Errata for LC-1 PID

**mistermike** · June 18th, 2005

The calculated PID for the LC-1 was based on a 0.5 volt offset, which turns out not to exist, at least on my pair of LC-1's.
The original formulas:
"(({EXT.AD1}-0.5)*3.3418)+7.35"
and
"(({EXT.AD2}-0.5)*3.3418)+7.35"
yielded a calculated AFR that was too low by around a point. The BEN map was at around .91 everywhere on a car that had been dialed in reasonably well using LTFT's.

I hooked up the LM Programming software and the graph showed an AFR of 7.35 at 0 volts and 22.39 at 5 volts as shown below. 14.7 should be at 2.45 volts.

Faced with the choice of programming the LC-1 for 0.5 volts at the 7.35 AFR or re-doing the calculated PIDs, I took the lazy approach and simply made the LC-1 fit the PID, shown in the second graph. Stoich now hits at 2.70 volts.

I believe for a factory default LC-1 the formulas should be a simpler:
"({EXT.AD1}*3)+7.35"
and
"({EXT.AD2}*3)+7.35"

If you're using LC-1s, I suggest first checking them with the supplied utility . If they show 7.35 AFR at 0 volts as mine did, then you need to make the correction to the LC-1 or the PID.

Since reprogramming the LC-1, everything is right on the money.

**GMPX** · June 18th, 2005

What are your thoughts on the LC-1?.
From the pictures I could see it appears to have headphone type jacks for the voltage output?.

Cheers,
Ross

**Black02SS** · June 18th, 2005

Excel does a very good job at figuring out the slope and intercept of linear functions for tasks like this

Voltage AFR
0.5 10
4.5 20
2.5 8.75

so afr=v*2.5+8.75

=SLOPE(B3:B4,A3:A4)
=INTERCEPT(B3:B4,A3:A4)

**mistermike** · June 18th, 2005

Originally Posted by GMPX

What are your thoughts on the LC-1?.
From the pictures I could see it appears to have headphone type jacks for the voltage output?.

Cheers,
Ross

They're pretty nice, so far. I've only had them running just today. I put one on each bank, so I can achieve the same level of frustration as someone with two wristwatches. The headphone jacks are for serial in and out. You can daisy chain a bunch of them into a single port. Probably a good thing for someone with dyno headers who wants to sample each cylinder.

The B+, grounds, analog, and N/B simm connections are all hard wired. I built a little time-delay circuit to power them up about 20 sec. after key-on, so they don't generate an error message due to the B+ drop during cranking, and to give a little time to purge condensation before they heat up.

**mistermike** · June 18th, 2005

Originally Posted by black02ss

Excel does a very good job at figuring out the slope and intercept of linear functions for tasks like this

Voltage AFR
0.5 10
4.5 20
2.5 8.75

so afr=v*2.5+8.75

=SLOPE(B3:B4,A3:A4)
=INTERCEPT(B3:B4,A3:A4)

Fantastic!
If I plug in the values from the LC-1 factory default programming it falls right into place.

It even works if I put in the stoich value

kp · June 20th, 2005

I had good luck with the LC1 so far, I also have the XD1 gauge. I just used the PLX PId and formula programmed into the LC-1 - forget what it is. EFIlive (annalog) reads exactly what the XD1 (serial data) does so to me thats close enough. I may pick up another LC1 down he road to log both banks when they are more readily availalble. Its a great little unit for the money.

**SSpdDmon** · June 21st, 2005

Doesn't the LC-1 output the same 0-5v signal as the LM-1? If so, can't we just use the LM-1 PID that is already in Live? I'd like to keep the LC-1 factory settings and not have to change it to .5-4.5v unless it improves accuracy.

**Blacky** · June 23rd, 2005

Originally Posted by mistermike

The calculated PID for the LC-1 was based on a 0.5 volt offset, which turns out not to exist, at least on my pair of LC-1's.
The original formulas:
"(({EXT.AD1}-0.5)*3.3418)+7.35"
and
"(({EXT.AD2}-0.5)*3.3418)+7.35"
yielded a calculated AFR that was too low by around a point. The BEN map was at around .91 everywhere on a car that had been dialed in reasonably well using LTFT's.

I hooked up the LM Programming software and the graph showed an AFR of 7.35 at 0 volts and 22.39 at 5 volts as shown below. 14.7 should be at 2.45 volts.

Faced with the choice of programming the LC-1 for 0.5 volts at the 7.35 AFR or re-doing the calculated PIDs, I took the lazy approach and simply made the LC-1 fit the PID, shown in the second graph. Stoich now hits at 2.70 volts.

I believe for a factory default LC-1 the formulas should be a simpler:
"({EXT.AD1}*3)+7.35"
and
"({EXT.AD2}*3)+7.35"

If you're using LC-1s, I suggest first checking them with the supplied utility . If they show 7.35 AFR at 0 volts as mine did, then you need to make the correction to the LC-1 or the PID.

Since reprogramming the LC-1, everything is right on the money.

You're right Mike, I had a (really!!!) bad math day when I "figured" that out. What was I thinking? I have changed the default LC-1 settings to V*3+7.35
Paul

**BowlingSS** · July 25th, 2005

Originally Posted by Blacky

Originally Posted by mistermike

The calculated PID for the LC-1 was based on a 0.5 volt offset, which turns out not to exist, at least on my pair of LC-1's.
The original formulas:
"(({EXT.AD1}-0.5)*3.3418)+7.35"
and
"(({EXT.AD2}-0.5)*3.3418)+7.35"
yielded a calculated AFR that was too low by around a point. The BEN map was at around .91 everywhere on a car that had been dialed in reasonably well using LTFT's.

I hooked up the LM Programming software and the graph showed an AFR of 7.35 at 0 volts and 22.39 at 5 volts as shown below. 14.7 should be at 2.45 volts.

Faced with the choice of programming the LC-1 for 0.5 volts at the 7.35 AFR or re-doing the calculated PIDs, I took the lazy approach and simply made the LC-1 fit the PID, shown in the second graph. Stoich now hits at 2.70 volts.

I believe for a factory default LC-1 the formulas should be a simpler:
"({EXT.AD1}*3)+7.35"
and
"({EXT.AD2}*3)+7.35"

If you're using LC-1s, I suggest first checking them with the supplied utility . If they show 7.35 AFR at 0 volts as mine did, then you need to make the correction to the LC-1 or the PID.

Since reprogramming the LC-1, everything is right on the money.

You're right Mike, I had a (really!!!) bad math day when I "figured" that out. What was I thinking? I have changed the default LC-1 settings to V*3+7.35
Paul

I just finished my AutoTune but now after reading this I need to check my PID setting. Has this change been place in the latest software?

Bill

**Blacky** · July 25th, 2005

Originally Posted by BowlingSS

I just finished my AutoTune but now after reading this I need to check my PID setting. Has this change been place in the latest software?
Bill

It is fixed in the current pre-release version of V7.2.3 (not publicly available yet), check the version you are using as follows:

Using Notepad, open the file:
Program files\EFILive\V7\Configuration\sae_generic.txt
Search for LC-1, if it is in there, make sure the expression is:

Code:

*CLC-00-926
V                  0.0           5.0       .1  "&#123;EXT.AD1&#125;"
AFR               10.0          20.0       .2  "&#40;&#123;EXT.AD1&#125;*3&#41;+7.35"
*CLC-00-927
factor             0.0           2.0       .1  "&#123;CALC.AFR_LC11.AFR&#125;/&#123;GM.AFR&#125;"

*CLC-00-928
V                  0.0           5.0       .1  "&#123;EXT.AD2&#125;"
AFR               10.0          20.0       .2  "&#40;&#123;EXT.AD2&#125;*3&#41;+7.35"
*CLC-00-929
factor             0.0           2.0       .1  "&#123;CALC.AFR_LC12.AFR&#125;/&#123;GM.AFR&#125;"

If it is not in there, then check the expressions in:
My Documents\EFILive\V7\User configuration\calc_pids.txt

Regards
Paul

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