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I'm running a MS3Pro- and it will compensate for the fuel pressure.
When I was first setting the car up- it stalled. I was like- what just happened? Look and see very little fuel pressure- had run out of gas!!!! If not for the gauge- I would have been messing with everything else for hours!!!
I have this LS6 that I just wrapped up and an LS3 I finished up last year, both could use some tuning as they have slightly more aggressive cams than stock. Rather than take them somewhere I am considering doing it myself, it looks like this is what I would need. What hardware do I need to get this to work? I already have the ODB2 bluetooth connectors that I use with the Torque app, and I have a few windows laptops, would that suffice?
Are you using GM ECMs in your installs? For thos, HPTuners is what I’ve used in the past. I believe LS1 Edit and EFI Live are other options, but I haven’t shopped around in a decade. HPTuners is still very prevalent, though.
I messed with OEM LS PCMs with HPTuners and it’s not for the nondedicated and like to try and figure **** out type personalities. I went from needing a laptop all the time and having to adjust for ambient temp swings with HO tuners on a boosted LS to standalone ECMs with self tuning capabilities. I run a fitech ultimate LS on my boosted LS now and it took 10min to setup and started right up. Gave it nothing but idle time to learn and went right into boost on my first drive out and it tuned for boost on the fly (AFRs). I now am trying the terminator X on my cammed 5.3 that I just put in my 78 C3 and expect similar results. Coming from tuning myself to self tuning is night and day. I actually get to enjoy the car now and never bring a laptop with me. Now I just start it, drive it and repeat. If you not needing to run stock LS OEM type gauges don’t even bother the stock PCM... go right for the aftermarket as it will make your life a lot easier.
Last edited by 78vette5.3; Apr 10, 2021 at 08:11 PM.
To bring this full circle, I found the issue with the gas guage, the ohms input line had been cut near where it enters the cabin, soldered and heat wrapped it and the gauge seems to read perfectly.
And to bring it even fuller circle, I replaced the temperature sending unit with an ACDelco one and now it read much closer, still a bit high, but useable. It is still installed in the passenger side and the adapter that is used does not seem like it allows much coolant to really circulate through so I am sure it is reading high as it is right next to the exhaust manifold. I put some heat shielding around it to insulate it as much as possible.
And to bring it even fuller circle, I replaced the temperature sending unit with an ACDelco one and now it read much closer, still a bit high, but useable. It is still installed in the passenger side and the adapter that is used does not seem like it allows much coolant to really circulate through so I am sure it is reading high as it is right next to the exhaust manifold. I put some heat shielding around it to insulate it as much as possible.
Scott
For the water gauge just get the LS 3 wire coolant temp sensor, Think it was stock on a 98 trans am. It has 3 wires vs the normal 2 wire LS coolant temp sensor. One lead is for the coolant gauge and the other is for the ECM input. Gauge wire connects to the stock C3 gauge and works perfectly (same ohm range) as GM was smart to keep it universal. Then just wire the other wire to the ECM pin that you have on your current harness. You can pick up a 3 pin connector for a cleaner install. This way you use the correct sensor with adequate coolant flow over the sensor in the stock (optimal) location. Works fine with my 78 stock gauge. Reason I opted for this is the stock sensor is 3/8 NPT and adapters push it out to far, then its on the wrong side (SBC on driver head, LS only has open sensor on PS head) so you would have to move the wire over and extend. Plus I've noticed a 10-15*F different in real time on a LS motor with sensors installed on driver and pass side heads. Pass side head receives cooler water from lower rad hose, then heats as its flows through the block, PS head, and then over to the driver side before exiting our the pump to the upper rad hose. The stock coolant sensor is in the hottest part of the coolant as its right before it leaves to go to the rad to cool and repeat. Putting the coolant sensor in pass head is like putting a temp sensor in the trans cooler outlet vs the pan... you get a reading but its not accurate. A 15*F difference is alot especially if your running hotter than you want to!
Save yourself the trouble and trying to help fix what you got, get the correct sensor ($20 or so) and be done with it!
For the water gauge just get the LS 3 wire coolant temp sensor, Think it was stock on a 98 trans am. It has 3 wires vs the normal 2 wire LS coolant temp sensor. One lead is for the coolant gauge and the other is for the ECM input. Gauge wire connects to the stock C3 gauge and works perfectly (same ohm range) as GM was smart to keep it universal. Then just wire the other wire to the ECM pin that you have on your current harness. You can pick up a 3 pin connector for a cleaner install. This way you use the correct sensor with adequate coolant flow over the sensor in the stock (optimal) location. Works fine with my 78 stock gauge. Reason I opted for this is the stock sensor is 3/8 NPT and adapters push it out to far, then its on the wrong side (SBC on driver head, LS only has open sensor on PS head) so you would have to move the wire over and extend. Plus I've noticed a 10-15*F different in real time on a LS motor with sensors installed on driver and pass side heads. Pass side head receives cooler water from lower rad hose, then heats as its flows through the block, PS head, and then over to the driver side before exiting our the pump to the upper rad hose. The stock coolant sensor is in the hottest part of the coolant as its right before it leaves to go to the rad to cool and repeat. Putting the coolant sensor in pass head is like putting a temp sensor in the trans cooler outlet vs the pan... you get a reading but its not accurate. A 15*F difference is alot especially if your running hotter than you want to!
Save yourself the trouble and trying to help fix what you got, get the correct sensor ($20 or so) and be done with it!
