3 replies to this topic

[CRXer87hf]

I realize that there are a lot of thread on devacing carbed engines, but not a lot for the PGMI engines, so... here you go:

 

SI DEVAC (Ditch that hideous black box): 

 

Step 1: Remove the black box, vacuum hoses and all.  Then disassemble it.  There will be a small sensor that you will have to salvage from the box in order for the devac to work.  It is riveted to a metal bracket inside the box.  Grind the back of the rivets off and remove it, and it's harness.  

 

 

 

Step 2: Once you've salvaged the sensor from the black box, you'll need to loop two connections on the main harness connector that was connected to the box.  If you hold the connector with the snap feature up, you'll need to bridge the top two left connector slots.  The best way to do this is with a short section of wire with two male flat connectors crimped to either end (see below).  Once you've completed steps 1 & 2, get some zip-ties and secure the black box harness and sensor to nearby wiring to make sure they are not damaged.

 

 

Step 3: Start pulling vacuum lines!  Almost all vacuum lines can come off the intake.  See below images for details one what to remove, and what not to remove.

 

 

 

NOTE: In above image, leave the vacuum lines that go to your distributor!! (The two lines shown to the left of the capped vacuum ports)

 

 

Step 4: (Note, this is optional) Remove the dashpots from the throttle body.  Once you've removed the vacuum lines, they are pointless.  You can leave them, but the throttle body looks better, and simpler without them.  If you plan on putting them back on in the future, pay close attention during removal.  There are a lot of small parts that go on in a certain order.  Take pictures.

 

 

Step 5: (Also Optional)  Relocate this thingamabobber (See below).  Not sure what it does to be honest, but instead of leaving it mounted towards the top of the drivers side shock-tower, slip it under the hose bracket that holds your clutch cable.

 

 

RESULTS: In my mind, it makes the engine bay look a lot cleaner.  Keep in mind though that your ECU will not have the ability to adjust your idle speeds based on engine temp, or air temp.  This will cause you to tweak your idle a little.  Do this with the idle screw on the top of the IACV.  If you live in colder climates, you will likely have to adjust the idle between summer and winter when the temp changes are drastic.  The other benefit to all this is fewer chances of vacuum leaks!  This is huge when the idle is very sensitive to vacuum leaks.  

 

 

 

Thanks for reading, and I hope it is helpful.

[mEATy]

One thing I did differently on my devac was to use a vacuum line 'T' fitting (taken from elsewhere inside the black box) to tie both distributor vacuum lines together and connect both to the same port on the intake manifold.

 

The way you have it on your car the yellow (top) vacuum advance line is fully capped off on the drivers side of the manifold.  

 

According to the FSM that yellow-taped distributor line should see vacuum above 1,700 RPM (advancing your ignition). So you may sacrifice some power off idle with those lines joined (?) but there's not much down there anyway...  

 

My car ran much better in the mid/upper RPMs with those lines tied together.

 

Also you can then remove all the other vacuum caps from the hard lines under the manifold (they are not doing anything other than capping off opposite ends of unused hardlines) and unbolt that entire hardline sub-assembly from the underside of the intake manifold to further clean up the appearance of the IM. The only vacuum ports that need caps are the two by the FPR, and your unused booster port.

 

Also... QUESTION, I didn't bridge any of the pins on the larger black box plug on my devac (87 civic Si), but everything seems to be running exactly as before... ? What does that enable/prevent?  

[CRXer87hf]

One thing I did differently on my devac was to use a vacuum line 'T' fitting (taken from elsewhere inside the black box) to tie both distributor vacuum lines together and connect both to the same port on the intake manifold.

 

The way you have it on your car the yellow (top) vacuum advance line is fully capped off on the drivers side of the manifold.  

 

According to the FSM that yellow-taped distributor line should see vacuum above 1,700 RPM (advancing your ignition). So you may sacrifice some power off idle with those lines joined (?) but there's not much down there anyway...  

 

My car ran much better in the mid/upper RPMs with those lines tied together.

 

Also you can then remove all the other vacuum caps from the hard lines under the manifold (they are not doing anything other than capping off opposite ends of unused hardlines) and unbolt that entire hardline sub-assembly from the underside of the intake manifold to further clean up the appearance of the IM. The only vacuum ports that need caps are the two by the FPR, and your unused booster port.

 

Also... QUESTION, I didn't bridge any of the pins on the larger black box plug on my devac (87 civic Si), but everything seems to be running exactly as before... ? What does that enable/prevent?  

 

Great info, thanks!  I'm interested in your distributor hose mod, so I'll look into that.  

 

Yeah, that tip about bridging those connectors was something I read in multiple threads in different places, so I just did it.  Honestly, I haven't tried it without, so I'm not sure it's actually doing anything.  It may be fine to run without it.

[OG-TJ]

The thingamabobber is the fuel injector resistor.