vetteboy86

I have had some drive ability issues that I am trying to work out. Please see this thread for that info:

https://www.thirdgen.org/forums/tpi/...miss-need.html

I am looking into moving my timing a few degrees to see if there is any change. In tunerpro with the 32 xdf definition, my spark advance table goes from 400 rpm to 4800 and load from 32 to 208. I think there should be more to the table both for rpm and for load variable. Am I correct. If not what happens for values higher than whats in the table?

RBob

iTrader: (1)

Whenever the end of any table is met, the last row or column is used. So at any RPM > 4800 RPM the 4800 RPM row is used.

Same for the beginning of a table. First row/column is used.

I would remove (electrically) the MSD and see what happens.

RBob.

vetteboy86

Thank you for the reply and the suggestion. I will try and see if anything changes.Also I pretty sure I know the answer to this but I want ask before I screw anything up. In tuner pro my base timing is set at 6, because that is where I set the ignition timing. If I move the ignition timing forward or backwards a degree without changing it in tuner pro, that will have added or subtracted a degree over the whole table?

RBob

iTrader: (1)

By moving the distributor (without BIN changes) the timing across the board will follow. With the BIN at 6 BTDC, setting the distributor to 8 BTDC adds 2 degrees across the board.

Same affect if the distributor is set to 4 BTDC. Removes 2 degrees across the board.

The BIN value has the opposite affect. As it subtracts the BTDC SA value, it will remove 2 degrees if set to 8 (with distributor at 6).

RBob.

vetteboy86

Thanks, I never thought of the results by changing the bin value.

RBob

iTrader: (1)

I figured to mention it as it is easier to make global SA changes. This comes in hndy. However, the tuner needs to keep this change in mind.

RBob.

pandin

Also remember that more then just one table affects the Spark Adv, COOLANT ADVANCE CORRECTION vs LOAD VAL vs Coolant Temp,

HIGHWAY MODE SPARK CONTROL ADVANCE vs LD8 LOAD, and START UP SPARK ADVANCE vs COOLANT TEMP,to name a few.

vetteboy86

Yes, thanks I will keep that in mind. What I would like to do is lower the total advance by a few degrees. It may be easier to hand edit these few values rather than change it globally.

pandin

I usually monitor the spark retard and pull a little timing at the rpm & load were it just starts or a little before. Then retest, the knock heats the cylinder and causes more knock. The ramp back in is slow so the retarded spark will last after the conditions have left, and start before the knock sensor can detect. A good place to run spark adv is the least it takes to get r done, more only heats the oil and bearings. (You are squeezing a hot burning mixture on the way up, it needs to burn on the way down for good power).

vetteboy86

Well, thats where I am not sure spark knock is my problem. I am not getting any retard but right when I romp the gas, then through the pull as the RPM's go up, knock retard goes down. I am going to try to post the graph from datamaster.

All I can tell is that at WOT, the knock retard is still a few degrees, and it feels as if I am hitting a wall. It does however seem unaffected while knock retard is at its greatest amount. Hopefully I can post the graph in a few minutes.

vetteboy86

This is a shot of the graph from datamaster. You can see that as soon as I nail the pedal, knock retard jumps to 6 deg. There is a setting in my bin that has this. I didn't do this, as I think it may be leftover from the tune I paid for.

However you will notice that throughout the increase in RPM's knock retard slowly decreases, but still doesn't decrease totally until after the WOT run.

gta324

What are your load values at higher rpm's? It looks like its sinking with rpm? (=restriction on intake side maybe?)

You may need more AE and/or less timing.

/N.

vetteboy86

Yes, you are absolutely correct. I never noticed that before, I don't know how I missed it. Attached is exported data from that picture, and it is easy to see the data.

What exactly could cause this?

vetteboy86

I have done some research and found that LV8 is air flow/RPM. I did see somewhere that replaced RPM with TPS position. Okay, so here is a graph, and the data from that graph. Air flow doesn't really go down, but doesn't increase as steady as RPM does.

So am I know seeing issues other then at WOT? I don't notice any conditions other then at the top of the RPM curve.

vetteboy86

Okay, this is where my inexperience shows. I am seeing a lean spike on the wide band as soon as I jump on the throttle. At that point I am basically wide open throttle, so is that still AE. From reading AE is mainly to lean or richen during driving conditions not WOT. Is this correct?

Also, I am looking at a table called Fuel PW vs. Load. I notice that there is values for PW, and I am getting very close to those values for the specified load, however my duty cycle isn't more than 50%. What happens if PW reaches this value, but Duty cycle is low like this?

pandin

AE is Acceleration Enrichment, this is used to increase the fuel to cover the rpm "bog" when the throttle is suddenly mashed. One adjustment (Acceleration Enrichment Factor % BPW Injector and Acceleration Enrichment Factor vs Change in LV8) tables are the amounts , the other (Acceleration Enrichment Decay Factor vs Coolant Temp) table is time (how long).

In a Carburetor this is the Accelerator pump, Holly made a "Double Pumper" with 2 large pumps, to squirt fuel down the throttle bores, on engines with "Big" Cams and Carbs.

It depends on this setting "Air Fuel Optional Word 3 - Bit 6 - Calculate Base Injector Pulse". If set the ECM/Eprom bin calculates the fuel, unset it uses the fuel tables.

BUA Bin (1986)

;----------------------------------------

Duty cycle is a direct result of the IBPW (Injector Base Pulse Width), so nothing will happen.

My guess is you are running set (IBPW Calculated). In this mode the tables are not used, in fact in the $6E bins (1989) they were eliminated, to free up space for other functions.

vetteboy86

Thanks, for that information. So would you recommend using the tables, or allowing these to be calculated? If they are calculated what influences this calculation that can be manipulated to achieve different pulse widths.

RBob

iTrader: (1)

Highly recommended that you start with a stock BIN. May also consider jumping to $6E, which was used in '89. Much better code then the $32 stuff.

As you mentioned some of the oddities that you are seeing may be left over from another tuners tune. That doesn't help which why we recommend starting with a stock calibration.

RBob.

vetteboy86

First of all thanks to everyone for the help and info.I thought about switching to a stock 6E bin a while ago. With this added encouragement I think I will. My motor isn't stock, so is there anything I should change out of the gate like injector size?thanks again!

RBob

iTrader: (1)

Injector size. Then if you have a bunch of work in the SA tables, can copy those over. May need to change the fan NO/NC settings. But those are easy enough to try as is and then change them if incorrect. And don't forget about VATs if the '86 doesn't have it.

If starting with ARAP definately need to back the SA timing down. Will also want to change the DRP's vs. cranking fuel pulse. Otherwise it will crank a bit before providing fuel pulses.

Another up side to $6E is lean cruise mode.

RBob.

vetteboy86

That is where I wil start.Thanks.