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LS4/Megasquirt questions by Meistromichael
Started on: 02-26-2015 01:40 PM
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Last post by: eph_kay on 03-04-2015 07:36 PM
Meistromichael
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Report this Post02-26-2015 01:40 PM Click Here to See the Profile for MeistromichaelClick Here to Email MeistromichaelSend a Private Message to MeistromichaelEdit/Delete MessageReply w/QuoteDirect Link to This Post
Looking at running the LS4 with Megasquirt (MS3 Pro). Ls4/f40 combo

1) MS3 Pro can run 24x and 58x crank sensors. Isn't the 06 ls4 the 24x and 07+ the 58x?
2) Is there a significant benefit from having the 58x crank trigger over te 24x?
3) What issues do you see running MS3 Pro? (In case you think of something that I haven't already)

Thanks guys
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Report this Post02-26-2015 01:58 PM Click Here to See the Profile for Darth FieroClick Here to visit Darth Fiero's HomePageClick Here to Email Darth FieroSend a Private Message to Darth FieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Meistromichael:

Looking at running the LS4 with Megasquirt (MS3 Pro). Ls4/f40 combo

1) MS3 Pro can run 24x and 58x crank sensors. Isn't the 06 ls4 the 24x and 07+ the 58x?
2) Is there a significant benefit from having the 58x crank trigger over te 24x?
3) What issues do you see running MS3 Pro? (In case you think of something that I haven't already)

Thanks guys


I don't know much about the Megasquirt ECU, but I can answer your first two questions.

1) 05-06 LS4's are Gen3 LS engines that had 24x crank sensors. 07-newer LS4s are Gen4 LS engines that had 58x crank sensors.
2) I don't see any particular benefit to using a 58x crank sensor over a 24x sensor if the ECU you are using can be set up to use either one.

-ryan

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Report this Post02-26-2015 02:38 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Darth Fiero:
I don't know much about the Megasquirt ECU, but I can answer your first two questions.

1) 05-06 LS4's are Gen3 LS engines that had 24x crank sensors. 07-newer LS4s are Gen4 LS engines that had 58x crank sensors.
2) I don't see any particular benefit to using a 58x crank sensor over a 24x sensor if the ECU you are using can be set up to use either one.



I don't know much about the MS either. However,

1) All LS4 engines are Gen IV (the block is Gen IV, and all 05-06 Gen IV engines used 24x reluctor, only Gen III engines still in use in 05-06 were truck Vortec motors). All 07+ LSx/Vortec engines use the 58x reluctor. It's common for people to refer to the reluctor change as the generation split poitn, but the split is in some changes in the block/cam design.

2) The 58x reluctor allows a bit better control over timing and is necessary if you want to retrofit VVT. If you're doing MegaSquirt though, you're probably looking to build something with a bigger cam and DoD delete and probably aren't concerned as much about emissions or MPG, so isn't necessary to use.

EDIT: Found the thread. Kemp3 has done an LS4 swap running on MS3. You might want to talk to him: http://www.fiero.nl/forum/Forum1/HTML/091298.html

[This message has been edited by dobey (edited 02-26-2015).]

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Meistromichael
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Report this Post02-26-2015 03:10 PM Click Here to See the Profile for MeistromichaelClick Here to Email MeistromichaelSend a Private Message to MeistromichaelEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks guys. I had dug through the forum trying to find someone who had done this. Apparently I need to refine my search skills. Thanks for the link, That'll help a lot
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Report this Post02-26-2015 06:05 PM Click Here to See the Profile for 87antuzziClick Here to Email 87antuzziSend a Private Message to 87antuzziEdit/Delete MessageReply w/QuoteDirect Link to This Post
Firstly the crank trigger input will have a higher resoulition with the 58. However I have had hit and miss luck with MS on flywheel inputs on several different cars and have said screw it all around and started using CAS sensors from DSM's for trigger input. They are easy to program and both will work however if it were me I would go with the 58 as once again, youll have a higher resolution and if you're doing a 2 step setup with a spark cut it will make it easier to tune depending if you're going to tell the MS box to skip teeth or not. Ive never had good luck with VR sensors so I went to DSM CAS and my problems got easier and my distributor went away.
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Meistromichael
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Report this Post02-26-2015 07:48 PM Click Here to See the Profile for MeistromichaelClick Here to Email MeistromichaelSend a Private Message to MeistromichaelEdit/Delete MessageReply w/QuoteDirect Link to This Post
i have never seen anyone use the DSM cas on an an Ls engine or a v8 for that matter. Did u buy new or pull from a yard?

[This message has been edited by Meistromichael (edited 02-26-2015).]

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Darth Fiero
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Report this Post02-27-2015 03:17 PM Click Here to See the Profile for Darth FieroClick Here to visit Darth Fiero's HomePageClick Here to Email Darth FieroSend a Private Message to Darth FieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:
I don't know much about the MS either. However,

1) All LS4 engines are Gen IV (the block is Gen IV, and all 05-06 Gen IV engines used 24x reluctor, only Gen III engines still in use in 05-06 were truck Vortec motors). All 07+ LSx/Vortec engines use the 58x reluctor. It's common for people to refer to the reluctor change as the generation split poitn, but the split is in some changes in the block/cam design.




You are correct. I just checked into this on GM's powertrain website and indeed all LS4 engines ever produced were referred to as Generation IV (Gen4) engines - which describe their mechanical design and architecture.

Like many other people, I've apparently been incorrectly using the Gen3/Gen4 nameplate to describe LS engines based on what type of crank sensor reluctor wheel they used.
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Report this Post02-27-2015 03:40 PM Click Here to See the Profile for 87antuzziClick Here to Email 87antuzziSend a Private Message to 87antuzziEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Meistromichael:

i have never seen anyone use the DSM cas on an an Ls engine or a v8 for that matter. Did u buy new or pull from a yard?



Im not running a 8 cyl but rather a boosted 4cyl. I have a adapter that runs off the intermediate shaft that used to turn the dizzy. I got the actual sensor from a junkyard and bought a new encoder online
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Report this Post02-27-2015 06:46 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Darth Fiero:
You are correct. I just checked into this on GM's powertrain website and indeed all LS4 engines ever produced were referred to as Generation IV (Gen4) engines - which describe their mechanical design and architecture.

Like many other people, I've apparently been incorrectly using the Gen3/Gen4 nameplate to describe LS engines based on what type of crank sensor reluctor wheel they used.


Yeah. I see it all over the internet, mostly when people are discussing the LS2 and LS4, since they both had a few small changes in 07. Gen IV blocks have cam sensor at front in the timing cover, have venting between cylinders to help control crankcase pressure and windage, can be machined for the LS9/LSA piston oilers, and can have VVT and AFM. Gen III blocks have cam sensor in the rear of the block with the reluctor machined into the camshaft, don't have cylinder venting, can't use piston oilers, and can't be retrofitted with VVT/AFM. The only production Gen III V8s that came in cars (not trucks) were the LS1 and LS6. All other Gen III V8s were Vortec engines in truck/SUV/van platforms.

Anyway, just spreading the knowledge. Now you know.
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Report this Post02-28-2015 09:16 PM Click Here to See the Profile for eph_kayClick Here to Email eph_kaySend a Private Message to eph_kayEdit/Delete MessageReply w/QuoteDirect Link to This Post
I don't see any advantage of 58x vs 24x on the motors, the 58x is a 60-2 signal, but I think the 24x on the ls motors is way more complicated than that, its not a 26-2 or anything, it actually has a sequenced spacing that will give a nice precise signal.

I am running ms3 on my vr6 rabbit with ls truck coils and it seems to run nice up to redline of about 7k, I haven't really pushed it all the way up there, just upped the boost to 15psi and my maf isn't quite scaled properly yet. I also have microsquirt on a yamaha vmax with a turbo on it, and I have't gotten a chance to really tune it, but it has a custom crank trigger wheel and uses subaru crank position sensors, I ended up with a 20-2 crank wheel to give enough room to run the cam trigger wheel off a cam lobe set in the valve cover, and so far running wise its doing good, still a lot to work out on it though

Chris

*edit*
the rabbit runs off a 60-2 signal

[This message has been edited by eph_kay (edited 02-28-2015).]

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Report this Post03-01-2015 06:09 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by eph_kay:
I don't see any advantage of 58x vs 24x on the motors, the 58x is a 60-2 signal, but I think the 24x on the ls motors is way more complicated than that, its not a 26-2 or anything, it actually has a sequenced spacing that will give a nice precise signal.


I have no idea what you mean by a 60-2 or 26-2 signal here. The ECM doesn't see 60 pulses and then subtract two of them. The crank sensor is an inductive type. The signal is on when the teeth pass through the magnetic field of the pickup. As the 24x reluctor's teeth are not evenly spaced, this produces a slightly odd and uneven signal. The 58x reluctor on the other hand, has evenly spaced teeth, and will produce an even signal. The 58x reluctor also has more teeth, and will thus have a higher precision than the 24x engine (which is exactly why GM made the switch in the first place).

The 24x signal looks like this:


(I can't find an image of the 58x signal, but the signal steps are evenly spaced, save for the one large gap.

Here is what the reluctor wheels look like:


Having more teeth and having them more evenly spaced means a more precise reading. It also allows for more accurate control of any other electronically controlled actions which rely on the reading of the crankshaft position, such as ignition and variable valve timing. For GM, this means lower emissions and better fuel economy, so they can better meet the new regulations coming at them.

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engine man
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Report this Post03-01-2015 06:18 PM Click Here to See the Profile for engine manClick Here to Email engine manSend a Private Message to engine manEdit/Delete MessageReply w/QuoteDirect Link to This Post
60-2= 58x it just means there are 2 teeth missing out of a 60 tooth wheel so there is 58 teeth the same with 26-2 =24x just two different ways to say the same thing
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Report this Post03-01-2015 10:42 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by engine man:
60-2= 58x it just means there are 2 teeth missing out of a 60 tooth wheel so there is 58 teeth the same with 26-2 =24x just two different ways to say the same thing


I can do math, but that is not how the wheels are designed. Maybe adding two teeth to the 58x LSx reluctor could make it a 60 tooth wheel, but it's not a 60x reluctor that had two teeth removed. The extra spacing in the one spot on the wheel is intentionally there as a marker for the pickup. And as you can see in the picture, the 24x wheel has no such gap. Instead it has two planes of teeth. This is why the 24x and 58x also have sensors specific to those applications.
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Report this Post03-02-2015 01:31 AM Click Here to See the Profile for MeistromichaelClick Here to Email MeistromichaelSend a Private Message to MeistromichaelEdit/Delete MessageReply w/QuoteDirect Link to This Post
Dobey, IIRC, didn't you entertain the idea of retrofitting VVT on the LS4? I remember reading it somewhere, I think there was an issue with the water pump clearance. If I'm right about that, did you ever get around to testing it, or was it just extremely impractical?
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Report this Post03-02-2015 08:28 AM Click Here to See the Profile for engine manClick Here to Email engine manSend a Private Message to engine manEdit/Delete MessageReply w/QuoteDirect Link to This Post
OK i see what you are saying on the 24x I think i would go with the 58x wheel and a Hall sensor i know some have good luck with the VR sensor but why go through all the pain of trying to get it tuned in when you can just plug in the Hall sensor and be done with it
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Report this Post03-02-2015 10:28 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Meistromichael:

Dobey, IIRC, didn't you entertain the idea of retrofitting VVT on the LS4? I remember reading it somewhere, I think there was an issue with the water pump clearance. If I'm right about that, did you ever get around to testing it, or was it just extremely impractical?


Not entertaining the idea. I'm doing it. It requires a lot more on the LS4 than just the cam, gear, bolt, timing cover, water pump, and wiring/ECM though. The LS4 balancer also won't clear the VVT front cover. So a crank with standard length post must be used, as well as a balancer design that will clear the pump. If using a mechanical water pump and other accessories, this also means changes to the entire accessory drive. I'm only going to be running an alternator I think, and using an electric pump, so I should mostly be OK there. I do need to find a crank I want to use, and the right balancer. I'm wanting to save as much weight as possible within economical reason, too, so I haven't got there yet.
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Report this Post03-02-2015 10:32 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post

dobey

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quote
Originally posted by engine man:

OK i see what you are saying on the 24x I think i would go with the 58x wheel and a Hall sensor i know some have good luck with the VR sensor but why go through all the pain of trying to get it tuned in when you can just plug in the Hall sensor and be done with it


I don't think a Hall sensor would work. The reluctor isn't magnetized. The OEM inductive sensor is what it's designed to work with, and it's not that hard to tune for it. I don't know what all the MS3 needs there, but for an OEM ECM, you just use the right ECM and right sensor/reluctor combo, and the timing tables are using crank angle, not number of pulses, I think.
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Report this Post03-02-2015 12:00 PM Click Here to See the Profile for engine manClick Here to Email engine manSend a Private Message to engine manEdit/Delete MessageReply w/QuoteDirect Link to This Post
the Hall for crank sensor doesn't need a magnetic wheel as i went from VR to Hall on the Audi and the trigger wheel is not magnetic i bought mine from Megasquirt

[This message has been edited by engine man (edited 03-02-2015).]

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Report this Post03-02-2015 12:29 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by engine man:
the Hall for crank sensor doesn't need a magnetic wheel as i went from VR to Hall on the Audi and the trigger wheel is not magnetic i bought mine from Megasquirt


OK. Well either one should result in the same signal going to the ECU, so I don't see how trying to switch to a hall sensor would make it "easier" to tune. The OEM sensor for either the 24x or 58x wheel on the LSx engine will work fine. I wouldn't switch from OEM sensors unless absolutely necessary.
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Report this Post03-02-2015 06:27 PM Click Here to See the Profile for engine manClick Here to Email engine manSend a Private Message to engine manEdit/Delete MessageReply w/QuoteDirect Link to This Post
i don't mean tune the engine , the VR you have to tune the signal from it by turning pot screws but the hall you don't have to go through all of that and the VR is more sensitive to back ground noise
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Report this Post03-02-2015 08:43 PM Click Here to See the Profile for MeistromichaelClick Here to Email MeistromichaelSend a Private Message to MeistromichaelEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:


Not entertaining the idea. I'm doing it. It requires a lot more on the LS4 than just the cam, gear, bolt, timing cover, water pump, and wiring/ECM though. The LS4 balancer also won't clear the VVT front cover. So a crank with standard length post must be used, as well as a balancer design that will clear the pump. If using a mechanical water pump and other accessories, this also means changes to the entire accessory drive. I'm only going to be running an alternator I think, and using an electric pump, so I should mostly be OK there. I do need to find a crank I want to use, and the right balancer. I'm wanting to save as much weight as possible within economical reason, too, so I haven't got there yet.


Awesome, will/do you have a build thread documenting the process? Also, I have access to quite a few junkyard ls's, so if you come up with one you want to try, let me know. I'd be happy to ship you one at cost just to keep you going on the idea, so I'll have a baseline to start with in a few months

Edited to add: what about the 4.8/5.3's with VVT. A L20 4.8 rotating assembly would make a nice high revving project. More realisticly, the 2010+ 5.3 vortec shad VVT and might work

[This message has been edited by Meistromichael (edited 03-02-2015).]

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Report this Post03-03-2015 09:34 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by engine man:
i don't mean tune the engine , the VR you have to tune the signal from it by turning pot screws but the hall you don't have to go through all of that and the VR is more sensitive to back ground noise


The LSx crank sensor does not have that. Nor did the one on my Mini Cooper when I replaced it. I don't know what the sensor on the Audi is like, but that seems odd to me.
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Report this Post03-03-2015 10:13 AM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by Meistromichael:
Awesome, will/do you have a build thread documenting the process? Also, I have access to quite a few junkyard ls's, so if you come up with one you want to try, let me know. I'd be happy to ship you one at cost just to keep you going on the idea, so I'll have a baseline to start with in a few months

Edited to add: what about the 4.8/5.3's with VVT. A L20 4.8 rotating assembly would make a nice high revving project. More realisticly, the 2010+ 5.3 vortec shad VVT and might work


Yes, I do have a build thread already. I have a 4.8 (non-vvt) short block sitting in my garage, which I was going to use the rotating assembly from. So I have that if I decide to use a stock crank. I've been thinking of going to fully forged though, if I can save a reasonable amount of weight with it. So I've been doing a lot of searching to see if I can find a rotating assembly that would actually be lighter than stock, for a reasonable price. My stock LS4 crank weighs 53 lbs though, so I'm still trying to decide how much weight savings will make the cost reasonable to go forged, and finding out much it will cost to get that weight savings. So it's going a bit slow.

If you want something easy though, you don't want VVT. And you don't want the truck accessory drive. The accessories on the trucks stick out pretty far, which will create interference with the cradle/frame even on the LS4.
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Report this Post03-03-2015 11:27 AM Click Here to See the Profile for eph_kayClick Here to Email eph_kaySend a Private Message to eph_kayEdit/Delete MessageReply w/QuoteDirect Link to This Post
Dobey, engine man is talking about trim pots inside the megasquirt computer, only on the custom applications do you have to tweak them to get the megasquirt happy, the trim pots aren't anything to do with the stock ecus or the sensors.

It doesn't always happen on megasquirt, I didn't have to readjust my trim pots at all on my car, and honestly on the microsquirt it doesn't give the option, then again, it might require hall effect over vr, but then again, people run the ls motors on microsquirt quite often with all stock stuff.

Chris
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Report this Post03-03-2015 11:45 AM Click Here to See the Profile for engine manClick Here to Email engine manSend a Private Message to engine manEdit/Delete MessageReply w/QuoteDirect Link to This Post
i am sure you wont have to adjust if you buy the Megasquirt all built but i built mine you might even be able to buy a plug and play for the LS engine and that would be the way to go
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Report this Post03-04-2015 07:36 PM Click Here to See the Profile for eph_kayClick Here to Email eph_kaySend a Private Message to eph_kayEdit/Delete MessageReply w/QuoteDirect Link to This Post
Other than the micrsoquirt that you can't build, I did all the build on my megasquirt, I just adjusted them to the recommend setting and they were good to go

Chris
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