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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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