sotaku

iTrader: (4)

After some searching and reading it looks like the FAQ may be missing some goodness in the area of 96/97 EasyTherm settings (looks like it may just be place holder copy and pasted from the NB settings?). Since I'm getting about 3 different stories I thought I'd post a thread and see if I can get this sorted out for my parallel install.

1. R4 and R7 need to be removed to keep from messing with the stock ECUs readings
2. EasyTherm settings should be RX7 on CLT, and GM on AIT both with a bias of 1205. This is for stock CLT and AIT.

Number #2 is where I'm sketchy. I've seen 1544 for the bias as well, and I'm not sure if the AIT needs to be the GM sensor or if it can be either or. Also saw where DIY posted a CLT scale for these cars (I believe that broke down like so):

16000 ohms at -4 degrees F,
2450 ohms at 68 degrees,
580 ohms at 140 degrees.

Anyway, I'm having a problem now with the RX7 CLT + GM AIT defaults a bias of 1205, and with R4 and R7 removed where my CLT looks it's about spot on (maybe a little bit warm) and my AIT is reading ~40 degrees too warm (the car hasn't been started all day so it's not heat soak).

So anyway how does all of this shake down? Been tough finding a really difinitive answer. Perhaps the FAQ has spoiled me.

Also other NA OBDII users, what are you using for your settings?

cjernigan

iTrader: (13)

You are supposed to leave R4 installed for the GM IAT sensor unless you're sharing the IAT sensor with the stock ECU. The settings you have seen on the board are usually for people with R4 installed. Only R7 needs to be removed so that the stock ECU will turn the fans on at the correct temperature.
The bias of 1544 is for NBs, not for your NA so that shouldn't work for you. 1205 for the bias is most likely for the coolant only. If you want a really trouble free IAT reading you should run a dedicated wire to the sensor from the MS instead of going through the stock wiring, then ground the sensor at the engine block where the rest of the ECU grounds are.

You can test the IAT sensor readings with ice water, ambient temperature, and boiling water while messing with the BIAS setting. You don't need to do that if you just run a wire to the sensor instead.
Your fans should be coming on at a indicated 207-210* F in Megatune, if that isn't accurate then you need to make some adjustments.

sotaku

iTrader: (4)

Awesome. That certainly helps sort out a few things. Now one last thing. Right now I'm using the stock MAF/AIT or what not and am sharing it with the stock ECU at the moment. What would be the settings for that? Here I've been thinking the GM settings applied to that.

Also would having no sensor going to the stock ecu cause problems at Idle (which the stock ecu controls) or could it not care less what the temp is for idle.

Thanks for the hand holding while I get these final bits sorted. =D

Saml01

iTrader: (9)

MAF & CLT (degF): Bias = 1500
-4 16150
104 1150
176 330


GM (degF): Bias = 2490
48 7000
87 1930
146 560

Thats what im using.

Courtesy of Jerry from DiyAutotune for the curves, and Arkmage and Paul for the Bias for CLT. They both have 96 cars. These are what I run and they are accurate.

sotaku

iTrader: (4)

Freaking beautiful man. This is stupidly helpful. I just measured the bias on the AIT and mine is quite close to that from what I can tell at ~2980. I'll try your settings first since they're tried and true.

Saml01

iTrader: (9)

You have to measure the resistor you have in R4.

Do as Cjernigan mentioned and run a dedicated wire for it and run a ground from the MS to the block.

sotaku

iTrader: (4)

Per Arkmage's Parallel install thread, I removed it. However once I run a dedicated wire, I'll need it back if I'm not sharing if I understand right. Right now I measure AIT Bias via the harness at 2980 without the MS plugged in and oddly enough around 2640 or something like that with it in.

Using your CLT settings right now I'm getting fans ~210. So pretty close. My stock AIT reading seems rather high still. About 20 degrees perhaps? Is this because I'm not using the GM sensor from DIY? I need to get some contacts and slap that thing in there because I'm sick of the silly with the AIT numbers. Does the stock ECU even need the AIT numbers for anything once MS is running squirt and spark?

Sorry for the noobish questions, this thing has gotten me all turned around. =/

Saml01

iTrader: (9)

You are getting high numbers for your AIT because you arent using a GM ait, so yes.

As for the AIT if you are using the stock maf, you should input the same numbers as the CLT supposedly, according to Jerry.

If you run a dedicated wire for GM AIT, yes you need it back. I dont recall arkmages install thread using the factory AIT though, so I wonder why he removed it. I think you are confusing it with R7 for the CLT.

akaryrye

iTrader: (5)

So this is with R7, without R4, shared oem clt, and IAT separate or plugged in the oem harness, MSPNP style?

Can we have this stuff added into the sticky?

Arkmage

iTrader: (3)

I removed it because I fucked up... I realized shortly after that my AIT didn't seem to move in megatune and put it back in.

I had such a pain in the *** getting the stock sensors to play nice with megasquirt I ended up running dual sensors for everything but CAS.

Saml01

iTrader: (9)

Yea. Thats right. But I dont use the factory harness because I need to pass OBD 2, so the AIT is separate.

akaryrye

iTrader: (5)

Ok, so I am trying to bang out my coolant bias right now. Car is a 97 and I am sharing the stock CLT with MS and the stock ecu and R7 is removed. Bias of 1455 ohms is reading about 30 to 40 degrees too cold and its screwing up my cold start enrichment.

Also I am sharing the GM IAT with the stock ecu and have left R4 in. Has anybody tried this or should I just pull R4 out? From what I understand, it should work if i can figure out the bias and the only reason to pull R7 is so that the stock ecu sees the correct temps to turn on fans and stuff. Ive so far tried bias' of 1455 and 1250, but both read too low.

Braineack

iTrader: (62)

yeah that's pretty important stuff...



But seriously, if you guys took ten minutes to work on it, it would be easy to get perfect for any install. I always recommend a separate AIT sensor for a 96-97 piggy install so the ecu doesn't throw codes and screw up it's control over the fans and other AIT based things. Since we know the GM AIT resistance scales and 2490ohm at R4 are correct, the issue is now only the coolant. R7 should be removed as to not alter the CLT scale to the stock ecu.

Start with a value, I believe in my writeup I say use 1544. From what I was told from the few 96-97 guys that installed a MS I built this value is correct. Here is where you need to invest your ten minutes. Make sure your car is cold, the coolant and AIT should match if the car has been sitting overnight. If they don't, you need to change the bias. Create a new easytherm file with a different CLT bias, but don't bother flashing it. Simply move the .inc files to your project folder and open MT back up. The CLT temp reading should have changed. Fool around with the bias until you get the AIT and CLT to match. Then flash that firmware.

akaryrye

iTrader: (5)

wait ... I thought the CLT was responsible for the fans.

Anyway, I guess I will have to go with the dedicated wire for the AIT and then match up the CLT to that.

Braineack

iTrader: (62)

whoops, yeah; that's why we pull R7 actually, so it doesn't screw up the ECUs reading of the signal so it can control the fans properly. One of those mornings...Now I remember, the ECU will throw a code if you remove the MAF, so I tend to suggest wiring the AIT separate and keeping the MAF in place.

Saml01

iTrader: (9)

Just to reiterate. 1544 is the correct value. I have 1500 up top, but thats because I had 2 text files with different values and only after going back and retesting both did I confirm that 1544 is the correct one to use.

akaryrye

iTrader: (5)

if 1544 is correct, then why am I barely seeing 160 degrees when warmed up?

Saml01

iTrader: (9)

Because you touch yourself at night.


I dont know. Whats different with your setup from mine?

Maybe you screwed up your temp curves when burning the firmware?

Did you make sure to copy the therm files into the mtcfg directory?

240_to_miata

iTrader: (2)

I screwed up mine TWICE...

double and tripple check you are typing in the right numbers

akaryrye

iTrader: (5)

hey how did you know i do that!

Anyway, i think you just told me what may be wrong ... i thought I just needed to copy the therm files into the src folder, but i need to copy them into mtcfg as well?