There was in interesting thread regarding knock sensor tuning issue of a bone-stock LS3 crate motor located here.https://www.corvetteforum.com/forums/c5-scan-and-tune/4145557-remote-tuning-an-ls3-swapped-c5.html

I too am looking at a LS3 Crate Motor swap but in my case, I want to go with the LS3 Chevrolet Performance LS376/480 LS3 6.2L 495HP Crate Engine.Note> The Chevy Performance Parts Document that comes with this engine has the following USER NOTE.

User Note: The Chevrolet Performance Parts LS376/480 crate engine comes equipped with the LS Hot Cam and the LS376/525 comes with the LS ASA cam both of which are aggressive high performance camshafts that may cause slight surging below 2500 rpm under light load. This should be considered a normal functioning occurrence given the aggressive nature of these camshafts. This surging can be avoided by increasing either the rpm or throttle of the engine at the same given velocity.
OK after review, “may cause slight surging below 2500 rpm under light load” which means if you are cruising down the highway in 6th gear, below 2500 rpm you MAY experience slight surging…

In my Case> Reviewing the knock sensor tuning issue in the above thread and the “possibility of surging below 2500 rpm” I have come to the conclusion that I need to get further info…Fortunately for me, I live in an area whereas where as I can meet the Katech’s/ Lingenfelter’s and such, face-to-face to get their take on these issues and possible solutions to these issues.
Way forward; We have a few industry shows coming up in the next two months in my area and I plan to meet/discuss these tuning topics for with these heavy hitters with the hopes of moving forward with this swap…

Just though I would share my situation…

Cheers,

Goose

 

 

My engine is fine, just want a ltttle more reliable power.

 

 

Resolving the knock sensor issue wont fix the low end surging/bucking from an aftermarket camshaft. Most shops only focus on WOT because thats the number that sells.

WOTs pretty easy to calibrate. In my book, the money is made calibrating the low end properly then moving on to WOT.

Like I said in the linked thread, if your doing a swap, your tuner will love you if your engine, transmission and computer come from the same donor car then build on it.

 

While trolling the interwebs, I stumbled across the following at https://www.lsenginediy.com/

Knock SensorKnock sensors are used by the PCM to reduce ignition timing if detonation occurs. With varyingfrequencies produced by the engine, the knock sensor vibrates to generate a small voltage thatis interpreted by the PCM as normal (no ignition timing retard necessary) to severe (retardignition timing by predetermined amount).

For best results, the knock sensor(s) should be located where detonation-related frequenciescan be detected. The sensor should be of a design that accurately generates the appropriatevoltages to the PCM when those frequencies occur. With the introduction of aftermarketvalvetrain upgrades, larger-cubic-inch engine builds, and other aftermarket parts that alterengine frequencies, matching a knock sensor, its location, and PCM calibration details can bedifficult.

There are two types of knock sensors used with the LS-series PCMs: resonant and flatresponse. The resonant sensor is a single-wire connection to the PCM and the flat-responsesensor is a two-wire connection to the PCM.

Resonant Knock SensorThe single-wire resonant knock sensor was introduced with early small-block engines. This sensor typically threads into one of the coolant plug holes near the center of the block justabove the oil pan. TPI engines use only one knock sensor and, with the exclusion of theCamaro and Firebird, LT1 engines use two knock sensors.

LS-series engines use a similar knock sensor with a straight M10x1.5 thread. In the LSseries engine, resonant knock sensorsare found under the intake manifold.

Flat-Response Knock SensorThe two-wire, flat-response knock sensor requires either an attaching bolt or stud forattachment to the engine. The flat-response knock sensor was introduced with the 2005 LS2engine and with the 2001 4.3L Vortec engine. With proper calibration changes and a littleengine wiring work, the early LS-series PCM can be configured to use the flat-response knocksensors. It’s a convenience for LS2 engine swaps into LS1 vehicles.

OK>>”With proper calibration changes and a little engine wiring work, the early LS-series PCM can be configured to use the flat-response knock Sensors”.

Has anyone out there who has performed the LS3 Crate Motor Swap using LS2 or LS3 (GEN IV) Knock Sensors got their C5 Based PCM to tune/work with these (GEN IV) Knock Sensors?

Goose

 

The whole surging thing is all Bs. All you have to do is tune the car correctly, trouble is most people don't do that. When you go to a tuner, it is unlikely they are going to do enough idle tuning and driveability tuning to get rid of all those problems. Anytime you have a big cam in a car, you sacrifice something on the low end. GM is simply covering their butt by telling you to expect that but you can easily find a tuner who can make the car run as nice as a brand new one. Just be prepared to pay. It's not going to be $100 tune.

your best bet is to pay $500 for the tuning school and then to nothing yourself. Your time is plentiful at $0 per hour where a tuners time, not so much.

 

x2. There are plenty of capable tuners but when they tell a guy they need his car for a few days and it costs a ton they cheap out hoping for the best. It never works.
If you still get alittle surge then drive around it, regear. Dont try and drive it like its stock trying to get 30mpg then complaining. ITs not stock anymore

 

After 15 years why is the software(EFI/HP) not capable of self tuning a basic h/c/i car?

 

probably because the work to write the code to do that job is not worth the time of any competent programmer. They have a bad enough situation with liability just bricking PCMS during communication. Can you imagine the BS they would have to put up with when people's cars blew up after they auto-tuned?

 

I've just read the posts re the 495 HP LS3. There another issues that might be the cause, let me begin...

I'm think that the issues mentioned are a result of the Gold Blade Throttle Body, Plus the new ECM in GM's newer Crate Engine ECM with Wiring harness kit. There are posts re the Gold Blade vs better Silver Blade.

I have the same engine 495 HP LS3, except my set up is with Twin Nelson Racing Mirror Image Turbo's, I also have two C5 Vettes and I've spent months researching the EMC's and many associated issues. My first BAD taste was the Fast Burn ZZ4 Swap into my C4 Vert, hate that #$& ECM, soon it will be swapped out !!

This LS3 going into my new '37 Chevy Coupe build. Now I know what some you are thinking, no, no.no. This is a '37 Chevy Coupe Carbon Fiber Body (Chopped, sectioned and Channeled and close to being Fiber Glass), a full custom frame with extensive roll cage. Modified C4 Vette suspension front and rear with Dutchman's 9 inch IRS center housing, C5/C6 Calipers & Rotors, C5 Instrument Panel and Steering Column, and etc. But Note the C5 Instrument Panel.. Lots of Vette parts... Love Em. Lots of Vette Parts!!

If anyone plans on installing a new LS crate engine into a C5,,, be aware that since about 2006 they all were switched to 58 Tooth Crankshaft Reluctor. And in 2009 or there about the Throttle Body was changed to the Gold Blade. Two important areas that will need to be modified.

I've spoken to many LS ECMProgrammers and engine builders, Most tell me that the newer Gold Blade Throttle Body is acceptable for any performance tuning or general tuning PERIOD !!!, Same for the New ECM is their new Kit.

So if you wish to install any LS engine in your C5 or early C5 then you have two basics choices, Purchase the small electronic 24 to 58 tooth reluctor adapter $275, or change the ECM wiring harness to 2007 or 2008, there many be other years. Changing the Wiring harness is not for the inexperienced, in general terms !! The 24 -58 module is a simpler solution for a C5 or early C6 LS3 swap.

The 2009 up engine wiring harness, the Throttle Body in Pinned out for the Gold Blade Throttle Body, but previous C6 years are the Silver Blades. Now this is weird. GM Engineers wired the Stepper Motor for the Throttle Blade has reversed pins, and the Throttle Position Sensor are also reversed. You can just Swap the Pins, same connector. If one wishes to install the great Silver Blade Throttle Body into their C5, then you'll need a adapter , electrical pigtail {or swap the intake), both easy, Gold Blade has a Gold colored Throttle plate, silver Blase is Silver... There is a post for this pin swap.

So what I have come to understanding is that if your like most performance enthusiasts, you will want the Silver Blade Throttle Body. This part is simple, but $350 up AND the Silver Blade will provide better tuning,,, esp initial throttle opening from a dead stop and light throttle pressure. From what I've also learned, this not possible with the Gold Blade and MOST after market Throttle Bodies, esp for that initial throttle opening from a dead stop.

I have a C6 2008 complete Engine wiring harness. I'm using this wiring harness because it is for a 58 tooth reluctor, and the C5 & C6 Vettes have the fuel level sensors wired into the ECM and that's important to me because I'm using a C5 Instrument panel. I've spoken more than a few times to the GM Tech and Engineers re the various issues that POP-UP during these crate motor engine swaps. All of the GM completer modules that exchange their Data in on a Star wired network and GM has named their LAN text GMLAN. So the various modules can all communicate wit h GMLAN.

You may need to purchase a Injector wring harness cable adapter of the different Fuel Injectors, most likely you will. Under a $100.
And again depending on your particular swap, you may need to upgrade the Throttle pedal as well.This is where the Engine Wiring Harness connects to the Fuel Injector Harness.

And forget the GM $1300 ECM with wiring harness. This kit includes the late Gold Blade throttle body and the Tuner that Has been tuning my cars for over 10 years says they will not Touch anything with the Gold Blade or this new ECM, ""NOT PROGRAMMABLE""

I've checked the GM part numbers on everything else and I could find zero additional issues. one can always compare part numbers for individual parts or sensors. There might be something else that I've missed but nothing that can be overcome. the Throttle Body and ECM is Critical to good performance and a smooth Ride, and NOT wasting $$$ at multiple ECM programming.

I'm not new to this LS engine swap research, I've completes several LS & LT1 swaps and always modified GM Factory ECM wiring harnesses. I'm a retired Electronic Engineer, so I'm more accustom to the research. Finding exact dates to the year or month in a mid year part change difficult. I previously installed a LS1 & Tremic T-56 into my '56 Chevy in 2007. A great swap and not a single repair of maintenance issue, except replacing the headers this last Summer.

Almost forgot. A friends of mine also is doing a LS swap, but his neighbor just completed his swap. A LS3 Auto combo, with the wildest Cam I've seem on the street Comp Race only Cam. Silver Blade and great Wild Idle,, and smooths right out and a good drive/

To my knowledge, these are all of the issues or required mods or changes that are ECM related.

Michael...

 

Great thread with lots of useful information. I am still curious as to which "programming changes" will allow the knock sensors to function correctly in my swap (L92/LS3 in 2000 C5).

 

nsogiba

RE the Knock sensors. I've got no idea to what if any special program changes are required ofr these side mount knock sensors. But if you wold like the contact number for the company that I've used on a few LS installs, send me a PM and I'll send the info.

Re the Fuel Injector connections. The C6 wiring harness has the injector connectors and they fit perfectly.

I've begun to strip off all of the plastic tape and plastic protective coverings, what a mess. Some Genius decided to include the ECBM massive connector and several other non engine related connections into the engine harness on the C6 Corvettes. Plus the main fuse box. I've got a nice large pile of leftovers.

I've plugged in all of the engines sensor connections and happy happy, They all fit . The alternator is still on the drivers side and it fits my low mount bracket kit. Also the A/C clutch compressor connector is on the passenger side low. I'll utilize this wire and leave it in the loom, but I'm using an aftermarket mini pump and A/C suitcase under the dash with combined heat..

I'll need to add new Pigtails for a few items like the Throttle pedal assembly, VSS (vehicle speed sensor), Reverse lockout solenoid on the trans, and a few others. But it's pretty east and the new pigtails are available and for a good price..

Still, a lot less expensive...

 

I swapped a GM Crate LS3/525 into my 2002 Z06. Pretty straight forward swap. Had it tuned by a reputable shop, ran good, but it did have a noticeable "bog" when accelerating - particularly when coming out of a turn. Tuner said he had spent a considerable amount of time on that and could not solve the problem. A year later, I took the car to another tuner - "bog" is completely gone. I am very happy with the end results.

 

If using a LS2/3 knock sensor in an LS1 car you have to change the knock sensor type in the tune to "flat response". I just had to change out the LS1 knock sensors in my LS3 C5Z to the LS2/3 style due to the new headers contacting the LS1 sensors. Its a pretty straight forward change. Racetronix LS2/3 to 1 knock sensor harness, new LS2/3 knock sensors and quick change to the tune.

 

I purchased the Racetronix LS1 to LS2 (Resonant to Flat Response) knock sensor adapter harness:
Knock Sensor Relocation Harness LS1>LS2

I plan to install the LS2 knock sensors on my 2004 C5 Corvette (with a 0411 PCM).

Even though I have an adapter harness, do I still have to re-pin the PCM? I think the answer is "YES" but want to confirm.

Thanks,
Chris