a few beginner questions on MS

[StrokinIT]

Hey guys I currently have a 76 280z with headers and exhaust, intake, and an unknown cam. I believe the ignition system is stock, and so is the ECU. I’d like to upgrade to megasquirt to take full advantage of my mods, and have a few questions.

 

I went through the thread on “MS useful thread links†and found this thread <http://forums.hybridz.org/index.php?showtopic=48292> thinking it would have some answers. It was very informative but is a few steps ahead of me right now.

 

Can MS control spark based off the 76 distributor? Or am I limited to controlling fuel only until I upgrade to a different ignition system? Based off of what I read in Braaps thread “BRAAPs L6 EFI-induction advice and tips,†the tuning I need to do to take advantage of my cams and exhaust work is tuning the fuel maps with MS, and then I can mechanically tune the distributor to get the proper ignition timing.

 

One thing I’m worried about is, do I need to get a throttle position sensor? Or is MS able to read off the stock throttle position switch that I currently have? I believe the stock ECU is closed-loop until ¾ throttle and then is open loop above that, so I feel that I could run the stock throttle position switch and then when that switch tells MS to go from closed loop to open loop, have the open-loop tables based off of MAP instead of TPS? (I have never tuned before, so I’m not sure if that idea even makes sense. What would the closed-loop tables be based off?)

 

As for the MS system I am looking to get, I was thinking of getting this unit (http://www.diyautotune.com/catalog/megasquirtii-ems-system-smd-pcb357-black-case-p-171.html). I was thinking this unit because I would eventually like to be able to control spark as well, and have been considering the idea of a turbo build in the future, so I think this system would allow me to go in any direction without having to upgrade my ECU system in the future. I would also be ordering a wiring harness for it, an IAT sensor, wideband O2 sensor, and a MAP sensor.

 

What is the difference between an open and closed element IAT sensor? As for the wideband 02 sensor, it seems most people use the Innovate one, but I heard that they burn out relatively quickly, and was thinking of going with the AEM kit (http://www.summitracing.com/parts/AVM-30-5130/?rtype=10). Does anyone know if MS will play nice with this gauge?

 

I think this might cover most of my questions, although some of them are probably very basic. I appreciate any and all feedback you can give me.

[Cannonball89]

I can answer one of your questions, the difference between open and closed element IAT sensors is simply that the closed element sensor has the actual sensor enclosed in a copper jacket, while the open element sensor is exposed. The closed element sensor is really for use as a coolant temperature sensor as water will not damage it, while the open element sensor is better for intake air temperature because it is more sensitive and will have less "lag time" between when ambient air temperature rises or falls and when the sensor can read it. You can use the closed element sensor for both coolant and intake though for NA cars, because intake temperatures do not change very rapidly. Turbos really need the open element sensor though.

 

I can also say that MS II is a great choice. MSIII is based on MSII and you could upgrade your MSII to an MSIII later if you ever wanted sequential injection or any of the other spare outputs and inputs.

[sweetleaf]

You will need a different TPS, as the one you have is just a switch.

[Leon]

One thing I’m worried about is, do I need to get a throttle position sensor? Or is MS able to read off the stock throttle position switch that I currently have? I believe the stock ECU is closed-loop until ¾ throttle and then is open loop above that, so I feel that I could run the stock throttle position switch and then when that switch tells MS to go from closed loop to open loop, have the open-loop tables based off of MAP instead of TPS? (I have never tuned before, so I’m not sure if that idea even makes sense. What would the closed-loop tables be based off?)

 

I'll cover another question. I've never used MS but I'm pretty sure you can run a speed-density setup with enrichment coming based on dmap/dt, someone correct me if this can't be done.

 

This eliminates the need for a throttle position switch whether you're running open or closed loop. A TPS is really only required if you plan to run TPS-based acceleration enrichments and/or you plan to run the fuel map based on alpha-N instead of speed-density.

Edited March 23, 2011 by Leon

[StrokinIT]

Thanks guys for the answers, I think I should be able to run the fuel map based on speed-density using the MAP sensor. However the main problem I'm running into right now is how to control spark with MS. I can't go check right now since my car is at my dad's house, but I think the 76 distributor has a VR sensor in it, correct? If so, I can set it up so that MS reads the VR sensor and subsequently will be able to control the spark. I would like to eventually convert to EDIS but I don't feel that I could properly install that setup myself while the engine is still in the car, and have it running for this summer.

 

I have literally spent about 5 hours reading up on the spark aspect of MS yesterday and today, and am so confused. So if someone could clarify the best way to go about it with my current setup (stock 76 distributor), I would be eternally grateful.

 

Thanks in advance.

[mobythevan]

In order to have MS control the spark with a VR type dizzy you will need to weld/lock the dizzy if it has a mechanical advance mechanism. There are threads that talk about ways to do this. Once MS controls the spark it will take care of all the advance/retard.

[NewZed]

The 76 does have a VR sensor system. If it's a Federal model it will actually have two VR sensors (pickup coils) on the breaker plate. One for warmed up normal driving, one that advances the timing when the engine is cold.

[Two80z4me]

hey, don't mean to thread jack, but I have a few questions myself.

 

When removing the stock 280z wiring harness, do you need any of the capacitors and fuse boxes that are attached to the wiring harness that is down below the brake booster and clutch reservoir?

 

And, do you need any of the thermostat housing sensors? I also hear somewhere that the CLT sensor from DIYautotune fits in one of the holes but so far I haven't found that it does...

 

Thanks.

[Doc Hawk]

In order to have MS control the spark with a VR type dizzy you will need to weld/lock the dizzy if it has a mechanical advance mechanism. There are threads that talk about ways to do this. Once MS controls the spark it will take care of all the advance/retard.

 

Have a link to any of those threads? I have been searching at length (2 days) and I run into plenty of question threads, but few definitive answers. X64v seems to have wired up a non-optical distributor in 2006, but never provided a writeup. Others have asked questions about getting signals directly off the VR. Still no sign of someone saying, "I wired the electronic ignition module with star wheel hall effect/VR sensor for MS. Here are the wires I used, here are the pins I connected them to, and here's how I froze the stock advance."

 

Links appreciated! I have over a dozen bookmarks of people saying it can be done, but none showing how. I am hoping to control fuel and spark on my L28ET with MS Extra on a 3.57 board using a 280zx ignition with a NA electronic ignition module (star wheel, not optical turbo).

Edited May 14, 2011 by Doc Hawk

[akeboshi]

heres a link to a vid i made. i didnt actually weld the advances but i used jb weld instesd. you can just tack with a wire welder but i dont have one so thats what i did. my buddy said that if you grind on jb weld it will spark so it convinced me to go that route. it took me a long time searching with no answers and disassembling the dizzy to get my answers. you have to lock the centrifugal advances (the ones with the springs) and cap off the vacuum advance with a nipple where the hose used to go ( i just left the vacuum canister attached cuz i didnt want the disc that the vacuum can was attached to to start wandering on its own)

also, i would highly recommend getting a tps from a 240sx from autozone it will help alot. get the one for an auto 240 its cheaper (25$$ i dont know why, it just is) and you will need to wire it with the attached pigtail. red is 5v ref, white is ms signal and black is the ground. another thing that would help is a closer look at the sensor diagram the grounds for the sensors go to pin 19 (i didnt catch this till i asked on msefi.com.)

you could use the link for the pinout on the stock harness but i would recommend junking the old one for the diyautotune one if you can afford it. its not necessary but its nicer and just a heads up the wiring is not for ametuers and i thought the assembly of the controller itself was easier than making the new harness. just go slow and lay out the wiring in the car before you solder and loom it up. i acually ended up removing my dash and am in the middle of tucking the harness behind it and putting the controller in the glove box.

those are the biggest tips i can think of right now. good luck but heads up ms comes with a steep learning curve and if you have anymore questions just ask. i plan to go edis soon, ill take pics for ya.