JPrevost

I'd like to know exactly how some of you go about your open loop tuning for a new setup.
I tried it a little but just am not confident enough to go full out open loop for extended periods of time.
I already know a wideband is the tool of all tools.
What I'm looking for is somebody's routine. I like trying different routines to see if I can save time somewhere and not have to backtrack on a table and re-tune it over and over and over.
What I've done; Start up car cold, let it warm up and get a stable cts. From there I watch the IAT to make certain it's faily stable (summer is usually fairly stable). Then I tuned the fuel ruff all trying to get 13.8 across up to 80kpa, anything higher is richer to failsafe. After I get as much data possible I go back and check the IAT fuel. If it's good I leave it and just focus on the VE table. I haven't gotten the chance/time/money for gas to just go tuning like crazy so I've taimed my SA vs cts table down to only adding a couple degrees at freezing temps and below. Even the TCC lockup SA table vs vacuum is zeroed out (no knock counts yet when lockup).
Does everybody start like I do or is there something I'm missing? What about IAT vs SA?
Do you just datalog on a common "route" and watch the map, tps, SA, AFR, rpm, mph to see how much SA you can get? I know Grumpy watchs oil pressure also but I have no way of doing that, not even oil temps (yet). I've got an EGT but I'm forcing myself to tune without it so I can become a better all-around tuner. I do the basic stuff and do a LOT of my work through driver feedback with back to back runs. I guess I just want to give the owner the best drivability and not necessarily the violent hp monster.... is this making sence or have I been drinking too much?
If there is a topic already talking about open loop I'd like to see it, I just find looking at ALL of those values overwhelming to say the least.
My guess is that open loop tuners like Grumpy have a way of watching their TPS so when they run there route they have the ability to get back to back comparisons for tuning SA.
Here's my question, do you do the TPS vs MAP to tune SA first or do you tune the VE table to get an AFR that shows the lowest MAP given a constant TPS?

RBob

iTrader: (1)

Check out this thread:

https://www.thirdgen.org/techbb2/sho...hreadid=250949

Has a decent disussion on open loop.

As for starting out on a new engine. The basic approach I take is:

Create a SA table(s) that is conservative but also from experience should be decent. If not sure of what to use create a main SA table that resembles a centrifugal distributor advance with a little vacuum advance thrown in.

This can be tricky as too little SA can be just as bad as too much SA. Both experience and checking other GM bins can be helpful. Two examples of GM bins are using teh iron headed LT1 tables with Vortec heads. And on a LG4 305 using the original SA tables from the CCC ECM, not the LO3 tables(!).

Enable closed loop, warm up engine and if driveable, drive the car while data logging. If not driveable make corrections until it is.

Using BLM data make corrections to the VE table(s). Continue the drive, data log, correct VE tables until only minor corrections are being made.

(during this time look for knock, cold run problems, crank to run flair, etc., correct as required. Don't go overboard on these corrections as they will probably change as the VE table is changed).

During the closed loop sessions ease into the throttle a few times as a check of injector DC and fueling. Adjust fuel pressure, injector size, injector/BP constants as required. At this point you need to be sure that there is enough fuel available for WOT.

There isn't much sense in going further if major changes are required now.

At this point disable closed loop. Set the closed loop enable temperature as high as possible.

Using a WB log the ALDL data along with the WB data. During open loop the commanded AFR will vary as the load varies (coolant also but we are doing all of this tuning while at normal operating temperatures).

Correct the VE table to have the commanded AFR match the WB reported AFR. Again, while going WOT ease into it. Back off if the engine doesn't sound right or is missing. Double check the logs for injector DC and proper AFR.

Continue the repetitive drive, data log, correct VE until the commanded AFR matches the WB AFR.

During this time AE, DE, crank to run flair, along with any other anomalies can be worked out. Changes in cold start AFR's, crank PW's, mid-temperature stuttering can be worked on.

Once the commanded AFR matches the WB AFR, changes to the commanded AFR will change the actual AFR accordingly.

RBob.

JPrevost

It's hard to just put in a centrifugal distributor advance curve because the manifold pressure isn't measured the same. On a mechanical vac advance dizzy the idle vacuum isn't seen so there isn't any advance, but in our MAP tables we have an area for the idle that is also shared with deceleration (low speed high gear). It's kind of odd, I did the math. For me, the best starting point was the Lt1 main SA map, I had to add 4 to 6 degrees of timing at idle and from 1200rpm to 2400rpm, 2 degrees at high load. The table was then flattened out a bit and I've just now started removing timing at the <30kpa range to aid in decel, very cool stuff and in closed loop is working extreamely well.

Grumpy

I have that Scanmaster thingy on the dash.
It displays a single ALDL item at a time.

20d idle at timing.
~35 at cruise
WOT timing, 18d turbo, 28d N/A SBC.
VE idle entries of ~80, and at 100 K/Pa 230s.
If I have a VEII table then I work that out for maintaining a constant PW at WOT. And only mess with that when I'm almost done. I prefer to risk too rich at WOT, then lean.

I can start with either fuel or timing, and just work back and forth. Its a balance of both, that gets the car right. After a few chips, the ecm bench gets a work out. Then back to the car.

How much time it takes is about what you consider close enough. If your going for correct, then it takes alot of time.

And if no WB the LOTS and LOTS, and LOTS of plug reading.

JPrevost

That's what I was thought.