Advance And Retard Question

[Slo 283 1 Cars]

When i first got my car it was stupid quick for an old bog standard cti.

The first time i serviced it i discovered that not only the advance and retard pipe wasnt connected

but it also had a bolt screwed into the end of the pipe to block it off, i removed it and put it back to normal. That was last year and i had forgotten all about it until tonight when i got to thinking that either i had just got used to the car or it had got slower so i have taken the pipe back off and blocked it off with another bolt and my god what a difference. Its got the k&n induction kit on it, so is this normal or is there possibly some other modification thats not obvious to the eye?

[dcc 855]

Nah youre right. its definitely there for no reason. I found folding down he rear seats helped 0-60 times because of centre of gravity too.

[Anthony 1,000]

That's for the vacuum advance unit on the dizzy.

 

It shouldn't feel quicker with the pipe disconnected/blocked - if anything, it should feel more responsive on part throttle with it plugged in and should make a noticeable improvement in fuel economy if it's working.

 

Many these days however are broken - easiest test is that you shouldn't be able to suck through the pipe when it's connected to the vacuum advance, and if you can, chances are that the diaphram inside the unit has failed.

[ALEX 98 1 Cars]

If it's slower with it connected then it must be advancing the timing too far (that is if it's working, do the simple test above)

Get a strobe or a mobile tuner to set it up when you've got a working vac advance connected.

If you end up having to buy a new vac advance, note it will pay for itself with the fuel you'll save.

[309jazzpanda 39]

Had to have my vac advance done last year and you can really tell the difference in fuel with it disconnected

[forbeslongden 32 13 Cars]

Help guys! I'm having the same problem, my 1.9 is sucking fuel like a Hummer and all my silicon pipes have been blocked off with bolts and a silly K&N Filter has been used instead of the airbox, where can I get a VAC advance from? It's so hard to find 205 bits :#

/

[309jazzpanda 39]

H and h ignition solutions

[forbeslongden 32 13 Cars]

Thank you!

 

I don't understand why someone decided to wreck the engine bay like they have, I suspect being a non-sunroof means it was destined for the track, the car is really, really fast but I'd sooner discount the speed instead of visiting the pumps every three journeys.

[welshpug 1,626]

nothing "wrong" with a K&N, it certainly makes the engine bay a little less cluttered, but the rest is inexcusable.

[forbeslongden 32 13 Cars]

I've heard the K&N can lower the MPG, is that true or just a myth?

[welshpug 1,626]

its quite true, because anyone who fits one will be putting the toe down making noise even more than with a standard engine!

 

other than that, no

[forbeslongden 32 13 Cars]

Haha! I must admit, it certainly produces some sound. In fact, I also have a diesel 205 and it's far quieter than my GTi!

[Slo 283 1 Cars]

Seeing as i'm not the only one who got their car with a k&n already fitted and the vacuum advance blocked off, the fact that the engine is more responsive with it disconnected and blocked off must prove that the timing is also altered from standard when the k&n was probably fitted back in the day no? Wish i'd actually tested mine with my strobe light now while i had the chance as it's always bugged me this,

[Anthony 1,000]

With the vacuum advance pipe connected to a broken vacuum advance unit, you'll effectively have a small airleak.

 

The K&N fitting will make no difference to ignition timing.

[forbeslongden 32 13 Cars]

Mine currently is super-fast but won't behave when it comes to idling. All my silicon breathers are cut off so I assume all of this gives better speed performance but rubbish idle/fuel results.

 

Mine I'm pretty sure was going to be kicked out onto a track since its a non-sunroof, funny thing is, I was told when taking it to a garage that the passenger side hub was shot and sure enough, I took it upto 110mph and the car veered and bounced into the next lane on the motorway - needless to say, I saved the car and no doubt the previous owners life if it was intended to be raced.

[Slo 283 1 Cars]

Anthony i mean the dizzy must be advanced or retarded somewhat when k&n people fitted them years ago, themselves manually. How else can blocking off the pipe create such a huge difference in response hmm

 

oh and i do mean compared to a connected and working advance and retard diaphram not one thats leaking before anyone else jumps in

[ALEX 98 1 Cars]

Anthony i mean the dizzy must be advanced or retarded somewhat when k&n people fitted them years ago, themselves manually. How else can blocking off the pipe create such a huge difference in response hmm

 

oh and i do mean compared to a connected and working advance and retard diaphram not one thats leaking before anyone else jumps in

 

If the vac advance is broken it wont be advancing, but it will be sucking unmetered air (Bypass the AFM) into the engine.

This means the ECU thinks its getting less air than the engine is actually getting, so the mixture will be weak.

If you plug the pipe from the advance unit to the the throttle body then you've fixed the air leak, but it still won't be advancing under acceleraion.

My guess it's been advanced on the dizzy mechanically (on it's slots) so it drives superb on acceleration, but I fuel economy will be suffering, unless you fit a working advance.

 

Edit:

Chances are that the Vac advance was broken, and instead of replacing it it was bypassed.

 

Editi edit:

If you're so sure a working advance gives poor performance, then something has been tinkered with to compensate it.

I've seen mobile tuners pop covers off the AFM and messed with the spring tension, but they are just concerened about emissions and to get it to run. I found later that the AFM is clibrated at the factory and its setting shouldn't need touching.

Our local mobile tuner messed with my mates after it wouldn't start, he eventually got it running though it ran like sh*t, but within emissions.

Eventually we found the blown ECU coolant temp sensor causing the problem but we couldn't get the AFM back to how it was, we found another unopened 2nd hand one and it ran perfect.

Edited July 17, 2013 by ALEX

[Slo 283 1 Cars]

And someone jumps in

[ALEX 98 1 Cars]

And someone jumps in

 

Well this is a forum

[Tom Fenton 1,526]

The vacuum advance does what it says on the tin, it advances ignition timing when under vacuum. As soon as you put your foot down and open the throttle fully there is no longer any vacuum hence it does nothing at all to do with acceleration or "throttle response".

What it does is advance the timin during cruise for a better more efficient burn under light load part throttle, result being that in turn you open the throttle less for a given speed hence use less fuel. When working right the 205 Jetronic can be remarkably good on fuel, my turbo car in its pre turbo days did over 40mpg at autoroute speeds in France, this was with a recently fitting and working vac advance can on the dizzy.

[ALEX 98 1 Cars]

The vacuum advance does what it says on the tin, it advances ignition timing when under vacuum. As soon as you put your foot down and open the throttle fully there is no longer any vacuum hence it does nothing at all to do with acceleration or "throttle response".

What it does is advance the timin during cruise for a better more efficient burn under light load part throttle, result being that in turn you open the throttle less for a given speed hence use less fuel. When working right the 205 Jetronic can be remarkably good on fuel, my turbo car in its pre turbo days did over 40mpg at autoroute speeds in France, this was with a recently fitting and working vac advance can on the dizzy.

 

If the vac advance is broken it wont be advancing, but it will be sucking unmetered air (Bypass the AFM) into the engine.

This means the ECU thinks its getting less air than the engine is actually getting, so the mixture will be weak.

If you plug the pipe from the advance unit to the the throttle body then you've fixed the air leak, but it still won't be advancing under acceleraion.

My guess it's been advanced on the dizzy mechanically (on it's slots) so it drives superb on acceleration, but I bet fuel economy will be suffering, unless you fit a working advance.

 

My bad

Edited July 18, 2013 by ALEX

[Anthony 1,000]

Further to Tom's comment, in my experience on both of my current 205's when they were 1.9 8v's used on the daily commute, a working vacuum advance unit is worth about 3-4 mpg in terms of improved fuel economy - in real terms, that's about another 40 miles to a tank.

 

And yes, Jetronic in general can be very economical when it's in good working order - my current 1.9 8v is averaging 38mpg on my daily commute, which frankly is outstanding when you consider that both the engine and fuel injection/management design is well over 30 years old.

[ALEX 98 1 Cars]

Further to Tom's comment, in my experience on both of my current 205's when they were 1.9 8v's used on the daily commute, a working vacuum advance unit is worth about 3-4 mpg in terms of improved fuel economy - in real terms, that's about another 40 miles to a tank.

 

And yes, Jetronic in general can be very economical when it's in good working order - my current 1.9 8v is averaging 38mpg on my daily commute, which frankly is outstanding when you consider that both the engine and fuel injection/management design is well over 30 years old.

Put it in a car that doesn't weigh half a gram then i bet you wouldn't see much past 25 mpg

[forbeslongden 32 13 Cars]

Mine is really bugging me, the car stalls when starting it up around 3 times and will idle at 2K without too much trouble, 1.5k it'll do but not without almost cutting out anything below that and it doesn't want to know. It also cuts out when warm on hills and when reversing. Will the VAC thing sort mine out or at least go towards the problem?

 

It's such a pretty car - it's just embarrassing when people look at it and it decides to stall

[DanteICE 72]

Mine is really bugging me, the car stalls when starting it up around 3 times and will idle at 2K without too much trouble, 1.5k it'll do but not without almost cutting out anything below that and it doesn't want to know. It also cuts out when warm on hills and when reversing. Will the VAC thing sort mine out or at least go towards the problem?

 

It's such a pretty car - it's just embarrassing when people look at it and it decides to stall

 

Replied to your thread regarding the stalling and high revs, the Vacuum advance is unlikely to cause this. Plug off the vacuum advance to rule it out, get the rest of the car sorted then test and trial it.