timing advance
 

i have been told, that the timing can be advanced 8 degrees more than the stock 20 degrees, using the subaru select moniter. i have called two subaru mechanics, and one svx expert at SOA , plus a teacher of mechanics at a subaru training center, but none of them know how. can anyone here advise me?

thank's

I know, I know!!
 

It involves a rain dance and sacrificing a chicken on top of the intake manifold.


I know the exact procedure, but if I told you I'd have to kill you, as it is top secret voodoo.








Haha j/k... I have no idea. LOL

Wouldn't timing advance involve physically altering the angle of the camshaft without changing the angle of the crankshaft? Isn't that what adjustable cams are for. Now, spark/ignition advance would be computer controlled. Am I right? Hey, ob_au....what's the deal with this?

He's referring to the ignition timing. It's totally controlled by the ECU, as the car has distributorless electronic ignition.

Yes,But ,the ECU controls ignition firing or timing along with injector firing based on crank/cam sensor inputs so maybe you could modify or advance the sensor or trigger wheel. Tried this on a friends LHS chrysler for the hell of it and it wont even start,Scanner shows cam synch error and will not fire ignition. All depends on the program and tolerances I guess. Seems I read somewhere that advancing the cams on this engine disturbs the combustion efficiency or for lack of a better word,Factory engineered tuned runner volume that was a design characteristic of the Long intake and small ehxaust .Maybe someone with more technical knowledge could chime in !

SVX's have 10.5:1 compression. Why would you possibly want to advance your timing more? You can barely run the car on premium as it is. Furthermore...........subaru computers are for lack of a better term "bad ass." They actively seek knock. Subaru computers continuously monitor the knock sensor and advance the timing up until the knock sensor gets the first hints of knock. So don't worry, our cars are already running with their timing advanced all the way to the edge, there's nothing left to be gotten there.

I used to advance the timing on the little red wagon up to 24btdc - stock was also 20. It required premium but did not knock even at 24 and it was defninitely more powerful - evidenced by a great increase in top speed.
The local suby tech - before he was evicted- told me he had his legacy sedan "altered" using only the select monitor to be way faster than the svx. He said there is a ton of potential in the engine that is untapped. If only we had a curious master tech with an svx that could expreiment.

Why not set the ECU up to be able to advance the timing even more - like you said the watchdogs are in there to reign it in if it's to much.

you could get an ignition computer... but that's not just using the select mon

i have no problems running the car on 93, and the ppl in calif run on 91 or lower, so i think that 93 should be fine w/ some advance

and my guess as to what it does with the advancing in conjunction to subaru's knock computer, is right now the ecu will advance it continually until it senses knock, OR it reaches 20 deg advance, whichever comes first, so if you give it an extra 6 degrees to go to sense knock you'll get more power

Actually the 20 degress is the base timing. The ecu then uses a factory created 3d table to determine how much to advance the timing from there according to engine rpm and load. It then advances it a lil more until it senses knock so that it runs on the very edge.

As for reprogramming the base timing in the computer via the select monitor I'd love to hear that that is possible but i highly doubt it. I wouldn't advance the base timing but that would indicate the computer was flashable. That is how it is done on the newer subaru computers; however, subaru has offered a program change for the svx once before and it was installed via an eprom chip (this was to address issues caused by lower octane fuel in i believe 92 and 93 cars). Eprom's were the standard at the time of svx manufacture. It's an Erasable Programable Read Only Memory chip which must be removed, erased with uv light, and then reprogrammed with a programmer in order to change the program (code, constants, table values). I've considered examing the svx ecu to determine the processor so i could look up it's opcodes and what memory configurations it is available in and if there is an assembler/dissambler program available for it but as of yet I haven't done that.

Oh, now that you guys have me thinking about the svx ecu again...........if anyone has a select monitor i'd love to get the chance to use it and log the datastream between it and the ecu. That's by far the easiest way to start labeling program loops and tables even after dissambling the program.

timing advance
 

thanks for the input. on page 3 of section 2.2 of the factory service manual, it says,"ignition timing [BTDC/rpm]:20º ± 8°/610"

OK then, what i understand about this is, up untill detonation, the more advance the better so that the flame has time to burn the air gas mixture and has its maximum pressure at tdc. in comparison to other engines the subarus have a very conservitive timing map. on my 92 , with the newly installed headers, the select moniter shows a timing retard of up to 10 degrees, the timing advance goes up to 50 advance. when i tip in on the throttle, the timing retards, possibly due to the slightly louder exhaust, causing the spaek knock sensors to react.
when the timing retards the engine goes off song, and power drops off as well. i know i can insulate the 2 knock sensors, but that takes away a very good safeguard.

Re: timing advance
 

I don't know about svx's in particular but you could be right about some change you made to the exhaust getting picked up by the knock sensor. I know with chevy rebuilds often forged pistons will trip the factory knock sensor. I don't really know what to do about it.