Timing "bouncing"

[Javi802]

I have a 98 s13 blacktop (j4 ecu) stock, 8psi off waste gate

cxracing fmic

isis fuel pump

aeromotive afpr set to 36-38 psi at idle

ngk bkr7e (gapped to about .31)

Anyways, I've noticed that with my consult hooked up that my timing is doing some weird stuff...

Upon start up it will idle at 15btdc and fluctuate between 15,9 and 7... When i say fluctuate i mean it will switch between those values in a blink of an eye. Which is all well being as I've read that is normal...

BUT, sometimes it will stick at 7btdc and jump to 9btdc and stay between those two values, UNLESS i tap the throttle... Then it will go back up to 15 and fluctuate as normal...

When fully warmed up though it will then be jumping from 15 to 17 and if i give it a quick rev (up to about 1500 rpm) timing will advance to the 30's, but when letting off the throttle it will settle to 0 for an instant and then jump to 19-21 for a second and the settle back to 15, where it then fluctuates between 15-17.... or 15,9 and 7

What would cause this? Ive read and found no other threads with people mentioning this.
Ive also set my timing using conzult.

Car was idling at 850-900
put it in timing mode via conzult, idle dropped to 650-700
adjusted iacv screw until idle jumped up to 850 (screw was all the way in before adjusting..?)

checked timing with timing light and the crank pulley appeared to be lining up with the 15btdc mark.

shut car off

took it out of timing mode

started car back up

put it into timing mode again to see if base idle changed and it did not

[rwtf]

who cares?

[Kingtal0n]

its normal. the ecu (the factory program) is smarter than us. If we are smart we would tune our engines the same way. locking idle timing at 15 is not proper manners.

:D

Also, it is healthy and desirable to care. God forbid anybody tries to learn more about their engine or passion. Ignore the sheep that just drive/do without thinking about why.

[Javi802]

Thanks King.

And Yes, i DO care... As I've put too much money in to my car to not. That along with the fact that i want to learn why the engine does what its doing and whether or not its doing what it should be doing..


That said, about 10 minutes ago i hooked the computer back up and i guess at a cold start is when the timing at idle jumps down.

it'll start out at 15, but then retard to 5,7 and 9. And stay within those values.. Unless i tap the throttle, then it goes back up to the 15 range

[Nikzilla]

It's natural when idling. It bounces the timing up and down to maintain a stable idle. The reason it defaults to 15 when you tap it is it's because it's no longer fighting to keep a stable idle. Also you got it wrong. Going to 30 from 15 is retarding timing not advancing. You have to remember that that is -15 and -30 degrees or 15 and 30 degrees BTDC (before top dead center).

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[aga]

i dont know about stock ecu's but the power fc as soon as the car is warmed up keeps the ignition stable at 15. i had problems recently with ignition advance, turned out to be a bad CAS....