LS ECU options

[another69]

I'm looking for some input & weighing my options for controlling my new LS3 480 crate motor (I will be orderingit this winter).
I currently have a Holley HP ECU because I ran it with my old SBC. I was planning on using it to run the LS, because I really like the cable TB vs the DBW. Also making chsnges via laptop is pretty user friendly. The thing I don't like about it is the way it only uses 1 O2 sensor.
It will cost me about $700 for the correct Holley harness + $400 for a cable TB, which puts me in the ballpark of the Chevrolet performance ECU and also Speartech.
Any experience or opions on which way I should go?

[rushca01]

I may be wrong but isn't the Holley ecu much easier to tune then the GM ecu? My vote would be the Holley setup.

[another69]

I thought so too, but I hsve only used the Holley so I have no idea what it takes to work with the GM ECU. I do know that the Holley uses speed density, and GM uses mass air but I don't know if there is an advantage to one or the other.

[Samckitt]

Talk to Dan Howe, he originally had either Holley or FAST (Cant remember), but switched to the GM PCM & was able to get more HP from it than the aftermarket PCM.

[another69]

Ok, this is what I am looking for. I don't want to leave any power on the table.

[rushca01]

By more power did he lean the mixture out....have to be careful.

[andrewb70]

Ok, this is what I am looking for. I don't want to leave any power on the table.

I have the GMPP ECU on my GTO and a Holley Dominator in my Cougar. The GM stuff works very well but tuning is less than intuitive. The Holley is easier to tune, especially once you start getting into more radical cams, forced induction, etc...

I don't believe there is any power to be gained between different ECUs IF they are both tuned optimally. WOT tuning is very easy. What gets hard is drivability, etc...

If GM makes a pre-tuned ECU for the LS3 480, then I would go with that and go to DBW (I will never have a cable TB ever...). However, if you plan on making changes to the engine, then stick with the Holley.

Andrew

[Schwartz Performance]

Talk to Dan Howe, he originally had either Holley or FAST (Cant remember), but switched to the GM PCM & was able to get more HP from it than the aftermarket PCM.
Dan had FAST and switched to GM via a PSI harness. Yep he got a bunch more horsepower from doing so.

[another69]

Thanks for the responses. Andrew- I'm curious why you dislike the cable TBs, because I am totally opposite with my thinking on that. It probably just boils down to personal preference, but still curious...

It would be great if Holley had a base calibration for an LS3, but the closest looks to be the LS2 480 HP. Maybe the self learning function will help, I don't know.
I do plan to make changes, which makes the HP more desirable for that.

[Samckitt]

By more power did he lean the mixture out....have to be careful.

That I don't know.

[another69]

It sounds like any ECU will need some tuning. At least it's pretty easy to monitor A/F with the Holley.

I'm thinking of putting the Holley wideband O2 sensor in the driver's side header, and a separate wideband O2 sensor (that I have laying around) in the passenger header just to monitor it. It would be great if there was a way to run two O2 sensors with the Holley HP, or a way to monitor both banks with one O2 sensor.

[gator68428]

My understanding on the GM ECU is that it is a hybrid of Mass-air and speed density. Apparently for all around performance and driveability having both is better than either option on its own. Perhaps the MAP signal is best at low air-flow (higher vacuum levels) and MAF is better at higher airflow? Anyways, with GM ECU you'd want a tuning software platform like HP Tuners.

[another69]

I've never used HPtuners, I wonder how user friendly it is?

[71RS/SS396]

I don't believe the Holley does bank to bank tuning so it's pointless to have 2 O2's unless it just makes you feel better to look at the data.

[dontlifttoshift]

Tim, are you talking about the HP or the Dominator.....or both?

[nokones]

I would use the Holley. If you have any questions, contact one of the Holley's Tuners that is certified by Holley with the Holley Advanced Training. They are listed on the Holley website. I used Autotrend EFI and he has the capability to connect to your Holley ECU remotely over the internet.

[gator68428]

There are plusses and minusses to both systems.

The benefits of an aftermarket system are greater simplicity for the important tuning parameters of interest and the inclusion of a wideband and ease of tuning. For example the FAST XFI 2.0 system (and from what I hear, the Holley system as well) I have experience with is designed for exactly what ppl typically need: the ability to make tuning changes after modifying engine hardware etc (a factory computer system was not designed to be modified). For example in the fueling VE table after you've taken a data log, as you scroll through your data log, there is a bubble that tracks your position in the VE table, so you know exactly where to make changes. I think HP Tuners does something similar though... But not my Ford EEC (from a 90s Mustang) in my Firebird (long story...).

The benefits of the GM LSx ECU is the usage of MAP and MAF sensors together, which permits perfect driveability under all conditions (with hours of tuning to attain perfection) with the tradeoff of greater complexity: 1) from it being a hybrid system and 2) because its a factory platform in general there are many more parameters of less interest to get bogged down in for novices. And have to consider whether or not a factory system comes with a wideband and how to interface with it for tuning... (not a trivial expense).

My experience involves the MAF based system on my Firebird (Ford A9L EEC, from Mass-FLO EFI circa 2006, now Pro-M racing). Long story short the system (then) was not plug and play for my Pontiac 428. But I'm better for it because now I know how to modify and tune EFI systems.

I've heard many tuners for GM ECUs will disable the MAP and only use the MAF signal for airmass/fueling. It is simpler with a MAF, just a single function (airmass vs sensor voltage) versus a 2 dimensional table (volumetric efficiency as a function of MAP and RPM). But there are auto tuning functions on the FAST and Holley systems... I haven't really tried the FAST auto tuning feature... but wasn't as easy to control as i first thought (maybe Holley is easier?).

My short answer would be HP Tuners if you already had an LSx car with ECU. And stand alone like Holley or Fast if you don't already have an ECU--if you have Holley already then bingo. I have experience with FAST (my father purchased the XFI 2.0 system for his car because Jim Butler sold a kit for Pontiacs) and the system works as advertised and was straightforward; costumer service usually a 30min wait for the callback with differing levels of helpfulness depending on who you talk to; very good user manual however.

MAP systems are more configurable for carb style throttle bodies as well.

[gator68428]

HP Tuners is an established well supported and widespread platform.
Here is the sticky general HowTo for Gen4 Ls if you go that route:
http://www.hptuners.com/forum/showthread.php?9700-Read-Me!!!-Tuning-How-To-s-amp-General-Information

See the first item "Engine Modes" describes the MAF/MAP situation for these engines.

[another69]

I don't believe the Holley does bank to bank tuning so it's pointless to have 2 O2's unless it just makes you feel better to look at the data.

I have the HP, so basically your response is pretty accurate. I just wanted to make sure the bank that the Holley HP is blind to is "in the ballpark" of the other bank.

[another69]

I would use the Holley. If you have any questions, contact one of the Holley's Tuners that is certified by Holley with the Holley Advanced Training. They are listed on the Holley website. I used Autotrend EFI and he has the capability to connect to your Holley ECU remotely over the internet.

Thanks - I had no idea that this was a possibility and seems like it could be a huge help!

[another69]

HP Tuners is an established well supported and widespread platform.
Here is the sticky general HowTo for Gen4 Ls if you go that route:
http://www.hptuners.com/forum/showthread.php?9700-Read-Me!!!-Tuning-How-To-s-amp-General-Information

See the first item "Engine Modes" describes the MAF/MAP situation for these engines.

Thanks for shedding light on the factory ECU. You are steering me towards just going with the Holley, but the detailed response is appreciated!

[71RS/SS396]

Tim, are you talking about the HP or the Dominator.....or both?

I believe the Dominator has the option to connect 2 O2's, but it's an option, I don't THINK it does bank to bank tuning. Most of the aftermarket ecus I've seen ultimately get the tune all jacked up over time if you leave the O2 correction turned on. Get the tune right and leave it alone, no reason to keep fiddling with it imho.

[another69]

I believe the Dominator has the option to connect 2 O2's, but it's an option, I don't THINK it does bank to bank tuning. Most of the aftermarket ecus I've seen ultimately get the tune all jacked up over time if you leave the O2 correction turned on. Get the tune right and leave it alone, no reason to keep fiddling with it imho.

Do you mean the self learning feature? I was curious when & if it should be turned off, but according to Holley they said leave it on. Your logic of turning it off after the tune is right makes more sense to me.

[howehot]

I had FAST ez efi running my LS1 383 to start. Liked the idea of self learning being in NE Iowa a tuner was far away. Long story short it ran at 12:1 afr at best down to 18:1 wot. West Bend Dyno help correct it but it was far from ideal.

I switch to GM with a PSI harness and gain 150 rwhp. Yes, a knowledgeable tuner is required. I was told by a very smart man at one point, who has a bigger budget to perfect efi, GM or some aftermarket. Best advice out there.

[andrewb70]

Thanks for the responses. Andrew- I'm curious why you dislike the cable TBs, because I am totally opposite with my thinking on that. It probably just boils down to personal preference, but still curious...

It would be great if Holley had a base calibration for an LS3, but the closest looks to be the LS2 480 HP. Maybe the self learning function will help, I don't know.
I do plan to make changes, which makes the HP more desirable for that.

I like DBW because running wires is much easier than running a cable. I also like the extra tuning flexibility. The Holley (Dominator only) system has a table for adjusting %pedal vs. %TPS. This allows you to tune how quickly the throttle blades open relative to the pedal travel. This is great because you can slow down the throttle blade movement at low %pedal so driving slowly in traffic is easier. This feature is also vital for me since I have dual TBs.

The 480HP LS2 tune will get you close and you can tune from there. Once the self-learning is done, it is advisable to reduce the % correction in case the O2 sensor goes out. This is easily done in the software.


I had FAST ez efi running my LS1 383 to start. Liked the idea of self learning being in NE Iowa a tuner was far away. Long story short it ran at 12:1 afr at best down to 18:1 wot. West Bend Dyno help correct it but it was far from ideal.

I switch to GM with a PSI harness and gain 150 rwhp. Yes, a knowledgeable tuner is required. I was told by a very smart man at one point, who has a bigger budget to perfect efi, GM or some aftermarket. Best advice out there.

A good tuner is required regardless of what system is being used. I don't know anything the FAST systems, but I can guarantee you that any competent tuner can get the same power from any number of different EFI systems.

As I mentioned before, WOT tuning is easy. Stuff that is hard is part throttle, and believe it or not, idle. It's not so much just the fueling, but spark, and other IAC parameters that can take a long time to get right, especially on engines with big camshafts and low idle vacuum.

Andrew

[Rhino]

Thanks for the responses. Andrew- I'm curious why you dislike the cable TBs, because I am totally opposite with my thinking on that.

I think I understand your viewpoint. I used to be against DBW TB's because they seemed like black magic. I didn't like the fact that there wasn't a mechanical link between what the throttle body and my foot. What changed my mind was putting a new 6.0 in place of one of my truck's existing 5.3. Since it was already DBW I didn't want to swap it out. Tuning is a little different, but easily attainable. Now that I've worked with it on a few projects, I do prefer it. Maybe it's just me, but idle tuning seems simpler with DBW.
As it turns out I was afraid of DBW for no reason other than it wasn't familiar.

My '68 (w/LS1) is still a traditional TB. After working on a few projects with DBW it feels like I'm stepping backwards in time.

[andrewb70]

I think I understand your viewpoint. I used to be against DBW TB's because they seemed like black magic. I didn't like the fact that there wasn't a mechanical link between what the throttle body and my foot. What changed my mind was putting a new 6.0 in place of one of my truck's existing 5.3. Since it was already DBW I didn't want to swap it out. Tuning is a little different, but easily attainable. Now that I've worked with it on a few projects, I do prefer it. Maybe it's just me, but idle tuning seems simpler with DBW.
As it turns out I was afraid of DBW for no reason other than it wasn't familiar.

My '68 (w/LS1) is still a traditional TB. After working on a few projects with DBW it feels like I'm stepping backwards in time.

Idle tuning with DBW is easier because there is no need to strike a balance of correct throttle blade opening with proper IAC values. With DBW there is no actual IAC solenoid.

Andrew

[howehot]

I like DBW because running wires is much easier than running a cable. I also like the extra tuning flexibility. The Holley (Dominator only) system has a table for adjusting %pedal vs. %TPS. This allows you to tune how quickly the throttle blades open relative to the pedal travel. This is great because you can slow down the throttle blade movement at low %pedal so driving slowly in traffic is easier. This feature is also vital for me since I have dual TBs.

The 480HP LS2 tune will get you close and you can tune from there. Once the self-learning is done, it is advisable to reduce the % correction in case the O2 sensor goes out. This is easily done in the software.



A good tuner is required regardless of what system is being used. I don't know anything the FAST systems, but I can guarantee you that any competent tuner can get the same power from any number of different EFI systems.

As I mentioned before, WOT tuning is easy. Stuff that is hard is part throttle, and believe it or not, idle. It's not so much just the fueling, but spark, and other IAC parameters that can take a long time to get right, especially on engines with big camshafts and low idle vacuum.

Andrew

FAST said I didn't have enough injector with the stock units and sold me 60lbs units that made zero difference. Also there programmer only read to 14:1 so I thought not good but driveable.

West Bend determined the problem was the FAST unit was not supplying fuel fast enough so the adjusted the afr rich so the FAST pulled fuel out instead of trying to add it. It was still far from ideal. FAST, although they tried, never came up with a solution. Starting was always a crape shoot. One time a touch of the key it ran, next you frantically pump the gas and cranked. It often stall from a standing start when you nailed it. Just ask Chad Reynolds, he laughed at me on occasion as I took a second shot at the start of many an autox. These problems all went away with GM's system. FAST cost me a lot of money in the unit itself, injectors, Dyno time, the 5 hour drive to the Dyno, and the process of redoing the system.