SA table tuning--am I really getting knock? - Third Generation F-Body Message Boards

troll5501 · 08-09-2009, 07:34 PM

The amount of knowledge in this forum is amazing! But I can't seem to find a good answer for my issue...

I'm in the early stages of tuning with the EBL Flash. I'm trying to work on the SA table but I'm having some trouble. I keep getting a few knock counts around 1800-2200rpm and 70-75kPa. At that same rpm and load I can hear a high-pitched sound/frequency from the engine and I need help understanding if I'm hearing knock/pinging. Or could it be the sounds of the injectors firing rapidly? It's definitely not the "marbles in the can" sound that people use to describe knock. It almost sounds like a very high frequency test tone maybe 10-15KHz. When I continue to accelerate it goes away as the engine rpm and load increases.

At first I thought it was knock, but little by little I've reduced the SA values in that area of the table to 10 degrees and I still get the same sound and several knock counts. I've tried several SA tables from the included EBL bins and also created by own with a nice smooth curve maxing out at only 30 at 3600rpm/20kPa and around 20 at 3600rpm/100kPa.

Engine is a 383 with Dart Iron Eagle S/S heads and a Comp X4260HR Cam (210/214, .474/.474, 111*).

I'd really appreciate any suggestions on what this noise is and what SA table would be a good starting point for this engine. Thanks!!

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Drumer919 · 08-09-2009, 08:08 PM

I have heard coils make a noise while testing them that I would describe about the same but I really dont think the KS would pick it up. Can you re-produce the problem free revving it or only while driving?

troll5501 · 08-10-2009, 12:15 PM

Interesting...I never thought about the noise coming from the coil. I have an MSD 6AL so if it's indeed coil noise then the MSD may be making it worse. Maybe I'll bypass the MSD to see if the noise is reduced.

As for the knock, what exactly does it sound like? I don't want to risk engine damage while tuning so I'm trying to use conservative SA values, but I'd like to know what I should be listening for. It seems like what I'm hearing is probably not knock.

Also, I found some threads mentioning about using a different knock sensor module when switching to roller rockers. Since that's what I have, should I get something like an LT4 module? I'm using the stock module from my 350 TBI (1990 truck). I don't know if the LT4 is the same type of module so I don't know if there are any replacements that I can use.

Drumer919 · 08-10-2009, 12:33 PM

I have a MSD 8220 coil and digital 6+ and if I take the coil wire off the disty and put it somewhere it will spark then do the MSD test procedure to fire it it will make the noise. Maybe give that a try?

Knocking sounds like just that, a knock coming from inside the engine, a real knock is un-mistakable (atleast to me). I got a good way to describe it- imagine your swimming and you have a rock in each hand and you hit them together underwater, know what noise I'm talking about?

I suppose your from Deleware state, not the city here in Ohio?

troll5501 · 09-16-2009, 04:22 PM

I think the high-pitched noise I'm hearing is probably the coil or the injectors, and I don't think it's related to knock. But I believe my knock counts were coming from exhaust rattle.

The other day when leaving work I got huge knock counts (much more than usual) when I accelerated onto the highway. Later, I stopped at a light and noticed a cloud of smoke around the vehicle. I pulled over and nothing looked or sounded unusual. So I continued on and eventually noticed that the exhaust noise was gone! It's been a few days and it's still quiet and my knock counts have dropped significantly. There are still a few but EGR is disabled for tuning so it's probably expected.

Is it possible that something was loose in the catalytic converter and it broke free causing the smoke and eliminating the rattle and knock counts? I can't figure out what else could have happened but having something fix itself is nice for a change...

Also wondering if I should pull the converter to check it or replace it but it's only 3 years old.

Ronny · 09-17-2009, 12:08 PM

I believe the best way to determine if K is real is add a 50/50 blend of 93 octane and racing gas. It is available near me at pump. I will be doing that test soon as I reduced my SA at rpm/map area quite a bit and still KC appears.

whitelightnin92 · 09-17-2009, 10:26 PM

what part of delaware you from? im from greenwood

troll5501 · 09-17-2009, 10:38 PM

Quote:

Originally Posted by whitelightnin92

what part of delaware you from? im from greenwood

Just outside of Newark. Hadn't heard of Greenwood but it looks like you're not too far from the DE beaches!

troll5501 · 09-17-2009, 10:50 PM

Quote:

Originally Posted by Ronny

I believe the best way to determine if K is real is add a 50/50 blend of 93 octane and racing gas. It is available near me at pump. I will be doing that test soon as I reduced my SA at rpm/map area quite a bit and still KC appears.

I'm still playing the "reduce the timing in the SA table" game, but I'm starting over as my previous numbers were probably skewed by the rattling exhaust.

But it's looking like I'm going to end up with a similar odd-looking curve this time, with less timing in the 2000-2400 RPM range above 60kPa than at 1400-1800. Based on some other posts, I guess maybe it's related to the power band of the cam and not necessarily a bad thing. One of the sample EBL BINs (EBL_F_0023) has a similar graph.

And I'm not sure when I should re-enable the EGR (disabled it for VE learn)...should I try to get the SA table ironed out first?

whitelightnin92 · 09-17-2009, 10:55 PM

i have noticed that at lower rpms at high load with the tcc locked i get occasional knock, but unlocked its fine. i think it could be a situation where the motor just doesnt have enough power for the task.

whitelightnin92 · 09-17-2009, 10:57 PM

Quote:

Originally Posted by troll5501

Just outside of Newark. Hadn't heard of Greenwood but it looks like you're not too far from the DE beaches!

ah your a little too far north for me.

. about 15-40 min from the beach, depending where i go