Basic Questions

[flumph]

So I'm coming up on installing MS3 in my Eta, with the intention to eventually swap in an 885 head and I have a couple of questions. I'm starting from a scratch wiring harness (don't worry, I bought the 8' one with labeled wires). I do not ever plan on forced induction, if it matters. Everything is nice and blinky on the stim, so I hope I put it together right.

• Given that I have the whole top half of a B25, will the intake manifold bolt onto the B27 head? I know this won't be any significant performance difference, but it would be way more convenient for a couple of reasons. One, it saves me from having to do any modifications that I might need to do twice. Two, it allows me to clean and prep everything *before* I start taking stuff apart. Might save me some headaches.
• "What modifications?" I hear you asking. Well, where do I put the IAT sensor? I have ordered one of the GM open element ones off of DIYautotune, and I'm reading a lot of different opinions on this. Should I drill and tap a hole in the intake manifold itself, somewhere in the main plenum? This is the thing that I don't want to have to do twice if I don't need to. Alternatively, I can try putting it in the PCV hole in the throttle body, and then just use a vented catch can? Or the intake boot elbow between the TB and the airbox?
• If I do choose to swap out the TB and intake manifold, would it be an issue if I used the 19# injectors standard in the B25 in a B27?
• Just how hot can I expect the TB to get? My TPS adapter plate is 3D printed, but it's PLA, which can get soft and warpy past around 80 degrees Celsius. It looks like the factory TPS case is made out of ABS of some sort. Should I try to reprint with ABS, or maybe try to fabricate a plate with flat stock aluminum/steel/wood/cereal boxes? I ordered an adapter plate from RHD, but shipping takes a while between Australia and Texas.
• Is my gauge cluster still going to work? I have no idea how the wiring for the instruments works. I know there's a trigger wheel in the diff for the speedometer, but does this sensor return to the ECU or to the cluster? Does the tach run off of the factory VR sensors in the bell housing? Can I fit a wheel speed sensor that returns to the MS3 box, and have a speedo on the Tunerstudio dash?
• Building a wiring harness for non-FI use: solder, crimp, or both? What crimp splices are good?

Besides all that, I've been reading about this stuff for weeks, and I feel like I'm ready to go through with it without blowing anything up. But still, do you guys have any advice? Traps to dodge, maybe something that nobody ever seems to think about?

Thanks in advance.

[E30-325iS]

I'm no expert, but I wouldn't mount the IAT on the manifold due to heat soak. I think somewhere between the air box and elbow would be better.
You can run the 19# injectors once you have the MS3 wired in.
You can buy a superb quality alloy TPS adapter from member Frankensteined.
Your cluster should work except for the econogauge. The tachometer is driven by a square wave (I think) signal from the MS3.
Interested to see how you go with this as I'll be changing the ecu in my car.

[Digitalwave]

Answering in the same order as your list...

• I am actually not sure if it would fit, but there is no modification needed to the intake manifold so you could just leave the eta one on there. I would probably advise just putting the 885 head and all Motronic 1.3 accessories on now, before you start tuning with your MS3.
• I put my IAT sensor in the intake tube I made to delete my AFM. Pic here. The options you listed seem overly complicated to me.
• Stock M20B25 injectors are 14.5 lb/hr high impedance injectors. They will work fine with MS3. I would suggest upgrading to a Gen 3/EV6 style injector that has 4 spray nozzles.
• I've seen people using 3D printed adapters. I wouldn't think the TB gets hot enough to cause any issues. The one I am using is machined aluminum.
• Everything in the gauge cluster should work as stock. Exceptions possibly being the Check Engine Light and I guess the econometer as E30325IS mentioned? I could have sworn mine was working, but I have a tablet gauge cluster mounted in front of my stock cluster now, so I haven't looked in a while.
• You'll get a lot of different answers to this question as it's kind of personal preference. I like both soldering and crimping depending on the situation. Marine grade shrinkable butt end connectors are very nice and secure. It might depend on how confident you are in your soldering skills. If crimping, a high quality ratcheting crimping tool can make your life much easier.

Lastly, MS3 does have an input for VSS signal. You would not be using a wheel speed sensor, you'd be using the speed sensor on the diff. I don't think that would be helpful to have in Tuner Studio, unless you are using advanced features or using a tablet dashboard (in which case you can use GPS for the speedo). The stock speedometer will work properly regardless.

[e30davie]

I play with PLA 3D print. PLA has a glass transition temp of 60degrees, it will get soft before this temp. you can use your PLA printed item as a template to cut out some aluminium.

[nando]

Answering in the same order as your list...

Lastly, MS3 does have an input for VSS signal. You would not be using a wheel speed sensor, you'd be using the speed sensor on the diff. I don't think that would be helpful to have in Tuner Studio, unless you are using advanced features or using a tablet dashboard (in which case you can use GPS for the speedo). The stock speedometer will work properly regardless.

you would actually want to use the processed sensor from the speedometer (there's like 3 outputs on the back), rather than the VSS sensor directly.

[flumph]

I've got all my parts and tools ready to go, and I read the installation manual one more time last night before I realized something. How do you check the timing on an M20? It looks to me like the timing marks aren't visible unless you take off the distributor and crank it with the starter. Is there a window of some sort that I'm missing? I've googled it and the only results I get are related to vacuum advance canisters and variable timing advance.

I know for a fact that my timing is lined up fine as it is, since the car's been running great for the last 4000 miles or so. Should I just not worry about it?

[Digitalwave]

While your timing on the head and block is probably set right, you still should verify timing with a timing light since it is electronically controlled. That is to ensure that whatever timing values you are entering on your ignition table are the actual values the motor is seeing. For instance, your car would probably still run fine if your timing were off by +4 degrees. However, if you enter 35* timing on your table, you'd actually be at 39*.

It's fairly easy to test and set. First, you lock your timing on your tune to 0* (or 10* if your car won't idle at 0). This is under Ignition Options / Wheel Decoder. Then set your timing light to the same. You can shoot it down from the driver's side of the car, kind of by the top radiator hose, in front of the alternator. It's not an easy angle, but you can do it. There is an external timing mark on the lower timing cover, and an O|T mark on the toothed wheel. You want those to line up. You can adjust the Tooth #1 Angle under the same menu (Ignition Options). That is how you make the marks line up. Keep experimenting until its pretty spot on. You can burn the change while the car is running. It should only take a few minutes to get it right.

Settings should be:

Spark mode: Toothed wheel
Skip pulses: 3
Ignition capture: Rising edge if your board is an MSII board, falling edge if it's Microsquirt (more info here)
Spark output: Going high

Trigger wheel arrangement: Single wheel with missing tooth
Trigger wheel teeth: 60
Missing teeth: 2
Tooth #1 angle: 84* (to start, this is the setting you are going to adjust to 0 out your timing)
Wheel speed: Crank wheel

[nando]

I usually put some whiteout or something on the O|T mark to make it easier to see as well.