mikevanky

I have seen ppl using both IAC and ECT with relays and resistors to use the stock computer to pull timing and add fuel. I have looked in the tune and I see ways to pull timing and add fuel with with either sensor. So... what are the pro and cons of using one vs the other or even using both?

Thanks for helping the noob!

Three6GMC

iTrader: (11)

I have seen just the IAT sensor used to pull timing without issue. A lot of guys local do it. Just add resistors till the correct timing is pulled. Pretty easy.

Atomic

iTrader: (42)

You don't need a resistor at all, just have a switch or relay disconnect it and the computer will read the lowest value.

Three6GMC

iTrader: (11)

I use resistors to pull a certain amount of timing... wouldn't disconnecting it pull too much? I just do what my tuner tells me when it comes to that.

Atomic

iTrader: (42)

It just goes to the last row and you can make it pull or add however much you want to.

GM1697

iTrader: (1)

Yup this is how I did it. The relay killed the IAT signal when the nitrous hits, the computer reverts to the lowest temp column, and you edit that column for whatever timing you want.

It's a brilliant little trick. Jeff HooWybrow's "ruined4x4" uses this also.

Three6GMC

iTrader: (11)

Hmm that's cool I'm no tuner so I didn't know about doing it that way. Good to know

MaroonMonsterLS1

https://ls1tech.com/forums/nitrous-o...de-system.html

Here's a great writeup from the tech

The idea is you use a relay to tell the computer that it is seeing -40° Intake temps. It will then reference the table that changes timing based on iat and use whatever values you put into the table. For a 150, I'd recommend 4 to 6 degrees pulled. The relay is setup so it activates at the same time as your nitrous, so the normal driving conditions are unaffected, and you stay safe when spraying.

stroker87

iTrader: (6)

man wish i knew about this sooner, i used the LNC-2000 retard box what you guys are talking about is much cheaper and a lot less wiring!

the corvette forum they just like to spend money the truck forum they get it done for less!

chris99gmc

For what it's worth, I would highly encourage anyone running a SD tune to Not use this method to pull timing. It's far too risky. Some have successfully used this method, a few have not. Another method to pull timing with our PCMs is to activate the traction control to kick on and just set the amount of retard in your the TC table on your tune. I've thought about using the PCMs output with a relay in series to have the TC request signal function as an rpm window switch as well, since the tables for TC request is scaled in rpms on the x-axis.

Can anyone confirm if the TC retard method is reliable and works on any year PCM?