Thread: Timing drift: Aem ems vvl n/a + 20v coils + 24-1 disk

AEM EMS v1
SR20VE N/A
VE Distributor as CAS w/24-1 DISK
20V COILS
Crank/Cam Rising Edge (On Falling it doesn't start)
Fuel Teeth 24 / Ign Teeth 24 / 3 Teeth / 50ms
Ign Sync 21.17 / Pick up Comp 260uSec / Ign Tooth 0, 18, 6, 12 / Inj Teeth 12, 6, 18, 0

The car runs good and all but when checking timing the pulley shows some timing drift above 5000 rpm in set ignition lock timing mode, the logs also show some timing oscillations in high rpm, about 0.5-1.0 degree.

Tried different Pick Up Delay Comp settings from 0 to Max setting, at least 50uSec intervals, best is 260 uSec, but still shows this.

Before on VE Distributor with its stock CAS Disc it never show any timing drift.

Any ideas besides playing with Pick up Delay Compensation???

Does AEM use the inner and outer parts of the wheel ??? The 90deg and the 1deg outer or only the inner ???

I really am not sure

Rising or falling is up to you... either are possible... You'll just have to change your sync value to have the correct timing again if you change it.

To keep it from drifting you'll have to change your pickup delay comp, until it gets better. Start at 0 if you like.

.......

EDIT
Oh see you already tried that.

Try logging your sensors and make sure its not a bad signal.
@coach & @BenFenner

would know more.

The AEM uses both inner and outer triggers. However, he swapped the stock 360+4 CAS disc (or however many it has) to the 24+1 CAS disc as recommended by AEM. And AEM still uses both on that disc.

As for correcting the timing drift, the Pickup Delay Compensation is the designated control for that. You've already worked with that, so I'm sort of out of ideas as well.

Are you sure your timing light is known good over 5k rpm? It's possible that chain slop is causing the issue. Although not likely since you say this is a new development?

Let me take a look at my calibration and verify your other settings.

This is with AEM installed? Same timing light?

Chain slop is an interesting idea, the tensioner is not new... I should try that. It really scares me that this may be it, revving to 8500...

Tried two timing lights, both I used before to check timing drift when on distributor and Nissan Stock Disk, no timing drift at all above 5K, so it should not be that.

Settings, maybe I should also try using falling edge and adjusting ign sync to match to see if it makes any difference?

And the #4 Coil is connected to the #5 coil output.

What about switching to a crank trigger with mag pickup and use cam only for TDC reset? High RPM motors I think should have more accurate crank wheels.. Chains may not be too bad but I heard RBs going off like 6deg

BTW how much drift are you seeing and at what RPM?


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^One year ago mr....