Gti6 + Pt81 Lumpy Idle.

[Kapi306 0]

Hy all!

 

Ive got pt81 camshaft in my engine with VEMS ecu. The stable idle is 1100 rpm.

Is normal the MAP at idle is 60 kpa or ive got timing problem?

 

 

[petert 601]

A camshaft bigger than standard is always going to effect the idle vacuum and quality. Expect to have less vacuum than standard as the inlet valve closes later, reducing the dynamic compression ratio. I'd be happy with -60kPa. What lobe centre line did you install the cams on?

[welshpug 1,666]

I had no idle issues at all with the PH2 cams, on standard ecu and inlet.

[Kapi306 0]

The lobe angle is 110 deg.

Sorry, The Map is -40 kpa, -0,4 bar.

[petert 601]

Did you install them both at 110 deg.? How did you measure it?

[Kapi306 0]

Yes, Both at 110. Measure it with cam timing tolls. Timing disk and dial gauge.

[petert 601]

I'd experiment by moving the inlet to 108 and the exhaust to 112. This will increase dynamic CR and help maintain the overlap period.

[Kapi306 0]

Ok. I will try it. Thanks.

[petert 601]

Be careful though, as there's not much valve to piston clearance.