Tbitz and IACV

Steam Driver · Steam Driver's Garage

I am using the Tbitz kit as the starting point for a project of my own. It began as a conversion of the CIS on my SC but since I had access to the parts I now have what is essentially a 964 intake. I originally thought this would be relatively simple, but maybe not so much. So here are some questions for those more ECU-savvy than I.

How can I connect the IACV to the Megasquirt? I originally thought I could use wire 20, grey, but this brings up that the IACV has two wires, grey and red. So what about the red wire?

Next up, the flapper valve. Is there a pin on the Megasquirt that can be programmed to trigger this? This sort of fru-fru at this point but it would be good to be able to use it.

I’m beginning to think I may have exceeded the MS capabilities, but then again I have seen that others have used IACV’s, so how did they do it.

trond · trond's Garage

consider hand throttle ? very easy and intuitive to use as well. I did this while pondering the IACV but see no point now.... One less thing to struggle with

jpnovak · 01-22-2023, 04:10 PM

The challenge is that the components required to drive the ICV are likely not included on the Bitz PCB.

Yes, it should work provided circuits are complete. There are many options to drive different ICVs and they work just fine.

Showdown · Showdown's Garage

+1 on hand throttle.

Not all that difficult to fabricate provided you can fabricate stuff.

wreckah · wreckah's Garage

i've experimented a little bit with my microsquirt bitzkit 81 SC, tried a new nissan ICV but never could get it to work properly. The ecu was definately talking to the ICV, bu felt like i could not add enough air to make the engine idle high enough when very cold.
Also quite hard to troubleshoot as you only have one or 2 cold starts every day.

So i went with hand throttle as well, i bought a handbrake/handthrottle lever from an older 911, and been using it for 4 years or so now, it's second nature now.

TargaWoods · 01-25-2023, 05:35 AM

Quote:

Originally Posted by wreckah

So i went with hand throttle as well, i bought a handbrake/handthrottle lever from an older 911, and been using it for 4 years or so now, it's second nature now.

Do you know if the cold start lever on the 1978 Euro 911sc can be adapted to also function as a hand throttle, I want to remove my AAR but still need that higher idle speed. I also don’t want to just keep my foot on the gas pedal lol!

Steam Driver · Steam Driver's Garage

Wreckah, how was your Nissan IACV connected, what wire(s) and what port on the Megasquirt? I have a 964 IACV and it has two wires, a red and a grey. I was thinking about using the grey wire on the ECU, but that leaves the red; what to do with it?

In the ignorant, learning mode here . . .

AlKidd · AlKidd's Garage

Tonys kit is MS1. Unless you upgrade to MS2 and or a daughter board I dont believe you can make it work, even though the wires are in place.

wreckah · wreckah's Garage

Quote:

Originally Posted by TargaWoods

Do you know if the cold start lever on the 1978 Euro 911sc can be adapted to also function as a hand throttle, I want to remove my AAR but still need that higher idle speed. I also don’t want to just keep my foot on the gas pedal lol!

i am trying to remember, but apparently it's been 5 or 6 years ago lol
yes you need the lever, impossible with the pedal.

i remember buying an older 911 handbrake assembly, from earlier injection cars (information was somewhere on the bitz site) , they had the cold start lever on there from standard, on the left side of the handbrake. The right side is a 1 piece heating lever. The cold start lever pulls on the throttle cable with a simple plastic 3D-printed clip you can buy all over ebay. Or maybe even from pelican or porsche itself.

The heating control is now 1 piece instead of the 2 (left-right) piece 81 SC system. So my wife is always icecold and i'm sweating my ass off.

Working on the handbrake controls is a bit fiddly, but in the end not a big deal. I tried to make a hybrid version with coldstart lever and 2 piece heater lever, but didn't manage.

wreckah · wreckah's Garage

Quote:

Originally Posted by Steam Driver

Wreckah, how was your Nissan IACV connected, what wire(s) and what port on the Megasquirt? I have a 964 IACV and it has two wires, a red and a grey. I was thinking about using the grey wire on the ECU, but that leaves the red; what to do with it?

In the ignorant, learning mode here . . .

i'm sorry, it's been so long i cannot find any ebay purchases anymore, also, and i did not annotate my experiments sadly...i'm a bit chaotic like that. I was experimenting with COP at the time as well, and upgrading to EDIS etc...

plenty of idle valve info on the megasquirt manual pages, but yea, it's a bit of a learning curve...i gave up sorry.

Otter74 · 01-25-2023, 08:02 AM

I've got an MS2 on my car with an IACV from a Jeep Cherokee six in a little billet manifold. I can look up how it's wired, etc. later this week or this weekend if you like.

Steam Driver · Steam Driver's Garage

Yes Otter I would appreciate that. So it appears the solution is the MS2?

Otter74 · 01-25-2023, 02:14 PM

Yes, you do need MS2. I remembered that the PO - who did the installation on my car - wrote something about it, and I found the post here:

Megasquirt success - VE and Ignition Tables

This may be helpful to you. I won't be home (where all my info for the car is) until tomorrow and won't have time to see the car itself until this weekend, but I'm happy to help more if I can.

Steam Driver · Steam Driver's Garage

Thanks for all the info. It will be a huge help. I saved that link, it appears to be invaluable.

AlKidd · AlKidd's Garage

You may want to check with Tony. He was working on a newer version, due to supply issues when I spoke with him last year. Those familiar with MS can confirm if a MS2 daughter board will drive an IAC? I have the daughter board but havent installed it yet since it runs so nice.

Steam Driver · Steam Driver's Garage

I have decided to go the hand throttle route for the moment at least. (Mechanics are more my forte than electronics!) I have managed to run down all of the parts but a critical one. That would be:

901.424.329.00 “Screw Nipple” (this is item #90 on the parts drawing)

This a barrel-shaped item with a slot for the throttle cable and a threaded hole for the clamping screw. It clamps on the throttle cable and gives the lever something to work against.

This would be easily made. Can someone provide me with the diameter, length, and cable slot width on this? Or if you have one sell it to me?

Thanks.

Showdown · Showdown's Garage

I found one from some German site but it was $50 plus shipping!!

So, I 3D modeled and printed one out of PA12 with Shapeways and then tapped and threaded it with two set screws from McMaster. I printed one out of aluminum but then I lost it... that cost like $35 if you're les trusting of the PA12. Worked like a charm and cost a heckuva lot less:

Hand throttle collar stop for throttle rod (NLA):
https://www.thingiverse.com/thing:5447656

Set Screws:
https://www.mcmaster.com/catalog/92605A514

Tap:
https://www.mcmaster.com/catalog/8305A32

Steam Driver · Steam Driver's Garage

Thanks for the information. I’m not sure I understand the site;; is that a place to download the program for the printing?

Showdown · Showdown's Garage

Thingverse is an online repository where you can download the file and then use that file to 3-D print the part. So, download the file from thingverse and then upload it to a website like 3-D hub, or Shapeways, etc. and 3-D print it from there.

jpnovak · 02-02-2023, 06:45 AM

Might be easier to take a section of aluminum rod and cut a slot with a hacksaw. Drill and tap a hole and put a machine screw in it.

I admit I use my 3D printer all the time. But the aluminum would be stronger and hold up to the pinch pressure caused by the set screw on the throttle rod much better over time.