MJJ_ZX6RR

Hi all,

I am looking for a little (well, a lot would be nice too) LS2 engine management knowledge, and am drowning in forum posts, opinions and recommendations everywhere with no way of validating sources/expertise. I am hoping some of you good folk on here will have some pointers to start me down the right path - being based in the UK, the breadth of knowledge on these engines is patchy.

I have just bought a Caterham clone kitcar, that had a crate LS2, TR6060 box, and standard GM engine management ECU engineered into it back in 2014. The car is mechanically finished, and has been used for 1,500 miles or so perfectly happily, but the tune is far from perfect. It is running lean in the midrange, so lean that it won't pull through 3,000 rpm most of the time. I think a combination of restrictive cats needed to pass the initial tags/registration/IVA here in the UK, a less than perfect intake, and a stock ECU are all the root cause problems.

What I am trying to find out is, should I be going straight to aftermarket management, or is the GM ECU readable and mappable to the DIY-er? I am well versed in Megasquirt from my turbo MX5, but the LS2 lump is a mystery to me. I have been reading about EFILive, but I don't know whether the $1,000 for software to read the stock ECU is worth it, or if I should be putting that money towards a MoTec, DTA, etc.

I knew the tune was poor when I bought it, but the potential of 400bhp/400lb-ft of reliable power in a 600kg toy made this worth taking on.

If anyone has any tips for books/blogs/forum posts etc. that I can use to rapidly increase my LS knowledge, I would be eternally grateful.

Thanks all, and yes I know this is still a Miata forum. The car has a Miata diff in it if that helps ........

Martin

ps: A couple of pics so you have an idea of what I am talking about.

JasonC SBB

hptuners

Art

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DaWaN

I think you should be able to get the tuning software for less than 1000 dollars?
Apart from EFI Live, also have a look at HPTuners. The HPTuners VCM Suite is 500 dollars and I think it is capable of retuning your GM ECU.
I see no real point in swapping out the ECU for something different if you just wish to adjust the tune.

Padlock

I haven't had an LS2 car specifically, but I have used HpTuners to re-flash the factory ECU on my 6.0 LQ9 Chevy Silverado, 6.0 L76 Pontiac G8, 6.2 LSA Cadillac CTS-V, and 2.0 LNF Chevy Cobalt SS. It works fantastic. Great logging capabilities right out of the box, and retains the OBD2 port if you live in an area that requires emissions testing. Buy the pro version ($600 I think) as it allows you to input (2) additional 0-5v sensors, so for your sake you would take value in logging a wideband o2 sensor. (LS cars only have factory narrowband). The standard cable doesn't have the additional 0-5v inputs, which limits what you can log. Once you have the cable and software, you can log into their website and view an online tune repository. In there you will find tons of tune files that people have saved with a wide variety of modifications done. USE THOSE AT YOUR OWN RISK, but its still a nice value if you want to compare what you did to someone else. Depending on the OEM ECU you have, HpTuners gives you the option to run it on MAF or do Speed Density. Its as simple as re-flashing the operating system which is a no cost ordeal. The HPTuner forum is a great reference tool if you run into issues.

About the ONLY reason I'd recommend not going HPTuners and going through the hassle of a full standalone such as an MS3-Pro would be if you find the need to add a traction control / launch control systems. HpTuners on factory ECU doesn't have those capabilities.

acedeuce802

iTrader: (1)

I am in process of building an LS1 Miata, and I chose to use the Diyautotune MS3pro LSx Drop on Harness, even though I won't have any power adders or anything (turbo, nitrous, etc). One large reason is that I already am familiar with Tuner Studio, and have the paid license for it. I've been tuning my turbo Miata for years with it and am very comfortable with it. HP Tuners also has costs associated with software and purchasing tokens for you ECU, so it's not like it's free to tune the ECU. However, I didn't look too much into the costs of HP Tuners or anything. Another reason is the feature content. I love to play around with cool controls features, such as flex fuel blend tables, launch/traction control, flat-foot shift, PWM fan and fuel pump speed, and much more as I'm sure you know with Megasquirt experience. The last reason is the ability to use a cheap Raspberry Pi instrument cluster (or tablet). If I were to use a stock ECU, I would likely use a Racepak, which the GM ECU's don't broadcast over all data too and that forces redundant sensors. I'm not sure if HP Tuners has the same on-the-fly tuning ability as Megasquirt, but I love how you can tune a fuel or spark map real-time, and not have to pull over, shut the car off, flash, and go again. VE Analyze Live is also very nice.

Regarding the MAF vs. MAP, the stock ECU can be retuned for MAP. A lot of guys do this with success, and report on it running better than the stock MAF tune. On paper, I like the idea of a MAF, but have no experience with one. When I get mine running, I will be using an LS7 intake and MAF, as well as have the MAP sensor hooked up to Megasquirt. I'll start with a speed density base tune, optimize it, datalog the MAF while running, then eventually convert over to a MAF tune with the data that I collected to create the mass transfer function. Then I will assess whether the car ran better on speed density or MAP.

MJJ_ZX6RR

Thanks for the replies all, very helpful. Sorry for the delayed comeback, I picked the car up yesterday and drove the 170 miles back to my place.

The car car drives very well in most instances, and that mountain of LS2 torque in a lightweight car is great fun. The fuelling hole is at around 2,800rpm, and is only a problem if I try to gently accelerate through it - go hard from 2k and it just flies through and beyond the flat spot.

It sounds like continuing with the OEM ECU is the way to go, sounds like the ECU can cope with a wide range of changes from a stock map. I just need to decide which software route to take. Speaking to the previous owner, the ECU has already been mapped using EFILive, so using that route may be best.

Interesting comment about the intake being swapped round. I had not spotted that. The car runs well with it the way it is, perhaps GM designed it to be reversible to fit a wider range of standard cars.

Does anyone know how good the datalogging capabilities of HPTuners or EFILive are? I really need to log air/fuel from both banks using the two narrowband sensors (one in each side exhaust, pre-cats) already installed, as that should point me toward the map problems.

Martin

DaWaN

I think you should install at least a wide band to get any decent knowledge of A/F ratios while tuning. Narrow band will only tell you if you are lean or rich, that is not enough information to tune it where you want it to be I am afraid.

MJJ_ZX6RR

Good point. I have an AEM failsafe and wideband. I only have two bosses in the exhausts currently, both with narrowbands in. I wonder if I could replace one with the AEM WB, and feed both the failsafe gauge and the GM ECU at the same time ....

Some more searching to do.

Padlock

EFI Live is not nearly as popular for the LS platform as HPTuners is, although I'm sure it still works find. EFI Live is used much more prevalently in the states for diesel trucks.

HPTuner Pro can log (2) 0-5v signals at once.
You could have one wideband sensor in each bank (replacing the narrowbands) and wire the wideband signal from the controller to the failsafe and HPT cable, then have the narrowband signal from your wideband controller go to the GM ECU. This would allow both your ECU and your cable to read AFR on both banks and require no welding, but would require 2 wideband controllers/sensors.
OR
You can just weld in another bung pre-cat on both banks, plug one bung and have the wideband sensor in the other, then wire the wideband controller outputs going to your gauge and HPT cable. If you want to read which bank is leaner, just switch your plug and sensor in your exhaust. Not sure how much of a pain swapping a sensor across to the other side of the car would be for you.
OR
Delete the cats. Remove the secondary o2 sensors and eliminate them from triggering a check engine light with your fancy HPT cable. Now you have 2 open bungs to either plug or use for wideband sensors to wire in like above. This is the route I chose on my CTS-V.