasionally, i've never bothered to look for a solution, and its never got worse in the last year n a half so havent had much motivation to do so lol

 

[mikeoh]

Right, sorry to keep draggin this out....

With all this talk about contaminated fuel lately got me wondering. When i had the throttle body cleaned out donkeys ago (as mentioned above) the mechanic used WD40 to clean it out, the idling issues only started happening after this clean out.

Could this have knackered my lambda sensor and be causeing my idling woes?

Cheers,
Mike

 

[petewon]

You sure its not the air flow meter? I had a very simialr problem recently where the idle was all over the place, even cutting out quite frequently. Try unplugging the lead off it and see if it sorts the idle out. That should rule it out at least.

 

[mikeoh]

Yeh. I tried driving it with the MAF disconnected and it drove *****. To be honest though i didn't drive it long enough to see if it would still idle funny with the MAF disconnected. Would you recommend i give it another shot?

Have tried replacing the coolant temperature sensor this morning and it hasn't fixed the problem The temp display on the dash also barely budged above 70°C for the duration of my test drive (and the car wasn't particularly cold as i'd already driven it earlier). So could my knew sensor be dodgy? Arrrrgrghhhhhh.

I can forsee a trip to the stealership coming

*EDIT* Just had it idling odly on the drive, switched off, disconnected MAF, started up, still idles odly. Not the MAF then.

 

[RichA3Turbo]

Mine is an AGU, and i have the same dodgy jerking, and also, my temp doesnt get above 70 when driving....but hits 90 when in traffic...Pretty certain my 'stat is screwed again, and i need a new temp sensor. Also, i think the jerkyness is the TPS, which means a whole new throttle body.

Rich