Been looking into tuning the spark timing. The high octaine numbers are the same a low. Got some good fuel in here at last. Been advancing the timing 2 degrees at a time using a VCM control in HP Tuners, when i see knock i pull the timing a little in the table. Think I'm at about 28 degrees of timing at WOT at 4000 RPM, got a little knock there, so will take a little timing off that, also had a little knock at 1600 RPM.

My question is, I havn't seen knock between 2000 and 3600 RPM, shall I just keep increasing timing until I see knock and take a few degrees off. I'm aiming to get about 1 degree of knock at most RPM levels, and then take 3 degrees of the timing to run nice and sweet. But a little cocerened i havn't seen knock between 2000 and 3600 RPM, is something turning of my knock sensors, or havn't I gont far enougth with the timing, at about 34 degrees at WOT @ 2600 RPM. Cant hear any odd noises at this RPM, and its running very well at that RPM range, certainly feel it accelerating dam good. Shall I keep adding timing?

I'm only adding timing above half throttle, as no point playing around in the cruise area since is running fine.

 

there is a definite point of diminished return. depending on your SOTP sensitivity you may be able to feel it on the street. That area of the curve can typically handle some decently steep timing though... the dyno can tell you for sure.

 

Damn! 34* @ 2600RPM? That's a lot more than mine will take. Then again, it's an '02 with a stall. So, I'll never see 2600RPM @ WOT.

 

Thats why I was thinking I must be doing something wrong.
At WOT this is what I currently have.
1600 = 24*
1800 = 30*
2000 = 33*
2200 = 35*
2400 = 36*
2800 = 37*
3200 = 36*
3600 = 34*
4000 = 31*
4400 = 27*
4800 = 28*
5200 = 31*
5600 = 32*
6000 = 32*

With these values I wont see knock at 4400 RPM or at 1600 RPM unless I add 2 degree's, still tuning at the mo, so not final values, will keep on advancing and hope the knock sensors stop me soon, the sensors do work as I have seen plenty of knock when on the lower octane fuel.

Does this timing look wrong? The car is running very good, so I dont think I'm doing wrong, just need some re-assurance.

What does anyone else have?

 

Get on a dyno and see what makes power. Those low end values are a hell of a lot higher then I would think they should be at. More timing doesnt mean more power. You just need the correct timing for the best burn, can be 10* or 35*, best and fastest way is to get on the dyno.

 

if you want the poor mans results you can just take it to teh street..and watch AFR..do a run.... increase spark..change nothing else..if it leans out..then you keep adding more....
when it stops leaning out...you have gone too far...
basically when you get to teh point where it burns no more then you have gone as far as you can...if it doesnt change or goes richer than you have gone too far

 

The Dyno is the only way to find your optimum timing.

 

no its not...but it is the easiest too to use to find your optimal timing
and you still have to know what you are looking at to understand if its optimal or not

 

If anything my increase in timing at the lower rev's, 2000-3000rpm it has decreased my AFR from 12.5 to 12.0. In all I have probably added 6* of timing in that range. So would that mean I have gone too far as it's not leaning out like 'Soundengineer' said. I was going to keep increasing till saw knock, then back of 3 degrees, would this method be incorrect? I guess everyone has their views on spark tuning, I'm just trying to get some ideas and try them out.

I wouldn't mind giving it a go on a dyno, and getting some of their advice, it would be good to get some proper figures but I havn't really got access to a dyno, however I do a lot of my tuning on the road, and has worked well so far. Perhaps I ought to learn a bit more about the internals of an engine before I understand the spark timing.

 

Yes it is, and the way Scott explains it is one of the ways I get it done on the street. It has worked well on the cars I have done so far.

 

Is there a write up somewhere with guide lines on spark tuning.

My mid range stuff feels okay, good throttle response etc..

I just want to get the most power out of WOT I can. So does that mean shouldn't be looking for knock, but rather changes in AFR?

 

Generally, the more airflow and leaner the car gets, it means its sucking in more air and using the fuel more efficently. This will make more power. There is really no write up on it, you just have to learn over time how to look at it. With those basics though, it shoudl be easy to start on.

 

What I'll do tonight is a few WOT runs on the same bit of freeway.

Start with WOT timing simular to stock high octane.

I'll be in 4th gear, at 50mph, go WOT till 120mph. logging AFR
slow down, increase the timing using the HP tuners VCM controls, increse by 2 degrees. Do another pull the same as before, slow down and add 2 more degrees. Do the same again and again util about 8 degrees higher than stock. Checking for knock and looking at what timing gave the leanest AFR. Lock that timing into the VCM and perhaps looking at fine tuning to 1 degree. Then adjust my AFR to desired AFR knowing my spark is at optimum timing.

Reasons for pulling in 4th as its a nice long gear, 5th would be better but with police being about its easier to slow down from 120mph than 160mph.

Thinks for the info everyone, it does make sence that if its starting to go leaner then it must be buring better.

 

just make sure you give yourelf a little bit between pulls for the ECT to stabilize after hamering on it

and start doing it with about 12.5 AFR so you you can stave off any knock that might happen from leaner AFR's