spark advance

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outtamymind
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spark advance

Post by outtamymind »

question for you guys. what is the spark advance supposed to be for a 3400 motor? currently i am helping my room mate Banzai with his car and its a 3400 bottom end with a 3500 top end and cams. finally got the data logging to actually log and found that the spark advance is ranging from -20* to -30*

this seems a little off to me. but maybe you guys can shed some light.


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3X00-Modified
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Re: spark advance

Post by 3X00-Modified »

That is right... I push 28* of advance at WOT... It will vary for RPM and load and engine design... If you want a 3500 file to look at the spark table I can send you the xls of the table. I use that as a baseline to start with on most of my hybrid tunes that I've been doing since the spark map fits the combustion chamber design and also with the lower compression you shouldn't have any issues with it being too much timing. Boosting on top of it is a completely different story though, you will have to pull timing and probably want to be in the low 20's at WOT full load.

Ignore the - symbol in front of it too if that's throwing you off... I don't know why that's there. Except my wife did throw me a good explanation as to possibly why... It's 28 degrees before top dead of the piston so technically it is -28 before the piston is all the way up...


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Barry
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Re: spark advance

Post by Barry »

I madder out at 22 I think on my 3500. Without a knock sensor. I never pushed it any further because I couldn't monitor my knock but 93 octane at 22 advance was safe for me


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Re: spark advance

Post by outtamymind »

Thanks guys. I'm trying to pinpoint the cause of the misfires. I got some data logging from a run we did yesterday but I can't post it yet.


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Re: spark advance

Post by banzai92gt »

interesting...

some of the numbers from the logs seem a bit off, but at WOT they change drastically..


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outtamymind
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Re: spark advance

Post by outtamymind »

ya....and i don't think its the cam's or the tune at the moment just because if it was the cam's it would be misfiring on more then 1 cylinder and if it was the current stock tune it would be misfiring on more then 1 cylinder. i just don't want to throw parts at it aimlessly. and the fact that it increases in misfires then drops back to no misfires and repeats is kinda weird as well.


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Re: spark advance

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outtamymind
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Re: spark advance

Post by outtamymind »

thanks buddy for posting that :)


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Re: spark advance

Post by 3X00-Modified »

as in the other thread.. 3 and 6 share the same coil and both are showing misfires... Ohm check the coil top posts and compare to another one. I bet its bad.


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Re: spark advance

Post by outtamymind »

Never thought of doing that. I'm checking on the price for a new icm at the parts store I used to work at as the last I recall they weren't too expensive at my price


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Re: spark advance

Post by 3X00-Modified »

Two threads going... Lets Keep the diagnostic info in the other thread since this was a question about spark advance.


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Re: spark advance

Post by outtamymind »

well technically its all related but ya i'll keep all the info in the other thread from now on. mods you can close this thread now if you like.


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Re: spark advance

Post by 3X00-Modified »

Not really because some of your timing drop is due to KR at wot... for instance one part at 96map aka wot there is 2degrees of KR and the timing is down from 16 to 14. I'm also guessing the original owner put in a very low timing table due to the boost... IIRC I'm at 13degrees on my subaru but that Combustion chamber is shaped differently so that may not be fair to compare 100%.


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Re: spark advance

Post by banzai92gt »

3X00-Modified wrote:Not really because some of your timing drop is due to KR at wot... for instance one part at 96map aka wot there is 2degrees of KR and the timing is down from 16 to 14. I'm also guessing the original owner put in a very low timing table due to the boost... IIRC I'm at 13degrees on my subaru but that Combustion chamber is shaped differently so that may not be fair to compare 100%.

This is Chris' car, ill ask him what he did in for the timing table.


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Re: spark advance

Post by 3X00-Modified »

I knew who's car it was I just couldn't think of the name at the time. he must have done something but whats really odd is the less than 100 map reading... Are you not going into boost yet?

I found a 103 reading but that still low... unless that is a 1 bar map only.


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