Jerky At Low Speeds - Wisdom Required

[chocolate_o_brian 0]

It's starting to annoy me a little now. Dunno if it's getting progressively worse, but the jerkyness of the car in 1st, 2nd and 3rd at low speeds is a right p.i.t.a. ('88 1.9GTi)

 

Wasn't there (or wasn't as bad before), and I'm trying to think of a list of possibilities. I find I'm constantly dipping the clutch when in constant traffic as it seems to wanna bunny hop/jerk about. It's not smooth at all (although I don't expect Bentley smoother), but not noticeable at higher speeds like 30-40mph.

 

So far I've thought of...

 

1. Clutch mis-aligned somewhere or wearing unevenly

2. Something do do with the ignition (plugs, leads, coil)

3. Maybe fueling at low speeds?

 

Any advice appreciated, as I know these are noted for it, but I've had the car about 9 months and haven't always had jerkyness as bad as this. Slow moving traffic or approaching junctions is a constant dread

[pugdamo 111 2 Cars]

The main cause is the throttle switch,soon as you come off the throttle it cuts the fuel supply,then when you try and give it a bit of gas to maintain a constant speed off it shoots again,it can be very irritating when moving in slow moving traffic trying to maintain a very low speed. Its only the speed and gearing that make it less severe at higher speeds.

I spaced out the buffers on my top engine mount to limit the amount of movement in the engine,that really helped,my other mounts are in good condition but if your others are weak aswell replacing these may help,nothing will stop it though,its the design of the fuel injection,there is a knack that i expect loads of GTI drivers have adapted to make it smoother aswell.

 

I have heard of people disconnecting the throttle switch but i wouldnt recommend it,you would have no fuel shut off on engine over run.

[chocolate_o_brian 0]

The main cause is the throttle switch,soon as you come off the throttle it cuts the fuel supply,then when you try and give it a bit of gas to maintain a constant speed off it shoots again,it can be very irritating when moving in slow moving traffic trying to maintain a very low speed. Its only the speed and gearing that make it less severe at higher speeds.

I spaced out the buffers on my top engine mount to limit the amount of movement in the engine,that really helped,my other mounts are in good condition but if your others are weak aswell replacing these may help,nothing will stop it though,its the design of the fuel injection,there is a knack that i expect loads of GTI drivers have adapted to make it smoother aswell.

 

I have heard of people disconnecting the throttle switch but i wouldnt recommend it,you would have no fuel shut off on engine over run.

 

 

Thanks for that fella. I am considering changing the HT leads as they aren't 100%, and whether they make a difference or not, at least they can't be blamed. They do need changing in all respects. I just wondered as the problem has come on but wasn't always there. I will check the connections tomorrow, and maybe even pop it to my local garage who do my MOT's and fiddling, check the fuel set up. Just don't wanna go around changing loads of bits when they are perfectly fine. Having done a search more thoroughly, the TPS did pop up a couple times. But you got it nail on head re. slow moving traffic. Horrible to drive at anything under 1500-1600rpm in 1st 2nd or 3rd. One thing I have noticed too is when approaching a juntion/lights etc, and I'm slowing down from say 40mph, I have to just dip the clutch until I come to a halt. If I don't and try changing down gears, it's terrible jerky. Or if I slow down and its hovering about 1200rpm in 5th and I wanna change down to 2nd, as soon as I dip the clutch the car jerks forward and I have to press harder on the breaks. Again something that has not always been there.

 

Certainly more of an annoyance than anything else, but it is making me think "do I want this all the time" as my driving is mainly round town and not on A/B-roads.

Edited March 10, 2009 by chocolate_o_brian

[pugdamo 111 2 Cars]

Did you mean the revs are holding up at around 1200rpm? If so you could have an air leak,this would cause the revs to be higher than normal. when changing down if it is revving high it would try accelerating a little .

 

Of course you want to do it all the time,just take it for a drive on a b - road and all will be forgiven

[chocolate_o_brian 0]

Did you mean the revs are holding up at around 1200rpm? If so you could have an air leak,this would cause the revs to be higher than normal. when changing down if it is revving high it would try accelerating a little .

 

Of course you want to do it all the time,just take it for a drive on a b - road and all will be forgiven

 

No fella, think I've explained it wrong. I'll try again

 

Say I'm approaching a set of traffic lights and need to come to a halt. Usually in any other car I would be in 4th/5th gear and would simply apply the brakes without changing gear until going quite slow. Then when going quite slow, dip the clutch and pop into either neutral or 1st. If I do this in the Pug, I have to go down gear by gear. I can't simply slow down from say 40 to 15mph in 5th (for example) and then drop straight into 2nd as if I do the car lurches forward when depressing the clutch. Idle and revs are fine, I just get that jerk forward. (But only when depressing the clutch in high gear @ low speed).

 

Is that a bit easier, as I'm pants at explaining stuff like this

Edited March 10, 2009 by chocolate_o_brian

[pugdamo 111 2 Cars]

I know what you mean,mine doesnt do this and havnt noticed it on any others so i cant help you on that one im afraid

[davey205 7 1 Cars]

I know what you mean,mine doesnt do this and havnt noticed it on any others so i cant help you on that one im afraid

mine is the same i always thought it was to do with the fuel cut off like you said but im changing the leads and plugs soon hoping it will run a bit smoother

[chocolate_o_brian 0]

mine is the same i always thought it was to do with the fuel cut off like you said but im changing the leads and plugs soon hoping it will run a bit smoother

 

Ah, thank god! Not just me then?

 

Defo gonna change the HT leads and ill have the fueling checked again. Was quite cold here this morning and for some reason (even when warmed up fully), car seemed to idle at 1900rpm No air leaks though that I'm aware of. Maybe she needs a bit of a B-road battering.

[davey205 7 1 Cars]

Ah, thank god! Not just me then?

 

Defo gonna change the HT leads and ill have the fueling checked again. Was quite cold here this morning and for some reason (even when warmed up fully), car seemed to idle at 1900rpm No air leaks though that I'm aware of. Maybe she needs a bit of a B-road battering.

mine idles not quite as high as that but when really cold at like up to 1700 rpm which worries me a bit but as soon as shes warm it goes down to between 900 - 1200rpm

Edited March 11, 2009 by davey205

[chocolate_o_brian 0]

mine idles not quite as high as that but when really cold at like up to 1700 rpm which worries me a bit but as soon as shes warm it goes down to between 900 - 1200rpm

 

Idle's just been fine for me when I had to pop into the town centre. I would put it down to the denser and cooler air this A.M.

 

I'm gonna find some decent HT leads somewhere and see what difference that makes to the jerk. If not maybe coil or a faf with the TPS.

[CosKev 16]

As above,throttle position switch is the key to sorting this problem

Get it to Skip Browns for a rollling road tune up,he did mine and its a different car

He sets the throttle position switch so you get no fuel cut on over run,which does not affect the car/emissions etc at all,just stops the jerky s*it

Well worth getting it set-up properly,they will also adjust the spring in the AFM while on the rollers if need be

 

Usually in any other car I would be in 4th/5th gear and would simply apply the brakes without changing gear until going quite slow.

 

You need to learn how to drive!!!!!!!

 

Pretty sure you would not pass driving test driving like that

Edited March 12, 2009 by CosKev

[chocolate_o_brian 0]

As above,throttle position switch is the key to sorting this problem

Get it to Skip Browns for a rollling road tune up,he did mine and its a different car

He sets the throttle position switch so you get no fuel cut on over run,which does not affect the car/emissions etc at all,just stops the jerky s*it

Well worth getting it set-up properly,they will also adjust the spring in the AFM while on the rollers if need be

 

 

 

You need to learn how to drive!!!!!!!

 

Pretty sure you would not pass driving test driving like that

 

Wish I had the money to go to Skip Brown. I Don't even wanna think what it costs to get everything set up and then petrol on top Can't be as expensive as Subaru tuners can it?

[CosKev 16]

Wish I had the money to go to Skip Brown. I Don't even wanna think what it costs to get everything set up and then petrol on top Can't be as expensive as Subaru tuners can it?

 

LOL,no

 

£50 at Skip Browns for rolling road set-up

 

Excellent value for the difference it made to mine anyway

[chocolate_o_brian 0]

LOL,no

 

£50 at Skip Browns for rolling road set-up

 

Excellent value for the difference it made to mine anyway

 

Thats not too bad then considering. I guess then you find out the cars power and any possible faults too which is always good to know.

 

I've just been and bought some decent oem quality HT leads from a local car parts shop along with some carb cleaner for the AFM. Got home and swapped the old leads over for the new ones (one by one ) and then turned the engine over. The idle was a little high (1900rpm or so), so I thought "what the hell, it's dry and I know a good back road". Off I went. My findings were the following...

 

1. Very smooth through the rev range as before there was a mis/backfire at about 5,500rpm which sounded terrible. This has gone.

2. The car still has a misfire on idle, so maybe some NGK plugs to replace the Bosch ones (if I can source them cheap that is). It's not really problematic, just a pain.

3. Car still has that lurch forward and jerky ride. I haven't tried it in slow moving traffic since swapping the HT leads, but it is evident still.

 

So from the above I would deduct the HT leads were fooked and very loose, and the TPS needs setting up properly. The leads are done, and I will have a go at cleaning out the AFM next time I'm round my mates. For now unless it magically disappears, I'll have to put up with the jerky ride.

[davey205 7 1 Cars]

Thats not too bad then considering. I guess then you find out the cars power and any possible faults too which is always good to know.

 

I've just been and bought some decent oem quality HT leads from a local car parts shop along with some carb cleaner for the AFM. Got home and swapped the old leads over for the new ones (one by one ) and then turned the engine over. The idle was a little high (1900rpm or so), so I thought "what the hell, it's dry and I know a good back road". Off I went. My findings were the following...

 

1. Very smooth through the rev range as before there was a mis/backfire at about 5,500rpm which sounded terrible. This has gone.

2. The car still has a misfire on idle, so maybe some NGK plugs to replace the Bosch ones (if I can source them cheap that is). It's not really problematic, just a pain.

3. Car still has that lurch forward and jerky ride. I haven't tried it in slow moving traffic since swapping the HT leads, but it is evident still.

 

So from the above I would deduct the HT leads were fooked and very loose, and the TPS needs setting up properly. The leads are done, and I will have a go at cleaning out the AFM next time I'm round my mates. For now unless it magically disappears, I'll have to put up with the jerky ride.

just changed my plugs to ngk ones and changed the filthy grotty old filter to a smart new k and n and wow! i too know a suitable country road nearby and its like a different car.

[chocolate_o_brian 0]

just changed my plugs to ngk ones and changed the filthy grotty old filter to a smart new k and n and wow! i too know a suitable country road nearby and its like a different car.

 

There was a K&N induction kit on the Pug when I bought her. Give it a recent clean with one of their proper kits. Made a difference. Also ordered some more plugs too. Got the NGK ones at £1.11 each off Ebay BARGAIN!

[fangio 1]

Had a similar problem on my sixed 205 and had the injectors cleaned - what a difference.

 

Not only does it drive sweetly at low revs now with no stuttering and farting around but, give it the gun and it smoothly and cleanly pulls like it never has before.

 

Well worth the £69.

[chocolate_o_brian 0]

Had a similar problem on my sixed 205 and had the injectors cleaned - what a difference.

 

Not only does it drive sweetly at low revs now with no stuttering and farting around but, give it the gun and it smoothly and cleanly pulls like it never has before.

 

Well worth the £69.

 

Didn't think of the injectors. For £69 would it not be better to buy new ones (or am I gonna get a suprise at the cost of them new ).

 

Car drove quite well this morning dropping off the Mrs at work, so hopefully the decent on order NGK plugs will add to it.

 

Just found out this morning also that I have a couple fuses gone after the hazards refused to work alongside the rear heated window - I suppose that falls into insignificance compared to the other issues I've overcome

[CosKev 16]

Didn't think of the injectors. For £69 would it not be better to buy new ones (or am I gonna get a suprise at the cost of them new ).

 

Car drove quite well this morning dropping off the Mrs at work, so hopefully the decent on order NGK plugs will add to it.

 

Just found out this morning also that I have a couple fuses gone after the hazards refused to work alongside the rear heated window - I suppose that falls into insignificance compared to the other issues I've overcome

 

Not sure on price of Pug injectors,but needed a new one in my old Astra GTE and that was just over £70 brand new

 

Had my injectors cleaned/re-conned here:

http://www.injectorcleaning.co.uk/index.htm

Costs just over £50 including Special Delivery back to you.

You get a sheet stating all the flow rates pre-recon and then post recon,and a bag of old bits that they replace(filters/seals/caps etc)

Can't fault the service

[lemmingzappa 75 1 Cars]

Say I'm approaching a set of traffic lights and need to come to a halt. Usually in any other car I would be in 4th/5th gear and would simply apply the brakes without changing gear until going quite slow. Then when going quite slow, dip the clutch and pop into either neutral or 1st. If I do this in the Pug, I have to go down gear by gear. I can't simply slow down from say 40 to 15mph in 5th (for example) and then drop straight into 2nd as if I do the car lurches forward when depressing the clutch. Idle and revs are fine, I just get that jerk forward. (But only when depressing the clutch in high gear @ low speed).

 

My GTi actually sometimes stalls completely when doing exactly what you explained. Less so when the weather is hot though.

 

I've found that for some reason if I press the clutch at the last possible minute when coming to a stop the revs drop as low as they can, but not enough to stall. (i dont need to do this if the engine is toasty)

 

So i've sort of learned to drive my 205 this way and don't notice it any more.

[feb 47]

Mines the same , it is jerky at 40mph in 4th gear!!! It is so annoying.

I am booked at SBC tomorrow to check this among a few things.

[KRISKARRERA 2 1 Cars]

My Mi16 has done this for ages, or at least something similar. For example: end of my road is only about 30 feet away so I only get to stay in 1st gear. As the end of road approaches I lift off accelerator completely, revs drop obviously, then as the revs drop back towards idle the injectors open again and my god the engine jerks the car so hard it's like I've done an emergency stop!

Also let's say I'm in gear at fairly low revs, foot off the gas, then I go to accelerate I get throttle lag followed by an intermittent uptake of power then the acceleration smoothens out. Similarly, upon releasing the accelerator peddle the engine cuts power intermittantly.

I've changed loads of parts over the years and adjusted the throttle body and TPS in various positions, tried different octanes of fuel etc. Only thing left is to have injectors cleaned. There's a chap in town I know, he does them for £36. But then I wonder if such things are caused by play in CV joints and/or worn engine mounts. An old mag I've got of a 405 road test has the test driver moaning that "This car has the awful drivetrain shunt so characteristic of the XU engines".

 

What I've noticed on newer cars is that they do seem to have a fuel cut off on the overrun, but instead of the fuel being cut instantly, it's cut very gradually over a few seconds. Surely it wouldn't have been hard to program the ECU to behave in this way on older cars too?

[Grim.Badger 15]

New cars don't cut the fuel, doing so burns out the CAT apparently, they just run with very little fuel.

 

Adjusting the TPS is cheating and you may as well remove it entirely as it is a SWITCH not a sensor so it only knows when its shut, it doesn't tell the car how far open it is. Its only purpose is to tell the ecu that the throttle is shut so stopping it doing this is kinda stupid.

 

In my experiance jerkyness is caused by:

 

1 - Worn/improperly fitted engine mounts

2 - Old AFM with a worn carbon track

3 - Badly adjusted throttle cable, or the cable is catching on something

4 - Badly set up AFM

 

New plugs, leads, filter etc won't stop this, although they may help with other related problems.

[CosKev 16]

New cars don't cut the fuel, doing so burns out the CAT apparently, they just run with very little fuel.

 

Adjusting the TPS is cheating and you may as well remove it entirely as it is a SWITCH not a sensor so it only knows when its shut, it doesn't tell the car how far open it is. Its only purpose is to tell the ecu that the throttle is shut so stopping it doing this is kinda stupid.

 

In my experiance jerkyness is caused by:

 

1 - Worn/improperly fitted engine mounts

2 - Old AFM with a worn carbon track

3 - Badly adjusted throttle cable, or the cable is catching on something

4 - Badly set up AFM

 

New plugs, leads, filter etc won't stop this, although they may help with other related problems.

 

Adjusting the TPS works though,stops the jerkyness alltogether,has no other side affects on fueling or the way the car runs

 

Have you driven a car that has had this done to the TPS????????

 

I think you would soon change your opinion

[Paul_13 212 1 Cars]

Dodgy alternator? I had this problem, the ring inside it kept getting jammed