Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: 5.7 vortec with 24x and cnp is cdi possible?

  1. #1
    New Member
    Join Date
    Jul 2016
    Posts
    5

    Default 5.7 vortec with 24x and cnp is cdi possible?

    I am rebuilding and preparing, a 97 vortec 5.7 I pulled from my Tahoe, to prepare it so it can go into my 2002 crew cab Sonoma. I am building this engine for reliability and fuel economy. I am planning to use the 24x reluctor wheel kit from efi connection so I can use ls1 coil near plug coils. This will greatly increase reliability by allowing me to use a double roller timing chain and making the distributor be only a cam position sensor. And being able to tune more timing and dwell will help fuel mileage. the Sonoma already has the 411 pcm and I will be using a nv3500 5 speed and np241 manual transfer case from a different 97 truck. so I won't have to worry about transmission or 4wd low when tuning. Most people use a base tune from a ls early 2000s camaro when converting a 5.7 to ls cnp. I have read a few things saying ac won't work with that tune something about analog cycling still trying to figure that out. One thing I was reading said a tune from a 03 up express van with the ls motor will fix the ac issue, still looking into that. But biggest question I have is is there a cdi ignition system that will work with ls cnp? I know the ls coils are smart coils meaning they have internal ignitors. And cdi's don't work with internally ignited coils. But AEM makes ls1 dumb coils design for external ignitors. But I can't find anything on if a cdi ignition like msd's street fire can run multiple coils like this or if there is a cdi ignition that can. I know msd sells a controller for ls engines to control spark when you run a carb but I don't think that's a cdi. Also if there is a cdi that would work how would a cdi system be wired into coil near plug mainly the coil trigger wires from the pcm to control the coil ignitor. Is there an external ignitor module I would have to wire in? Thank you in advance for any help or info you can give

  2. #2
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    4,798

    Default

    If you're paying all the $$ for an EFI Connection 24x kit, cant you just find some junkyard LS coils off a truck and use those?

    Or is your question really related to how to ensure the AC will function properly in your base tune? You can change the function of the pin input for the AC on 0411 PCMs from AC to recirc.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, starting the mods
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  3. #3
    New Member
    Join Date
    Jul 2016
    Posts
    5

    Default

    Quote Originally Posted by ScarabEpic22 View Post
    If you're paying all the $$ for an EFI Connection 24x kit, cant you just find some junkyard LS coils off a truck and use those?

    Or is your question really related to how to ensure the AC will function properly in your base tune? You can change the function of the pin input for the AC on 0411 PCMs from AC to recirc.
    I could use junkyard coils but was planning new coils. My question on coils is there a way to make the 8 coils work with a capacitive discharge ignition (cdi) cdi's like msd are a common upgrade on older distributor type ignitions. But I can't find nothing on if they can be made to work with coil on plug. Only thing I have found is that cdi's don't work with "smart" the coils. But AEM makes a version of ls coils that are "dumb" coils. But still haven't found if there's a way to make it work

    For ac my question was if you could switch it in the tune from analog cycling and to recirculation. Do you have any links to that? Also which type does a 98-03 corvette use? That's the base tune I will probably use because 98-03 vettes used the same 411 computer a ls1 dbw electric fans and had standard transmissions so that should be a good starting point then adjust everything from there

  4. #4
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    4,798

    Default

    Got it, but my question is why? There's a reason GM went with self-contained coils with the LS motor, they're pretty dang reliable (even used). You could likely use the "dumb" AEM coils and a CDI setup, but that sounds like adding complexity where a simple solution would work just fine. It's your project and $$, so please build it how you prefer, I just dont know of the advantage of going this route vs normal coils and if the additional work is worth it in the long run. I know the advantage of upgrading CDIs on older, dizzy engines, but if you're planning to run this like an LS then my vote would be to convert everything over to LS-style otherwise I dont know why you'd spend the time/$$ to use an older engine with the stock 0411 in the Sonoma?

    If you want to use the stock 02 PCM, you'll need to use an 02 Vette/Camaro/truck OS as in 02 GM moved to a 1MB LS1 PCM (03-07) and the 512kb vs 1MB OS's are not interchangeable. For an 02 manual vehicle, that's pretty simple as there are multiple options available.

    G0106 is the parameter in a 02 OS 12212156 that controls Fan #2 to Recirc. I checked a Camaro and Vette file, both are set to Fan #2 control by default. It appears both ETC/DBW tables for the Vette and Camaro OS are configured the same way, the Camaro tune just has it disabled from the factory as they run DBC throttles.

    I might recommend using a DBC throttle as it might make the wiring and programming simpler, but YMMV.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, starting the mods
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  5. #5
    New Member
    Join Date
    Jul 2016
    Posts
    5

    Default

    Quote Originally Posted by ScarabEpic22 View Post
    Got it, but my question is why? There's a reason GM went with self-contained coils with the LS motor, they're pretty dang reliable (even used). You could likely use the "dumb" AEM coils and a CDI setup, but that sounds like adding complexity where a simple solution would work just fine. It's your project and $$, so please build it how you prefer, I just dont know of the advantage of going this route vs normal coils and if the additional work is worth it in the long run. I know the advantage of upgrading CDIs on older, dizzy engines, but if you're planning to run this like an LS then my vote would be to convert everything over to LS-style otherwise I dont know why you'd spend the time/$$ to use an older engine with the stock 0411 in the Sonoma?

    If you want to use the stock 02 PCM, you'll need to use an 02 Vette/Camaro/truck OS as in 02 GM moved to a 1MB LS1 PCM (03-07) and the 512kb vs 1MB OS's are not interchangeable. For an 02 manual vehicle, that's pretty simple as there are multiple options available.

    G0106 is the parameter in a 02 OS 12212156 that controls Fan #2 to Recirc. I checked a Camaro and Vette file, both are set to Fan #2 control by default. It appears both ETC/DBW tables for the Vette and Camaro OS are configured the same way, the Camaro tune just has it disabled from the factory as they run DBC throttles.

    I might recommend using a DBC throttle as it might make the wiring and programming simpler, but YMMV.
    Mostly curious if using a cdi ignition would make any improvements on a ls cup system. the ls cup is already a huge improvement over the distributor ignition just wondering if there is a way to make it work and if can make it work would it be any more of a gain? that's mainly why

    I plan to use the marine intake for 08 and up mercruiser it is designed for 4 bolt throttle bodys like ls2 throttle body. So ya I am planning dbw I was planning on using pedal and tac module from a 97-03 vette and that is also the base tune I plan to use. The complexity of the wiring I should be able to figure out its the tuning that I am trying to learn more about and figure out.

    I am using the older vortec not an ls because i already have it and I am more familiar with them engines. Plus It will be unique and I find it fun building things differently and figuring out how to make it work ya I could go to the junkyard grab a 5.3 or 6.0 and have it in and running in a week or 2 for a lot less but were is the fun in that

  6. #6
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    4,798

    Default

    MSD makes upgraded LS coils; I dont know anyone that runs them because the stock LS coils are plenty powerful even up to really high HP levels. You might see a minuscule improvement with something else like the setup you're thinking about, but I would bet money you'll never notice a difference. I get wanting to be unique, I just dont want to see this fail or spend lots of time/$$ on it chasing issues that could easily be avoided.

    Didnt know the Mercruiser manifold has a 4 bolt GM throttle body pattern (makes sense though). Should open up a bunch more options for throttle bodies. Since you want to run an 02 Vette OS, you'll need to make sure the TAC, OS, and pedal work with the newer LS2/LS7 style throttle body. I'm not super familiar with the limitations around the LS1 PCM and different DBW throttle bodies/pedals (Gen IV stuff is super picky).

    I know I said it before, but going DBC would be pretty simple. Slap an (aftermarket) 90mm DBC throttle body, use the stock pedal setup that's in your Sonoma, flash V8 Camaro OS, make sure wiring matches Camaro setup.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, starting the mods
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  7. #7
    New Member
    Join Date
    Jul 2016
    Posts
    5

    Default

    A lot of people use ls2 throttle bodys on ls1 corvettes they either use adapters for the tb to bolt to intake or they use modified manifolds so it will bolt on. wiring uses a different connector for the throttle body so they have to switch connectors or use a wiring adapter. Then just got to modify the tune for the larger throttle body otherwise the ls2 throttle body Works. Tac modules and pedals have to be a matched set.

    And who knows if a cdi would help or not or even be worth it

  8. #8
    New Member
    Join Date
    Jul 2016
    Posts
    5

    Default

    Do 02 corvettes have case grounded 02s or are they grounded through the pcm for heater circuit malfunction detection?

  9. #9
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    4,798

    Default

    Ok, if the TAC module will run a LS2 style tb then you should be set. Gen IV setups dont play nicely with different tb, pedal, OS combinations.
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, starting the mods
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  10. #10
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    27,752

    Default

    Quote Originally Posted by 87bluebird View Post
    Do 02 corvettes have case grounded 02s or are they grounded through the pcm for heater circuit malfunction detection?
    4-wire NBO2 grounded via harness.

Page 1 of 2 12 LastLast

Similar Threads

  1. 58x vs 24x waveform?
    By N0DIH in forum Gen IV V8 Specific
    Replies: 10
    Last Post: October 12th, 2018, 10:26 AM
  2. 24x reluctor for Vortec truck apps
    By hog in forum Vortec V6/V8 Specific
    Replies: 13
    Last Post: November 4th, 2014, 02:19 AM
  3. Replies: 3
    Last Post: August 29th, 2014, 12:32 PM
  4. New 24x and 58x for SBC and 4.3L V6
    By S10Wildside in forum Conversions / Aftermarket Parts
    Replies: 4
    Last Post: April 29th, 2013, 01:17 AM
  5. 24x conversion questions
    By monzaaddict in forum Conversions / Aftermarket Parts
    Replies: 1
    Last Post: July 5th, 2009, 11:11 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •