Starting to Learn on 95 G30 5.7 for Towing

[Fast355]

To know if the base timing is accounted for you would need to look at the equation for the spark advance in the .ads file.

I really need to pull the $OD Hack and look at it really well. Something tells me that zero'ing out the altitude spark bias is what is causing your values to be off so far. Where there is a bias table their is an offset value.

There are also other spark advance tables in play that would keep you from matching the Main Spark advance table. Abuse Mode spark retard, Coolant Temperature compensation, Catalyst Overheat spark, etc come to mind.

^^^ I was onto that bias table still having a value other than zero and zeroing the table bias as causing an issue.

You can easily edit the ADX to include the initial timing value in the datalogged value.

From what I remember Initial advance is actually subtracted out of the final spark advance values right before the PCM checks that the values are within the Min/Max values and uses it for EST calculations.

Whoever wrote that article straight up plagerized some of my own tuning information I put on a forum years ago not that I really care.

[Fast355]

Post #7 in this thread.
https://www.thirdgen.org/forums/tbi/...i-buildup.html

[donf]

Fair enough, there is a LOT of contradictory information here. So care has to be taken. Even some of my post would probably mislead, so its a learning process. I tried to edit out the most confusing parts. I did try the Lt timing table from the 1995 Caddy with the towing package. It seemed to increase responsiveness a bit but as soon as I hooked the enclosed trailer to the van and started pushing it the knock counts started to rise in several areas and that was at the winter air temps, it would be worse in the summer. I went back to the mostly stock vortec table for now that I had in the beginning. I will work on the table once the dyno gets pulled back out. The weekend weather has been crud for the last few weekends so I am not pulling the dyno out in that. I am pretty happy with the 40hp and the 50ftlbs of torque over the base line and it does pull the trailer better. Comparing different dyno readings is just speculation. Like I mentioned before, Dyno Dynamics has tested other makes of dyno's and said they sometimes show more than true crank hp at the rear wheels. I don't know how others owners calibrate theirs, but mine is super easy to check for accuracy. I checked it again, the dyno is within 1 percent of perfect, slightly low. 1996 literature said the l31 is 245hp and 325 tq with a much better intake system, flow wise and a slightly worse cam and and those numbers are not taken at the rear wheels. With the head swap and small cam. I really don't think there is anything wrong with the numbers I got. I also locked the converter at very low rpm for the dyno test this time.The reason is to be able to use the dyno brake to load the engine much lower for repeatable tuning and to keep the rpm from falling back, messing up the printout for the run like in the first test where it has three 3100 readings. I am sure that has some effect too. That's not the chip I run on the road though. The fuel table is more refined now. Its snowing outside but I think I will burn a chip again at a fixed number and see if what the computer says its getting is really what the crank says timing wise. I found this thread and it seems like something worth a look at. https://www.thirdgen.org/forums/diy-...ncy-table.html

[donf]

So along yesterday's discussion, from the other thread where changing the o2 stoich from 14.7 to another number for E10...
I started my tune with the setting at 14.2. On the dyno months ago, I ran several passes with it set at 14.2 then ran a few with it set at 14.7 without touching anything else. The haltech wideband logging the showed a slight difference but it was almost not even readable. Run to run variation showed almost as much change and block learn at WOT did not move. So I left it at 14.7 and continued to refine the tables once in a while. Yesterday after the discussion I decided to change the stoich afr to 14.4 and see. I was hoping that it would not mess up the tables. There have been two very noticable changes in the table since the start, once was when I filled up with gas after the first tank. Everything across the board went slightly lean. The second was my doing. I decided I didn't like the richness of the VE table on decel even though I never hit a lot of them over 3600, and copied the first three columns from the stock bin and pasted them in to redo that area.

Today I was worried that the change from 14.7 to 14.4 would cause the need for big table changes. Again I was surprised with the real results. It did not change a lot. WB02 readings stayed good and the block learn was very good in most cells. I am attaching the worksheet. It's not done there is straggler data where the sample count as very low. I have not weeded that out. It seems that sweating over setting it at 14.2 or 14.4 or 14.7 makes no real drastic change in the VE table, even when the table was dialed in at another setting. The difference between tanks of fuel made a bigger change in the tables.

[Fast355]

I wish I had screenshots of the fuel trim maps on my L31 running E10 back in the day before it was ever tuned. The fuel trims were all +8 to +11%. Changed stoich from 14.73 to 14.12 and the fuel trims all went to within +/- 1-2% Made a substantial change in my otherwise stock L31.

[donf]

I think it should have made a much bigger difference than it did. My thinking is, maybe the data is mislabeled or misaddressed and we are not changing what we think we are changing? I will leave it at 14.4, either way it seems to make no big difference in the map so far if its changed slightly. I have a brand new A/C Delco sensor

[donf]

I gave the van a real towing test a few months ago. I got called to tow the dyno to a small town in middle Oregon. Only about 80 miles each way but its in old volcano areas. The highway is straight up and down. The engine torque from the upgrades is noticeable it did fine, right where its needed rpm wise too. I went over the truck scales at very close to 10,000 lbs total. The problem was the trans temp. I had to let off on the steepest parts as the temps were going to cook the trans. I had the factory trans cooler as an option. One person told me there is a bypass built in and its a poor design. After many miles the bypass tubes work better than the other tubes and not much cooling gets done. I sourced another cooler from TruCool. They made the original too, but this one is twice as thick and has no bypass so it all has to go through the cooler. B&M Supercoolers are reboxed Tru-Cool coolers. I went with the Tru-cool box since it was less than half price. It was pretty easy. Since the same manufacture one side of the bracket was perfect, the other side needed a square piece of sheet metal. I had to trim the grill a bit from the backside because of the extra thickness. I have not pushed the trans that hard locally but it seems to cool better. There is one area where the factory add on trans cooler line has a necked down area to slide into the main cooler line. I think that may hurt cooling as well. I have not cut that out yet but will if trans temp continues to be a problem.

[donf]

In the factory open loop table, why is the af ratio set so lean? I am getting the closed loop tables dialed in, but noticed if I cold (80F) started the van at idle, It would run to 12.1 on the wide band for a few seconds and then go to around 16.1 until it warmed up enough to go into closed loop or I just drove off then it would go closed loop fast. Once it was running in closed loop, with the fuel mixture in the 14s, the idle was smoother. The open loop idle with such a small cam was not bad, but it definitely likes 14.2 better than 16 in open loop. It seems to go into closed loop faster with the table changes also. I am interested in saving as much money at the pump as I can, but in this case slightly richer seems to give better results.

[donf]

The project ended today, but in a good way. I learned a lot. I wanted to thank everyone for the input. I very much appreciate the guidance. A startup company decided they wanted delivery vehicle with some character. It is actually going to get wrapped and lowered. Its not my style but I am glad its going to a good home and I got very paid well for my project.

The vortec style heads(just don't buy Jegs home brand) and the ramjet cam were great for the money with towing. No problems pulling 5000 lbs at all power wise, within reason. It will never pull like a diesel. It was the wide gear spacing of the 4l60e that had me wishing for a 4l80e. 3rd some times was too high and 2nd was a long way down ratio wise. First was way too low also for the 350 with more torque. It did it but it was not ideal. The trans is still in great shape so I could not see ripping it out so I just decided move on.

[Fast355]

The project ended today, but in a good way. I learned a lot. I wanted to thank everyone for the input. I very much appreciate the guidance. A startup company decided they wanted delivery vehicle with some character. It is actually going to get wrapped and lowered. Its not my style but I am glad its going to a good home and I got very paid well for my project.

The vortec style heads(just don't buy Jegs home brand) and the ramjet cam were great for the money with towing. No problems pulling 5000 lbs at all power wise, within reason. It will never pull like a diesel. It was the wide gear spacing of the 4l60e that had me wishing for a 4l80e. 3rd some times was too high and 2nd was a long way down ratio wise. First was way too low also for the 350 with more torque. It did it but it was not ideal. The trans is still in great shape so I could not see ripping it out so I just decided move on.

No suprise on that cam working well. It did ok for me as well in the low-midrange. Its a marine cam designed to make as much torque as possible from off-idle through 4,800 rpm.

Glad someone can get use out of the G-van.

[donf]

I picked up the vans replacement yesterday. 1996 c2500 with 110,000 miles and 454/4l80e/4.10. It doesn't need much. Some shocks, hoses and all the fluids replaced/flushed. I spent a few hours today removing the old man accessory kit: running boards, bug deflectors, mudflaps, deer whistles, and the window air deflectors. I may not even mess anything except maintenance for a while as it tows 5000 lbs just fine.