1st start with C5 LS1 PCM, 525hp LS3 engine...any major issues?

[beeman]

Really close to 1st start. Any problems with 1st start of a 525 hp LS3 with the C5 LS1 stock tune PCM? Obviously will need a tune, but will anything bad happen?
I'm not worried about components, compatibility, that's been sorted out...mainly fuel management (rich, lean) I guess.
Thanks!
Dave

[Shoeless]

I'm sure this is something you have already sorted but thought I'd mention the difference in 24 x and 58 x timing between your LS1 PCM and your LS3 engine.

[beeman]

Yep, have the lingenfelter module for that, thanks.

[Shoeless]

Yep, have the lingenfelter module for that, thanks.

Excellent!!! Looking forward to hearing to good news when you fire it up.

[HerculezJT]

do you have a 1x cam sprocket installed? in LS3s they are 4x cam and 58x crank. it wont cause running issues, but the PCM will flag it. you will run a bit lean due to the pcm thinking you have 26ish lb/hr injectors vs the 42 or higher on a ls3, might cause some idle issues. what year the PCM? the 97/98s are trash for tuning.

[HerculezJT]

What the original LS1s had was D, since the cam sensor was in the back of the block with the stock cam having the tooth for count. Since the LS3 has the cam sensor up front on the timing cover, you will need C to clear the code, i dont know what cam you have, but it will either be a 1 bolt or 3 bolt design needed with a 1X. Learned this the hard way with my CTS-V1 when I went from stock LS6 to a B/S LQ9.

Attachment 138642

LS1 cam with trigger

LS1 stock cam.png

LS3 cam without trigger

LS3 stock cam.png

[beeman]

Thanks, you seem to know your stuff, I'm stuck with learning from guys like you.
Fortunately, the Lingenfelter module interprets both the crank and cam signals, so that should be OK. I believe the PCM is 99 or 00, so hopefully that is good. It's from an auto C5, hope that's OK too.

https://www.lingenfelter.com/product/L460065397.html

[HerculezJT]

Thanks, you seem to know your stuff, I'm stuck with learning from guys like you.
Fortunately, the Lingenfelter module interprets both the crank and cam signals, so that should be OK. I believe the PCM is 99 or 00, so hopefully that is good. It's from an auto C5, hope that's OK too.

https://www.lingenfelter.com/product/L460065397.html

its all lessons learned on my part, or my tuner yelling at me , im dabbling in tuning myself but dont have the knowledge near with other experienced tuners.

the PCM will start the car with the A4 program. Expect codes and the PCM will lockout reverse because those wires are used for something else on the A4. You can test that you get ignition start and you can test all forward gears, maybe reverse based on your set up

as for the pcm, i found this in my notes for a c5 vette, year unknown
"We used a Tech 2 to reprogram the PCM. HP Tuners will work as well. The trick is to get the OS ID number for the PCM code for your vehicle. I used HP Tuners to find the OS ID. Once I had this ID I went out to the HP Tuner site and downloaded several stock transmission tunes for manual transmissions and found one with my same OS ID. Most of the OS IDs are the same each year so this is not hard. Once I knew I had the same OS ID for a manual car, I wrote the VIN number down. The PCM code for that VIN number was loaded into the Tech 2 and into my car. Once done, the car is configured as an LS1/M6 setup. I use HP Tuners to eliminate skip shift and any other tuning adjustments."

Having the M6 set-up shouldnt be a concern, the pcm just cares that it isnt looking for the Auto I/Os

[HerculezJT]

if i can also recommend for the future, look into the 0411 PCMs. they are considered to be an upgraded version to the PCMs for 99-04 Vettes and 99-02 Camaro/Birds. If im not mistaken as well, that PCM has the option for Flex Fuel.

it is good for Flex, found this link in my notes of "things I want to do"
https://ls1tech.com/forums/pcm-diagn...-write-up.html

[beeman]

Appreciate it

[Shoeless]

So when are you going to hit the go button ?

In all seriousness, have you cranked it over to make sure oil pressure is good yet?

[beeman]

Yeah, I've been talking about 1st start for way too long now! Bear with me, life is not being conducive to getting out there. I have a friend who is very experienced with LS engines, I want him present, waiting for our schedules to click. 2 post lift being delivered this afternoon to compliment the 4-poster, I'm excited about that.

[jkrueger]

I recently switched from a GenIII engine (LM7) in my Daytona to a GenIV 6.0 block but still using the GenIII PCM. My biggest issue was dealing with the knock sensors. The GenIII PCM is looking for the one wire sensor that is the valve valley and the GenIV blocks use the 2 wire sensors on the outside of the block. How are you dealing with this???? I bought the wire harness adapter that grounds the one wire to the block and the other still goes to the PCM, but I assume that programing in the PCM is set for the older sensor in a different position on the block so I'm not sure it is working correctly.

Looking back on this whole switch and the hassles I've had with it I should have just gotten a GenIV PCM and harness or switched to a stand alone ECU.

JC

[beeman]

I kept the LS1 knock sensors, the LS3 block has unused threaded bungs on both sides of the block that the LS1 knock sensors thread right into. Seems to be the common fix for that issue.

switched to a stand alone ECU

Do you have A/C? Standalone ECUs don't play well with the A/C.

[Shoeless]

That should be awesome getting another lift in the shop and completely understandable about life. I’m currently headed to TN for my brothers weekend. So about the only work I’m doing is on the laptop planning out my engine harness while the wife is driving. Currently working on the power supply splice design.

On my standalone ECU I’ve got a couple nice options. There are several idle controls that I can utelize to make sure my engine doesn’t stall when the AC or fan kicks on. If also got a high side output (+12V) that I’ve got wired into the full throttle switch on the VA A/C unit and I can set what RPM this will trigger at so I don’t blow up my compressor. Say 4,000 RPM.

[beeman]

Hope you have a great time with your family. Yeah, the aftermarket ECUs are awesome, I was thinking of the GM ones.

[jkrueger]

I kept the LS1 knock sensors, the LS3 block has unused threaded bungs on both sides of the block that the LS1 knock sensors thread right into. Seems to be the common fix for that issue.


Do you have A/C? Standalone ECUs don't play well with the A/C.

You'll have to let us know if they work in that position since they weren't tuned for that position. I don't know a lot about how knock detection works and if it matters where the sensors are.

I used to have AC but as the car has become more of a dedicated track car I have removed it. Most stand alone ECUs have generic inputs/outputs that could be programed to run the AC.

JC

[crash]

Just so you all are aware, the only way you are going to know if the knock sensors are working is to data log and then look at the retard tables/data. This will tell you if knock was detected. The problem is that if the sensors do not work you will really never know unless you hear a knock or it is bad enough to do engine damage.

We regularly have timing pulled out of our setup due to the knock sensors on the FFR PDG GTM race car, and, as a driver, I never hear or feel anything. The only way we know is to look at the data.

If you tune with 87 octane on a hot day on a dyno, you could then put 89 or 91 in and pretty much be sure you will not need the knock sensors to operate. I would do this on a street car where an extra 10 horsepower is really meaningless.

[Shoeless]

Hey crash,

Now that we are on the topic of knock, do you have some experience with respect to what timing settings on various LS platform engines are knock limited at? I know it’s a broad question, and while I go through my tuning I’ll have separate knock detection equipment installed, but wondering if you had any general guidance to share.

[HerculezJT]

I recently switched from a GenIII engine (LM7) in my Daytona to a GenIV 6.0 block but still using the GenIII PCM. My biggest issue was dealing with the knock sensors. The GenIII PCM is looking for the one wire sensor that is the valve valley and the GenIV blocks use the 2 wire sensors on the outside of the block. How are you dealing with this???? I bought the wire harness adapter that grounds the one wire to the block and the other still goes to the PCM, but I assume that programing in the PCM is set for the older sensor in a different position on the block so I'm not sure it is working correctly.

Looking back on this whole switch and the hassles I've had with it I should have just gotten a GenIV PCM and harness or switched to a stand alone ECU.

JC

If i remember correctly, you can turn down the threads on the Gen III knock sensors and then mount them on the side of the block. I think that is what i had to do when i went LS6 to LQ9

EDIT:

Confirmed: LS1 Knocks sensors are 10x1.5, LS2s are M8x1.25. so just take the LS1 knock sensors and turn it down to LS2 knocks sensors threads.

[HerculezJT]

Hey crash,

Now that we are on the topic of knock, do you have some experience with respect to what timing settings on various LS platform engines are knock limited at? I know it’s a broad question, and while I go through my tuning I’ll have separate knock detection equipment installed, but wondering if you had any general guidance to share.

I think its only 1-2 degrees per knock event. Also, i dont think the sensors actually listens for a "knock", its more like a sound sensor and when it hears a sound over a certain voltage threshold, the pcm/tuner determines if it is a knock or not. I had a bad timing chain in one of my LS2s that caused my knock count to constantly tick up to a point where the car wouldnt idle. gave off just enough noise for the sensors to pick it up and the pcm to recognize it as a knock

[crash]

We have debates on the knock sensors. We run a Mendeola sequential dog ring transaxle and it appeared that the "noise" from the transaxle shifting may have led to the knock sensors kicking in the retard. I don't personally do the tuning or table inputs. That has been done over the years by a couple of different professional tuners. I would guess that it is a degree or two at a time, but I really do not know.

[Shoeless]

No worries, thanks for the feedback.

[beeman]

Was just under the car, here's the C5 knock sensor, 1 on each side

h548obay.jpg

[HerculezJT]

Was just under the car, here's the C5 knock sensor, 1 on each side

h548obay.jpg

looks like one of the engine mount locations. using the first 4, forward of the engine? If the GTMs only use the 4 forward holes, then anyone can use LS1/LS6 knock sensors can utilize the last 2 holes. if you have an iron block, your SOL, they only have a 4 bolt pattern vs the aluminum 6 bolt pattern.

[beeman]

My GM motor mounts are closer to the accessories, here's another angle.

u7245c4p.jpg