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1971 240z ITB install


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  • 1 month later...

ITB with IAC take 3. My last bmw IAC wouldn’t play nice with my haltech (basically it’s the opposite of how haltech controls it). This one let’s by a tiny bit of air at full closed. I plan to see if I can set the butterfly’s and it to play nicely and not idle too high when the engine is warmed up. Fingers crossed.



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What idle rpm do you shoot for ? I let mine idle pretty high - 1000rpm. I figure it keeps oil on the lobe and easier to find a happy spot for the engine to idle . 
I use stepper IAC myself , and it’s been a challenge . Getting the idle to come back to the same spot every time with a big cam was also part of the challenge . 
I also think my 3/8 I’d hose is too small for this engine . I need to put a 1/2” since that what a lot of OEMS use . 


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I promised my wife rock solid starts/ modern starts when I went down this ITB rabbit hole.  Once my car is warm, I don't need it.  I do not like a car idling at 1000 rpms when warm though.  I like around 850-900 rpms.  I will use timing and IAC for idle control.  


The Haltech Elite 750 can't do a stepper motor.  

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  • 3 weeks later...


Well I am a liar. My wiring was wrong. Iac wasn’t even working. But it lets by 20% air or so with 0 volts. So this is cold start with 20% air going by. On my haltech  You can set voltage at a percentage of 0-12v. So roughly set the lowest voltage it can go to 33%. Should work, but to be determined.  I need to run a new DPO wire

Pics volts vs flow.jpg

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  • 1 month later...

I finally got my car remote tuned. I had a few settings I didn’t understand, totally wrong, then my biggest issue is my iac. The haltech ecu doesn’t like my balance bar setup. I won’t give up. But I ended up plugging it for my road tuning. 

First impressions is wow. The car feels so fast. Even peels out a little, which seems crazy for a bone stock 2.4L. Wot passes sound magical. I ended up using Animal Tuning, who works for haltech and tunes on the side. 

I have dual o2 sensors, 1-3 and 4-6. 1-3 needed about 5% more fuel to obtain the same afr. Which was a pretty cool feature. 

Next is more wot passes and making sure AFR is on to protect the motor. 


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Now that my ITB is running nicely. Should I try my SK / OER inner fits. 

Poor google translates to power torque of the concave fast limits improves. 

Power torque in the medium and low speed range is impoved. 

Sort of like a jet nozzle. They come in 30, 34 and 38mm.

I have 8x 38mm and 4x 34mm




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  • 3 months later...
Something in from Australia! A progressive cam for the overhead bar and my ITB. It would also work with triples.
Basically it increases pedal modulation, so this gives you more pedal movement with less throttle blade movement. Should help with street driving and my throttles trying to take huge gulps of air with a tiny amount of pedal travel.
Weber kc332
Now machined out to 10mm.  Just barely enough room.  I had to have the allen bolt turned down.  

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I don’t even know what coil bracket version this would be? Number 10? Platinum racing helped me originally when i came up with the design to use the r35 coils on an L series. They helped with which coil to use, wiring harness, springs and stalks, so now we have teamed up to design this bracket. 

I never liked the giant bend in my coil stalks. I’m not loving the offset brackets, but it’s to keep the design size down and it would use the same aluminum blanks as the rest of their coil brackets. 

Also thank you Joseph Monti for the help along the way. 

I think I can live with this overall design.



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  • 2 weeks later...

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