# Stock 16v cts w/ms2?



## Luv_My_VDub (Mar 25, 2010)

*Stock 16v cts w/ms2? (plus other questions now)*

Why can't I use it? Or can I? The only info i seem to be finding is for using gm sensors. I know the saturn sensor is a direct plug in, but if i don't HAVE to buy it to get my car running at first, I don't want to.
thanks


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## Luv_My_VDub (Mar 25, 2010)

I found this @ http://www.scirocco.org/list/archives/2004/February/msg00010.html


">... It's not that the VW sensors are not accurate enough. The problem is
> accurately determining the
> resistance at various temperatures to input the data into Megasquirt.
> I did boiling water, freezing water and room temp with the sensor sitting
> over a heat register
> blowing ambient air. i.e. heater and AC not on.
> Despite trying to be as accurate as possible the resistance varied quite a
> bit during these
> measurements. With the sensors installed and MS running the engine temp
> normally maxed out at 180
> degs which I think is probably low. So, that is the basis of my statement.
> Maybe somebody else can do a better job of measuring the resistance than I
> did.
> All of this really only applies to the coolant sensor anyway since the 16V
> has no air temp sensor.
> And if you think about it the accuracy of the coolant temp sensor isn't very
> important. It isn't
> used for mixture control unless you're cold running and then you can put in
> any % in the warm up
> bins that your engine needs.
> So, now having thought about it using the stock sensor is adequate for
> coolant...."

So, I guess I answered my own question. :screwy:


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## Prof315 (Jan 5, 2009)

Luv_My_VDub said:


> I found this @ http://www.scirocco.org/list/archives/2004/February/msg00010.html
> 
> 
> ">... It's not that the VW sensors are not accurate enough. The problem is
> ...


Just one comment here .....Get an air temp sensor.....MS will be very unhappy without it.


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## Luv_My_VDub (Mar 25, 2010)

yep, I already have one of those bad boys =D
also, I know MAF isn't requirwd, but if I add one on, and use the MAF/MAP setting, will this be easier to tune than just having MAP? I don't plan on using a TPS as of yet (dont have one), and already have a DIGI MAF, so I thought maybe the added sensor would give better information to MS2. 
any thoughts?


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## Prof315 (Jan 5, 2009)

Dump the MAF and use the onboard MAP sensor. And you can tune the acceleration enrichment with mapdot. I just did an MS conversion on a 79 280ZX with no TPS and it worked fine.


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## need_a_VR6 (May 19, 1999)

Agreed. MAPDOT working well depends a lot on throttle body size and the engine displacement. I was not a big fan of it on my motor when I 'had' to use it with my 75mm mustang tb.


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## Luv_My_VDub (Mar 25, 2010)

Ok, I'm getting mixed messages. The Prof seems to be saying that tuning with MapDot isn't all that bad on a small car like the 280zx, and Paul, you're saying that it was a pain with a larger engine/tb like the 'stang? So, where does my 2.0 16v slot in there? Paul, if I'm having trouble dialing in my accel enrichment with MAP alone, would it be worth it to add the MAF on there until I can source a TB w/TPS? Or will this present no problem on a stock TB and intake mani with my gti? 
I'll be ordering my unassembled kit from DIYautotune this next week, I've read, re-read, and read again everything in the megamanual, and the msextra stuff as well.
I've got the basics down, and understand most of the advanced concepts, but still trying to dial in exactly what I'll need for start up for my specific engine. Any help is appreciated. Thx!


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## Prof315 (Jan 5, 2009)

Luv_My_VDub said:


> Ok, I'm getting mixed messages. The Prof seems to be saying that tuning with MapDot isn't all that bad on a small car like the 280zx, and Paul, you're saying that it was a pain with a larger engine/tb like the 'stang? So, where does my 2.0 16v slot in there? Paul, if I'm having trouble dialing in my accel enrichment with MAP alone, would it be worth it to add the MAF on there until I can source a TB w/TPS? Or will this present no problem on a stock TB and intake mani with my gti?
> I'll be ordering my unassembled kit from DIYautotune this next week, I've read, re-read, and read again everything in the megamanual, and the msextra stuff as well.
> I've got the basics down, and understand most of the advanced concepts, but still trying to dial in exactly what I'll need for start up for my specific engine. Any help is appreciated. Thx!


You'll be fine with mapdot. I've also done a 1.8L 8V (same throttle as you) with just mapdot and it was fine even with a big duration cam (race motor).

The biggest thing you'll need is patience. What I did on my first couple of V3.0 builds was to print the megamanual assembly instructions as well as all of the instructions for the Extra code hardware mods i wanted to use and kept them side by side checking steps off as I completed them. And be sure to do ALL of the tests during assembly.


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## need_a_VR6 (May 19, 1999)

If it's a stock throttle body, give it a whirl. I've just seen certain setups *not* like it. Less about the cam size, more displacement vs throttle area.

Read the megamanual again once you read this...


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## Luv_My_VDub (Mar 25, 2010)

need_a_VR6 said:


> Read the megamanual again once you read this...


:thumbup:

Sound advice!


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## ValveCoverGasket (Mar 20, 2002)

Prof315 said:


> You'll be fine with mapdot.


indeed :thumbup:


and no problems using your stock 16v CTS with MS2, but im sure thats already been covered 

...and heres a table of some of the VW temp sensor resistance curves, assuming youre using the "stock" MS bias resistors
http://spitfireefi.com/files/EasyTherm/tempsensorvalues.txt

:beer:


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## Luv_My_VDub (Mar 25, 2010)

Thanks all! :beer:
MS2 ordered today! So i'll put all this 'theory' in to practice soon as i get it all built up! =D


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## ValveCoverGasket (Mar 20, 2002)

excellent :thumbup:


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## Prof315 (Jan 5, 2009)

Luv_My_VDub said:


> Thanks all! :beer:
> MS2 ordered today! So i'll put all this 'theory' in to practice soon as i get it all built up! =D


Feel free to holler if you've got questions.


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## Luv_My_VDub (Mar 25, 2010)

I am SOOOO effing close to getting this baby running! But! Some more questions...

ok, so when I have the stim (jim stim) plugged in, and I'm playing around with the settings in tuner studio, 
A. I have no 'engine speed' or rpm readouts
B. When I set 'Tacho Output' to be on, and make the output IGN (JS10) and speed normal, then burn, and restart megasquirt, it says I have a 'Config error'. This goes away if I change the settings back.

so what's up with that? Don't I need tacho out to run my coil from megasquirt's vb921?
am I missing a jumper somewhere?
I didn't build the hall input circuit, could that be a problem? Even though I built the vr circuit as Paul suggested? 
or is this just a shortcoming of the jimstim?
argggg:banghead::banghead:

(100th post! Wanted to save it for saying I got my car running =/ )


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## Prof315 (Jan 5, 2009)

Luv_My_VDub said:


> I am SOOOO effing close to getting this baby running! But! Some more questions...
> 
> ok, so when I have the stim (jim stim) plugged in, and I'm playing around with the settings in tuner studio,
> A. I have no 'engine speed' or rpm readouts
> ...


Tacho out is a signal to drive a tachometer not the coil.

You have to make sure the Jstim is properly set up for your ignition input. see here : http://jbperf.com/JimStim/JimStim_v2_0_Wheel_Simulator_Setup.html#mode


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## Luv_My_VDub (Mar 25, 2010)

Sweet! That worked. thanks again!
Can't wait til monday to wire it all up!


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## Luv_My_VDub (Mar 25, 2010)

Ok folks.
The Temp sensors work great, as far as i can tell. They have both read within 1* of ambient air temp the last few days i've tried to start my car.

But I can't get any spark!

I've been talking with Need a VR6, as I'm using his suggested hall sender mod (http://forums.vwvortex.com/showthre...nder-Trigger&p=67101392&posted=1#post67101392)
But wanted to get any other thoughts from folks.
I'm trying to run my coil directly from megasquirt, so the high current driver has been built.
Pin 36 is run to my coil (-), and 24 is going to my hall sender signal with tps VREF to hall power and ground run to sensor ground.
I'm at a loss :banghead:

edit: Thanks Paul, I meant (-)


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## need_a_VR6 (May 19, 1999)

Just to clarify, pin 36 should be coil *-* the other side with switched 12v.


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