Iscv valve on m112 sc

['00_taco]

i am currently fitting a m112 sc to a 1uz

i am new to supercharger setups and wondering how crutial the iscv
is on a supercharged motor. if so would it be better to try and retrofit
the 1uz iscv to the m112 or get a ford iscv.

photos of iscv valves would also help a lot.

thanks

 

[cribbj]

I drive a 2JZ without an ISCV and it can be a real pain without it when the A/C kicks on or the electric fans kick on. The RPM's vary quite a bit and in the summer it can cause the car to stall.

I'm not a fan of mounting the ISCV's on the manifold the way Lexus & Toyota do it, and like the way the GM's are built into the throttle bodies. Have a look at some LSx throttle bodies and you'll see what I mean.

If/when you're running a pretty high boost level, the Toyota/Lexus style ISCV has to seal really well to prevent a boost leak, but since the GM unit is "usually" on the intake side of the supercharger, it doesn't have to have a great seal.

 

['00_taco]

Thanks for the reply from what i can tell the ford iscv is on the intake side of the sc. but that would mean that i would have to use the cobra intake
and tps.

would the ford tps and iscv work well with an aem ems?

 

[cribbj]

Probably, if you have a good tuner!

Both the GM TPS and ISCV worked fine with my Supra AEM after some experimentation by Mitch Pederson.

 

[Zuffen]

I use a LS3 style throttle body with the ISCV built in.

Works very well and it was simple to adapt to my supercharger intake.

No chance of a leak as it is pre-boost.

In all honesty I wouldn't muck around with fabricating anything when you can get genuine or aftermarket LS style throttle bodies so cheaply.

 

[Cobber]

Agree, LS throttle body is a good way to go and that is waht I would use if I were doing mine again.

 

[Lextreme II]

Mitch is working on my AEM at we speak. No ISC for my LS400.

 

[cribbj]

Mitch is working on my AEM at we speak. No ISC for my LS400.

Hmmm, I don't know that you'll be happy with that, David.

In the AEM there's an ignition "trim" table that in theory can be used to help maintain idle speed if an ISCV isn't used, but I must admit I haven't tried tuning that table after I disabled my ISCV.

Hopefully the UZ isn't quite as twitchy as a 2JZ with a light flywheel. My RPM's would swing 500 or so with the A/C kicking on/off.

 

[Lextreme II]

Me too John, I never ran it without isc. So i am crossing my fingers that Mitch can help me. Right now the LS is ready for the Plug and Play AEM he is making for me. Mechanically it is ready..

 

[Cobber]

Surely the AEM can run an ISCV? I'm sure it would be able to run the Ford ISCV no problem with a PWM output The Ford throttle body has a built in ISCV too right?

I used the std lexus ISCV and mounted it to a plate behind the supercharger and hooked it up with a -10 hose. works great.

 

[cribbj]

Yep, the AEM runs an ISCV just fine, either stepper, PWM, or nearly whatever type you have. But there are so many idle settings, maps & tweaks that it can be challenging to setup. That's the one area of my 2JZ setup I've not been happy with so I just blocked off the ISCV port in the manifold. I suspect I've got a sticking motor in the ISCV itself, but was just too lazy to diagnose it at the time. I keep thinking that 1UZ will be going in "any day now" so I tend to neglect things on the 2JZ

 

['00_taco]

Agree, LS throttle body is a good way to go and that is waht I would use if I were doing mine again.

My M112 didn't come with a TPS or ISCV, but did come with the throttle body.

Found that the TPS is about $30 and the ISCV is $70 to $90, and wouldn't have to fab any conversion plates either.

About how much do the LS throttle bodies run??

 

[LP1]

I fabricated a manifold to go from the M112 to connect the SC throttle body and IAC. I used a stand alone filter on the IAC at first then ended up hooking the IAC to the intake tube. I use the stock ECU and the IAC works great except for a slight idle hunt of plus or minus 200 rpm on start for about 10 secs. If you step on the gas and back off it hunts for idle more aggressively. You can go to a fast idle by stepping on the gas or wait the 10 seconds which is a better option. I have a '95 so it doesn't have a cold start injector. I haven't got around to trouble shooting the idle as it doesn't bother me but it feels like the computer is overcontrolling the IAC to find the correct idle right now. You need an IAC.

 

[Lextreme II]

I fabricated a manifold to go from the M112 to connect the SC throttle body and IAC. I used a stand alone filter on the IAC at first then ended up hooking the IAC to the intake tube. I use the stock ECU and the IAC works great except for a slight idle hunt of plus or minus 200 rpm on start for about 10 secs. If you step on the gas and back off it hunts for idle more aggressively. You can go to a fast idle by stepping on the gas or wait the 10 seconds which is a better option. I have a '95 so it doesn't have a cold start injector. I haven't got around to trouble shooting the idle as it doesn't bother me but it feels like the computer is overcontrolling the IAC to find the correct idle right now. You need an IAC.

Nice work. Can u do me a favor and take some pictures of your M112 bypass valves and its vacuum signal?

 

[LP1]

I used the Ford bypass valve which is double chambered. I hooked up both originally, one to vacuum and one to boost, but the double chamber is there to limit boost which it did (about 4.6 psi). The picture shows the original double configuration. You only need to hook up one vacuum source to the top chamber (now puts out 8+ psi). I used the existing vacuum ports at the back of the M112 and added a few more vacuum ports to satisfy the stock requirements. Somewhere on line I noticed they put a restriction in the vacuum line for their bypass valve so I did the same thing (a .035 MIG tip). I think it has the benefit of keeping it in boost between shifts. Works great. I documented the build but haven't had a chance to put it on line yet.

 

[Lextreme II]

Upper chamber from a vac source. What about the lower chamber?

 

[LP1]

Lower chamber not required, it was used to limit boost on the Ford. The picture is from my original configuration, now lower chamber is not connected.

 

[Lextreme II]

Thank you very much