How should a 2.9i run?
Discussion
Had a run in the S3 and starting to get familiar with its quirks,which may be that or they may be things not quite right,depending on your comments.
The car starts fine from cold.If you blip the throttle at this stage them the engine stutters a bit but it ticks over OK.
As the car warms up it naturally runs more cleanly but tickover seems high,showing just over 1000 on the counter when hot.Revs seem to drop too slowly when lifting off so gear changes up need to be slow.
Normal or not?
As a supplementary comment, gear-changes are notchy when the box is cold improving as things warm up but the change is never the slickest....would Molyslip help?
The car starts fine from cold.If you blip the throttle at this stage them the engine stutters a bit but it ticks over OK.
As the car warms up it naturally runs more cleanly but tickover seems high,showing just over 1000 on the counter when hot.Revs seem to drop too slowly when lifting off so gear changes up need to be slow.
Normal or not?
As a supplementary comment, gear-changes are notchy when the box is cold improving as things warm up but the change is never the slickest....would Molyslip help?
Most probable cause is a dirty idle speed control valve, easy to remove and clean. If that improves things but you still have a fast tick over then the throttle stop probably needs adjusting. The butterflies should be completely shut at tick over as the ISCV provides all the tick over air. Do a search on idle speed control should bring up lots of history.
Rob
Rob
Griffinr said:
Most probable cause is a dirty idle speed control valve, easy to remove and clean. If that improves things but you still have a fast tick over then the throttle stop probably needs adjusting. The butterflies should be completely shut at tick over as the ISCV provides all the tick over air. Do a search on idle speed control should bring up lots of history.
Rob
Thanks,I've done a search and see it's a much discussed topic!Rob
Anyway,I'll have a go at cleaning the valve first.
John,
No the revs should drop off immediately when your foot releases the loud peddle.
I currently have the same problem that has only manifested itself in the past few months. I have tried swapping out the Throttle potentiometer, throttle by-pass valve (and returned both having cleaned thoroughly) without much joy. Also sprayed carb cleaner up the air intake, cleaned the plenum and butterflies, replaced the oil breather/vacuum pipes - little change, if anything made it worse!
One thing that I have done that has seemed to make a bit of a difference, made for a smoother drive and cured the slight hunting issue too, was to set up the air flow meters for idle to minimise the HC emissions. The only thing that I have yet to try and change out is the temperature sensor on the front nearside of the engine block under the butterflies - when disconnected the engine idles faster so I have my doubts. The only other thing that I can think of beyond the ECU playing up with mind is the need to replace the various gaskets (rocker covers/plenum/fuel rail) all of which I have had apart recently.
Mark
If you find the solution, please post, I'd be interested to see what I have missed.
No the revs should drop off immediately when your foot releases the loud peddle.
I currently have the same problem that has only manifested itself in the past few months. I have tried swapping out the Throttle potentiometer, throttle by-pass valve (and returned both having cleaned thoroughly) without much joy. Also sprayed carb cleaner up the air intake, cleaned the plenum and butterflies, replaced the oil breather/vacuum pipes - little change, if anything made it worse!
One thing that I have done that has seemed to make a bit of a difference, made for a smoother drive and cured the slight hunting issue too, was to set up the air flow meters for idle to minimise the HC emissions. The only thing that I have yet to try and change out is the temperature sensor on the front nearside of the engine block under the butterflies - when disconnected the engine idles faster so I have my doubts. The only other thing that I can think of beyond the ECU playing up with mind is the need to replace the various gaskets (rocker covers/plenum/fuel rail) all of which I have had apart recently.
Mark
If you find the solution, please post, I'd be interested to see what I have missed.
The idle will only drop completely once you stop the car it will then drop to base idle of circa 850 rpm, ir at a junction or whatever.
When you are rolling the ecu will hold a fast idle circa 1200 rpm on my old engine.
I read this was normal behaviour and it's what my car did. Although I had all sorts of odd idle issues prior to this and swapped all the usual parts out. in the end it was cured by new (yes new) afms.
Many of our cars don't work quite as they did when new because of age and mileage etc. that said this sorted mine right out so much so that I was very tempted to can the 24v conversion at the time.
My old AFMs were oily and clogged and someone had broken the adjustment mech in the past.
Cheers
Damian
When you are rolling the ecu will hold a fast idle circa 1200 rpm on my old engine.
I read this was normal behaviour and it's what my car did. Although I had all sorts of odd idle issues prior to this and swapped all the usual parts out. in the end it was cured by new (yes new) afms.
Many of our cars don't work quite as they did when new because of age and mileage etc. that said this sorted mine right out so much so that I was very tempted to can the 24v conversion at the time.
My old AFMs were oily and clogged and someone had broken the adjustment mech in the past.
Cheers
Damian
DamianS3 said:
When you are rolling the ecu will hold a fast idle circa 1200 rpm on my old engine.
Something to do with emissions I think?DamianS3 said:
My old AFMs were oily and clogged and someone had broken the adjustment mech in the past.
The electrical contacts/tracts inside are prone to surface corrosion if car has stood for a long time
Just a couple of comments on your post.....
1. Do not add friction modifiers of any type to a syncro gearbox. The syncro rings work by using the friction between the syncro cone and the gear to slow down the gear you wish to select. Once the cone becomes worn the friction effect is lost and this is why you get issues with gear selection in worn boxes. Adding things like molyslip makes things worse, even on a perfect box. Just as a comment, people who drive with their hand constantly on the gearlever put pressure on the cones and wear them out quicker too.
2. I had a car once which took its time for the revs to drop..it was simply due to someone who had helpfully GREASED the accelerator cable making it lazy to return. Just check that the cable is quite free first...you have probably already thought of this but thought to mention it on the offchance as simple things sometimes get missed.
Regards
Graham
1. Do not add friction modifiers of any type to a syncro gearbox. The syncro rings work by using the friction between the syncro cone and the gear to slow down the gear you wish to select. Once the cone becomes worn the friction effect is lost and this is why you get issues with gear selection in worn boxes. Adding things like molyslip makes things worse, even on a perfect box. Just as a comment, people who drive with their hand constantly on the gearlever put pressure on the cones and wear them out quicker too.
2. I had a car once which took its time for the revs to drop..it was simply due to someone who had helpfully GREASED the accelerator cable making it lazy to return. Just check that the cable is quite free first...you have probably already thought of this but thought to mention it on the offchance as simple things sometimes get missed.
Regards
Graham
TopVpowerRoadste said:
Hi guys,
Thanks for the pictures.
Is the plenum situated at the end of cylinder shaped part?
Thanks,
Geoffrey
Then plenum chamber is the thing that says EFI on it this attaches to the inlet manifold in the engine v.Thanks for the pictures.
Is the plenum situated at the end of cylinder shaped part?
Thanks,
Geoffrey
The ISCV is bolted to the plenum next to the throttle bodies. Ie it is the cylindrical thing.. There are some cleaning guides on the web that may help..
Damian S3
Here were the 2 sources of strange noises coming from my tiv :
1) Gearbox needed some oil, I plan to make a full drain soon, the gears would go even smoother I think
2) fuel pressure regulator that "grunted" a bit, it is quite a normal noise for these parts but replacing mine from a bigger from burtonpower did improve the throttle response and the accelaration seems more linear
1) Gearbox needed some oil, I plan to make a full drain soon, the gears would go even smoother I think
2) fuel pressure regulator that "grunted" a bit, it is quite a normal noise for these parts but replacing mine from a bigger from burtonpower did improve the throttle response and the accelaration seems more linear
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