running my car at the track and using tunerpro rt to data log I see my timing is showing 27 degrees total. So do I now add in my 6 inital to get 33 or is it only getting the 27. The car ran last time out with a siameesed tpi lower and slp runners 7.8 at 95 in the eigth and now with the hsr I am getting only 8.2 at 90mph. I watched the o2 (I know not the best but all I have right now) and it is 935 most of the way and sees 950 at some points too so alittle rich. I am really baffeled the car has slowed down. I went from it laying over at 6000 to pulling to 6400 now and it is slower. It has cut a 1.60 60 foot wheels up 2 inches and gets flat from there. Not sure if timing curve is the problem or all fuel. I added off the other intake and now not sure if it is flowing much more than the lower I had simassed over 6 inches down the runners. Car is 12 to 1 or so and I put 110 in it to make sure I was safe to play with timing just cant figure where 5 mph has gone. It also says 11to1 afr is that a true reading or what it is trying to get to and how do I get it to try for 12.5 if that is what it wants?

 

The 6 degrees should already be included, so you are only getting 27 Total. If you have more timing programmed in the eprom, then your car may be taking timing out due to "knock retard".

Check you knock retard to see if there is any knock occuring and how much timing it is pulling out.

And, the Narrow Band O2 sensor is completely useless for tuning. You are better off looking at your plugs if you want to tune your engine. Alternatively, go to a dyno that has a Wideband O2 sensor and tune your engine there.

 

all knock is zeroed out. On the table for timing when you put in a figure is that actual or add your base to it to get true number? Like stock bins have 28 or so total so is that it? Seems alittle low even for a stock car. It would make sense that you would add in the base of 6 to get actual but I am not sure and why I am asking it. I also have the pe zeroed out so what I see is it for the main and extended tables easier to keep track of that way. Same with the fuel in the ve table for wot. Just tune it in at 95 and 100 kpa rather than the pe side of it. also easier to keep track of changing things.

 

The timing you see in the Main Spark Table is suppose to be include the Base Timing to derive the Total Spark Advance. However, any spark bias due to the Cold Start, Highway Mode or Power Enrichment will be added to the Main Spark Table to compute the Total Spark Advance. But the Base Timing is included in the Main Spark Table and not added.

For example if your Base Timing is 6* and the Main Spark Table shows 28* at 100 kpa @ 4,000 rpm. Then the Total Spark Advance at 100 kpa @ 4,000 rpm should be 28*. Now if the conditions for Cold Start Bias, Highway Mode or Power Enrichment exist, then these additional values will need to be added to the Main Spark Table to compute the Total Spark Advance.

So, if the conditions for Power Enrichment were met and the P/E Spark Table added 6* @ 4,000 rpm, then your Total Spark Advance should be 34*.

Ditto for the Cold Spark and/or Highway Mode.

 

got it so if I zeroed out the pe tables I am getting the value I have in my tables at wot for 100 kpa. I was recording at the track this past weekend with tunerpro rt and saw 27 during the run and needed to know if that was it or with the base added in making it 33. Well since my pe table is at 0 for wot 27 degrees would explain the fact it was flat up top and why the car lost 4 mph with this tune in it . Hsr now and had a siameesed lower and slp runners. 12.0 at 113 vrs 11.5 at 117 with the old was alittle upsetting. Didnt have recordings from those runs but for some reason when I put it together I was detionating like mad so I just dumped a bunch of timing to get it down the road so need to get back on tuning for the new intake I guess. Time for a wideband to make it easier this time though.
thanks

 

yes if your PE is zero'd out, then your not getting the additional power enchriment spark and that is hurting you. Main table does include the base. If your table reads 28 degrees at WOT 100kPa, then you have 6 degrees base + 22 degrees added for total 28 in the main table.

add more spark to the main table if you would like to keep PE zero'd out, or just put the spark back into the PE tables. either way you should like 34-36 degrees timing at WOT. And try bringing that total timing in sooner like 3200-3400 rpms. it should like that

 

The $8D code (are using $8D?), outputs 2 different SA values in the ALDL stream. You first need to know which one you are looking at. The one value is relative to TDC, is unlimited in advance, and does NOT include knock retard.

The other ALDL SA value is the final SA as programmed into the distributor. It has the initial SA subtracted out and includes all modifications to the SA value (knock, PE, etc.). So if you are using this value the initial needs to be added back in.

RBob.

 

Which may, or may not, already be done in the xdf file.
He needs to look at the conversion math in the xdf he's actually using, methinks.

 

And if the initial is added back in via the .ads file, the user needs to check that it is the same base timing that their engine is set to. It always helps to check the .ADS against the .DS file, and against your calibration.

RBob.

 

All of that to say, that to be SURE, run TPRT at the same time you put a timing light on it, and see if they agree.
Don't feel all alone. Many have been there. ( OK, me anyway )

 

Just to make sure all is correct can I check it with a timing light with the dis left pluged in and at 2400 rpm to check full advance? (2400 is where I bring it all in causes 1.61 60 foot so seems to work) Checking this all started because the car slowed down 5 mph in the 1/4 mile with the hsr over the siameesed lower and slp runners. I saw it was getting 26 to 27 degrees total showing on the tunepro rt program I was using to datalog with. I have been told that using the narrrow band at wot will get you in the ball park for fuel. Needs to show 890 to 920 for max power. Well I had in a new sensor 3 wire heated from a 95 chevy pickup and set up with a relay for the heater. ( improves driveability 10 fold over the single wire when in long tube headers) So I really didnt play with the fuel that much. took alittle out and trying adding and no change that made me keep going in a direction. Well I got the innovative wideband set up and put it on the car yesteday and it was 15.1 when I touched the throttle and climbed to 17.1 at 6400. Ouch!!!! No wonder it slowed down. Really didnt feel all that bad just alittle flat but not enough to say fuel was a huge problem. So those that have heard you can use the narrow to get you in the ballpark DONT DO IT!!!!!!! I have been using it for years and cars ran good and seemed to be right. Wide band is the only way I see now. Actually by the time I got to the pits to check a plug it looked good for those who were going to say should have checked the plugs I did. It runs at 13.0 at idle so I guess the short ride back in made them brownish again. No signs of being super lean other than when I tried to add alittle timing it spark knocked to where I heard it and had to back out of it and abort the run. 32 total and why this all came up about the fact of was I seeing 32 or 38 with the base added in which seemed to make sense at the time. 114 gas with 32 and knock didnt add up unless you add in super lean I guess. Now cant wait to get back in Jan when gainesville opens back up to put a smack down on the 12.0 @114 it ran on a 1.61 60 foot. Wheels up about 2 inches was sweet but 114 wasnt at all especially when it had ran 117 to 118 with my old intake setup. Thanks to those who helped. I have other questions about fuel and am starting a new post for those who want to follow.

 

When I was checking mine, 'cause I didn't know either, I set the laptop on a step ladder next to the vehicle, ran the serial and power to it, and set it to display spark advance. Changed NOTHING on the vehicle, as I wanted to know that it worked as it would normally work, or that it didn't and needed fixed. Ran the ALDL through a 100 foot extension cord, 'cause it was handy. Worked.
Ran the engine to about 4K RPM or so, but without a load. Don't have a chassis dyno at home. ( yet. HA ! )
Turned out that wasn't necessary. If the light agrees at 1K, it'll agree at 6K. ( unless you've got slop in dist drive gear, or that sort of thing )
Also, took a bit of masking tape around the damper, and marked off every ten degrees all the way around. Didn't know for sure what would be needed, so covered it all. Don't have a set-back light, which would have made it harder anyway.
Mine was off by about 10 degrees, which was then traced to the way the XDF and the ADS files had been setup by whoever authored them.
Now, mine work my way, which is pretty much what you want.
Then, when the spark didn't do what I thought it should in the logs, at least I knew it wasn't a log error. BIG help, that !

About 98% of what I know about ECM timing logic, ads files, and xdf files, came from two places.
1. The stuff some guy named Rauscher wrote about. ( thanks, Bob )
2. That hour or so in the garage with a timing light.

 

agreed mine showed near 900mv and i thought that was somewhat rich but it was showing 14.5 to 1 on the chassis dyno with their tailpipe wideband.

 

Just reconfirming this due to major questions concerning my timing and lack of performance or so I think anyway.
Seems I get max power when I'm over 40* which tells me something is not right. I'm in the 46* range when sweeping the bin on the bench and am only seeing 36-38 in my logs running the car with no retard being indicated.
I have very few knocks and am considering going to more spark next time out. I've built up the spark tables over time but have never gotten them where I think they should be. Could just be my tuning values but am still chasing it without a dyno.
I've always seen " DEGREE SA = "Value" * (90 / 256)" for the ADS calc.

So, for the ADS output using the Base in the display(No modifiers):
"Rel to TDC" should be (X * 0.35160 +0)

For the ADS output not using Base (but including Retard modifies etc):
"Rel to Ref" should be (X * 0.35160 +0)
Adding +6* (or Base) would show exact output in the ADS.

For the XDF, Should the Base be added as an offset to the main spark tables to make them equal the output?
Currently mine does not.

Like stated above, just clearing the cobwebs to try and make sense of what I'm seeing.
TIA,
Jp

 

Here's what happened.
Started with a 7747 and imported an ECU file to create an XDF.
Worked with that for a long time, knowing that when my map said 51 degrees advance, that *really* meant 51-base-bias. Bias was 10, and base was 10, so 51-10-10 meant the light should show 31, which it did. Fine.
Got an 8746 ECM to play with. Downloaded an XDF, and discovered that copying in my well massaged map knocked and pinged scarey !
Edit XDF info, conversion showed 0.351563*X-B
-B ??
Well, B was a link to the main bias value, so it was ALREADY subtracted out in what was displayed, meaning that when I'd copied my 7747 table over, this little conversion "correction" was adding 10 across the board, and the map showed crank plus base, not crank plus base plus bias. Surprise !
This is why I say you gotta know who wrote what into the XDF and ADS file you're using ! Turns out you *can* do all those linked corrections to other bin entries in both. It helps a lot if you know they are there, or that they are not, or that they are in one but not the other, or that some of them are, and some are not.

That hour in the garage with a light was quite valuable ! The light don't lie !

 

Nope, leave the base distributor timing out of the XDF. In the $8D code the main SA table is WYSWYG. The ECM subtracts out the Initital SA (distributor base) before programming the hardware. And the distributor position adds it back in. So if the main SA table is at 20 BTDC, a timing light will show 20 BTDC (ignoring other SA modifiers such as CTS comp, choke, etc).

Note that $8D doesn't use a bias value, such as the '7747 & '8746 ECMs. So forget about that.

For the ALDL data stream, logging stuff. Here if using the limited final SA value, will need to add the base/initial timing back in. If it can be done is the .ads file, can do it that way. The issue here is will it always match your real base/initial timing?

Very easy to change those and not change the .ads file. Or if both are changed you now can't look at the older log files, as the SA will be incorrect. Some one else may be using a different base/initial timing, so they don't get the correct results.

It can be better to use the limited final timing and add the base in mentally. Setting the base/initial to 10 BTDC makes it easy (ier). And on a modified engine a base of 10 BTDC is probably better then 6 BTDC anyway.


To really throw everyone for a loop, the ECM code can be modified to have the base added back in to the final SA value. That way the ALDL SA value also becomes WYSWYG

RBob.