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Discussion Starter #1
How exactly does our ECU controll timing? Im guessing there are set maps based on rpm and load and makes adjustments based on input from the knock sensor; but how does the ECU determine load? Does the kv signal come into play at all?

If anyone could provide a better explanation or links to useful info it would be greatly appreciated.

Thanks.
 

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wastegate hose is pulled
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Ignition timing is the big pink elephant standing in the corner of the room that noone wants to mention. Why? There is no way to monitor it on a stock ecu (shawndude is working on a monitor). There is no piggyback computer that can control it properly (emanage does a bit). All you can do is set the base and hope for the best, unless you want to go with a standalone EMS.

Timing has to be load based. Load is calculated from sensor inputs like the KV, IAT, HAC, TPS and CPS. No one has a clear idea of exactly what the stock ecu is doing with timing. Hopefully Shwandude's idea will come thru in a major way for the community.
 

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2/3 HP to the Paws
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1,519 Posts
Reg Reimer figured out the timing maps, and has been fiddling with them via his techtom chips for some time now.

He's the only one I know of who's really gotten into the guts of timing thus far.
 

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Flying Dutchman Pilot!
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Actually thats not true about no piggy back being able to control timing. I had an Apex ITC on my car and it did a fine job of controlling it. The problem was it opened up a few other problems like the car taking a bunch of cranks to turn over and it would backfire on cranking once in a while. Some times it would take a real long time to start. If you didnt wanna crank the motor forever you could just disconnect the CPS and plug it back in and it would fire right up. Once the car was running though it did exactly what is was designed to do. I didnt wanna deal with this though so I pulled it.
 

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wastegate hose is pulled
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joliroger4 said:
Actually thats not true about no piggy back being able to control timing. I had an Apex ITC on my car and it did a fine job of controlling it. The problem was it opened up a few other problems like the car taking a bunch of cranks to turn over and it would backfire on cranking once in a while. Some times it would take a real long time to start. If you didnt wanna crank the motor forever you could just disconnect the CPS and plug it back in and it would fire right up. Once the car was running though it did exactly what is was designed to do. I didnt wanna deal with this though so I pulled it.
Ah! I said properly. Extended crank periods don't count as properly in my book. I would have ripped it off of my car too!

If the emanage problems get sorted out, that is great! Techtom, yeah, that is Reg Reimer's monopoly. :(
 

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Flying Dutchman Pilot!
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Yeah I agree, it may control timing, but its a backyard way of doing it and you give up a lot in the process. Same thing with any fuel controller that messes with the AFM signal, you end up increasing the timing when you go leaner. Everything is give and take with piggybacks.
 
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Discussion Starter #7
Since load is based partially on kv, using say a S-AFC to pull out 20% of the kv signal would majorly affect timing, would it not? So if your trying to keep the timing maps as close to stock as possible, it is best to tune the a/f's as close as possible with fuel pressure and fine tune with the S-AFC to leave the kv signal as accurate as possible (with the lex afm :p).

The ECU advances timing with increase in load to a certain point correct? So if you used the S-AFC to ADD fuel as opposed to taking it out, increasing the kv signal tells the ECU there is more load on the engine and it would advace timing.

Im just throwing ideas out here...correct me please if Im talking out of my ass. Im just trying to learn a little more. :D

It will be really interesting to see how Sdude's monitor turns out. It could really answer a lot of questions.
 
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Silver88Turbo, this document will explains how the timing is calculated and adjusted:
http://www.autoshop101.com/forms/h40.pdf

How our ignition works:
http://www.autoshop101.com/forms/h23.pdf

There is more information about it on that site, but you'll have to dig through the various different chapters, even ones that are not directly related to it:http://www.autoshop101.com/autoshop15.html

The timing monitor I'm working on will show us what the timing advance is under different conditions. It will take a lot more thinking and data logging on our part to figure out exactly why, and how to manipulate it, to work for us. :)

The good news is, the circuit will be able to be data logged by units such as e-manage or similar piggy-backs. It can also be made to be a standalone with a display, but this would be difficult to use in real time while driving.
 
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Discussion Starter #9
Wow thanks for the links Shawn. Ill be looking those over tonight.

I cant wait to see the results from the timing monitor.....

Thanks again man.
 
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