As far as start up timing goes. Some vehicles have slow crank (for whatever reason), keeping the cranking timing low under 200 rpm is useful for that reason. I like to have it ramped up by 500 rpm to aid in startup, some big cam vehicles, depending on the ecu, need it.
After watching your EOIT/SOIT video a while back I messaged you about my stock Boundry table (08’ Silverado 5.3) being the same as your stock Boundry table which starts at 520 then gradually decreases to a number in the 300’s. I also use e85 with FIC 1000cc injectors. After many failed attempts by professional tuners, I’ve had to do a lot of self tuning with tons of trial and error to get things right. I found that my truck runs better using the stock Boundry table. When my Boundry was set to 520 across the board and using the Normal ECT and RPM table to make SOIT adjustments, I had a constant black spot about the size of basketball on my white paint just above the exhaust. But as soon as I switched to stock injection timing the black spot went away and I had no more cranking issues, cold or hot. My Normal ECT table is stock except for minor changes to the running temp areas (150-200)+- 5 to 10 to tweak idle and also the rest of the rpm range because I found that even slight changes to SOIT greatly affects the smoothness of my VVE table allowing me to bring the fuel trims within a defined zone closer together. So instead of having one column all -2 and the next column all +3 (because that’s the best it will allow), I can get all the columns within that zone to be all negative or all positive allowing a smoother VVE table. I found that changing the NORMAL ECT in the cold cranking areas greatly impacted cold cranking. So Making the number smaller by as little as 5 made it harder to start and increasing it by 5 made it easier to start. Not sure on hot starts because mine cranks fine when heat soaked. I also found that small changes to transient fueling tables had a big impact on cranking. 08’ Silverado 5.3 D1x procharger Fast 102 intake 103mm TB Trickflow 205 heads BTR centrifugal truck cam 223/240 610/590 1 3/4 long tubes
This is very interesting. I wish you lived closer to me so we could try this in person and run a lot of tests. I am curious though, using the factory injection timing with no black spot vs other changes I have suggested...which one results in the richest trims/shorted IPW? Also, the black spot, does this appear with normal closed loop driving or do you get your foot into it a lot and go into PE?
Sorry for late response. The black spot from the exhaust would appear with regular closed loop operation, while idling, light throttle driving and cruising. Actually, driving it like I’m trying to tune part throttle MAF/VVE. I’m not satisfied with “good enough” and I want to know the cause and effect of every change made to every table in my ECM so, I experiment almost daily with my tune. For instance, a couple days ago I was messing around with injection timing and in the Normal ECT table I lowered the value in the 175 degree column by 5 points (115 to 110). I went out driving. After 15 minutes of driving I stopped at a store and after 30min of being in the store I returned to my truck, started the data log, turned the key to crank and I get nothing but the starter spinning. Try again, nothing but the starter spinning. WTF!! I don’t have issues with hot starts!! I look at my ECT and it’s sitting at 175 degrees! I change my Normal ECT table at 175 degrees back to 115, load the tune and it fires right up. So at idle there’s no difference in my stock injection timing and your custom approach. My stock Boundary angle from 0 to 1500 rpm is 520. Lowering the value of the 110 cells in my Normal ECT table resulted in leaner fuel trims. Increasing the stock 110 values to a max of 120 resulted in richer fuel trims. Over 120 the trims returned lean. Now, I didn’t leave my Boundry table completely stock but I also didn’t make it 520 across the board. I experimented with the Boundary angles effect on the fuel trims at different rpms and the transitioning of fuel trims from one VVE zone to another and making those transitions smoother using injection timing vs fighting the VVE table. What I mean is, I had an issue were my fuel trims at 1800 rpm’s would all be negative, then my trims at 2000 would all be positive, 2200 would all be negative, 2400 would all be positive. As you know, there is only so much correction allowed in the VVE table. Through changes to injection timing I was able to make all 4 of those rpm columns negative fuel trims and that resulted in a smoother VVE table.
Thanks for the shout out! I always see a lot of people trying to reinvent the wheel when GM already gave them what they need for the most part. I tell them, Let's not over complicate stuff. Look at the OEM files that do what people are trying to do.
I like using idle speeds a little higher than most people might use and run the engine open loop only. This allows for precise fuel metering based on your tune only and not on what the ECU thinks you might be needing for fueling. Also, if you remove any of your vehicle internet connector it will not crank as long before start since that system will no longer hold back while connection is verified to cell towers and satellite GPS. Technology is here to stay and has to be considered. Best of luck. Nice video.
18:00 admirable :) I think you can attribute your improvements in hot start time not from the piston/air velocity as you posited, but because the injection scheduling previously allowed too much fuel to be lost through the exhaust valve as the intake valve opened. Scavenging is not as absent as you might think; near TDC as the intake begins to open, the exhaust pulse will drag that fuel right out the exhaust valve. If your crank fuel doesn't account for this, it can become too lean to fire - as you experienced. Obviously the other way around this is delaying start of injection long enough that the fuel lost to the exhaust is minimized. However, this has a big downside...open valve injection. And larger injectors make the effect far worse. Without sufficient time to vaporize, a small, dense slug of fuel injected into an open valve won't homogenize well at all, which impacts combustion quality and directly contributes to the 'black spot' issue @Firestarter467 mentioned below... It causes particulate emissions much like a diesel due to diffusion combustion effects. So, the goal is balance...avoid losing fuel to the exhaust during valve overlap where possible, but not to the extent that it causes the other issues I mentioned. A surefire way to improve hot starts where fuel short circuits the chamber and out the exhaust is simply increasing the cranking fuel to account for the loss. I like the analysis effort overall.
you talking about hot start, but for me is this on cold engine more fuel less fuel more timing less timing no change. Could it be EOIT? stock injectors gen5
I have no experience on the Gen5 stuff. In theory there should be little to no transient fueling/wetting of the port walls since it is direct injection, so you don't have to worry about the incoming air having to "carry" the fuel into the cylinder. If you have tried everything else then perhaps you can experiment with SOI.
As far as start up timing goes. Some vehicles have slow crank (for whatever reason), keeping the cranking timing low under 200 rpm is useful for that reason. I like to have it ramped up by 500 rpm to aid in startup, some big cam vehicles, depending on the ecu, need it.
I’ve had good results waiting to crank until the pump has finished priming.
Thanks for all the knowledge and tuning tools!
I tried that too and that did not help/hurt.
After watching your EOIT/SOIT video a while back I messaged you about my stock Boundry table (08’ Silverado 5.3) being the same as your stock Boundry table which starts at 520 then gradually decreases to a number in the 300’s. I also use e85 with FIC 1000cc injectors.
After many failed attempts by professional tuners, I’ve had to do a lot of self tuning with tons of trial and error to get things right. I found that my truck runs better using the stock Boundry table. When my Boundry was set to 520 across the board and using the Normal ECT and RPM table to make SOIT adjustments, I had a constant black spot about the size of basketball on my white paint just above the exhaust. But as soon as I switched to stock injection timing the black spot went away and I had no more cranking issues, cold or hot. My Normal ECT table is stock except for minor changes to the running temp areas (150-200)+- 5 to 10 to tweak idle and also the rest of the rpm range because I found that even slight changes to SOIT greatly affects the smoothness of my VVE table allowing me to bring the fuel trims within a defined zone closer together. So instead of having one column all -2 and the next column all +3 (because that’s the best it will allow), I can get all the columns within that zone to be all negative or all positive allowing a smoother VVE table.
I found that changing the NORMAL ECT in the cold cranking areas greatly impacted cold cranking. So Making the number smaller by as little as 5 made it harder to start and increasing it by 5 made it easier to start. Not sure on hot starts because mine cranks fine when heat soaked. I also found that small changes to transient fueling tables had a big impact on cranking.
08’ Silverado 5.3
D1x procharger
Fast 102 intake
103mm TB
Trickflow 205 heads
BTR centrifugal truck cam 223/240 610/590
1 3/4 long tubes
Why the manufacturers decide to use fuel trims on their platforms ? To make the car run smoothly or make the catalytic converter happy
This is very interesting. I wish you lived closer to me so we could try this in person and run a lot of tests. I am curious though, using the factory injection timing with no black spot vs other changes I have suggested...which one results in the richest trims/shorted IPW?
Also, the black spot, does this appear with normal closed loop driving or do you get your foot into it a lot and go into PE?
Sorry for late response. The black spot from the exhaust would appear with regular closed loop operation, while idling, light throttle driving and cruising. Actually, driving it like I’m trying to tune part throttle MAF/VVE. I’m not satisfied with “good enough” and I want to know the cause and effect of every change made to every table in my ECM so, I experiment almost daily with my tune. For instance, a couple days ago I was messing around with injection timing and in the Normal ECT table I lowered the value in the 175 degree column by 5 points (115 to 110). I went out driving. After 15 minutes of driving I stopped at a store and after 30min of being in the store I returned to my truck, started the data log, turned the key to crank and I get nothing but the starter spinning. Try again, nothing but the starter spinning. WTF!! I don’t have issues with hot starts!! I look at my ECT and it’s sitting at 175 degrees! I change my Normal ECT table at 175 degrees back to 115, load the tune and it fires right up.
So at idle there’s no difference in my stock injection timing and your custom approach. My stock Boundary angle from 0 to 1500 rpm is 520. Lowering the value of the 110 cells in my Normal ECT table resulted in leaner fuel trims. Increasing the stock 110 values to a max of 120 resulted in richer fuel trims. Over 120 the trims returned lean. Now, I didn’t leave my Boundry table completely stock but I also didn’t make it 520 across the board. I experimented with the Boundary angles effect on the fuel trims at different rpms and the transitioning of fuel trims from one VVE zone to another and making those transitions smoother using injection timing vs fighting the VVE table. What I mean is, I had an issue were my fuel trims at 1800 rpm’s would all be negative, then my trims at 2000 would all be positive, 2200 would all be negative, 2400 would all be positive. As you know, there is only so much correction allowed in the VVE table. Through changes to injection timing I was able to make all 4 of those rpm columns negative fuel trims and that resulted in a smoother VVE table.
Thanks for the shout out! I always see a lot of people trying to reinvent the wheel when GM already gave them what they need for the most part. I tell them, Let's not over complicate stuff. Look at the OEM files that do what people are trying to do.
I like using idle speeds a little higher than most people might use and run the engine open loop only. This allows for precise fuel metering based on your tune only and not on what the ECU thinks you might be needing for fueling. Also, if you remove any of your vehicle internet connector it will not crank as long before start since that system will no longer hold back while connection is verified to cell towers and satellite GPS. Technology is here to stay and has to be considered. Best of luck. Nice video.
Thanks for taking the time to share your knowledge 👍
Love the videos good job!
Great video, 10/10 use of memes also. 😂
No need to give away anything other than your info. Thanks
18:00 admirable :) I think you can attribute your improvements in hot start time not from the piston/air velocity as you posited, but because the injection scheduling previously allowed too much fuel to be lost through the exhaust valve as the intake valve opened. Scavenging is not as absent as you might think; near TDC as the intake begins to open, the exhaust pulse will drag that fuel right out the exhaust valve. If your crank fuel doesn't account for this, it can become too lean to fire - as you experienced. Obviously the other way around this is delaying start of injection long enough that the fuel lost to the exhaust is minimized. However, this has a big downside...open valve injection. And larger injectors make the effect far worse. Without sufficient time to vaporize, a small, dense slug of fuel injected into an open valve won't homogenize well at all, which impacts combustion quality and directly contributes to the 'black spot' issue @Firestarter467 mentioned below... It causes particulate emissions much like a diesel due to diffusion combustion effects.
So, the goal is balance...avoid losing fuel to the exhaust during valve overlap where possible, but not to the extent that it causes the other issues I mentioned. A surefire way to improve hot starts where fuel short circuits the chamber and out the exhaust is simply increasing the cranking fuel to account for the loss.
I like the analysis effort overall.
you talking about hot start, but for me is this on cold engine more fuel less fuel more timing less timing no change. Could it be EOIT? stock injectors gen5
I have no experience on the Gen5 stuff. In theory there should be little to no transient fueling/wetting of the port walls since it is direct injection, so you don't have to worry about the incoming air having to "carry" the fuel into the cylinder. If you have tried everything else then perhaps you can experiment with SOI.