Vac Advance

[Guest yaztromo]

My 1.9 engine pinks under load so I had a mobile engine tuner out to it today.

 

He retarded the timing and discovered that the mixture was too lean; it was only giving 0.5% CO2 on the exhaust, so he increased the mixture to 1% CO2 emissions.

 

He told me that the vac advance is incredibly weak but said that I really shouldn't replace it because it would hardly help at all. Is this right? Does the vac advance change very little?

[Henry Yorke 269 3 Cars]

They are only about £18 from Peugeot. It depends how he has tuned it too. You will find it a bit sluggish low down if he has tuned it for the advance state. You have to think that these things are often there for a reason!

[petert 587]

vacuum advance = better fuel economy

[Rob_the_Sparky 9]

If it is pinking mi-range and it is a standard engine then the bob weight are probably giving too much rev related advance (or to look at it another way they are giving the right amount of advance just at too low a revs).

 

Probably due to duff bob-weight springs. However, the dizzy is "not servicable" so another dizzy may be the answer to your woes or do a search on here as it is possibnle to get the dizzy apart but it is a bit of a mission.

 

Rob

[kyepan 291]

He told me that the vac advance is incredibly weak but said that I really shouldn't replace it because it would hardly help at all. Is this right? Does the vac advance change very little?

 

when I replaced the dizzy for one in the scrapyard its vac advance was damaged... so i changed it, and all the dodgy idle problems i was having miraculously dissapeared. for the price of the part and the ten minutes it takes to get the new one seated correctly i think it was worth it.

 

JB

 

If it is pinking mi-range and it is a standard engine then the bob weight are probably giving too much rev related advance (or to look at it another way they are giving the right amount of advance just at too low a revs).

 

Probably due to duff bob-weight springs. However, the dizzy is "not servicable" so another dizzy may be the answer to your woes or do a search on here as it is possibnle to get the dizzy apart but it is a bit of a mission.

 

Rob

 

Scrappy will definitly have them and its only 2 bolts to get them off, but its a lottery as to whether you will get the right fitment cap.. as boshe dizzy has two fitments, and dulcuier may also have two. also you will need the right dizzy, as the 1.6 and 1.9 have different advance curves.. whatever that means.

 

Justin

[Rob_the_Sparky 9]

Advance curves (on a GTi dizzy): the amount of advance added by motion of the bob weights with relation to revs.

[hengti 2]

vacuum advance = better fuel economy

 

 

my understanding too

thought the function (or not - !) of vac adv has no affect on power (or pinking) - only part throttle fuel economy

[Rob_the_Sparky 9]

It certainly can effect pinking but it is not usually the cause. It gives more power on a trailing throttle and hence better fuel economy as on a cruise you use a trailing throttle most of the time. As it only makes a difference on a partly closed throttle it does not effect the headline power.

[Guest yaztromo]

It certainly can effect pinking but it is not usually the cause. It gives more power on a trailing throttle and hence better fuel economy as on a cruise you use a trailing throttle most of the time. As it only makes a difference on a partly closed throttle it does not effect the headline power.

 

In that case I'll probably not replace it. I was just worried it was losing me bhp.

[petert 587]

In that case I'll probably not replace it. I was just worried it was losing me bhp.

 

So you're not interested in part throttle torque? It's either idle or WOT?

[Guest yaztromo]

So you're not interested in part throttle torque?

 

Good point.

 

It's either idle or WOT?

 

What's WOT?

[petert 587]

wide open throttle