Hello all,

I was referred to this site seeking help with setting up and tuning the EBL Flash that's installed in a 1968 C10 pickup with a 250 4.1l L6 and 3 speed manual. From what I have found here, it seems there are a lot of you guys that are knowledgeable on this system here.

I will start off with the story from the beginning. This is my son's new truck, he brought it home last week. the truck has been sitting for a long time, long enough for the fuel to go bad along with the fuel pump to go south. the PO had installed the EBL some years ago with a TBI throttle body along with having the engine rebuilt. The engine only has 7500 miles on it since the rebuild, but not sure how long ago that was. The week prior to my son purchasing the truck, the PO cleaned out the tank, replaced the fuel pump, and added premium gas to get it running. Engine starts but runs very rich, to the point that when it's cold it acts like its under full choke blowing lots of black soot and smells of raw fuel in the exhaust. I have no idea how far he got with tuning and setting up the EBL though he was driving it some years ago.

Ok, here is what I have done so far.

The PO gave us all the software for the EBL Flash and I have found the documentation on it from the wayback machine for DynamicEFI. read through it and started looking at the bin file that I extracted from the ECM. I found that the tune is based from a 4.3l V6 engine and pretty much matches all of the parameters exactly other than the spark timing and VE tables. while I was slowing reading and learning how the EBL works, I connected a fuel pressure gauge to the TBI and found that it's running 18 PSI instead of the normal 11-12 that a TBI should have. One thing I did was use my pliers to pinch off the supply line which lowered the pressure to around 10 psi. This made the engine clean up and run smooth at idle.

Ordered an AC Delco TBI rebuild kit for it but have not gone though it yet. I'm still debating if I should rebuild it wondering if the regulator is just stuck or if it's been modified to run at full pressure. the fuel pump the PO installed is a P4601HP rated for 9-16 PSI, apparently it's able to do 18. I was talking with a fellow over on the GMC Motorhome forum that suggested to run the EBL utility using the 18 psi fuel pressure and use the BPC numbers for the BPC vs VAC tables and see what happens. So looking at the bin, the BPC was set across the board at 181 which matches the 4.3l bin. the numbers I got for 18psi and 45#/hr injectors was 150 across the board.

Changing the BPC table to 150 made a huge difference in the rich condition. it is running much better, still slightly rich when cold but once warmed up it idles almost perfect. After this I started a VE learn session and noticed right away that all of the corrections were landing on -10.

I decided to load the bin back into tunerpro and lower the entire VE table by 10% and try again. Started up and I noticed it idling even better, staring a new VE Learn resulted it the same thing. all of the corrections were landing on -10. Am I heading in the right direction here by lowering the entire VE table by 10% and possibly needing to do it again?

a side note: I am also seeing lots of spark knock counts as well, but the exhaust manifold gasket is blown out where the intake meets. I was kinda ignoring the spark knock counts thinking the exhaust leak is contributing to that. At least until I can pull the manifolds and replace the gaskets.

Here are some screenshots of the second VE learn corrections, spark knock counts, and the results from the EBL utility. I just want to know if I am going in the right direction here.

 

Be sure you are conducting your VE Learns during a particular temperature. The temperature of the incoming air due to varying engine temps plays a critical role in your corrections and you will find yourself chasing your tail if the window is too wide. Program the WUD to conduct its' learning only during your operating temperature (averaged depending on your Fan run/off time). So if your Fans come on at say 200*F and off at 185*F, set the Learn function in the WUD to Learn in between those two temperature readings, not outside of them. As you go you can then gradually tighten the window until you see 0's and -1/+1. You will never ever see a constant 0 when Learning due to temperature swings, as 5*F makes a difference in AFR, and the idea is to keep the readings as close to 0 as you possibly can but during your operating temperature range only. The rest of the VE table can be filled in and smoothed out manually...

- Rob

 

I haven't posted back in a while, but I think I have made some considerable progress getting things working. I found several issues other than the fuel tables and had gotten some help over on the GMC motor home forum. the speed sensor on the trans was non-functional among other things set in the tune for the EBL. those I think have been fixed now. I also had issues with constant fuel pressure as well as a huge exhaust leak around the manifold. had to pull the intake and exhaust manifolds to replace gaskets along with completely rebuilding the TBI throttle body.

Now I am trying to understand the timing tables. in the bin the SA initial was set to 0.00 and the distributor was set at 16 degrees. I have since moved the distributor to 8 degrees with a timing light along with setting the SA initial to 8.09. when I first looked at the SA main table in the bin it was showing numbers as high as 50.98 degrees for advance timing. I thought this was kinda high for an old 250 l6 engine. after doing some searching not being able to find any info for timing tables for this engine I ran across a spreadsheet that was posed here in the forums that would help build a timing table to start off with. below I have the screenshots of both the main table that was in the bin for the EBL and what I came up with using the spreadsheet. currently I have the new table flashed to the EBL and I am seeing a LOT of spark knock counts across all areas in WUD. I have double checked for rattles in the body and exhaust. even when holding the RPM steady as around 1500-2000 the engine runs seemingly smooth but the knock counts still climb steadily.

Then it occurred to me that I might be looking at these tables wrong, at idle I am seeing the map sensor reading in WUD around 40 kpa and was thinking that these readings correlated to the table in the same way, but now I am not so sure. I am curious if the Kpa on the tables are "Absolute Kpa" and not "Vacuum Kpa" meaning WOT would be in the red areas and the "idle state" would be in the blue. if this is true, I am looking at these table all wrong! I am very new to tuning and need to learn a lot here!

anyway here is the screenshots of both tables. First one is the main table that was setup by the PO. the second one is what the spreadsheet put together. I based it from a initial advance of 10 degrees and maxing out at 36 degrees going off from what I could find online what the timing advance should be for a 250 straight 6 engine. Can someone help me build a timing table for this engine?