DIY: IACV Blockoff Plate and Electrical Radiator Fan Wiring

Did this DIY when i was back in Jakarta a few weeks ago but only got around to write about it now since i just got my Samsung Galaxy S back. The photos below are in the phone. Also the air for my lungs apparently comes from it. Nearly suffocated without my Galaxy S.

The Dog had been running electrical radiator fan since the engine conversion finished but the fan was connected directly to the battery through an engine cutoff switch. Crude solution but it was only for temporary. It was only a few weeks ago that i finally installed proper relay and wiring system for the fan.

I wrote a guide on the wiring last year, you can read about it there. Since my thermoswitch is normally-close type, i am following diagram C from the guide.

As you can see on the diagram, a 5-pin relay is needed. The shops nearby only sell the funny looking kind with some special connector needed. Luckily the pin positioning matched my relay socket.

Using a wire cutter, 5 minutes later problem solved. No cursing involved.

Couldn't also find the special round-shaped thermoswitch connector, i had to cut off the plastics around the metal pin and solder a generic wire spade to the pin.

Forgot to take pics of the installation process, but here's a video of the system in action. You can see my Suzuki Wagon R fan turning off automagically after the temperature is lowered enough. The relays are on the passenger side strut tower.

Also notice how my idle speed is a bit too high. It was around 1500 RPM even on warm engine. The idle speed reduced significantly when i shut the IACV vent hole using my finger, a sign of faulty IACV indeed. Since i am too cheap to buy another one, i decided to just ditch the IACV and replace it with a custom block off plate. Read about IACV here.

IACV is located under the throttle body or TB. It's fixed with 5 bolts. You need to pull off the water lines and some vacuum hoses and remove the throttle body before you can comfortably unscrew the 5 bolts. Here's the IACV paired with TB.

Air route follows red arrows, goes into TB inlet hole, then green arrows into the IACV body and air passage, finally goes into the engine following blue arrows. Normal IACV blocks green dashed arrow route when the engine warms up but mine obviously didn't so i had to come up with this.

Right is the custom IACV block off plate and left is the gasket i made from carton paper. Notice how the bolt hole positions match the ones on the TB. Add some silicone sealer, shorter bolts (old bolts can't be used as my block off plate is too thin) and i end up with this.

Sure as hell didn't cost me US$19.99 to make.

No more air coming into the IACV vent and I'm now idling at 1100 RPM when warm. 1100 RPM is still a tad too high as the manual said it should be around 850 RPM but it's much better. My idle screw has been set to max so no air coming from there. I'm currently suspecting the PCV air passage inside the intake manifold is leaking air from the cut-n-shut work. It could also be a split vacuum line. Will have to check it this weekend.

Here's the block off plate in action.

By the way, ditching your IACV for this block off plate will disable your PS and AC idle up. Don't forget you'll also need to loop the cooling line or block both lines off.