Author Topic: LS factory ECU or aftermarket?  (Read 708 times)

Ryoko

  • Active Forum Member
  • *
  • Posts: 373
LS factory ECU or aftermarket?
« on: March 03, 2018, 10:04:35 PM »
I'm toying with going with an LS swap. However, the ECU is a bit of a concern. Namely, the requirement that it needs to be flashed to remove the VATS. The companies selling the reprogrammers really want to rape you and your wallet. This makes me want to consider just ditching the factory ECU and going with an aftermarket unit. I'm curious if anyone has some info on how the aftermarket units compare in performance/mileage to a factory unit (Gen4/5).

FormTA

  • Oracle Forum Member
  • *
  • Posts: 2282
Re: LS factory ECU or aftermarket?
« Reply #1 on: March 03, 2018, 10:36:45 PM »
I didn't reflash mine. I bought a little chip I soldered in creates the signal the ecm needs.
79 Trans am 301 (work in progress) LS swap n progress
79 Formula 301 (Work in progress)
67 RS Camaro (Work in progress)
See the recurring theme???

DynoLee

  • Active Forum Member
  • *
  • Posts: 87
      • Lee's website
Re: LS factory ECU or aftermarket?
« Reply #2 on: March 04, 2018, 06:48:42 AM »
I've dabbled in this, but my friend has extensive experience.  He actually had to buy a second HP Tuners, as he filled the first one with all the licenses that it could hold.  He has tuned a few thousand vehicles using HP Tuners.

The GM computer is excellent.  You can mount it anywhere, and it will work fine.  It is very tunable.  I've seen my friend use the factory computer to control turbocharged vehicles putting over 1,100hp to the wheels.  Once you buy HP Tuners, you can use it (as long as you have the licenses) on many different vehicles.

CONS to the factory computer & HP Tuners:  The factory computer is rather ugly, you'll probably want to mount it somewhere out of sight.  Different computers have different tuning screens, tuning options changed as GM "evolved" the computer, so you might find some screens that do things you might not understand.  HP Tuners gives you, I believe, 6 "credits" for licenses when you buy it - some licenses cost 1 credit, others cost more. 


FAST XFI pros:  Attractive unit.  My friend from above has tuned some of these, and complemented how easy to navigate and use.  He tuned a turbocharged BBC to right at 1,000rwhp with an XFI.  The XFI connects directly to a laptop, no interface devices needed. 

CONS:  These can be a bit finicky about electrical interference -  you will want to mount it well away from your ignition box and ignition components, and route the wiring harness away as well.


For me, if I'm using an LS engine, I'm going to use the LS computer.  They were designed hand-in-hand to work together.  Get HP Tuners and you can disable the VATS, do all the tuning you'll ever need, turn on/off CEL options, and also use it on other vehicles.

Ryoko

  • Active Forum Member
  • *
  • Posts: 373
Re: LS factory ECU or aftermarket?
« Reply #3 on: March 04, 2018, 08:38:44 AM »
I'd like to stay with the GM unit since they know the engine and it's requirements very well. But the steep price tag for a tuner is ridiculous. I'm leaning towards an LY6 swap. The questions become what to do about the VATS and what's going to happen if I disable the VVT. (Do I want to disable the VVT?) I haven't had a chance to delve into the details of fooling the VATS into working. But what I've seen so far is that it's not all that difficult. That leaves the VVT. There's also the issue of changing from an automatic to a manual. Most of the LY6's were mated to autos.

scarebird

  • Oracle Forum Member
  • *
  • Posts: 1185
  • Parts vender
      • Scarebird Classic Brakes
Re: LS factory ECU or aftermarket?
« Reply #4 on: March 04, 2018, 12:43:00 PM »
Something like this might be another option:

https://www.gmperformancemotor.com/parts/19354328.html

GM has quite a few swap PCM's and they may have one that works with the LY6.

Re: LS factory ECU or aftermarket?
« Reply #4 on: March 04, 2018, 12:43:00 PM »

jonathonar89

  • Oracle Forum Member
  • *
  • Posts: 1766
Re: LS factory ECU or aftermarket?
« Reply #5 on: March 04, 2018, 02:28:53 PM »
In regards to LS engines, if you you use a computer-controlled auto trans, the price price will go up significantly if chasing an aftermarket ecu.  You'll have to get an ecu that controls the engine/trans collectively or buy an engine computer and then a trans computer separately. 

For most people, the cheapest route to LS is to get a complete pull-out from a 4th gen F-Body.  Many prefer the '99-'02 cars for the later style computer and LS6 intake but the '98 engines are pretty decent too. 

If you go with a "cheap" truck engine like many recommend, you'll find yourself spending a lot of money chasing dumb parts like exhaust manifolds/headers, low-profile oil pan and other things that can add up real quick.  I'm not saying don't go this route but be forewarned of common things many people don't initially see upfront.
1979 Trans Am 400 T-top - Platinum Silver, Carmine Interior
http://transamcountry.com/community/index.php?topic=61460.0

Ryoko

  • Active Forum Member
  • *
  • Posts: 373
Re: LS factory ECU or aftermarket?
« Reply #6 on: March 04, 2018, 03:08:14 PM »
Yeah, I'm getting a pretty good handle on the gotcha's associated with each type of LS swap. I see that there are no LSx solutions that don't have pitfalls and traps. It would be nice if it were a drop-in option. Oh well. Considering how expensive the fuel management systems seem to be, I'm seriously tempted to just build an ECM from scratch.

jonathonar89

  • Oracle Forum Member
  • *
  • Posts: 1766
Re: LS factory ECU or aftermarket?
« Reply #7 on: March 04, 2018, 03:16:05 PM »
Yeah, I'm getting a pretty good handle on the gotcha's associated with each type of LS swap. I see that there are no LSx solutions that don't have pitfalls and traps. It would be nice if it were a drop-in option. Oh well. Considering how expensive the fuel management systems seem to be, I'm seriously tempted to just build an ECM from scratch.

Microquirt controllers are pretty well priced.  Might want to check those out.
https://www.efisource.com/wp/shop/microsquirt-for-ls-composite/#ecu
1979 Trans Am 400 T-top - Platinum Silver, Carmine Interior
http://transamcountry.com/community/index.php?topic=61460.0

Ryoko

  • Active Forum Member
  • *
  • Posts: 373
Re: LS factory ECU or aftermarket?
« Reply #8 on: March 04, 2018, 03:41:11 PM »
Been looking at those along with the Holley ($$$) and MegaSquirt units. I'll have to think about it. Maybe I'll do a design to see how much it would cost to build one. I'm thinking around $100 (not including the harness and sensors). I'm still a long way away from needing an ECM right now. But I like to plan ahead, especially since I got some down time due to weather and a lack of parts.

FormTA

  • Oracle Forum Member
  • *
  • Posts: 2282
Re: LS factory ECU or aftermarket?
« Reply #9 on: March 04, 2018, 04:37:04 PM »
See, I know nothing about this stuff. I know I wanted an LS in my car so I bought a perfect running driving 98, ( ya I hear the 98 is the least desirable but I ended up making money and got a great engine and trans). I dropped the whole thing right in with zero modifications. I just built a relay board and plugged it in. I added the VATs pulse generator and away we went. Engine started right up with only a few coats thrown for the missing emissions parts. I wish I knew more and how to tune... But my set up is fine for a basic daily driver.
79 Trans am 301 (work in progress) LS swap n progress
79 Formula 301 (Work in progress)
67 RS Camaro (Work in progress)
See the recurring theme???

jonathonar89

  • Oracle Forum Member
  • *
  • Posts: 1766
Re: LS factory ECU or aftermarket?
« Reply #10 on: March 04, 2018, 05:11:20 PM »
See, I know nothing about this stuff. I know I wanted an LS in my car so I bought a perfect running driving 98, ( ya I hear the 98 is the least desirable but I ended up making money and got a great engine and trans). I dropped the whole thing right in with zero modifications. I just built a relay board and plugged it in. I added the VATs pulse generator and away we went. Engine started right up with only a few coats thrown for the missing emissions parts. I wish I knew more and how to tune... But my set up is fine for a basic daily driver.

I must admit that I laughed when you said you added the VATS pulse generator and away you went....sounds simple enough to me hahaha jk
1979 Trans Am 400 T-top - Platinum Silver, Carmine Interior
http://transamcountry.com/community/index.php?topic=61460.0

FormTA

  • Oracle Forum Member
  • *
  • Posts: 2282
Re: LS factory ECU or aftermarket?
« Reply #11 on: March 04, 2018, 05:58:06 PM »
I meant as far as computer programming.  :D
79 Trans am 301 (work in progress) LS swap n progress
79 Formula 301 (Work in progress)
67 RS Camaro (Work in progress)
See the recurring theme???

TATurbo

  • Active Forum Member
  • *
  • Posts: 264
Re: LS factory ECU or aftermarket?
« Reply #12 on: March 17, 2018, 09:57:34 PM »
I've been researching this exact question for an LS1 swap into my '81.
I've been working on my cars forever. I've done a couple engine swaps in my 1981, and a replacement in my turbo'd 2004 Grand Prix. So, I wouldn't say I'm a novice with car stuff in general, but this is my first (and probably only) attempt at this type of swap.
The electronics were a significant concern for me. Ideally, I wanted to use a GMPP 'Connect and Cruise' LS3 (everything all in one box from GM). But that was outside my budget.
 After a lot of research, what I've come away with is that, just like choosing which LSx derivative to use for the swap, there are pros and cons for just about every option.  I don't think there's a wrong answer.  Consider your skill set, budget, project goals (time, ascetics, performance (Driver, show, racer?)) in making your decision. Then, bite the bullet and pick one.

I've decided to go with an aftermarket LS swap harness which includes a reprogrammed GM PCM (BRP Hotrods/MuscleRods for me...There are many options here too).
I plan on adding a turbo down the road, my car will be a driver, and I'm a beginner with these motors, so once the GMPP package was eliminated, I was as initially going to go with the 'Atomic LS EFI'.  Clean install, self learning, easy to hook up.  BUT, I ended up with a 1999 LS1/4L60E, which (I've learned) has the Trans and Engine all controlled in the one PCM. Later years use a separate Trans controller.  So, for this specific scenario I'd need to get the trans controller separately...On top of the already pricey Atomic LS EFI.   Time and money wise, the aftermarket harness and PCM programming seemed to be a good middle ground between doing it all on my own or going with a full aftermarket set up for the electronics.

I can't speak to how my choices have worked out yet...Motor should be here any day though!

Hope this helps a little.

-Tom     

   
Tom
King of Prussia, PA

1981 Turbo Trans-Am
Build thread - http://transamcountry.com/community/index.php?topic=69897.0

Re: LS factory ECU or aftermarket?
« Reply #12 on: March 17, 2018, 09:57:34 PM »
You can help support TAC!