Hy ,
A friend of mine just installed a new streetported engine in his car and has just managed to start it up.
The engine will go to normal idle instantly but it starts to bounce either after a few seconds or after tipping the throttle.
See this link for video
http://www.youtube.com/watch?v=P2g-acHoqLc
I had this with my own engine (same porting) but I managed to stabilize idle through the idle screw below right on the TB and the idle screw next to the TB cable.
enigine uses an Apexi PFC ECU, Emission stuff has been removed, Double throttle is still in place.
any thoughts?
Vac leak maybe?
air leak after throttle body/vac line,squirt brake cleaner around the manifold and see if it changes the running at idle
The warm up wax on the throttle body can also make it difficult to get a good idle
Also the pfc can take ages and a few restarts to get the idle
Id go with air leak for now though causes exactly that fault
thanks will sure check that.
Any other advice is still welcome so we can look for possible problems
thx
How heavy was the porting? Was it bridgeported? I know that an extended streetport can sometime cause idle quality issues. Has the car ever idled smoothly with the new engine?
idle control valve? or maybe the ignition timing
I build the engine with a big streetport. I build my owwn engine and for some other people as well with identical porting/templates. we did not experience this kind of bouncing. I did at first but my engine has the thermowax and double throttle removed os I straightened it out by adjusting the TB idle screw (bottom right) and the idle screw next to the TB valve (where the throttle cable attaches to the TB).
Ignition timing should be OK to start as it uses the PFC base map (same as standard)