What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Into the rabbit hole of EFI tuning. ( Speed density/VE )

So the instructions that came with my GMPP crate small block said to only use the centrifugal advance in the HEI and to leave the vacuum advance disconnected. Which I have since I installed it. Makes me wonder why now.
I might hook it up this weekend and see what happens.
 
So my tps wasn't reading right... at 100 the blade could move 1/4 inch or more open. Adjusted the cable and now it requires less skinny pedal but now I need to redo the trans programming.

And now the SD card won't read, says it's corrupt.
 
Last edited:
cheavyk10 said:
So the instructions that came with my GMPP crate small block said to only use the centrifugal advance in the HEI and to leave the vacuum advance disconnected. Which I have since I installed it. Makes me wonder why now.
I might hook it up this weekend and see what happens.
Click to expand...
I don't recommend that, that's worse than hooking the vacuum advance up to ported vacuum, at least then you would have vacuum advance at cruise. I recommend for efficiency and performance, you hook it straight up to full manifold vacuum.

Just to be sure to set the timing at about 34 - 36 at 4000 RPM with the vacuum advance disconnected. Then hook it back up and set the idle rpm and tune the A/F.
 
Now that the tps is reading 100 when it's actually at 100 the truck drives so much better. I put a black cat trans tune in it based off my gear and tire size.

I have never driven this and had it act the way it did. Once I dial in the line pressure it should be impressive.


Drives sooooo good.
 
folkenheath said:
I don't recommend that, that's worse than hooking the vacuum advance up to ported vacuum, at least then you would have vacuum advance at cruise. I recommend for efficiency and performance, you hook it straight up to full manifold vacuum.

Just to be sure to set the timing at about 34 - 36 at 4000 RPM with the vacuum advance disconnected. Then hook it back up and set the idle rpm and tune the A/F.
Click to expand...
Quick update: vacuum advance hooked up to full manifold vacuum. Runs good, no pinging. Timing is set at 16/36. My manifold vacuum reading actually went from 13 to 15 interestingly. After a quick drive I had to adjust the IAC to get the idle to come back down slightly on my Summit Max-EFI 500 (this unit does not control timing). Engine seems happy, slightly smoother idle, slight seat of the pants increase.
 
Its typical for the RPM to go up at idle when you go to full manifold vacuum on the advance, simply because...the engine likes more timing at idle.
 
Started messing with line pressure, how firm do you guys like the shifts? With the way the trans is built it can handle 250psi but I don't want to go that high...

I need to get a psi sensor on it but I gave it a little more because it felt "lazy" from the gm tune... and cause race truck.
 
Last edited:
Well, considering I have a big big block with gobs of torque even at low throttle in my Regal, I have it 75% of full pressure at idle, and ramp it up to 100% by quarter throttle, with 100% full pressure above 1/4 throttle. This is a very simple straight line.

You probably don't need to go that aggressive, but still, I would definitely be at 100% pressure (0% duty cycle) by half throttle. You could try 50% at 0 TPS and then highlight that and fill the values up until 46 or 53% at zero. That will ramp it straight. Or you can curve it, whatever you want to do.

If your pressure is going too high at 0% DC, then your trans is incorrect internally. The only way to know that is with a pressure gauge, I log it with a 500 psi sensor. My 4L80E I built only goes to 175 psi max in forward gears, that's all it has needed so far. I have no idea what your 4L60 needs to support your power level.

1645025771653.png
 
Remember, duty cycle is the inverse of pressure. That is a fail safe, if it fails it should fail at full pressure to get you home and not leave you stranded.
 
folkenheath said:
Well, considering I have a big big block with gobs of torque even at low throttle in my Regal, I have it 75% of full pressure at idle, and ramp it up to 100% by quarter throttle, with 100% full pressure above 1/4 throttle. This is a very simple straight line.

You probably don't need to go that aggressive, but still, I would definitely be at 100% pressure (0% duty cycle) by half throttle. You could try 50% at 0 TPS and then highlight that and fill the values up until 46 or 53% at zero. That will ramp it straight. Or you can curve it, whatever you want to do.

If your pressure is going too high at 0% DC, then your trans is incorrect internally. The only way to know that is with a pressure gauge, I log it with a 500 psi sensor. My 4L80E I built only goes to 175 psi max in forward gears, that's all it has needed so far. I have no idea what your 4L60 needs to support your power level.

View attachment 403065
Click to expand...
The trans was built by Greg here and he lists it to handle 600hp, during conversations he recommended wide open throttle line pressure should be about 235-260 psi and not to go higher or I risk pump damage.

I found the shift points during a data log and lowered it 10 on the graph. It barked 3rd gear on concrete yesterday going on the highway.
 
Ok, so Greg should know if it will go past that at 0% duty cycle, I wouldn't think so but I don't know what spring or shims he used. It wouldn't make much sense to shim it so if the computer failed it would fail mechanically too. He probably means don't shim the spring to higher pressure than he did.

@Greg Ducato can you please advise him if he can go to 0% duty cycle at higher loads?
 
folkenheath said:
Ok, so Greg should know if it will go past that at 0% duty cycle, I wouldn't think so but I don't know what spring or shims he used. It wouldn't make much sense to shim it so if the computer failed it would fail mechanically too. He probably means don't shim the spring to higher pressure than he did.

@Greg Ducato can you please advise him if he can go to 0% duty cycle at higher loads?
Click to expand...
That would be my guess as well. It was based on the factory gm tuning but a touch of his magic. @Greg Ducato
 
Interesting plug readings but confirms what I thought. Rich plugs, I wish I was better at reading these and could tell where the spark is hitting to adjust timing.

20220216_174317.jpg
 
Got my burb running finally, went through the terminator x wizard, and my injectors are not listed.
So now I'm not exactly sure what to do.
I selected the stock LS3 injectors to make it start and run. Figured they weren't far off.
I'm using the AC Delco 12613412
(From a 2010-14 flex fuel truck I believe)
What actual info do I need from those.
I found a few sets of numbers, but didn't know what ones I need.
 
shady said:
Got my burb running finally, went through the terminator x wizard, and my injectors are not listed.
So now I'm not exactly sure what to do.
I selected the stock LS3 injectors to make it start and run. Figured they weren't far off.
I'm using the AC Delco 12613412
(From a 2010-14 flex fuel truck I believe)
What actual info do I need from those.
I found a few sets of numbers, but didn't know what ones I need.
Click to expand...
I believe I have these same injectors and they were under the setup menu, when I get home I will double check and give you the info needed. Have you updated the software to v2?

https://documents.holley.com/techlibrary_termxinjectordatachart.pdf here is the data you need to enter. :waytogo:
 
Last edited:
shady said:
Got my burb running finally, went through the terminator x wizard, and my injectors are not listed.
So now I'm not exactly sure what to do.
I selected the stock LS3 injectors to make it start and run. Figured they weren't far off.
I'm using the AC Delco 12613412
(From a 2010-14 flex fuel truck I believe)
What actual info do I need from those.
I found a few sets of numbers, but didn't know what ones I need.
Click to expand...

These are the same injectors im running. I was un aware that the holley system seems to always command 60 psi of fuel pressure, so im at about 10% duty cycle of the injectors.. lots left to go. I was thinking i would run these at a lower psi until i need what these injectors offer. I also am contemplating using e85 on them but the only station that sells it here on the island has been tested by a few, and its more like e65... I dont like the idea of tuning the engine for a fuel that might be from e65-e85..? These injectors are listed in my holley software, I can give you the info it gave me for them if you need. I beleive its about 49.5 lb/hr @ 60 psi.
 
You must log in or register to reply here.

Latest Posts

Top Bottom