smoothing spark table

[smslyguy]

i have many peaks in my spark table tune and have tried to smooth it out, but i develop a lot of spark knock then and have to start back at the begining. here is a copy of my tune. The car runs great as is. I really don't want to decrease the spark table on the lower end,but if thats what it takes.

[WeathermanShawn]

I manually smooth.

You have a good point about not smoothing to the point of artificially raising or lowering a spark value, but for me it makes it easier to conceptualize and log when I have it 'smoothed' to some degree.

I prefer the 'distributor-like' Spark Advance curves advocated by member SSpdDmon. He uses the same value of spark after .60 g/cyl. Again, just easier for me to alleviate KR when I only have one spark value to worry about.

[DrkPhx]

Post a log. That's crazy looking. How did you arrive at those values? Is this for the car in your sig which looks like a bolt on car? If so, you really shouldn't have to alter the spark tables that much, unless you have other issues causing the knock.

[joecar]

If you're having knock, see if you can find the reason for it...
- check to see if you're getting oil sucked into the intake manifold (via PCV),
- change spark plugs (how do they look...? pics...?),
- check fuel pressure at rail,
- check for air leaks,
- has the MAF sensor been altered...?

Do yo have any log files...?

Like DrkPhx said, you should be able to run the stock timing tables.

[DrkPhx]

has the MAF sensor been altered...?

ruh-roh

ported and polished m.a.f.

[joecar]

Yes, that's exactly what caught my eye...

[WeathermanShawn]

OP, I went back to a stock MAF prior to my EFILive tuning began. Some people have no trouble with a descreened MAF, but ported and polished might be altering your Airflow velocity through the MAF, and making it difficult to tune.

Since your Spark is determined by your MAF (load)..it might be a vicious cycle.

You should be good to ~450 HP on a stock MAF (maybe more?). That would be my suggestion (stock MAF) if possible. Then you can probably run the Spark Advance you want. That MAF is really sensitive, especially if it has been altered.

Good luck..

[smslyguy]

OP, I went back to a stock MAF prior to my EFILive tuning began. Some people have no trouble with a descreened MAF, but ported and polished might be altering your Airflow velocity through the MAF, and making it difficult to tune.

Since your Spark is determined by your MAF (load)..it might be a vicious cycle.

You should be good to ~450 HP on a stock MAF (maybe more?). That would be my suggestion (stock MAF) if possible. Then you can probably run the Spark Advance you want. That MAF is really sensitive, especially if it has been altered.

Good luck..

Ya, it is a ported and polished m.a.f.. I guess which would stand to reason why i am chasing my tail. very good point.

[smslyguy]

well after finding a used m.a.f. sensor and installing it i am finding that i am running around 13.1-13.5 in p.e. mode. Before is was running around 12.5 afr in p.e. mode. If it were indeed running lean wouldn't the L.T.F.T. be adding fuel in p.e. mode? Why all the sudden changes? Is it cause the new m.a.f. sensor is actually reading acurate unlike the ported and polished one? It never did change the fact about my spark knock though.

[WeathermanShawn]

One would have to see a before and after log. When you are running MAF it calculates the CYLAIR and determines your Spark Advance.

If you have had a wideband reported AFR difference, then obviously you need to recalibrate the MAF. Thats a necessity when changing from any MAF that has been previously calibrated and had an altered airflow (ported and polished). Then you have to determine if the AFR discrepancy is just in PE Mode or also non-PE mode.

You would have to post up your LTFTBENS and see if they are indeed positive prior to entering PE Mode. Theres no way to know without a solid log.

Its possible as you recalibrate the MAF, your spark load will shift to a more favorable load reading..usually less spark. Whether that totally cures your spark knock is hard to say. There are multiple factors. But in my stock tune vs current I have eliminated all KR. I also used the stock MAF. It just takes time to find the right amount of spark for both part-throttle and WOT. A lot of time there can be a lot of carbon build-up in the cylinders. That effectively lowers your octane rating. It is a more likely cause than a lot of people realize.

You really did not have a choice on the MAF. Chances are you are now reading the correct MAF frequencies. Now you just need to calibrate those frequencies to the AFR you desire.

Good luck..