I've just fitted HKS 272 intake and exhaust cams with adjustable cam wheels to my 100kW factory EFI Sprinter.
Let me just say that the thing was running fantastically before I installed the new cams.
Having understood that the maximum the factory efi could cope with was 272 degrees duration, I got the HKS 272s.
Having translated the Japanese instructions it turns out that the duration is far greater than 272 degrees - something about 293 for the intake and 280-odd for the exhaust (they're different.
You'll need to check how the cam manufacturer describes duration. It turns out that HKS measures duration at 50 thou lift - giving in my case the label 272 - however the total duration (ie from 0mm lift) is far greater.
As a result the thing is almost undriveable below 2000 rpm. The idle drops to about 500 until the ECU decides it needs to do something about that and the revs rise to 900-odd.
Taking off from rest requires at least 1800-2000 rpm and then the thing bogs down and goes absolutely nowhere.
Backing off and coasting - as towards a set of red lights - the thing goes so rich and chugs back and forth very embarrassingly.
Suffice to say, I need to do some revisions to the EFI to get the thing working adequately.
I'll have a look at the specs for the 256s and 264s from HKS and check their actual duration.
Re: 4AGE cams and ECU questions
Wed, 21 May 2003 02:50
