new topend rebuild E-heads timing map?
 

i have just rebuildt the topend with E-heads rollercam intake etc.

Specs:
455 (469) 0-deck
Edelbrock/butler 310+ cfm CR 10.3:1
Custom comp cam 230/236 @0.50 with 0.510/ 0.520 lift
Hurricane singleplane intake.

I need to change my snipers timingmap since i now have 36 degrees at 90-100 KPA

i quiclky edited a timingtable i "think" migth work below.
But any input and real life experience with similar combos will be greatly apreciated.
https://i.postimg.cc/VsVchb3x/32-all-in-by-3100.jpg

This is a good starting point. You might be able to play with adding a degree or two of timing up around 4500-5000 rpm. I ramp 1 degree of additional timing from 3000-6000 on my setup and it helped to extend the power-band on my setup.

461, KRE 260, 232/238 112+4

Edit. I think your low load advance at timing might light a bit more as well. Your setup should be able to idle down around 700-750 rpm. 18 degrees is a good starting point, but try going a bit further, it might like 20-22. I run mine at 24 where it made best vacuum.

Thank you! i am running rigth around 24 myself with 6x heads, i was guessing the edelbrock heads needed less timing because of the new and improved heart shaped combustion chamber.

For the most part that is true, but pertains more to high load situations. At idle when load is quite low, the charge is inefficient and extra lead will help idle quality, and burn efficiency by increasing cylinder pressure. Result is you get a cooler combustion chamber and more vacuum.

Road tuning is experimentation though. For your idle tuning, set your readout on your hand held to monitor vacuum. You usually have to go back and forth a bit on fuel and spark, but work on both incrementally, one at a time and move in the direction of best vacuum. Start with fuel, and if a point or two leaner increases vacuum, move to timing, if a degree or two increases vacuum, move back to fuel. Keep going until you either plateau or reduce vacuum, then move back to your last adjustment level. Same thing you'd do with the carb rods and jets, except now you get to do it without leaving your drivers seat!

So i have a few short trips under my belt with the new setup. it is working good for the most part, but the engine have a tendency to die when coming to a stop, especially when braking hard or shutting the throttle suddenly. it never did this with cast iron heads and the performer.

i can see AFR go high into the 17-20 area for a split second, then go back to normal in this time frame if i do not press the throttle to let air in it can die, somethimes it recovers.
IT has a tendency to die out when the engine is not up to temprature and in open loop mode, in closed loop it has a tendency to save it, but just barley.

I have not done a thing to the fuel map, i figued self learing would take care of it, but i have limited self learning to 20% in areas below 75 KPA. just incase my O2 sensor should fail for some reason. I can see the sniper is correcting with up to 12 % extra fuel , i will transfer to basemap soon.

My thinking is that i migth need to tweak IAC setting , maybe hold time and wait time?

From the way you explain it, likely yes, how the IAC transitions could do that. Datalogs are helpful here

It sounds like the base fuel tables just need more dialing in, if you haven't transferred learn to base yet. 12% extra fuel correction is pretty big.

More drive time and transferring learn to base along with some table smoothing should make things better. Plus or minus 5% is usually acceptable but with patients 1 or 2% is obtainable.

Keeping in mind that the learn table is only learning off the commanded AFR values you put in. So if the engine doesn't like the values entered it may never be completely happy. It's a game of cat and mouse with some experimentation.

The lean spike you are seeing is a decel fuel cut. You can turn that off if you'd like, but in general I prefer to have it turned on. In that case you would need to look at your fuel return settings. The sniper needs to do two things after it cuts fuel on decel. It first needs to re-wet the intake walls and then provide relative fueling for the given rpm. This is controlled by several factors that include tps, rpm, MAP and then your calibration settings for fuel return.

The first thing I would look at here is where your decel fuel cut enables and when it disables. These will be MAP values and likely why you are seeing the change now. The new heads are wildly more efficient than your previous heads, your MAP values will show that, typically with lower Kpa.

You want your decel fuel enable MAP to be set so that at cruise with light off throttle (such as slowing for traffic) it doesn't enable. You want it to turn on during actual deceleration events like coming to a stop light. Typically this will mean lowering the setting. Then you may need to again adjust when the decel fuel cut disables and begins to reinstate fuel, you likely want that to happen earlier.

Scott makes a good point about your IAC as well. With the top end change, you're going to need to change quite a bit on the system from the previous fuel map. That will mean resetting your IAC. In fact if your system had quite a bit of long term learn on it from your iron head setup, my recommendation would be to clear the learn and start from ground zero.

Clear the learn and startup the car and let it idle from cold to normal operating temperature, usually about 10 minutes or so.
Reset your IAC per the Sniper instructions, typically 3-10 counts at warm idle is where you want to be.
Take the car for a drive between 5-10 miles with only mild throttle inputs, then bring it back and park it for a bit, don't let it cool completely.
Restart the car and again let it idle until up to operating temperature.
Take another drive, this time a bit longer and try to find some areas with hills where you can start giving it more load, you can use more throttle input here.

That's typically what I've done with my FiTech system any time I've made major changes that required a learn reset. It's worked well for me to get the system up to a more optimal tune as fast as possible.

Just for information purposes, these Snipers come with the base tune and the fuel decel cutoff disabled or turned off.

So unless it's enabled it is not functional with the tunes provided.

I've still not enabled mine, just haven't found a need to explore that area yet. However I still have lean situations when letting off the gas and coasting. Not while coasting, but when I go back to light throttle tip in after a long coast. There is a lean spike. From what you explain that might not be your issue, as mine is plenty fat on coast and returns to idle fine when coming to a stop, it's just throttle tip in after a coast situation. So maybe a little different.

When I have time, I usually do a short datalog of the situation and make small adjustments in the fuel table.

That would help diagnose tremendously exactly what you have going on.

I have not enabled decel fuel cut off, i did transfer learn to base late last nigth, and manually smoothed out sharp peaks and valleys, i now have about +- 3-ish on learn when i did a run today.

it is better and so far the car did recover after shutting the throttle from about 2000 rpm and coming to a stop, it still peaked to about 18 AFR but did recover.

But still stalles if i cold rev it to 2000 rpm and suddenly let go of throttle. But this is not a big deal as i should let the car varm up anyway, and when i am finished tuning the base table with engine warmed up and it still have this problem i'll look into iac settings, but as Formula jones said: it is tuning and smoothing of the base fuel table with the engine fully warmed that is most of the issue i am seeing.

The new intake and head runner area is a lot lager than my performer 6x-8 head combo, pic of my new setup:
https://i.postimg.cc/25wPdYRH/IMG-2547.jpg

I just did not forsee that changing cam, intake and higher flowing cylinder heads would have such an impact on off idle and back to idle transistions.
I guess the airspeed is a lot slower and fuel migth be out of suspension and start running along the intake walls insted of beeing atomized especially when cold.



I tried going online with my laptop, but of course there is a firmware mismatch between local ecu and snipersoftware that did not allow me to sync. i'll update it later on, i got the wind knocked out of me when i saw that my newly installed bop 2 pice viton seal is leaking :(

Yeah, if i can not get it up and running better that is a good suggestion, the self learning is really fast, and i migth get a better result faster anyway.

But the car idles awsome and iac is on point it is just the transitions. current idle and iac settings; https://www.youtube.com/watch?v=nAsGlLP9hjU