GT86 FA20 Intake Cams angle vvti issue

Hello there,

After rebuilding FA20 engine I have got issue with the intake cam avcs angles. It fires P000A and P000C (slow response to avcs command).

Engine setup is:

Cosworth supercharger

OEM crankshaft

pCoteMax Kings main and rod bearings

Bridgeway forged rods

JP pistons CR12.5 86mm

machined heads and block

DW 450cc PI

baffled sump plate

CUSCO water oil cooler

mishimoto thermostat (the one which comes with the supercharger kit)

I think about several reasons:

- bad one or both OCV selenoids ( less probable, because before disassembly of the engine, cams worked ok, I checked the previous logs)

- incorrectly aligned timing chain (less probable, because engine goes more-less ok)

Can I ask you for your opinion please? Check the logs bellow.

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intake cams

there is rapid oscilation of both cams all the time

none of the cam goes over 20FR deg

cam 1 is performing better than cam 2

[url=https://datazap.me/u/secho/loguju-vacky-abych-zjistil-intake-failure?log=0&data=10-11-52-53-54&zoom=8682-9476&mark=9166-9354]https://datazap.me/u/secho/loguju-vacky-abych-zjistil-intake-failure?log=0&data=10-11-52-53-54&zoom=8682-9476&mark=9166-9354

——————

intake cams angle ugly oscillation

[url=https://datazap.me/u/secho/loguju-vacky-abych-zjistil-intake-failure?log=0&data=10-11-52-53-54&zoom=5408-5893]https://datazap.me/u/secho/loguju-vacky-abych-zjistil-intake-failure?log=0&data=10-11-52-53-54&zoom=5408-5893

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exhaust cams

actual angles fluctuates much more when the oil temperature is low (one cam more then the other)

fluctuation stabilises when the oil temperature rise (both cams ok)

it follows target exhaust angles

[url=https://datazap.me/u/secho/loguju-vacky-abych-zjistil-intake-failure?log=0&data=10-11-42-43-44&mark=1384-8114]https://datazap.me/u/secho/loguju-vacky-abych-zjistil-intake-failure?log=0&data=10-11-42-43-44&mark=1384-8114

Thanks for any advice.

Jan

so these are stock cams?

Yes, stock cams, stock valve springs.

make sure you are getting good oil pressure to the solenoid ,then i would into the Solenoid Duty cycle if you can log that.

I think it's important to start with what possibly could be different. Oil pressure and oil grade seem to have quite a big effect on the VVT control in the FA20 so I'd be checking this first. Next I'd be checking the duty cycle the solenoids are reporting as it looks like the cams are never able to reach target. If the cam can't hit target and the duty is maxed then I'd be suspicious of a blockage preventing good oil flow to the cams.

Just to update the thread.. After all analytics of live data and trying basic stuff like change oil grade, measuring oil pressure etc. I decided to disassemble the engine to check all the oil paths. Everything seemed so I changed cam sprockets (expensive stuff). Now all the cam angles are ok and responses to cam timing are seamless.

Cam sprockets became clogged by residues after rod bearing failure.