dashpot spring or oil?
Turbo Mini Forums

hi all. just running in car moderate 4-5 psi. everynow and then from pull of engine splutters, then surges back to normal driving. this is at low rpm. afr is good. standard needle. part throttle lean off blocked to.
cheers.

When you say AFR is good. What sort of numbers are you seeing?

Is it around the point which you go from off boost to on boost?

In the 13's at last!.. Just

this is from pull off so around 13.5 to 14. but what i did notice is when i plant the throttle the gauge shoots all the way off past lean to --- then quickly gets round to 12 to 11.5, when reaching the boost rpm threshold. so could it be the dash pot spring is sticking?

Try a thicker oil, contrary to what your thinking, the piston needs to stay "closed" on throttle tip-in to generate the vacuum required to pull extra fuel out the jet for throttle enrichment. This is cause the su has no throttle pump. If the piston or spring were sticking it would help the situation, the oil provides a controlled level of stickiness

Edited by evolotion on 4th Jan, 2014.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

As above. You can try some thicker oil. 20/50 is pretty good and accessible.

You should aim for around 12.5:1 on boost.

In the 13's at last!.. Just

cheers lads will lean off slighty to get the 12.5 on boost. maybe this will help when pulling off from standstill and try the thicker oil. im using 75/80 gear oil as all i had at the time

in that case, swap to atf or 20w50, profile your needle again, then fettle with the tip-in by changing springs/oil. if your having to run 75/80 the needle probably aint right in the lower throttle areas :) imho though as i hvnt pissed about with an SU in over 10 years!

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

cheers. ill try the 20w 50.

lol now its the opposite. if you sit it nuetral give it a quick burst of throttle goes up rich which is good. but as the revs come back down goes off the scale to --- almost stalls then picks up to normal idle. like den said needle profile