Megasquirt: do I need stock iscv?

Mr nanotech · Postby **Mr nanotech** » Sat May 25, 2013 4:12 am

So I have a question. Do I need to run the standard ISCV with megasquirt and a GM IAT sensor? I have read it's possible and a lot of people have done it but others say it makes adjusting the idle very difficult and it's not a great I idea to delete in colder climates.
The reason I am leaning to ditching it is because my intercooler pipes will have to be modified to put a fitting for the idle speed control tube to connect to. I spotted a place online that does an adapter for silicone hoses. http://www.ebay.com/itm/Mx5-turbo-inter ... 3cc5e3a2dd

It seems a little pricey for what it is though. How did you do yours?

Quick question while I'm here. Do supercharged setups benefit from lowered engine compression the same way turbo motors do? I can't really find any technical info online about that sadly.

Mr nanotech · Postby **Mr nanotech** » Sun May 26, 2013 8:13 pm

Nobody?

Dweezle · Postby **Dweezle** » Sun May 26, 2013 8:14 pm

I had my intercooler pipe have a port on it so i could use the OEM hose and keep the ISCV.

Postby **NitroDann** » Sun May 26, 2013 10:03 pm

Hey josh, between this thread and the other I get tge feeling that whether through lack of communication or lack of info you didnt end up with exactly what you thought you wanted.

Ive been trying to call you to sort it out, give me a call Im happy to do what it takes to get the result you want.

Dann

Mr nanotech · Postby **Mr nanotech** » Sun May 26, 2013 10:56 pm

Don't say that, you did a great job. I'm happy with it, I've just changed my mind a little here and there and looking to make some changes. I got exactly what I asked for and no complaints. I SHOULD have asked you to put a bung on for a GM IAM sensor and a ISCV bit on too, but that's my fault since it skipped my mind at the time.

spaztikcamel · Postby **spaztikcamel** » Mon May 27, 2013 2:30 am

you do not need to use the isc valve.
idle tuning is extremely easy with megasquirt and deleting the iscv. you adjust your idle speed via the idle screw once its set it wont vary from there unless the engine comes across more load.
so say you screw it to sit at 750rpm it will stay pretty much right there (provided spark and fuel is tuned properly) until say you turn on the aircon where it will drop 100rpm(random figure).
the tuning gets easier because there is one less thing that has to be tuned.

also in regards to the compression question. yes superchargers do the same thing to the air so they get the same benefits of lower compression as a turbo would..

stb · Postby **stb** » Thu May 30, 2013 2:28 pm

spaztikcamel wrote:you do not need to use the isc valve.
idle tuning is extremely easy with megasquirt and deleting the iscv. you adjust your idle speed via the idle screw once its set it wont vary from there unless the engine comes across more load.
so say you screw it to sit at 750rpm it will stay pretty much right there (provided spark and fuel is tuned properly) until say you turn on the aircon where it will drop 100rpm(random figure).
the tuning gets easier because there is one less thing that has to be tuned.

also in regards to the compression question. yes superchargers do the same thing to the air so they get the same benefits of lower compression as a turbo would..

You're right in that you don't 'need' the ISC valve, and tuning is easier without it. Until, that is, you have cold starts/warmup, A/C load (which on my car dropped idle speed by ~300rpm), variations in electrical load etc. Basically it gets it back to factory quality, especially if you use gslender's alternate firmware.

I certainly agree with doing initial tuning without ISC valve enabled...

jerrah · Postby **jerrah** » Thu May 30, 2013 3:31 pm

Nb8 throttle body doesn't require separate idle tube as it sources the air pre butterfly. If you're using a 1600 engine grab the intake manifold off a nb6. I have a nb6 manifold in my garage & possibly a nb8 throttle body if you're lucky. I upgraded to an 1800.