So my LS1 GTA has been up and running for about a year now. My old motor went 11.50's, new one is gonna be alot faster. After starting my new motor the other night I was wondering how far off the stock water temp and oil pressure gauges are. I'm currently running the stock '98 LS1 water temp and oil pressure senders... just tying them to my stock dash gauges with the stock 3rd gen signal wires. I thought I read somewhere that the water temp signal wire needed a certain resistor inline or something to get the gauge to read correctly. True or not? Also, what about the oil pressure... will the LS1 sender work correctly with the stock 3rd gen gauge?? I just want to make sure my gauges are accurate... I know my temp gauge is about 20-30* low right now due to scanning the PCM but there's no way to confirm oil pressure unless I put a mechanical gauge in the block... Thanks!!! -Jeremy

my oil pressure gauge with the LS1 sender is dead on.....

the temp gauge isnt on the numbers, but the sweep is correct.. straight up is sitting just above the thermostat.

Have you verified your oil pressure gauge to a mechanical one or what?

As for water temp, is there anyway to correct that?

yep.
i compared it to the oil plug next to the oil filter....
i also compared it on my friends LT1 car..... his stock gauge matched the LS1 sender too.

i dont worry about it, since i know what it is, where its suppost to be, ect.... its basicly a "Hot/Cold" gauge now, but it works perfect for what i need it for... knowing its 213 instead of 215ish isnt important... seeing the needle sweeping upward, or seeing its cold, ect... thats what counts.

im having a little trouble with the tach on my 89 camaro?? its about 2k off?? would hp tuner fix that and what value should i use?

sorry for the Hijack

Bumping this up for answers on the coolant gauge and using a resistor. Mine reads about 50* low, and would like to make it work. Thanks!

Uh...lol, I hope the coolant sensor isn't that far off, I frequently see the 180-210 point when in traffic. It hasn't boiled over yet, but that would put the coolant at ~270*. I can't say for sure, but I believe mine is pretty accurate.

I just remembered, I believe we used the stock temp sender from an ls1 and retapped the hole on the LQ9. Oil gauge seems about dead on, 55-60 in the morning then about ~45 at idle, 55-60 WOT.

Also, I used a 1998 computer and harness, so that would make it the 3 wire CTS, one for gauge, 2 for pcm.

I havent seen a chart showing the resistance values for either the 3rd gen sensor or the 98 sensor. I do know the 98 has slightly more resistance in it so adding another resistor would push the value off even more. Once the resistance differences are found, adding a booster wire with a resistor inline to cut the voltage down should remedy the situation similar to the tach fixes

I might have to boil some sensors to figure out the range because TGO, ls1tech and google havent found anything

If you find anything let me know, I'd really like to make it read semi-accurately

Well I am going to be a bit lazy, I will read the temp with a temp gun when i get to work, and compare to what the gauge says. I'll take various temps of the hoses and average it out and see how close it is.

Also, could we test the resistance with a multimeter? I may have a spare 3rd gen sensor here some where.

Check the resistance at multiple temps. The hotter temps are the more important ones

I will try that tonight. For now I have some temp gun data. 98 PCM, with what I believe is a 98 coolant sensor.
Gauge says: 150-160*F

Temp at top coolant hose: 153*F
Temp at heater hose: 155*F
Temp at pass. side head: 178-186*F
Temp at lower driver's side hose: 156-160*F
Temp at Header primary: 250*F