Quote:
Originally Posted by Regan
Did you get to the bottom of the surging idle
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Sorry for the late reply Regan. I got it to idle steady by tweaking the
MAF transfer table.
Then I had another issue with “bucking” at light throttle levels while cruising below 2000rpm. Above 2000 it was ok, but below 2000 it was like I was towing a trailer that was jerking on the back of the car.
I thought of blocked injectors, valve issues with the Tickford heads I’d fitted. It drove me nuts.
Just found the issue thanks to some ideas on OS forums - the Tickford heads have 1.72 rockers so it’s effectively got more cam duration. At light throttle there’s more vacuum and with increased valve over lap (due to the bigger valves and increased duration) exhaust gas is being drawn back into the cylinder and intake plenum.
The solution seems to be to reduce the light throttle spark advance in the “PT Spark Adder for ECT vs Load” table. I’ve got the advance cut by 15 degrees at 5% load. Now it’s cruising nice and smooth