October 31, 2024, 07:52:53 PM

Author Topic: 403 LS2 FD - LS7 Build for 2020!  (Read 261393 times)

Offline Exidous

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1065 on: May 14, 2024, 09:15:24 AM »
The cam and crank should both be 0-5v square. They are hall sensors and absolutely should not be saw tooth.

First two images are the raw crank and cam respectively. Third is the trigger voltage levels.
94 BB Sleeved gen IV LS7, MS3ProU with TC, RONIN 8.8 and LT's with custom 3.5"single to VAREX muffler.

Online MPbdy

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1066 on: May 14, 2024, 10:21:39 AM »
Sorry the sawtooth is not the crank position sensor output - the sensor output is a square wave, and I didn't see any abnormalities with it.  The Holley tracks crank position as a saw tooth - must be an arbitrary value calculated 0-5000 for the two revolutions.  The start and end of the sawtooth aligns with two revolutions of the crank sensor pulses.  Not sure why they don't use 0 to 720* but that's neither here nor there. 

Offline Exidous

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1067 on: May 14, 2024, 06:34:23 PM »
Holley really likes to be weird. Injector timing is off bdc on the compression for them. Makes no sense haha
94 BB Sleeved gen IV LS7, MS3ProU with TC, RONIN 8.8 and LT's with custom 3.5"single to VAREX muffler.

Online MPbdy

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1068 on: May 14, 2024, 07:15:54 PM »
Yea I had to draw it out for injector timing, but it works ok once you understand the reference point.  By default it is at 540*, or 0* for them.  The intake valve closes ~60* after.  It isn't the worst, but idle sucks.  The biggest head scratcher is if you enable their injector timing table it is MAP vs RPM.  What MAP has to do with injector timing I have no idea lol.  You can make a custom 3d table that inj PW vs rpm vs injector end angle offset and then you actually have something useful.

What strategy did you use for your engine?  We have very similar valve events.

At idle/low RPM I'm targeting to advance the fuel spray as much as possible, starting just at or slightly before the exhaust valve closes as the fuel takes some time to reach the chamber.

As load increases, retarding the spray timing to get the bulk of the fuel sprayed into an open intake valve and during high piston velocity.  Obviously at longer duty cycles and higher rpm injector timing matters much less as the injectors will just be on for most of the time.

I'm not sure what my duty cycle is going to be yet.  I'm guessing ~60% on 91 octane and ~80% on E85.

I've done this strategy before with a slightly smaller cam on the GM ecu and actually found spraying on a closed intake valve like GM's approach to be easier to tune at low speed and take less fuel.  When I actually get to tuning this thing I plan to swing injector timing forward and back in some pretty big swings and see what it likes at low load.

Offline Exidous

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1069 on: May 14, 2024, 10:02:20 PM »
Ironically, I used a spreadsheet meant for Holleys and added a few tables to convert it to what everyone else uses.

Under load I have the injector closed 10° before the exhaust closes. At idle, the more time on the back of the valve the better. The upper and lower slope were adjusted to get the events where I wanted for idle, cruise and WOT. Used the table generator to fell the rest of the table.

Ex: I idle around 2.5ms pulse width. Intake valve opens at 356.5* after TDC on the power stroke(MaxxECU reference). Injector closes roughly 10-15* before the intake valve opens. So 356.5-15*=341.5*. After testing while running I ended up around 30* before so about 320*

I have zero issues with idle and cam surge now. Alex(shainiac) had issues with his and I redid his table based off his cam card. He's not back on the road yet but I'd expect it'll help a ton.

After the spreadsheet work, warm the car up. Disable closed loop fueling and play with the timing in the pulse width areas you are idling at. Adjust 10* at a time to find the richest reading you can. Redo the VE. Repeat one more time.

This is all from memory 3-4months ago. Your mileage may vary. ha

If you look at the cam overlap diagram. MaxxECU starts on the far left at 0. Holley is 540* later or 180* after 0* on the lobe diagram.


Edit: To follow up. I was playing around with the injection timing some more. Ended up around 250* from 330* before. I could not get the engine to idle below 950 before. At 250* it sits at 800 no problem and took 3% out of the VE table.
« Last Edit: May 15, 2024, 06:20:52 AM by Exidous »
94 BB Sleeved gen IV LS7, MS3ProU with TC, RONIN 8.8 and LT's with custom 3.5"single to VAREX muffler.

Offline Cobranut

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1070 on: May 15, 2024, 01:14:03 PM »
I struggled with ckp sync with my MS3Pro, trying to use it with my 24x reluctor.
I eventually figured out that the weird 2-piece reluctor in my engine has warped and separated.
I added a 36-1 wheel up front, made a bracket and switched to a 58X sensor.  It works well now.

Not sure this helps with your issue, but it was an oddball problem. :banghead:
1995 FD, 7.0 Liter stroked LS3, T56, 8.8, Samberg kit.

Offline Exidous

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1071 on: May 15, 2024, 06:32:17 PM »
That's always possible but should show up in the trigger logger if runout is there.
94 BB Sleeved gen IV LS7, MS3ProU with TC, RONIN 8.8 and LT's with custom 3.5"single to VAREX muffler.

Offline Cobranut

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1072 on: May 15, 2024, 11:00:07 PM »
That's always possible but should show up in the trigger logger if runout is there.

It was only possible with the oddball split wheel that GM used.
It wasn't a repeating error, but looked like random noise.  I tried every noise reduction method I could think of, until I finally put a borescope in the sensor hole and found the wheel was separated.
1995 FD, 7.0 Liter stroked LS3, T56, 8.8, Samberg kit.

Offline Exidous

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1073 on: May 15, 2024, 11:32:25 PM »
The dual plate 24x always was an oddball.
94 BB Sleeved gen IV LS7, MS3ProU with TC, RONIN 8.8 and LT's with custom 3.5"single to VAREX muffler.

Online MPbdy

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1074 on: May 22, 2024, 03:05:36 AM »
These are the most boring updates ever lol. I’ve confirmed it’s a cam sensor issue, and it’s not the cam sensor. Replaced the sensor and it wouldn’t even start. Disabled the cam sensor and ran it batch fire strategy and it fires immediately and sounds amazing. I can rev it slowly up to 5000 and free revs up to 6k sure sound nice.

Must be a problem in the harness? I had cam sensor issues with my ls2 and had to run it batch fire for the short time I ran it with the terminator. The only thing common at this point is the harness. I always blamed my past issues on the aftermarket dual roller timing set. With the stock ECU I’d have to crank it twice every time or it would backfire for some reason.

https://youtube.com/shorts/9RjdiqcEZkg?si=1Oxv0W2-Uu-M8NFM

I also ordered up a bunch of parts to install an anti gravity battery - got to test it out today and I’m extremely impressed. I’ve never had it spin so fast when cranking. Gotta get it mounted in the rear bins and run a battery cable. I need to drop the exhaust and driveshaft again sadly but it is what it is. Just making more work for myself.

Offline kinger

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1075 on: May 22, 2024, 09:32:55 AM »
These are the most boring updates ever lol. I’ve confirmed it’s a cam sensor issue, and it’s not the cam sensor. Replaced the sensor and it wouldn’t even start. Disabled the cam sensor and ran it batch fire strategy and it fires immediately and sounds amazing. I can rev it slowly up to 5000 and free revs up to 6k sure sound nice.

Must be a problem in the harness? I had cam sensor issues with my ls2 and had to run it batch fire for the short time I ran it with the terminator. The only thing common at this point is the harness. I always blamed my past issues on the aftermarket dual roller timing set. With the stock ECU I’d have to crank it twice every time or it would backfire for some reason.

https://youtube.com/shorts/9RjdiqcEZkg?si=1Oxv0W2-Uu-M8NFM

I also ordered up a bunch of parts to install an anti gravity battery - got to test it out today and I’m extremely impressed. I’ve never had it spin so fast when cranking. Gotta get it mounted in the rear bins and run a battery cable. I need to drop the exhaust and driveshaft again sadly but it is what it is. Just making more work for myself.

Well finding the problem is a nice accomplishment!

My battery cable runs through the interior pass side.  You are going to run yours external? 
93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights

Online MPbdy

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1076 on: May 22, 2024, 11:17:26 AM »
Ya I was thinking the underside of the trans tunnel I’ve seen a nice example of doing it that way. Where do you take yours outside?

Offline kinger

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1077 on: May 22, 2024, 11:35:18 AM »
Ya I was thinking the underside of the trans tunnel I’ve seen a nice example of doing it that way. Where do you take yours outside?

It shoots out under the ABS module.  I'll see if I can find a picture of it.  @halfspec obviously ran it but I like it up out of the way from heat and moisture, until it gets to the ABS area.  From my car stereo days long ago running 0AWG wire we never did it external unless it was protected inside of a frame rail on a truck (rectangle tube). 
93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights

Offline Esser

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1078 on: May 22, 2024, 11:41:45 AM »
I run the ATX 30 HD anti gravity battery and love it. It's a beast

Online MPbdy

Re: 403 LS2 FD - LS7 Build for 2020!
« Reply #1079 on: May 22, 2024, 11:57:29 AM »
I run the ATX 30 HD anti gravity battery and love it. It's a beast

Same one I got! While the cam sensor was preventing it from firing I had some time just cranking and the car damn near leapt off the stands lol. Tools shook off the fenders. It was 13.2V fully charged, 12.0V while cranking and while running with no alternator and an electric water pump going it was still 12.8V.

I had been using a fresh large capacity optima red top and the lithium battery feels way more powerful.